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Multi file concurrency in MultiGet using coroutines and async IO (#9968) 

Summary:
This PR implements a coroutine version of batched MultiGet in order to concurrently read from multiple SST files in a level using async IO, thus reducing the latency of the MultiGet. The API from the user perspective is still synchronous and single threaded, with the RocksDB part of the processing happening in the context of the caller's thread. In Version::MultiGet, the decision is made whether to call synchronous or coroutine code.

A good way to review this PR is to review the first 4 commits in order - de773b3, 70c2f70, 10b50e1, and 377a597 - before reviewing the rest.

TODO:
1. Figure out how to build it in CircleCI (requires some dependencies to be installed)
2. Do some stress testing with coroutines enabled

No regression in synchronous MultiGet between this branch and main -
```
./db_bench -use_existing_db=true --db=/data/mysql/rocksdb/prefix_scan -benchmarks="readseq,multireadrandom" -key_size=32 -value_size=512 -num=5000000 -batch_size=64 -multiread_batched=true -use_direct_reads=false -duration=60 -ops_between_duration_checks=1 -readonly=true -adaptive_readahead=true -threads=16 -cache_size=10485760000 -async_io=false -multiread_stride=40000 -statistics
```
Branch - ```multireadrandom :       4.025 micros/op 3975111 ops/sec 60.001 seconds 238509056 operations; 2062.3 MB/s (14767808 of 14767808 found)```

Main - ```multireadrandom :       3.987 micros/op 4013216 ops/sec 60.001 seconds 240795392 operations; 2082.1 MB/s (15231040 of 15231040 found)```

More benchmarks in various scenarios are given below. The measurements were taken with ```async_io=false``` (no coroutines) and ```async_io=true``` (use coroutines). For an IO bound workload (with every key requiring an IO), the coroutines version shows a clear benefit, being ~2.6X faster. For CPU bound workloads, the coroutines version has ~6-15% higher CPU utilization, depending on how many keys overlap an SST file.

1. Single thread IO bound workload on remote storage with sparse MultiGet batch keys (~1 key overlap/file) -
No coroutines - ```multireadrandom :     831.774 micros/op 1202 ops/sec 60.001 seconds 72136 operations;    0.6 MB/s (72136 of 72136 found)```
Using coroutines - ```multireadrandom :     318.742 micros/op 3137 ops/sec 60.003 seconds 188248 operations;    1.6 MB/s (188248 of 188248 found)```

2. Single thread CPU bound workload (all data cached) with ~1 key overlap/file -
No coroutines - ```multireadrandom :       4.127 micros/op 242322 ops/sec 60.000 seconds 14539384 operations;  125.7 MB/s (14539384 of 14539384 found)```
Using coroutines - ```multireadrandom :       4.741 micros/op 210935 ops/sec 60.000 seconds 12656176 operations;  109.4 MB/s (12656176 of 12656176 found)```

3. Single thread CPU bound workload with ~2 key overlap/file -
No coroutines - ```multireadrandom :       3.717 micros/op 269000 ops/sec 60.000 seconds 16140024 operations;  139.6 MB/s (16140024 of 16140024 found)```
Using coroutines - ```multireadrandom :       4.146 micros/op 241204 ops/sec 60.000 seconds 14472296 operations;  125.1 MB/s (14472296 of 14472296 found)```

4. CPU bound multi-threaded (16 threads) with ~4 key overlap/file -
No coroutines - ```multireadrandom :       4.534 micros/op 3528792 ops/sec 60.000 seconds 211728728 operations; 1830.7 MB/s (12737024 of 12737024 found) ```
Using coroutines - ```multireadrandom :       4.872 micros/op 3283812 ops/sec 60.000 seconds 197030096 operations; 1703.6 MB/s (12548032 of 12548032 found) ```

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9968

Reviewed By: akankshamahajan15

Differential Revision: D36348563

Pulled By: anand1976

fbshipit-source-id: c0ce85a505fd26ebfbb09786cbd7f25202038696
This commit is contained in:
anand76 2022-05-19 15:36:27 -07:00 committed by Facebook GitHub Bot
parent 5be1579ead
commit 57997ddaaf
31 changed files with 2182 additions and 1123 deletions
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1
CMakeLists.txt
View File

@ -796,6 +796,7 @@ set(SOURCES
trace_replay/trace_record_result.cc
trace_replay/trace_record.cc
trace_replay/trace_replay.cc
util/async_file_reader.cc
util/cleanable.cc
util/coding.cc
util/compaction_job_stats_impl.cc

1
HISTORY.md
View File

@ -13,6 +13,7 @@
* Add new stats PREFETCHED_BYTES_DISCARDED which records number of prefetched bytes discarded by RocksDB FilePrefetchBuffer on destruction and POLL_WAIT_MICROS records wait time for FS::Poll API completion.
* RemoteCompaction supports table_properties_collector_factories override on compaction worker.
* Start tracking SST unique id in MANIFEST, which will be used to verify with SST properties during DB open to make sure the SST file is not overwritten or misplaced. A db option `verify_sst_unique_id_in_manifest` is introduced to enable/disable the verification, if enabled all SST files will be opened during DB-open to verify the unique id (default is false), so it's recommended to use it with `max_open_files = -1` to pre-open the files.
* Added the ability to concurrently read data blocks from multiple files in a level in batched MultiGet. This can be enabled by setting the async_io option in ReadOptions. Using this feature requires a FileSystem that supports ReadAsync (PosixFileSystem is not supported yet for this), and for RocksDB to be compiled with folly and c++20.
### Public API changes
* Add rollback_deletion_type_callback to TransactionDBOptions so that write-prepared transactions know whether to issue a Delete or SingleDelete to cancel a previous key written during prior prepare phase. The PR aims to prevent mixing SingleDeletes and Deletes for the same key that can lead to undefined behaviors for write-prepared transactions.

8
Makefile
View File

@ -136,6 +136,13 @@ CXXFLAGS += $(PLATFORM_SHARED_CFLAGS) -DROCKSDB_DLL
CFLAGS += $(PLATFORM_SHARED_CFLAGS) -DROCKSDB_DLL
endif
ifeq ($(USE_COROUTINES), 1)
USE_FOLLY = 1
OPT += -DUSE_COROUTINES
ROCKSDB_CXX_STANDARD = c++2a
USE_RTTI = 1
endif
# if we're compiling for release, compile without debug code (-DNDEBUG)
ifeq ($(DEBUG_LEVEL),0)
OPT += -DNDEBUG
@ -226,6 +233,7 @@ dummy := $(shell (export ROCKSDB_ROOT="$(CURDIR)"; \
export ROCKSDB_NO_FBCODE="$(ROCKSDB_NO_FBCODE)"; \
export USE_CLANG="$(USE_CLANG)"; \
export LIB_MODE="$(LIB_MODE)"; \
export ROCKSDB_CXX_STANDARD="$(ROCKSDB_CXX_STANDARD)"; \
"$(CURDIR)/build_tools/build_detect_platform" "$(CURDIR)/make_config.mk"))
# this file is generated by the previous line to set build flags and sources
include make_config.mk

18
TARGETS
View File

@ -224,6 +224,7 @@ cpp_library_wrapper(name="rocksdb_lib", srcs=[
"trace_replay/trace_record_handler.cc",
"trace_replay/trace_record_result.cc",
"trace_replay/trace_replay.cc",
"util/async_file_reader.cc",
"util/build_version.cc",
"util/cleanable.cc",
"util/coding.cc",
@ -327,7 +328,13 @@ cpp_library_wrapper(name="rocksdb_lib", srcs=[
"utilities/wal_filter.cc",
"utilities/write_batch_with_index/write_batch_with_index.cc",
"utilities/write_batch_with_index/write_batch_with_index_internal.cc",
], deps=["//folly/container:f14_hash"], headers=None, link_whole=False, extra_test_libs=False)
], deps=[
"//folly/container:f14_hash",
"//folly/experimental/coro:blocking_wait",
"//folly/experimental/coro:collect",
"//folly/experimental/coro:coroutine",
"//folly/experimental/coro:task",
], headers=None, link_whole=False, extra_test_libs=False)
cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
"cache/cache.cc",
@ -545,6 +552,7 @@ cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
"trace_replay/trace_record_handler.cc",
"trace_replay/trace_record_result.cc",
"trace_replay/trace_replay.cc",
"util/async_file_reader.cc",
"util/build_version.cc",
"util/cleanable.cc",
"util/coding.cc",
@ -648,7 +656,13 @@ cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
"utilities/wal_filter.cc",
"utilities/write_batch_with_index/write_batch_with_index.cc",
"utilities/write_batch_with_index/write_batch_with_index_internal.cc",
], deps=["//folly/container:f14_hash"], headers=None, link_whole=True, extra_test_libs=False)
], deps=[
"//folly/container:f14_hash",
"//folly/experimental/coro:blocking_wait",
"//folly/experimental/coro:collect",
"//folly/experimental/coro:coroutine",
"//folly/experimental/coro:task",
], headers=None, link_whole=True, extra_test_libs=False)
cpp_library_wrapper(name="rocksdb_test_lib", srcs=[
"db/db_test_util.cc",

14
buckifier/buckify_rocksdb.py
View File

@ -145,7 +145,12 @@ def generate_targets(repo_path, deps_map):
# always add range_tree, it's only excluded on ppc64, which we don't use internally
src_mk["RANGE_TREE_SOURCES"] +
src_mk["TOOL_LIB_SOURCES"],
deps=["//folly/container:f14_hash"])
deps=[
"//folly/container:f14_hash",
"//folly/experimental/coro:blocking_wait",
"//folly/experimental/coro:collect",
"//folly/experimental/coro:coroutine",
"//folly/experimental/coro:task"])
# rocksdb_whole_archive_lib
TARGETS.add_library(
"rocksdb_whole_archive_lib",
@ -153,7 +158,12 @@ def generate_targets(repo_path, deps_map):
# always add range_tree, it's only excluded on ppc64, which we don't use internally
src_mk["RANGE_TREE_SOURCES"] +
src_mk["TOOL_LIB_SOURCES"],
deps=["//folly/container:f14_hash"],
deps=[
"//folly/container:f14_hash",
"//folly/experimental/coro:blocking_wait",
"//folly/experimental/coro:collect",
"//folly/experimental/coro:coroutine",
"//folly/experimental/coro:task"],
headers=None,
extra_external_deps="",
link_whole=True)

4
build_tools/dependencies_platform009.sh
View File

@ -20,3 +20,7 @@ VALGRIND_BASE=/mnt/gvfs/third-party2/valgrind/6ae525939ad02e5e676855082fbbc7828d
LUA_BASE=/mnt/gvfs/third-party2/lua/162efd9561a3d21f6869f4814011e9cf1b3ff4dc/5.3.4/platform009/a6271c4
BENCHMARK_BASE=/mnt/gvfs/third-party2/benchmark/30bf49ad6414325e17f3425b0edcb64239427ae3/1.6.1/platform009/7f3b187
BOOST_BASE=/mnt/gvfs/third-party2/boost/201b7d74941e54b436dfa364a063aa6d2cd7de4c/1.69.0/platform009/8a7ffdf
GLOG_BASE=/mnt/gvfs/third-party2/glog/32d751bd5673375b438158717ab6a57c1cc57e3d/0.3.2_fb/platform009/10a364d/
FMT_BASE=/mnt/gvfs/third-party2/fmt/ce0c25f67165f4d2c22a29b8ef50f5600d7873ca/6.1.1/platform009/7f3b187/
DBL_CONV_BASE=/mnt/gvfs/third-party2/double_conversion/109b3d9696d71f1048678cd7da1e22505470543d/20141126/platform009/7f3b187/
LIBEVENT_BASE=/mnt/gvfs/third-party2/libevent/4a4d3a79a76c2439b6bd471bf3586b3481dde75e/1.4.14b_hphp/platform009/7f3b187/

16
build_tools/fbcode_config_platform009.sh
View File

@ -14,7 +14,7 @@ source "$BASEDIR/dependencies_platform009.sh"
CFLAGS=""
# libgcc
LIBGCC_INCLUDE="$LIBGCC_BASE/include/c++/9.3.0"
LIBGCC_INCLUDE="$LIBGCC_BASE/include/c++/9.3.0 -I $LIBGCC_BASE/include/c++/9.3.0/backward"
LIBGCC_LIBS=" -L $LIBGCC_BASE/lib"
# glibc
@ -70,6 +70,18 @@ BENCHMARK_LIBS=" $BENCHMARK_BASE/lib/libbenchmark${MAYBE_PIC}.a"
BOOST_INCLUDE=" -I $BOOST_BASE/include/"
GLOG_INCLUDE=" -I $GLOG_BASE/include/"
GLOG_LIBS=" $GLOG_BASE/lib/libglog${MAYBE_PIC}.a"
FMT_INCLUDE=" -I $FMT_BASE/include/"
FMT_LIBS=" $FMT_BASE/lib/libfmt${MAYBE_PIC}.a"
DBL_CONV_INCLUDE=" -I $DBL_CONV_BASE/include/"
DBL_CONV_LIBS=" $DBL_CONV_BASE/lib/libdouble-conversion${MAYBE_PIC}.a"
LIBEVENT_INCLUDE=" -I $LIBEVENT_BASE/include/"
LIBEVENT_LIBS=" $LIBEVENT_BASE/lib/libevent${MAYBE_PIC}.a"
# location of jemalloc
JEMALLOC_INCLUDE=" -I $JEMALLOC_BASE/include/"
JEMALLOC_LIB=" $JEMALLOC_BASE/lib/libjemalloc${MAYBE_PIC}.a"
@ -101,7 +113,7 @@ BINUTILS="$BINUTILS_BASE/bin"
AR="$BINUTILS/ar"
AS="$BINUTILS/as"
DEPS_INCLUDE="$SNAPPY_INCLUDE $ZLIB_INCLUDE $BZIP_INCLUDE $LZ4_INCLUDE $ZSTD_INCLUDE $GFLAGS_INCLUDE $NUMA_INCLUDE $TBB_INCLUDE $LIBURING_INCLUDE $BENCHMARK_INCLUDE $BOOST_INCLUDE"
DEPS_INCLUDE="$SNAPPY_INCLUDE $ZLIB_INCLUDE $BZIP_INCLUDE $LZ4_INCLUDE $ZSTD_INCLUDE $GFLAGS_INCLUDE $NUMA_INCLUDE $TBB_INCLUDE $LIBURING_INCLUDE $BENCHMARK_INCLUDE $BOOST_INCLUDE $GLOG_INCLUDE $FMT_INCLUDE $DBL_CONV_INCLUDE $LIBEVENT_INCLUDE"
STDLIBS="-L $GCC_BASE/lib64"

432
db/db_basic_test.cc
View File

@ -12,6 +12,7 @@
#include "db/db_test_util.h"
#include "options/options_helper.h"
#include "port/stack_trace.h"
#include "rocksdb/filter_policy.h"
#include "rocksdb/flush_block_policy.h"
#include "rocksdb/merge_operator.h"
#include "rocksdb/perf_context.h"
@ -1180,10 +1181,17 @@ TEST_F(DBBasicTest, DBCloseFlushError) {
Destroy(options);
}
class DBMultiGetTestWithParam : public DBBasicTest,
public testing::WithParamInterface<bool> {};
class DBMultiGetTestWithParam
: public DBBasicTest,
public testing::WithParamInterface<std::tuple<bool, bool>> {};
TEST_P(DBMultiGetTestWithParam, MultiGetMultiCF) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
Options options = CurrentOptions();
CreateAndReopenWithCF({"pikachu", "ilya", "muromec", "dobrynia", "nikitich",
"alyosha", "popovich"},
@ -1240,7 +1248,8 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCF) {
keys.push_back(std::get<1>(cf_kv_vec[i]));
}
values = MultiGet(cfs, keys, nullptr, GetParam());
values = MultiGet(cfs, keys, nullptr, std::get<0>(GetParam()),
std::get<1>(GetParam()));
ASSERT_EQ(values.size(), num_keys);
for (unsigned int j = 0; j < values.size(); ++j) {
ASSERT_EQ(values[j], std::get<2>(cf_kv_vec[j]) + "_2");
@ -1254,7 +1263,8 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCF) {
keys.push_back(std::get<1>(cf_kv_vec[3]));
cfs.push_back(std::get<0>(cf_kv_vec[4]));
keys.push_back(std::get<1>(cf_kv_vec[4]));
values = MultiGet(cfs, keys, nullptr, GetParam());
values = MultiGet(cfs, keys, nullptr, std::get<0>(GetParam()),
std::get<1>(GetParam()));
ASSERT_EQ(values[0], std::get<2>(cf_kv_vec[0]) + "_2");
ASSERT_EQ(values[1], std::get<2>(cf_kv_vec[3]) + "_2");
ASSERT_EQ(values[2], std::get<2>(cf_kv_vec[4]) + "_2");
@ -1267,7 +1277,8 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCF) {
keys.push_back(std::get<1>(cf_kv_vec[6]));
cfs.push_back(std::get<0>(cf_kv_vec[1]));
keys.push_back(std::get<1>(cf_kv_vec[1]));
values = MultiGet(cfs, keys, nullptr, GetParam());
values = MultiGet(cfs, keys, nullptr, std::get<0>(GetParam()),
std::get<1>(GetParam()));
ASSERT_EQ(values[0], std::get<2>(cf_kv_vec[7]) + "_2");
ASSERT_EQ(values[1], std::get<2>(cf_kv_vec[6]) + "_2");
ASSERT_EQ(values[2], std::get<2>(cf_kv_vec[1]) + "_2");
@ -1283,6 +1294,12 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCF) {
}
TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFMutex) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
Options options = CurrentOptions();
CreateAndReopenWithCF({"pikachu", "ilya", "muromec", "dobrynia", "nikitich",
"alyosha", "popovich"},
@ -1328,7 +1345,8 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFMutex) {
keys.push_back("cf" + std::to_string(i) + "_key");
}
values = MultiGet(cfs, keys, nullptr, GetParam());
values = MultiGet(cfs, keys, nullptr, std::get<0>(GetParam()),
std::get<1>(GetParam()));
ASSERT_TRUE(last_try);
ASSERT_EQ(values.size(), 8);
for (unsigned int j = 0; j < values.size(); ++j) {
@ -1345,6 +1363,12 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFMutex) {
}
TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFSnapshot) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
Options options = CurrentOptions();
CreateAndReopenWithCF({"pikachu", "ilya", "muromec", "dobrynia", "nikitich",
"alyosha", "popovich"},
@ -1389,7 +1413,8 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFSnapshot) {
}
const Snapshot* snapshot = db_->GetSnapshot();
values = MultiGet(cfs, keys, snapshot, GetParam());
values = MultiGet(cfs, keys, snapshot, std::get<0>(GetParam()),
std::get<1>(GetParam()));
db_->ReleaseSnapshot(snapshot);
ASSERT_EQ(values.size(), 8);
for (unsigned int j = 0; j < values.size(); ++j) {
@ -1405,6 +1430,12 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFSnapshot) {
}
TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFUnsorted) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
Options options = CurrentOptions();
CreateAndReopenWithCF({"one", "two"}, options);
@ -1417,8 +1448,9 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFUnsorted) {
std::vector<std::string> keys{"foo", "baz", "abc"};
std::vector<std::string> values;
values =
MultiGet(cfs, keys, /* snapshot */ nullptr, /* batched */ GetParam());
values = MultiGet(cfs, keys, /* snapshot */ nullptr,
/* batched */ std::get<0>(GetParam()),
/* async */ std::get<1>(GetParam()));
ASSERT_EQ(values.size(), 3);
ASSERT_EQ(values[0], "bar");
@ -1426,10 +1458,18 @@ TEST_P(DBMultiGetTestWithParam, MultiGetMultiCFUnsorted) {
ASSERT_EQ(values[2], "def");
}
INSTANTIATE_TEST_CASE_P(DBMultiGetTestWithParam, DBMultiGetTestWithParam,
testing::Bool());
TEST_F(DBBasicTest, MultiGetBatchedSimpleUnsorted) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedSimpleUnsorted) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
do {
CreateAndReopenWithCF({"pikachu"}, CurrentOptions());
SetPerfLevel(kEnableCount);
@ -1448,8 +1488,10 @@ TEST_F(DBBasicTest, MultiGetBatchedSimpleUnsorted) {
std::vector<ColumnFamilyHandle*> cfs(keys.size(), handles_[1]);
std::vector<Status> s(keys.size());
db_->MultiGet(ReadOptions(), handles_[1], keys.size(), keys.data(),
values.data(), s.data(), false);
ReadOptions ro;
ro.async_io = std::get<1>(GetParam());
db_->MultiGet(ro, handles_[1], keys.size(), keys.data(), values.data(),
s.data(), false);
ASSERT_EQ(values.size(), keys.size());
ASSERT_EQ(std::string(values[5].data(), values[5].size()), "v1");
@ -1470,7 +1512,18 @@ TEST_F(DBBasicTest, MultiGetBatchedSimpleUnsorted) {
} while (ChangeCompactOptions());
}
TEST_F(DBBasicTest, MultiGetBatchedSortedMultiFile) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedSortedMultiFile) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
do {
CreateAndReopenWithCF({"pikachu"}, CurrentOptions());
SetPerfLevel(kEnableCount);
@ -1493,8 +1546,10 @@ TEST_F(DBBasicTest, MultiGetBatchedSortedMultiFile) {
std::vector<ColumnFamilyHandle*> cfs(keys.size(), handles_[1]);
std::vector<Status> s(keys.size());
db_->MultiGet(ReadOptions(), handles_[1], keys.size(), keys.data(),
values.data(), s.data(), true);
ReadOptions ro;
ro.async_io = std::get<1>(GetParam());
db_->MultiGet(ro, handles_[1], keys.size(), keys.data(), values.data(),
s.data(), true);
ASSERT_EQ(values.size(), keys.size());
ASSERT_EQ(std::string(values[0].data(), values[0].size()), "v1");
@ -1515,7 +1570,18 @@ TEST_F(DBBasicTest, MultiGetBatchedSortedMultiFile) {
} while (ChangeOptions());
}
TEST_F(DBBasicTest, MultiGetBatchedDuplicateKeys) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedDuplicateKeys) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
Options opts = CurrentOptions();
opts.merge_operator = MergeOperators::CreateStringAppendOperator();
CreateAndReopenWithCF({"pikachu"}, opts);
@ -1546,8 +1612,10 @@ TEST_F(DBBasicTest, MultiGetBatchedDuplicateKeys) {
std::vector<ColumnFamilyHandle*> cfs(keys.size(), handles_[1]);
std::vector<Status> s(keys.size());
db_->MultiGet(ReadOptions(), handles_[1], keys.size(), keys.data(),
values.data(), s.data(), false);
ReadOptions ro;
ro.async_io = std::get<1>(GetParam());
db_->MultiGet(ro, handles_[1], keys.size(), keys.data(), values.data(),
s.data(), false);
ASSERT_EQ(values.size(), keys.size());
ASSERT_EQ(std::string(values[0].data(), values[0].size()), "v8");
@ -1566,7 +1634,18 @@ TEST_F(DBBasicTest, MultiGetBatchedDuplicateKeys) {
SetPerfLevel(kDisable);
}
TEST_F(DBBasicTest, MultiGetBatchedMultiLevel) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedMultiLevel) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
Options options = CurrentOptions();
options.disable_auto_compactions = true;
Reopen(options);
@ -1625,7 +1704,7 @@ TEST_F(DBBasicTest, MultiGetBatchedMultiLevel) {
keys.push_back("key_" + std::to_string(i));
}
values = MultiGet(keys, nullptr);
values = MultiGet(keys, nullptr, std::get<1>(GetParam()));
ASSERT_EQ(values.size(), 16);
for (unsigned int j = 0; j < values.size(); ++j) {
int key = j + 64;
@ -1641,7 +1720,18 @@ TEST_F(DBBasicTest, MultiGetBatchedMultiLevel) {
}
}
TEST_F(DBBasicTest, MultiGetBatchedMultiLevelMerge) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedMultiLevelMerge) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
Options options = CurrentOptions();
options.disable_auto_compactions = true;
options.merge_operator = MergeOperators::CreateStringAppendOperator();
@ -1705,7 +1795,7 @@ TEST_F(DBBasicTest, MultiGetBatchedMultiLevelMerge) {
keys.push_back("key_" + std::to_string(i));
}
values = MultiGet(keys, nullptr);
values = MultiGet(keys, nullptr, std::get<1>(GetParam()));
ASSERT_EQ(values.size(), keys.size());
for (unsigned int j = 0; j < 48; ++j) {
int key = j + 32;
@ -1727,7 +1817,18 @@ TEST_F(DBBasicTest, MultiGetBatchedMultiLevelMerge) {
}
}
TEST_F(DBBasicTest, MultiGetBatchedValueSizeInMemory) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedValueSizeInMemory) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
CreateAndReopenWithCF({"pikachu"}, CurrentOptions());
SetPerfLevel(kEnableCount);
ASSERT_OK(Put(1, "k1", "v_1"));
@ -1744,6 +1845,7 @@ TEST_F(DBBasicTest, MultiGetBatchedValueSizeInMemory) {
get_perf_context()->Reset();
ReadOptions ro;
ro.value_size_soft_limit = 11;
ro.async_io = std::get<1>(GetParam());
db_->MultiGet(ro, handles_[1], keys.size(), keys.data(), values.data(),
s.data(), false);
@ -1761,7 +1863,17 @@ TEST_F(DBBasicTest, MultiGetBatchedValueSizeInMemory) {
SetPerfLevel(kDisable);
}
TEST_F(DBBasicTest, MultiGetBatchedValueSize) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedValueSize) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
return;
}
do {
CreateAndReopenWithCF({"pikachu"}, CurrentOptions());
SetPerfLevel(kEnableCount);
@ -1801,6 +1913,7 @@ TEST_F(DBBasicTest, MultiGetBatchedValueSize) {
ReadOptions ro;
ro.value_size_soft_limit = 20;
ro.async_io = std::get<1>(GetParam());
db_->MultiGet(ro, handles_[1], keys.size(), keys.data(), values.data(),
s.data(), false);
@ -1836,7 +1949,18 @@ TEST_F(DBBasicTest, MultiGetBatchedValueSize) {
} while (ChangeCompactOptions());
}
TEST_F(DBBasicTest, MultiGetBatchedValueSizeMultiLevelMerge) {
TEST_P(DBMultiGetTestWithParam, MultiGetBatchedValueSizeMultiLevelMerge) {
#ifndef USE_COROUTINES
if (std::get<1>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
// Skip for unbatched MultiGet
if (!std::get<0>(GetParam())) {
ROCKSDB_GTEST_SKIP("This test is only for batched MultiGet");
return;
}
Options options = CurrentOptions();
options.disable_auto_compactions = true;
options.merge_operator = MergeOperators::CreateStringAppendOperator();
@ -1908,6 +2032,7 @@ TEST_F(DBBasicTest, MultiGetBatchedValueSizeMultiLevelMerge) {
ReadOptions read_options;
read_options.verify_checksums = true;
read_options.value_size_soft_limit = 380;
read_options.async_io = std::get<1>(GetParam());
db_->MultiGet(read_options, dbfull()->DefaultColumnFamily(), keys.size(),
keys.data(), values.data(), statuses.data());
@ -1939,6 +2064,217 @@ TEST_F(DBBasicTest, MultiGetBatchedValueSizeMultiLevelMerge) {
}
}
INSTANTIATE_TEST_CASE_P(DBMultiGetTestWithParam, DBMultiGetTestWithParam,
testing::Combine(testing::Bool(), testing::Bool()));
#if USE_COROUTINES
class DBMultiGetAsyncIOTest : public DBBasicTest {
public:
DBMultiGetAsyncIOTest()
: DBBasicTest(), statistics_(ROCKSDB_NAMESPACE::CreateDBStatistics()) {
BlockBasedTableOptions bbto;
bbto.filter_policy.reset(NewBloomFilterPolicy(10));
Options options = CurrentOptions();
options.disable_auto_compactions = true;
options.statistics = statistics_;
options.table_factory.reset(NewBlockBasedTableFactory(bbto));
Reopen(options);
int num_keys = 0;
// Put all keys in the bottommost level, and overwrite some keys
// in L0 and L1
for (int i = 0; i < 128; ++i) {
EXPECT_OK(Put(Key(i), "val_l2_" + std::to_string(i)));
num_keys++;
if (num_keys == 8) {
EXPECT_OK(Flush());
num_keys = 0;
}
}
if (num_keys > 0) {
EXPECT_OK(Flush());
num_keys = 0;
}
MoveFilesToLevel(2);
for (int i = 0; i < 128; i += 3) {
EXPECT_OK(Put(Key(i), "val_l1_" + std::to_string(i)));
num_keys++;
if (num_keys == 8) {
EXPECT_OK(Flush());
num_keys = 0;
}
}
if (num_keys > 0) {
EXPECT_OK(Flush());
num_keys = 0;
}
MoveFilesToLevel(1);
for (int i = 0; i < 128; i += 5) {
EXPECT_OK(Put(Key(i), "val_l0_" + std::to_string(i)));
num_keys++;
if (num_keys == 8) {
EXPECT_OK(Flush());
num_keys = 0;
}
}
if (num_keys > 0) {
EXPECT_OK(Flush());
num_keys = 0;
}
EXPECT_EQ(0, num_keys);
}
const std::shared_ptr<Statistics>& statistics() { return statistics_; }
private:
std::shared_ptr<Statistics> statistics_;
};
TEST_F(DBMultiGetAsyncIOTest, GetFromL0) {
// All 3 keys in L0. The L0 files should be read serially.
std::vector<std::string> key_strs{Key(0), Key(40), Key(80)};
std::vector<Slice> keys{key_strs[0], key_strs[1], key_strs[2]};
std::vector<PinnableSlice> values(key_strs.size());
std::vector<Status> statuses(key_strs.size());
ReadOptions ro;
ro.async_io = true;
dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
keys.data(), values.data(), statuses.data());
ASSERT_EQ(values.size(), 3);
ASSERT_OK(statuses[0]);
ASSERT_OK(statuses[1]);
ASSERT_OK(statuses[2]);
ASSERT_EQ(values[0], "val_l0_" + std::to_string(0));
ASSERT_EQ(values[1], "val_l0_" + std::to_string(40));
ASSERT_EQ(values[2], "val_l0_" + std::to_string(80));
HistogramData multiget_io_batch_size;
statistics()->histogramData(MULTIGET_IO_BATCH_SIZE, &multiget_io_batch_size);
// No async IO in this case since we don't do parallel lookup in L0
ASSERT_EQ(multiget_io_batch_size.count, 0);
ASSERT_EQ(multiget_io_batch_size.max, 0);
}
TEST_F(DBMultiGetAsyncIOTest, GetFromL1) {
std::vector<std::string> key_strs;
std::vector<Slice> keys;
std::vector<PinnableSlice> values;
std::vector<Status> statuses;
key_strs.push_back(Key(33));
key_strs.push_back(Key(54));
key_strs.push_back(Key(102));
keys.push_back(key_strs[0]);
keys.push_back(key_strs[1]);
keys.push_back(key_strs[2]);
values.resize(keys.size());
statuses.resize(keys.size());
ReadOptions ro;
ro.async_io = true;
dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
keys.data(), values.data(), statuses.data());
ASSERT_EQ(values.size(), 3);
ASSERT_EQ(statuses[0], Status::OK());
ASSERT_EQ(statuses[1], Status::OK());
ASSERT_EQ(statuses[2], Status::OK());
ASSERT_EQ(values[0], "val_l1_" + std::to_string(33));
ASSERT_EQ(values[1], "val_l1_" + std::to_string(54));
ASSERT_EQ(values[2], "val_l1_" + std::to_string(102));
HistogramData multiget_io_batch_size;
statistics()->histogramData(MULTIGET_IO_BATCH_SIZE, &multiget_io_batch_size);
// A batch of 3 async IOs is expected, one for each overlapping file in L1
ASSERT_EQ(multiget_io_batch_size.count, 1);
ASSERT_EQ(multiget_io_batch_size.max, 3);
}
TEST_F(DBMultiGetAsyncIOTest, LastKeyInFile) {
std::vector<std::string> key_strs;
std::vector<Slice> keys;
std::vector<PinnableSlice> values;
std::vector<Status> statuses;
// 21 is the last key in the first L1 file
key_strs.push_back(Key(21));
key_strs.push_back(Key(54));
key_strs.push_back(Key(102));
keys.push_back(key_strs[0]);
keys.push_back(key_strs[1]);
keys.push_back(key_strs[2]);
values.resize(keys.size());
statuses.resize(keys.size());
ReadOptions ro;
ro.async_io = true;
dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
keys.data(), values.data(), statuses.data());
ASSERT_EQ(values.size(), 3);
ASSERT_EQ(statuses[0], Status::OK());
ASSERT_EQ(statuses[1], Status::OK());
ASSERT_EQ(statuses[2], Status::OK());
ASSERT_EQ(values[0], "val_l1_" + std::to_string(21));
ASSERT_EQ(values[1], "val_l1_" + std::to_string(54));
ASSERT_EQ(values[2], "val_l1_" + std::to_string(102));
HistogramData multiget_io_batch_size;
statistics()->histogramData(MULTIGET_IO_BATCH_SIZE, &multiget_io_batch_size);
// Since the first MultiGet key is the last key in a file, the MultiGet is
// expected to lookup in that file first, before moving on to other files.
// So the first file lookup will issue one async read, and the next lookup
// will lookup 2 files in parallel and issue 2 async reads
ASSERT_EQ(multiget_io_batch_size.count, 2);
ASSERT_EQ(multiget_io_batch_size.max, 2);
}
TEST_F(DBMultiGetAsyncIOTest, GetFromL1AndL2) {
std::vector<std::string> key_strs;
std::vector<Slice> keys;
std::vector<PinnableSlice> values;
std::vector<Status> statuses;
// 33 and 102 are in L1, and 56 is in L2
key_strs.push_back(Key(33));
key_strs.push_back(Key(56));
key_strs.push_back(Key(102));
keys.push_back(key_strs[0]);
keys.push_back(key_strs[1]);
keys.push_back(key_strs[2]);
values.resize(keys.size());
statuses.resize(keys.size());
ReadOptions ro;
ro.async_io = true;
dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
keys.data(), values.data(), statuses.data());
ASSERT_EQ(values.size(), 3);
ASSERT_EQ(statuses[0], Status::OK());
ASSERT_EQ(statuses[1], Status::OK());
ASSERT_EQ(statuses[2], Status::OK());
ASSERT_EQ(values[0], "val_l1_" + std::to_string(33));
ASSERT_EQ(values[1], "val_l2_" + std::to_string(56));
ASSERT_EQ(values[2], "val_l1_" + std::to_string(102));
HistogramData multiget_io_batch_size;
statistics()->histogramData(MULTIGET_IO_BATCH_SIZE, &multiget_io_batch_size);
// There is only one MultiGet key in the bottommost level - 56. Thus
// the bottommost level will not use async IO.
ASSERT_EQ(multiget_io_batch_size.count, 1);
ASSERT_EQ(multiget_io_batch_size.max, 2);
}
#endif // USE_COROUTINES
TEST_F(DBBasicTest, MultiGetStats) {
Options options;
options.create_if_missing = true;
@ -3308,6 +3644,11 @@ class DeadlineRandomAccessFile : public FSRandomAccessFileOwnerWrapper {
IOStatus MultiRead(FSReadRequest* reqs, size_t num_reqs,
const IOOptions& options, IODebugContext* dbg) override;
IOStatus ReadAsync(FSReadRequest& req, const IOOptions& opts,
std::function<void(const FSReadRequest&, void*)> cb,
void* cb_arg, void** io_handle, IOHandleDeleter* del_fn,
IODebugContext* dbg) override;
private:
DeadlineFS& fs_;
std::unique_ptr<FSRandomAccessFile> file_;
@ -3448,6 +3789,26 @@ IOStatus DeadlineRandomAccessFile::Read(uint64_t offset, size_t len,
return s;
}
IOStatus DeadlineRandomAccessFile::ReadAsync(
FSReadRequest& req, const IOOptions& opts,
std::function<void(const FSReadRequest&, void*)> cb, void* cb_arg,
void** io_handle, IOHandleDeleter* del_fn, IODebugContext* dbg) {
const std::chrono::microseconds deadline = fs_.GetDeadline();
const std::chrono::microseconds io_timeout = fs_.GetIOTimeout();
IOStatus s;
if (deadline.count() || io_timeout.count()) {
fs_.AssertDeadline(deadline, io_timeout, opts);
}
if (s.ok()) {
s = FSRandomAccessFileWrapper::ReadAsync(req, opts, cb, cb_arg, io_handle,
del_fn, dbg);
}
if (s.ok()) {
s = fs_.ShouldDelay(opts);
}
return s;
}
IOStatus DeadlineRandomAccessFile::MultiRead(FSReadRequest* reqs,
size_t num_reqs,
const IOOptions& options,
@ -3469,7 +3830,8 @@ IOStatus DeadlineRandomAccessFile::MultiRead(FSReadRequest* reqs,
// A test class for intercepting random reads and injecting artificial
// delays. Used for testing the MultiGet deadline feature
class DBBasicTestMultiGetDeadline : public DBBasicTestMultiGet {
class DBBasicTestMultiGetDeadline : public DBBasicTestMultiGet,
public testing::WithParamInterface<bool> {
public:
DBBasicTestMultiGetDeadline()
: DBBasicTestMultiGet(
@ -3492,7 +3854,13 @@ class DBBasicTestMultiGetDeadline : public DBBasicTestMultiGet {
}
};
TEST_F(DBBasicTestMultiGetDeadline, MultiGetDeadlineExceeded) {
TEST_P(DBBasicTestMultiGetDeadline, MultiGetDeadlineExceeded) {
#ifndef USE_COROUTINES
if (GetParam()) {
ROCKSDB_GTEST_SKIP("This test requires coroutine support");
return;
}
#endif // USE_COROUTINES
std::shared_ptr<DeadlineFS> fs = std::make_shared<DeadlineFS>(env_, false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options = CurrentOptions();
@ -3523,6 +3891,7 @@ TEST_F(DBBasicTestMultiGetDeadline, MultiGetDeadlineExceeded) {
ReadOptions ro;
ro.deadline = std::chrono::microseconds{env->NowMicros() + 10000};
ro.async_io = GetParam();
// Delay the first IO
fs->SetDelayTrigger(ro.deadline, ro.io_timeout, 0);
@ -3625,6 +3994,9 @@ TEST_F(DBBasicTestMultiGetDeadline, MultiGetDeadlineExceeded) {
Close();
}
INSTANTIATE_TEST_CASE_P(DeadlineIO, DBBasicTestMultiGetDeadline,
::testing::Bool());
TEST_F(DBBasicTest, ManifestWriteFailure) {
Options options = GetDefaultOptions();
options.create_if_missing = true;

3
db/db_impl/db_impl.cc
View File

@ -2590,7 +2590,8 @@ Status DBImpl::MultiGetImpl(
? MultiGetContext::MAX_BATCH_SIZE
: keys_left;
MultiGetContext ctx(sorted_keys, start_key + num_keys - keys_left,
batch_size, snapshot, read_options);
batch_size, snapshot, read_options, GetFileSystem(),
stats_);
MultiGetRange range = ctx.GetMultiGetRange();
range.AddValueSize(curr_value_size);
bool lookup_current = false;

8
db/db_test_util.cc
View File

@ -830,10 +830,12 @@ std::string DBTestBase::Get(int cf, const std::string& k,
std::vector<std::string> DBTestBase::MultiGet(std::vector<int> cfs,
const std::vector<std::string>& k,
const Snapshot* snapshot,
const bool batched) {
const bool batched,
const bool async) {
ReadOptions options;
options.verify_checksums = true;
options.snapshot = snapshot;
options.async_io = async;
std::vector<ColumnFamilyHandle*> handles;
std::vector<Slice> keys;
std::vector<std::string> result;
@ -875,10 +877,12 @@ std::vector<std::string> DBTestBase::MultiGet(std::vector<int> cfs,
}
std::vector<std::string> DBTestBase::MultiGet(const std::vector<std::string>& k,
const Snapshot* snapshot) {
const Snapshot* snapshot,
const bool async) {
ReadOptions options;
options.verify_checksums = true;
options.snapshot = snapshot;
options.async_io = async;
std::vector<Slice> keys;
std::vector<std::string> result(k.size());
std::vector<Status> statuses(k.size());

6
db/db_test_util.h
View File

@ -1199,10 +1199,12 @@ class DBTestBase : public testing::Test {
std::vector<std::string> MultiGet(std::vector<int> cfs,
const std::vector<std::string>& k,
const Snapshot* snapshot,
const bool batched);
const bool batched,
const bool async = false);
std::vector<std::string> MultiGet(const std::vector<std::string>& k,
const Snapshot* snapshot = nullptr);
const Snapshot* snapshot = nullptr,
const bool async = false);
uint64_t GetNumSnapshots();

145
db/table_cache.cc
View File

@ -32,14 +32,30 @@
#include "util/stop_watch.h"
namespace ROCKSDB_NAMESPACE {
namespace {
template <class T>
static void DeleteEntry(const Slice& /*key*/, void* value) {
T* typed_value = reinterpret_cast<T*>(value);
delete typed_value;
}
} // namespace
} // namespace ROCKSDB_NAMESPACE
// Generate the regular and coroutine versions of some methods by
// including table_cache_sync_and_async.h twice
// Macros in the header will expand differently based on whether
// WITH_COROUTINES or WITHOUT_COROUTINES is defined
// clang-format off
#define WITHOUT_COROUTINES
#include "db/table_cache_sync_and_async.h"
#undef WITHOUT_COROUTINES
#define WITH_COROUTINES
#include "db/table_cache_sync_and_async.h"
// clang-format on
namespace ROCKSDB_NAMESPACE {
namespace {
static void UnrefEntry(void* arg1, void* arg2) {
Cache* cache = reinterpret_cast<Cache*>(arg1);
@ -484,131 +500,6 @@ Status TableCache::Get(
return s;
}
// Batched version of TableCache::MultiGet.
Status TableCache::MultiGet(
const ReadOptions& options,
const InternalKeyComparator& internal_comparator,
const FileMetaData& file_meta, const MultiGetContext::Range* mget_range,
const std::shared_ptr<const SliceTransform>& prefix_extractor,
HistogramImpl* file_read_hist, bool skip_filters, int level) {
auto& fd = file_meta.fd;
Status s;
TableReader* t = fd.table_reader;
Cache::Handle* handle = nullptr;
MultiGetRange table_range(*mget_range, mget_range->begin(),
mget_range->end());
#ifndef ROCKSDB_LITE
autovector<std::string, MultiGetContext::MAX_BATCH_SIZE> row_cache_entries;
IterKey row_cache_key;
size_t row_cache_key_prefix_size = 0;
KeyContext& first_key = *table_range.begin();
bool lookup_row_cache =
ioptions_.row_cache && !first_key.get_context->NeedToReadSequence();
// Check row cache if enabled. Since row cache does not currently store
// sequence numbers, we cannot use it if we need to fetch the sequence.
if (lookup_row_cache) {
GetContext* first_context = first_key.get_context;
CreateRowCacheKeyPrefix(options, fd, first_key.ikey, first_context,
row_cache_key);
row_cache_key_prefix_size = row_cache_key.Size();
for (auto miter = table_range.begin(); miter != table_range.end();
++miter) {
const Slice& user_key = miter->ukey_with_ts;
GetContext* get_context = miter->get_context;
if (GetFromRowCache(user_key, row_cache_key, row_cache_key_prefix_size,
get_context)) {
table_range.SkipKey(miter);
} else {
row_cache_entries.emplace_back();
get_context->SetReplayLog(&(row_cache_entries.back()));
}
}
}
#endif // ROCKSDB_LITE
// Check that table_range is not empty. Its possible all keys may have been
// found in the row cache and thus the range may now be empty
if (s.ok() && !table_range.empty()) {
if (t == nullptr) {
s = FindTable(options, file_options_, internal_comparator, fd, &handle,
prefix_extractor,
options.read_tier == kBlockCacheTier /* no_io */,
true /* record_read_stats */, file_read_hist, skip_filters,
level, true /* prefetch_index_and_filter_in_cache */,
0 /*max_file_size_for_l0_meta_pin*/, file_meta.temperature);
TEST_SYNC_POINT_CALLBACK("TableCache::MultiGet:FindTable", &s);
if (s.ok()) {
t = GetTableReaderFromHandle(handle);
assert(t);
}
}
if (s.ok() && !options.ignore_range_deletions) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
t->NewRangeTombstoneIterator(options));
if (range_del_iter != nullptr) {
for (auto iter = table_range.begin(); iter != table_range.end();
++iter) {
SequenceNumber* max_covering_tombstone_seq =
iter->get_context->max_covering_tombstone_seq();
*max_covering_tombstone_seq = std::max(
*max_covering_tombstone_seq,
range_del_iter->MaxCoveringTombstoneSeqnum(iter->ukey_with_ts));
}
}
}
if (s.ok()) {
t->MultiGet(options, &table_range, prefix_extractor.get(), skip_filters);
} else if (options.read_tier == kBlockCacheTier && s.IsIncomplete()) {
for (auto iter = table_range.begin(); iter != table_range.end(); ++iter) {
Status* status = iter->s;
if (status->IsIncomplete()) {
// Couldn't find Table in cache but treat as kFound if no_io set
iter->get_context->MarkKeyMayExist();
s = Status::OK();
}
}
}
}
#ifndef ROCKSDB_LITE
if (lookup_row_cache) {
size_t row_idx = 0;
for (auto miter = table_range.begin(); miter != table_range.end();
++miter) {
std::string& row_cache_entry = row_cache_entries[row_idx++];
const Slice& user_key = miter->ukey_with_ts;
;
GetContext* get_context = miter->get_context;
get_context->SetReplayLog(nullptr);
// Compute row cache key.
row_cache_key.TrimAppend(row_cache_key_prefix_size, user_key.data(),
user_key.size());
// Put the replay log in row cache only if something was found.
if (s.ok() && !row_cache_entry.empty()) {
size_t charge = row_cache_entry.capacity() + sizeof(std::string);
void* row_ptr = new std::string(std::move(row_cache_entry));
// If row cache is full, it's OK.
ioptions_.row_cache
->Insert(row_cache_key.GetUserKey(), row_ptr, charge,
&DeleteEntry<std::string>)
.PermitUncheckedError();
}
}
}
#endif // ROCKSDB_LITE
if (handle != nullptr) {
ReleaseHandle(handle);
}
return s;
}
Status TableCache::GetTableProperties(
const FileOptions& file_options,
const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,

5
db/table_cache.h
View File

@ -24,6 +24,7 @@
#include "rocksdb/table.h"
#include "table/table_reader.h"
#include "trace_replay/block_cache_tracer.h"
#include "util/coro_utils.h"
namespace ROCKSDB_NAMESPACE {
@ -115,8 +116,8 @@ class TableCache {
// in the embedded GetContext
// @param skip_filters Disables loading/accessing the filter block
// @param level The level this table is at, -1 for "not set / don't know"
Status MultiGet(
const ReadOptions& options,
DECLARE_SYNC_AND_ASYNC(
Status, MultiGet, const ReadOptions& options,
const InternalKeyComparator& internal_comparator,
const FileMetaData& file_meta, const MultiGetContext::Range* mget_range,
const std::shared_ptr<const SliceTransform>& prefix_extractor = nullptr,

140
db/table_cache_sync_and_async.h Normal file
View File

@ -0,0 +1,140 @@
// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "util/coro_utils.h"
#if defined(WITHOUT_COROUTINES) || \
(defined(USE_COROUTINES) && defined(WITH_COROUTINES))
namespace ROCKSDB_NAMESPACE {
#if defined(WITHOUT_COROUTINES)
#endif
// Batched version of TableCache::MultiGet.
DEFINE_SYNC_AND_ASYNC(Status, TableCache::MultiGet)
(const ReadOptions& options, const InternalKeyComparator& internal_comparator,
const FileMetaData& file_meta, const MultiGetContext::Range* mget_range,
const std::shared_ptr<const SliceTransform>& prefix_extractor,
HistogramImpl* file_read_hist, bool skip_filters, int level) {
auto& fd = file_meta.fd;
Status s;
TableReader* t = fd.table_reader;
Cache::Handle* handle = nullptr;
MultiGetRange table_range(*mget_range, mget_range->begin(),
mget_range->end());
#ifndef ROCKSDB_LITE
autovector<std::string, MultiGetContext::MAX_BATCH_SIZE> row_cache_entries;
IterKey row_cache_key;
size_t row_cache_key_prefix_size = 0;
KeyContext& first_key = *table_range.begin();
bool lookup_row_cache =
ioptions_.row_cache && !first_key.get_context->NeedToReadSequence();
// Check row cache if enabled. Since row cache does not currently store
// sequence numbers, we cannot use it if we need to fetch the sequence.
if (lookup_row_cache) {
GetContext* first_context = first_key.get_context;
CreateRowCacheKeyPrefix(options, fd, first_key.ikey, first_context,
row_cache_key);
row_cache_key_prefix_size = row_cache_key.Size();
for (auto miter = table_range.begin(); miter != table_range.end();
++miter) {
const Slice& user_key = miter->ukey_with_ts;
GetContext* get_context = miter->get_context;
if (GetFromRowCache(user_key, row_cache_key, row_cache_key_prefix_size,
get_context)) {
table_range.SkipKey(miter);
} else {
row_cache_entries.emplace_back();
get_context->SetReplayLog(&(row_cache_entries.back()));
}
}
}
#endif // ROCKSDB_LITE
// Check that table_range is not empty. Its possible all keys may have been
// found in the row cache and thus the range may now be empty
if (s.ok() && !table_range.empty()) {
if (t == nullptr) {
s = FindTable(options, file_options_, internal_comparator, fd, &handle,
prefix_extractor,
options.read_tier == kBlockCacheTier /* no_io */,
true /* record_read_stats */, file_read_hist, skip_filters,
level, true /* prefetch_index_and_filter_in_cache */,
0 /*max_file_size_for_l0_meta_pin*/, file_meta.temperature);
TEST_SYNC_POINT_CALLBACK("TableCache::MultiGet:FindTable", &s);
if (s.ok()) {
t = GetTableReaderFromHandle(handle);
assert(t);
}
}
if (s.ok() && !options.ignore_range_deletions) {
std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
t->NewRangeTombstoneIterator(options));
if (range_del_iter != nullptr) {
for (auto iter = table_range.begin(); iter != table_range.end();
++iter) {
SequenceNumber* max_covering_tombstone_seq =
iter->get_context->max_covering_tombstone_seq();
*max_covering_tombstone_seq = std::max(
*max_covering_tombstone_seq,
range_del_iter->MaxCoveringTombstoneSeqnum(iter->ukey_with_ts));
}
}
}
if (s.ok()) {
CO_AWAIT(t->MultiGet)
(options, &table_range, prefix_extractor.get(), skip_filters);
} else if (options.read_tier == kBlockCacheTier && s.IsIncomplete()) {
for (auto iter = table_range.begin(); iter != table_range.end(); ++iter) {
Status* status = iter->s;
if (status->IsIncomplete()) {
// Couldn't find Table in cache but treat as kFound if no_io set
iter->get_context->MarkKeyMayExist();
s = Status::OK();
}
}
}
}
#ifndef ROCKSDB_LITE
if (lookup_row_cache) {
size_t row_idx = 0;
for (auto miter = table_range.begin(); miter != table_range.end();
++miter) {
std::string& row_cache_entry = row_cache_entries[row_idx++];
const Slice& user_key = miter->ukey_with_ts;
;
GetContext* get_context = miter->get_context;
get_context->SetReplayLog(nullptr);
// Compute row cache key.
row_cache_key.TrimAppend(row_cache_key_prefix_size, user_key.data(),
user_key.size());
// Put the replay log in row cache only if something was found.
if (s.ok() && !row_cache_entry.empty()) {
size_t charge = row_cache_entry.capacity() + sizeof(std::string);
void* row_ptr = new std::string(std::move(row_cache_entry));
// If row cache is full, it's OK.
ioptions_.row_cache
->Insert(row_cache_key.GetUserKey(), row_ptr, charge,
&DeleteEntry<std::string>)
.PermitUncheckedError();
}
}
}
#endif // ROCKSDB_LITE
if (handle != nullptr) {
ReleaseHandle(handle);
}
CO_RETURN s;
}
} // namespace ROCKSDB_NAMESPACE
#endif

256
db/version_set.cc
View File

@ -38,6 +38,10 @@
#include "db/table_cache.h"
#include "db/version_builder.h"
#include "db/version_edit_handler.h"
#if USE_COROUTINES
#include "folly/experimental/coro/BlockingWait.h"
#include "folly/experimental/coro/Collect.h"
#endif
#include "file/filename.h"
#include "file/random_access_file_reader.h"
#include "file/read_write_util.h"
@ -63,10 +67,23 @@
#include "test_util/sync_point.h"
#include "util/cast_util.h"
#include "util/coding.h"
#include "util/coro_utils.h"
#include "util/stop_watch.h"
#include "util/string_util.h"
#include "util/user_comparator_wrapper.h"
// Generate the regular and coroutine versions of some methods by
// including version_set_sync_and_async.h twice
// Macros in the header will expand differently based on whether
// WITH_COROUTINES or WITHOUT_COROUTINES is defined
// clang-format off
#define WITHOUT_COROUTINES
#include "db/version_set_sync_and_async.h"
#undef WITHOUT_COROUTINES
#define WITH_COROUTINES
#include "db/version_set_sync_and_async.h"
// clang-format on
namespace ROCKSDB_NAMESPACE {
namespace {
@ -505,12 +522,11 @@ class FilePickerMultiGet {
return file_hit;
}
FdWithKeyRange* GetNextFile() {
while (!search_ended_) {
// Start searching next level.
if (batch_iter_ == current_level_range_.end()) {
search_ended_ = !PrepareNextLevel();
continue;
void PrepareNextLevelForSearch() { search_ended_ = !PrepareNextLevel(); }
FdWithKeyRange* GetNextFileInLevel() {
if (batch_iter_ == current_level_range_.end() || search_ended_) {
return nullptr;
} else {
if (maybe_repeat_key_) {
maybe_repeat_key_ = false;
@ -541,7 +557,7 @@ class FilePickerMultiGet {
bool is_last_key_in_file;
if (!GetNextFileInLevelWithKeys(&next_file_range, &curr_file_index, &f,
&is_last_key_in_file)) {
search_ended_ = !PrepareNextLevel();
return nullptr;
} else {
if (is_last_key_in_file) {
// Since cmp_largest is 0, batch_iter_ still points to the last key
@ -565,10 +581,6 @@ class FilePickerMultiGet {
}
}
// Search ended
return nullptr;
}
// getter for current file level
// for GET_HIT_L0, GET_HIT_L1 & GET_HIT_L2_AND_UP counts
unsigned int GetHitFileLevel() { return hit_file_level_; }
@ -577,8 +589,16 @@ class FilePickerMultiGet {
// GetNextFile()) is at the last index in its level.
bool IsHitFileLastInLevel() { return is_hit_file_last_in_level_; }
bool KeyMaySpanNextFile() { return maybe_repeat_key_; }
bool IsSearchEnded() { return search_ended_; }
const MultiGetRange& CurrentFileRange() { return current_file_range_; }
bool RemainingOverlapInLevel() {
return !current_level_range_.Suffix(current_file_range_).empty();
}
private:
unsigned int num_levels_;
unsigned int curr_level_;
@ -2218,7 +2238,7 @@ void Version::MultiGet(const ReadOptions& read_options, MultiGetRange* range,
&file_picker_range,
&storage_info_.level_files_brief_, storage_info_.num_non_empty_levels_,
&storage_info_.file_indexer_, user_comparator(), internal_comparator());
FdWithKeyRange* f = fp.GetNextFile();
FdWithKeyRange* f = fp.GetNextFileInLevel();
Status s;
uint64_t num_index_read = 0;
uint64_t num_filter_read = 0;
@ -2228,164 +2248,92 @@ void Version::MultiGet(const ReadOptions& read_options, MultiGetRange* range,
MultiGetRange keys_with_blobs_range(*range, range->begin(), range->end());
// blob_file => [[blob_idx, it], ...]
std::unordered_map<uint64_t, BlobReadRequests> blob_rqs;
int level = -1;
int prev_level = -1;
while (!fp.IsSearchEnded()) {
// This will be set to true later if we actually look up in a file in L0.
// For per level stats purposes, an L0 file is treated as a level
bool dump_stats_for_l0_file = false;
// Avoid using the coroutine version if we're looking in a L0 file, since
// L0 files won't be parallelized anyway. The regular synchronous version
// is faster.
if (!read_options.async_io || !using_coroutines() ||
fp.GetHitFileLevel() == 0 || !fp.RemainingOverlapInLevel()) {
if (f) {
// Call MultiGetFromSST for looking up a single file
s = MultiGetFromSST(read_options, fp.CurrentFileRange(),
fp.GetHitFileLevel(), fp.IsHitFileLastInLevel(), f,
blob_rqs, num_filter_read, num_index_read,
num_data_read, num_sst_read);
if (fp.GetHitFileLevel() == 0) {
dump_stats_for_l0_file = true;
}
}
if (s.ok()) {
f = fp.GetNextFileInLevel();
}
#if USE_COROUTINES
} else {
std::vector<folly::coro::Task<Status>> mget_tasks;
while (f != nullptr) {
MultiGetRange file_range = fp.CurrentFileRange();
bool timer_enabled =
GetPerfLevel() >= PerfLevel::kEnableTimeExceptForMutex &&
get_perf_context()->per_level_perf_context_enabled;
mget_tasks.emplace_back(MultiGetFromSSTCoroutine(
read_options, fp.CurrentFileRange(), fp.GetHitFileLevel(),
fp.IsHitFileLastInLevel(), f, blob_rqs, num_filter_read,
num_index_read, num_data_read, num_sst_read));
if (fp.KeyMaySpanNextFile()) {
break;
}
f = fp.GetNextFileInLevel();
}
if (mget_tasks.size() > 0) {
// Collect all results so far
std::vector<Status> statuses = folly::coro::blockingWait(
folly::coro::collectAllRange(std::move(mget_tasks))
.scheduleOn(&range->context()->executor()));
for (Status stat : statuses) {
if (!stat.ok()) {
s = stat;
}
}
// Report MultiGet stats per level.
if (level >= 0 && level != (int)fp.GetHitFileLevel()) {
if (s.ok() && fp.KeyMaySpanNextFile()) {
f = fp.GetNextFileInLevel();
}
}
#endif // USE_COROUTINES
}
// If bad status or we found final result for all the keys
if (!s.ok() || file_picker_range.empty()) {
break;
}
if (!f) {
// Reached the end of this level. Prepare the next level
fp.PrepareNextLevelForSearch();
if (!fp.IsSearchEnded()) {
// Its possible there is no overlap on this level and f is nullptr
f = fp.GetNextFileInLevel();
}
if (dump_stats_for_l0_file ||
(prev_level != 0 && prev_level != (int)fp.GetHitFileLevel())) {
// Dump the stats if the search has moved to the next level and
// reset for next level.
if (num_sst_read || (num_filter_read + num_index_read)) {
RecordInHistogram(db_statistics_,
NUM_INDEX_AND_FILTER_BLOCKS_READ_PER_LEVEL,
num_index_read + num_filter_read);
RecordInHistogram(db_statistics_, NUM_DATA_BLOCKS_READ_PER_LEVEL,
num_data_read);
RecordInHistogram(db_statistics_, NUM_SST_READ_PER_LEVEL, num_sst_read);
RecordInHistogram(db_statistics_, NUM_SST_READ_PER_LEVEL,
num_sst_read);
}
num_filter_read = 0;
num_index_read = 0;
num_data_read = 0;
num_sst_read = 0;
level = fp.GetHitFileLevel();
}
StopWatchNano timer(clock_, timer_enabled /* auto_start */);
s = table_cache_->MultiGet(
read_options, *internal_comparator(), *f->file_metadata, &file_range,
mutable_cf_options_.prefix_extractor,
cfd_->internal_stats()->GetFileReadHist(fp.GetHitFileLevel()),
IsFilterSkipped(static_cast<int>(fp.GetHitFileLevel()),
fp.IsHitFileLastInLevel()),
fp.GetHitFileLevel());
// TODO: examine the behavior for corrupted key
if (timer_enabled) {
PERF_COUNTER_BY_LEVEL_ADD(get_from_table_nanos, timer.ElapsedNanos(),
fp.GetHitFileLevel());
prev_level = fp.GetHitFileLevel();
}
if (!s.ok()) {
// TODO: Set status for individual keys appropriately
for (auto iter = file_range.begin(); iter != file_range.end(); ++iter) {
*iter->s = s;
file_range.MarkKeyDone(iter);
}
return;
}
uint64_t batch_size = 0;
for (auto iter = file_range.begin(); s.ok() && iter != file_range.end();
++iter) {
GetContext& get_context = *iter->get_context;
Status* status = iter->s;
// The Status in the KeyContext takes precedence over GetContext state
// Status may be an error if there were any IO errors in the table
// reader. We never expect Status to be NotFound(), as that is
// determined by get_context
assert(!status->IsNotFound());
if (!status->ok()) {
file_range.MarkKeyDone(iter);
continue;
}
if (get_context.sample()) {
sample_file_read_inc(f->file_metadata);
}
batch_size++;
num_index_read += get_context.get_context_stats_.num_index_read;
num_filter_read += get_context.get_context_stats_.num_filter_read;
num_data_read += get_context.get_context_stats_.num_data_read;
num_sst_read += get_context.get_context_stats_.num_sst_read;
// Reset these stats since they're specific to a level
get_context.get_context_stats_.num_index_read = 0;
get_context.get_context_stats_.num_filter_read = 0;
get_context.get_context_stats_.num_data_read = 0;
get_context.get_context_stats_.num_sst_read = 0;
// report the counters before returning
if (get_context.State() != GetContext::kNotFound &&
get_context.State() != GetContext::kMerge &&
db_statistics_ != nullptr) {
get_context.ReportCounters();
} else {
if (iter->max_covering_tombstone_seq > 0) {
// The remaining files we look at will only contain covered keys, so
// we stop here for this key
file_picker_range.SkipKey(iter);
}
}
switch (get_context.State()) {
case GetContext::kNotFound:
// Keep searching in other files
break;
case GetContext::kMerge:
// TODO: update per-level perfcontext user_key_return_count for kMerge
break;
case GetContext::kFound:
if (fp.GetHitFileLevel() == 0) {
RecordTick(db_statistics_, GET_HIT_L0);
} else if (fp.GetHitFileLevel() == 1) {
RecordTick(db_statistics_, GET_HIT_L1);
} else if (fp.GetHitFileLevel() >= 2) {
RecordTick(db_statistics_, GET_HIT_L2_AND_UP);
}
PERF_COUNTER_BY_LEVEL_ADD(user_key_return_count, 1,
fp.GetHitFileLevel());
file_range.MarkKeyDone(iter);
if (iter->is_blob_index) {
if (iter->value) {
TEST_SYNC_POINT_CALLBACK("Version::MultiGet::TamperWithBlobIndex",
&(*iter));
const Slice& blob_index_slice = *(iter->value);
BlobIndex blob_index;
Status tmp_s = blob_index.DecodeFrom(blob_index_slice);
if (tmp_s.ok()) {
const uint64_t blob_file_num = blob_index.file_number();
blob_rqs[blob_file_num].emplace_back(
std::make_pair(blob_index, std::cref(*iter)));
} else {
*(iter->s) = tmp_s;
}
}
} else {
file_range.AddValueSize(iter->value->size());
if (file_range.GetValueSize() >
read_options.value_size_soft_limit) {
s = Status::Aborted();
break;
}
}
continue;
case GetContext::kDeleted:
// Use empty error message for speed
*status = Status::NotFound();
file_range.MarkKeyDone(iter);
continue;
case GetContext::kCorrupt:
*status =
Status::Corruption("corrupted key for ", iter->lkey->user_key());
file_range.MarkKeyDone(iter);
continue;
case GetContext::kUnexpectedBlobIndex:
ROCKS_LOG_ERROR(info_log_, "Encounter unexpected blob index.");
*status = Status::NotSupported(
"Encounter unexpected blob index. Please open DB with "
"ROCKSDB_NAMESPACE::blob_db::BlobDB instead.");
file_range.MarkKeyDone(iter);
continue;
}
}
RecordInHistogram(db_statistics_, SST_BATCH_SIZE, batch_size);
if (!s.ok() || file_picker_range.empty()) {
break;
}
f = fp.GetNextFile();
}
// Dump stats for most recent level

9
db/version_set.h
View File

@ -54,6 +54,7 @@
#include "table/get_context.h"
#include "table/multiget_context.h"
#include "trace_replay/block_cache_tracer.h"
#include "util/coro_utils.h"
#include "util/hash_containers.h"
namespace ROCKSDB_NAMESPACE {
@ -884,6 +885,14 @@ class Version {
// This accumulated stats will be used in compaction.
void UpdateAccumulatedStats();
DECLARE_SYNC_AND_ASYNC(
/* ret_type */ Status, /* func_name */ MultiGetFromSST,
const ReadOptions& read_options, MultiGetRange file_range,
int hit_file_level, bool is_hit_file_last_in_level, FdWithKeyRange* f,
std::unordered_map<uint64_t, BlobReadRequests>& blob_rqs,
uint64_t& num_filter_read, uint64_t& num_index_read,
uint64_t& num_data_read, uint64_t& num_sst_read);
ColumnFamilyData* cfd_; // ColumnFamilyData to which this Version belongs
Logger* info_log_;
Statistics* db_statistics_;

154
db/version_set_sync_and_async.h Normal file
View File

@ -0,0 +1,154 @@
// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "util/coro_utils.h"
#if defined(WITHOUT_COROUTINES) || \
(defined(USE_COROUTINES) && defined(WITH_COROUTINES))
namespace ROCKSDB_NAMESPACE {
// Lookup a batch of keys in a single SST file
DEFINE_SYNC_AND_ASYNC(Status, Version::MultiGetFromSST)
(const ReadOptions& read_options, MultiGetRange file_range, int hit_file_level,
bool is_hit_file_last_in_level, FdWithKeyRange* f,
std::unordered_map<uint64_t, BlobReadRequests>& blob_rqs,
uint64_t& num_filter_read, uint64_t& num_index_read, uint64_t& num_data_read,
uint64_t& num_sst_read) {
bool timer_enabled = GetPerfLevel() >= PerfLevel::kEnableTimeExceptForMutex &&
get_perf_context()->per_level_perf_context_enabled;
Status s;
StopWatchNano timer(clock_, timer_enabled /* auto_start */);
s = CO_AWAIT(table_cache_->MultiGet)(
read_options, *internal_comparator(), *f->file_metadata, &file_range,
mutable_cf_options_.prefix_extractor,
cfd_->internal_stats()->GetFileReadHist(hit_file_level),
IsFilterSkipped(static_cast<int>(hit_file_level),
is_hit_file_last_in_level),
hit_file_level);
// TODO: examine the behavior for corrupted key
if (timer_enabled) {
PERF_COUNTER_BY_LEVEL_ADD(get_from_table_nanos, timer.ElapsedNanos(),
hit_file_level);
}
if (!s.ok()) {
// TODO: Set status for individual keys appropriately
for (auto iter = file_range.begin(); iter != file_range.end(); ++iter) {
*iter->s = s;
file_range.MarkKeyDone(iter);
}
CO_RETURN s;
}
uint64_t batch_size = 0;
for (auto iter = file_range.begin(); s.ok() && iter != file_range.end();
++iter) {
GetContext& get_context = *iter->get_context;
Status* status = iter->s;
// The Status in the KeyContext takes precedence over GetContext state
// Status may be an error if there were any IO errors in the table
// reader. We never expect Status to be NotFound(), as that is
// determined by get_context
assert(!status->IsNotFound());
if (!status->ok()) {
file_range.MarkKeyDone(iter);
continue;
}
if (get_context.sample()) {
sample_file_read_inc(f->file_metadata);
}
batch_size++;
num_index_read += get_context.get_context_stats_.num_index_read;
num_filter_read += get_context.get_context_stats_.num_filter_read;
num_data_read += get_context.get_context_stats_.num_data_read;
num_sst_read += get_context.get_context_stats_.num_sst_read;
// Reset these stats since they're specific to a level
get_context.get_context_stats_.num_index_read = 0;
get_context.get_context_stats_.num_filter_read = 0;
get_context.get_context_stats_.num_data_read = 0;
get_context.get_context_stats_.num_sst_read = 0;
// report the counters before returning
if (get_context.State() != GetContext::kNotFound &&
get_context.State() != GetContext::kMerge &&
db_statistics_ != nullptr) {
get_context.ReportCounters();
} else {
if (iter->max_covering_tombstone_seq > 0) {
// The remaining files we look at will only contain covered keys, so
// we stop here for this key
file_range.SkipKey(iter);
}
}
switch (get_context.State()) {
case GetContext::kNotFound:
// Keep searching in other files
break;
case GetContext::kMerge:
// TODO: update per-level perfcontext user_key_return_count for kMerge
break;
case GetContext::kFound:
if (hit_file_level == 0) {
RecordTick(db_statistics_, GET_HIT_L0);
} else if (hit_file_level == 1) {
RecordTick(db_statistics_, GET_HIT_L1);
} else if (hit_file_level >= 2) {
RecordTick(db_statistics_, GET_HIT_L2_AND_UP);
}
PERF_COUNTER_BY_LEVEL_ADD(user_key_return_count, 1, hit_file_level);
file_range.MarkKeyDone(iter);
if (iter->is_blob_index) {
if (iter->value) {
TEST_SYNC_POINT_CALLBACK("Version::MultiGet::TamperWithBlobIndex",
&(*iter));
const Slice& blob_index_slice = *(iter->value);
BlobIndex blob_index;
Status tmp_s = blob_index.DecodeFrom(blob_index_slice);
if (tmp_s.ok()) {
const uint64_t blob_file_num = blob_index.file_number();
blob_rqs[blob_file_num].emplace_back(
std::make_pair(blob_index, std::cref(*iter)));
} else {
*(iter->s) = tmp_s;
}
}
} else {
file_range.AddValueSize(iter->value->size());
if (file_range.GetValueSize() > read_options.value_size_soft_limit) {
s = Status::Aborted();
break;
}
}
continue;
case GetContext::kDeleted:
// Use empty error message for speed
*status = Status::NotFound();
file_range.MarkKeyDone(iter);
continue;
case GetContext::kCorrupt:
*status =
Status::Corruption("corrupted key for ", iter->lkey->user_key());
file_range.MarkKeyDone(iter);
continue;
case GetContext::kUnexpectedBlobIndex:
ROCKS_LOG_ERROR(info_log_, "Encounter unexpected blob index.");
*status = Status::NotSupported(
"Encounter unexpected blob index. Please open DB with "
"ROCKSDB_NAMESPACE::blob_db::BlobDB instead.");
file_range.MarkKeyDone(iter);
continue;
}
}
RecordInHistogram(db_statistics_, SST_BATCH_SIZE, batch_size);
CO_RETURN s;
}
} // namespace ROCKSDB_NAMESPACE
#endif

3
include/rocksdb/statistics.h
View File

@ -543,6 +543,9 @@ enum Histograms : uint32_t {
// Number of prefetched bytes discarded by RocksDB.
PREFETCHED_BYTES_DISCARDED,
// Number of IOs issued in parallel in a MultiGet batch
MULTIGET_IO_BATCH_SIZE,
HISTOGRAM_ENUM_MAX,
};

4
java/rocksjni/portal.h
View File

@ -5593,6 +5593,8 @@ class HistogramTypeJni {
return 0x34;
case ROCKSDB_NAMESPACE::Histograms::PREFETCHED_BYTES_DISCARDED:
return 0x35;
case ROCKSDB_NAMESPACE::Histograms::MULTIGET_IO_BATCH_SIZE:
return 0x36;
case ROCKSDB_NAMESPACE::Histograms::HISTOGRAM_ENUM_MAX:
// 0x1F for backwards compatibility on current minor version.
return 0x1F;
@ -5716,6 +5718,8 @@ class HistogramTypeJni {
return ROCKSDB_NAMESPACE::Histograms::POLL_WAIT_MICROS;
case 0x35:
return ROCKSDB_NAMESPACE::Histograms::PREFETCHED_BYTES_DISCARDED;
case 0x36:
return ROCKSDB_NAMESPACE::Histograms::MULTIGET_IO_BATCH_SIZE;
case 0x1F:
// 0x1F for backwards compatibility on current minor version.
return ROCKSDB_NAMESPACE::Histograms::HISTOGRAM_ENUM_MAX;

2
monitoring/statistics.cc
View File

@ -286,7 +286,7 @@ const std::vector<std::pair<Histograms, std::string>> HistogramsNameMap = {
{ASYNC_READ_BYTES, "rocksdb.async.read.bytes"},
{POLL_WAIT_MICROS, "rocksdb.poll.wait.micros"},
{PREFETCHED_BYTES_DISCARDED, "rocksdb.prefetched.bytes.discarded"},
{MULTIGET_IO_BATCH_SIZE, "rocksdb.multiget.io.batch.size"},
};
std::shared_ptr<Statistics> CreateDBStatistics() {

1
src.mk
View File

@ -211,6 +211,7 @@ LIB_SOURCES = \
trace_replay/trace_replay.cc \
trace_replay/block_cache_tracer.cc \
trace_replay/io_tracer.cc \
util/async_file_reader.cc \
util/build_version.cc \
util/cleanable.cc \
util/coding.cc \

759
table/block_based/block_based_table_reader.cc
View File

@ -74,6 +74,30 @@
#include "util/stop_watch.h"
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
namespace {
CacheAllocationPtr CopyBufferToHeap(MemoryAllocator* allocator, Slice& buf) {
CacheAllocationPtr heap_buf;
heap_buf = AllocateBlock(buf.size(), allocator);
memcpy(heap_buf.get(), buf.data(), buf.size());
return heap_buf;
}
} // namespace
} // namespace ROCKSDB_NAMESPACE
// Generate the regular and coroutine versions of some methods by
// including block_based_table_reader_sync_and_async.h twice
// Macros in the header will expand differently based on whether
// WITH_COROUTINES or WITHOUT_COROUTINES is defined
// clang-format off
#define WITHOUT_COROUTINES
#include "table/block_based/block_based_table_reader_sync_and_async.h"
#undef WITHOUT_COROUTINES
#define WITH_COROUTINES
#include "table/block_based/block_based_table_reader_sync_and_async.h"
// clang-format on
namespace ROCKSDB_NAMESPACE {
extern const uint64_t kBlockBasedTableMagicNumber;
@ -139,12 +163,6 @@ inline bool PrefixExtractorChangedHelper(
}
}
CacheAllocationPtr CopyBufferToHeap(MemoryAllocator* allocator, Slice& buf) {
CacheAllocationPtr heap_buf;
heap_buf = AllocateBlock(buf.size(), allocator);
memcpy(heap_buf.get(), buf.data(), buf.size());
return heap_buf;
}
} // namespace
void BlockBasedTable::UpdateCacheHitMetrics(BlockType block_type,
@ -1653,298 +1671,6 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
return s;
}
// This function reads multiple data blocks from disk using Env::MultiRead()
// and optionally inserts them into the block cache. It uses the scratch
// buffer provided by the caller, which is contiguous. If scratch is a nullptr
// it allocates a separate buffer for each block. Typically, if the blocks
// need to be uncompressed and there is no compressed block cache, callers
// can allocate a temporary scratch buffer in order to minimize memory
// allocations.
// If options.fill_cache is true, it inserts the blocks into cache. If its
// false and scratch is non-null and the blocks are uncompressed, it copies
// the buffers to heap. In any case, the CachableEntry<Block> returned will
// own the data bytes.
// If compression is enabled and also there is no compressed block cache,
// the adjacent blocks are read out in one IO (combined read)
// batch - A MultiGetRange with only those keys with unique data blocks not
// found in cache
// handles - A vector of block handles. Some of them me be NULL handles
// scratch - An optional contiguous buffer to read compressed blocks into
void BlockBasedTable::RetrieveMultipleBlocks(
const ReadOptions& options, const MultiGetRange* batch,
const autovector<BlockHandle, MultiGetContext::MAX_BATCH_SIZE>* handles,
autovector<Status, MultiGetContext::MAX_BATCH_SIZE>* statuses,
autovector<CachableEntry<Block>, MultiGetContext::MAX_BATCH_SIZE>* results,
char* scratch, const UncompressionDict& uncompression_dict) const {
RandomAccessFileReader* file = rep_->file.get();
const Footer& footer = rep_->footer;
const ImmutableOptions& ioptions = rep_->ioptions;
size_t read_amp_bytes_per_bit = rep_->table_options.read_amp_bytes_per_bit;
MemoryAllocator* memory_allocator = GetMemoryAllocator(rep_->table_options);
if (ioptions.allow_mmap_reads) {
size_t idx_in_batch = 0;
for (auto mget_iter = batch->begin(); mget_iter != batch->end();
++mget_iter, ++idx_in_batch) {
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet);
const BlockHandle& handle = (*handles)[idx_in_batch];
if (handle.IsNull()) {
continue;
}
(*statuses)[idx_in_batch] =
RetrieveBlock(nullptr, options, handle, uncompression_dict,
&(*results)[idx_in_batch], BlockType::kData,
mget_iter->get_context, &lookup_data_block_context,
/* for_compaction */ false, /* use_cache */ true,
/* wait_for_cache */ true);
}
return;
}
// In direct IO mode, blocks share the direct io buffer.
// Otherwise, blocks share the scratch buffer.
const bool use_shared_buffer = file->use_direct_io() || scratch != nullptr;
autovector<FSReadRequest, MultiGetContext::MAX_BATCH_SIZE> read_reqs;
size_t buf_offset = 0;
size_t idx_in_batch = 0;
uint64_t prev_offset = 0;
size_t prev_len = 0;
autovector<size_t, MultiGetContext::MAX_BATCH_SIZE> req_idx_for_block;
autovector<size_t, MultiGetContext::MAX_BATCH_SIZE> req_offset_for_block;
for (auto mget_iter = batch->begin(); mget_iter != batch->end();
++mget_iter, ++idx_in_batch) {
const BlockHandle& handle = (*handles)[idx_in_batch];
if (handle.IsNull()) {
continue;
}
size_t prev_end = static_cast<size_t>(prev_offset) + prev_len;
// If current block is adjacent to the previous one, at the same time,
// compression is enabled and there is no compressed cache, we combine
// the two block read as one.
// We don't combine block reads here in direct IO mode, because when doing
// direct IO read, the block requests will be realigned and merged when
// necessary.
if (use_shared_buffer && !file->use_direct_io() &&
prev_end == handle.offset()) {
req_offset_for_block.emplace_back(prev_len);
prev_len += BlockSizeWithTrailer(handle);
} else {
// No compression or current block and previous one is not adjacent:
// Step 1, create a new request for previous blocks
if (prev_len != 0) {
FSReadRequest req;
req.offset = prev_offset;
req.len = prev_len;
if (file->use_direct_io()) {
req.scratch = nullptr;
} else if (use_shared_buffer) {
req.scratch = scratch + buf_offset;
buf_offset += req.len;
} else {
req.scratch = new char[req.len];
}
read_reqs.emplace_back(req);
}
// Step 2, remeber the previous block info
prev_offset = handle.offset();
prev_len = BlockSizeWithTrailer(handle);
req_offset_for_block.emplace_back(0);
}
req_idx_for_block.emplace_back(read_reqs.size());
PERF_COUNTER_ADD(block_read_count, 1);
PERF_COUNTER_ADD(block_read_byte, BlockSizeWithTrailer(handle));
}
// Handle the last block and process the pending last request
if (prev_len != 0) {
FSReadRequest req;
req.offset = prev_offset;
req.len = prev_len;
if (file->use_direct_io()) {
req.scratch = nullptr;
} else if (use_shared_buffer) {
req.scratch = scratch + buf_offset;
} else {
req.scratch = new char[req.len];
}
read_reqs.emplace_back(req);
}
AlignedBuf direct_io_buf;
{
IOOptions opts;
IOStatus s = file->PrepareIOOptions(options, opts);
if (s.ok()) {
s = file->MultiRead(opts, &read_reqs[0], read_reqs.size(), &direct_io_buf,
options.rate_limiter_priority);
}
if (!s.ok()) {
// Discard all the results in this batch if there is any time out
// or overall MultiRead error
for (FSReadRequest& req : read_reqs) {
req.status = s;
}
}
}
idx_in_batch = 0;
size_t valid_batch_idx = 0;
for (auto mget_iter = batch->begin(); mget_iter != batch->end();
++mget_iter, ++idx_in_batch) {
const BlockHandle& handle = (*handles)[idx_in_batch];
if (handle.IsNull()) {
continue;
}
assert(valid_batch_idx < req_idx_for_block.size());
assert(valid_batch_idx < req_offset_for_block.size());
assert(req_idx_for_block[valid_batch_idx] < read_reqs.size());
size_t& req_idx = req_idx_for_block[valid_batch_idx];
size_t& req_offset = req_offset_for_block[valid_batch_idx];
valid_batch_idx++;
if (mget_iter->get_context) {
++(mget_iter->get_context->get_context_stats_.num_data_read);
}
FSReadRequest& req = read_reqs[req_idx];
Status s = req.status;
if (s.ok()) {
if ((req.result.size() != req.len) ||
(req_offset + BlockSizeWithTrailer(handle) > req.result.size())) {
s = Status::Corruption("truncated block read from " +
rep_->file->file_name() + " offset " +
std::to_string(handle.offset()) + ", expected " +
std::to_string(req.len) + " bytes, got " +
std::to_string(req.result.size()));
}
}
BlockContents raw_block_contents;
if (s.ok()) {
if (!use_shared_buffer) {
// We allocated a buffer for this block. Give ownership of it to
// BlockContents so it can free the memory
assert(req.result.data() == req.scratch);
assert(req.result.size() == BlockSizeWithTrailer(handle));
assert(req_offset == 0);
std::unique_ptr<char[]> raw_block(req.scratch);
raw_block_contents = BlockContents(std::move(raw_block), handle.size());
} else {
// We used the scratch buffer or direct io buffer
// which are shared by the blocks.
// raw_block_contents does not have the ownership.
raw_block_contents =
BlockContents(Slice(req.result.data() + req_offset, handle.size()));
}
#ifndef NDEBUG
raw_block_contents.is_raw_block = true;
#endif
if (options.verify_checksums) {
PERF_TIMER_GUARD(block_checksum_time);
const char* data = req.result.data();
// Since the scratch might be shared, the offset of the data block in
// the buffer might not be 0. req.result.data() only point to the
// begin address of each read request, we need to add the offset
// in each read request. Checksum is stored in the block trailer,
// beyond the payload size.
s = VerifyBlockChecksum(footer.checksum_type(), data + req_offset,
handle.size(), rep_->file->file_name(),
handle.offset());
TEST_SYNC_POINT_CALLBACK("RetrieveMultipleBlocks:VerifyChecksum", &s);
}
} else if (!use_shared_buffer) {
// Free the allocated scratch buffer.
delete[] req.scratch;
}
if (s.ok()) {
// When the blocks share the same underlying buffer (scratch or direct io
// buffer), we may need to manually copy the block into heap if the raw
// block has to be inserted into a cache. That falls into th following
// cases -
// 1. Raw block is not compressed, it needs to be inserted into the
// uncompressed block cache if there is one
// 2. If the raw block is compressed, it needs to be inserted into the
// compressed block cache if there is one
//
// In all other cases, the raw block is either uncompressed into a heap
// buffer or there is no cache at all.
CompressionType compression_type =
GetBlockCompressionType(raw_block_contents);
if (use_shared_buffer && (compression_type == kNoCompression ||
(compression_type != kNoCompression &&
rep_->table_options.block_cache_compressed))) {
Slice raw =
Slice(req.result.data() + req_offset, BlockSizeWithTrailer(handle));
raw_block_contents = BlockContents(
CopyBufferToHeap(GetMemoryAllocator(rep_->table_options), raw),
handle.size());
#ifndef NDEBUG
raw_block_contents.is_raw_block = true;
#endif
}
}
if (s.ok()) {
if (options.fill_cache) {
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet);
CachableEntry<Block>* block_entry = &(*results)[idx_in_batch];
// MaybeReadBlockAndLoadToCache will insert into the block caches if
// necessary. Since we're passing the raw block contents, it will
// avoid looking up the block cache
s = MaybeReadBlockAndLoadToCache(
nullptr, options, handle, uncompression_dict, /*wait=*/true,
/*for_compaction=*/false, block_entry, BlockType::kData,
mget_iter->get_context, &lookup_data_block_context,
&raw_block_contents);
// block_entry value could be null if no block cache is present, i.e
// BlockBasedTableOptions::no_block_cache is true and no compressed
// block cache is configured. In that case, fall
// through and set up the block explicitly
if (block_entry->GetValue() != nullptr) {
s.PermitUncheckedError();
continue;
}
}
CompressionType compression_type =
GetBlockCompressionType(raw_block_contents);
BlockContents contents;
if (compression_type != kNoCompression) {
UncompressionContext context(compression_type);
UncompressionInfo info(context, uncompression_dict, compression_type);
s = UncompressBlockContents(
info, req.result.data() + req_offset, handle.size(), &contents,
footer.format_version(), rep_->ioptions, memory_allocator);
} else {
// There are two cases here:
// 1) caller uses the shared buffer (scratch or direct io buffer);
// 2) we use the requst buffer.
// If scratch buffer or direct io buffer is used, we ensure that
// all raw blocks are copyed to the heap as single blocks. If scratch
// buffer is not used, we also have no combined read, so the raw
// block can be used directly.
contents = std::move(raw_block_contents);
}
if (s.ok()) {
(*results)[idx_in_batch].SetOwnedValue(new Block(
std::move(contents), read_amp_bytes_per_bit, ioptions.stats));
}
}
(*statuses)[idx_in_batch] = s;
}
}
template <typename TBlocklike>
Status BlockBasedTable::RetrieveBlock(
FilePrefetchBuffer* prefetch_buffer, const ReadOptions& ro,
@ -2525,443 +2251,6 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
return s;
}
using MultiGetRange = MultiGetContext::Range;
void BlockBasedTable::MultiGet(const ReadOptions& read_options,
const MultiGetRange* mget_range,
const SliceTransform* prefix_extractor,
bool skip_filters) {
if (mget_range->empty()) {
// Caller should ensure non-empty (performance bug)
assert(false);
return; // Nothing to do
}
FilterBlockReader* const filter =
!skip_filters ? rep_->filter.get() : nullptr;
MultiGetRange sst_file_range(*mget_range, mget_range->begin(),
mget_range->end());
// First check the full filter
// If full filter not useful, Then go into each block
const bool no_io = read_options.read_tier == kBlockCacheTier;
uint64_t tracing_mget_id = BlockCacheTraceHelper::kReservedGetId;
if (sst_file_range.begin()->get_context) {
tracing_mget_id = sst_file_range.begin()->get_context->get_tracing_get_id();
}
BlockCacheLookupContext lookup_context{
TableReaderCaller::kUserMultiGet, tracing_mget_id,
/*get_from_user_specified_snapshot=*/read_options.snapshot != nullptr};
FullFilterKeysMayMatch(filter, &sst_file_range, no_io, prefix_extractor,
&lookup_context);
if (!sst_file_range.empty()) {
IndexBlockIter iiter_on_stack;
// if prefix_extractor found in block differs from options, disable
// BlockPrefixIndex. Only do this check when index_type is kHashSearch.
bool need_upper_bound_check = false;
if (rep_->index_type == BlockBasedTableOptions::kHashSearch) {
need_upper_bound_check = PrefixExtractorChanged(prefix_extractor);
}
auto iiter =
NewIndexIterator(read_options, need_upper_bound_check, &iiter_on_stack,
sst_file_range.begin()->get_context, &lookup_context);
std::unique_ptr<InternalIteratorBase<IndexValue>> iiter_unique_ptr;
if (iiter != &iiter_on_stack) {
iiter_unique_ptr.reset(iiter);
}
uint64_t prev_offset = std::numeric_limits<uint64_t>::max();
autovector<BlockHandle, MultiGetContext::MAX_BATCH_SIZE> block_handles;
autovector<CachableEntry<Block>, MultiGetContext::MAX_BATCH_SIZE> results;
autovector<Status, MultiGetContext::MAX_BATCH_SIZE> statuses;
MultiGetContext::Mask reused_mask = 0;
char stack_buf[kMultiGetReadStackBufSize];
std::unique_ptr<char[]> block_buf;
{
MultiGetRange data_block_range(sst_file_range, sst_file_range.begin(),
sst_file_range.end());
std::vector<Cache::Handle*> cache_handles;
bool wait_for_cache_results = false;
CachableEntry<UncompressionDict> uncompression_dict;
Status uncompression_dict_status;
uncompression_dict_status.PermitUncheckedError();
bool uncompression_dict_inited = false;
size_t total_len = 0;
ReadOptions ro = read_options;
ro.read_tier = kBlockCacheTier;
for (auto miter = data_block_range.begin();
miter != data_block_range.end(); ++miter) {
const Slice& key = miter->ikey;
iiter->Seek(miter->ikey);
IndexValue v;
if (iiter->Valid()) {
v = iiter->value();
}
if (!iiter->Valid() ||
(!v.first_internal_key.empty() && !skip_filters &&
UserComparatorWrapper(rep_->internal_comparator.user_comparator())
.CompareWithoutTimestamp(
ExtractUserKey(key),
ExtractUserKey(v.first_internal_key)) < 0)) {
// The requested key falls between highest key in previous block and
// lowest key in current block.
if (!iiter->status().IsNotFound()) {
*(miter->s) = iiter->status();
}
data_block_range.SkipKey(miter);
sst_file_range.SkipKey(miter);
continue;
}
if (!uncompression_dict_inited && rep_->uncompression_dict_reader) {
uncompression_dict_status =
rep_->uncompression_dict_reader->GetOrReadUncompressionDictionary(
nullptr /* prefetch_buffer */, no_io,
read_options.verify_checksums,
sst_file_range.begin()->get_context, &lookup_context,
&uncompression_dict);
uncompression_dict_inited = true;
}
if (!uncompression_dict_status.ok()) {
assert(!uncompression_dict_status.IsNotFound());
*(miter->s) = uncompression_dict_status;
data_block_range.SkipKey(miter);
sst_file_range.SkipKey(miter);
continue;
}
statuses.emplace_back();
results.emplace_back();
if (v.handle.offset() == prev_offset) {
// This key can reuse the previous block (later on).
// Mark previous as "reused"
reused_mask |= MultiGetContext::Mask{1} << (block_handles.size() - 1);
// Use null handle to indicate this one reuses same block as
// previous.
block_handles.emplace_back(BlockHandle::NullBlockHandle());
continue;
}
// Lookup the cache for the given data block referenced by an index
// iterator value (i.e BlockHandle). If it exists in the cache,
// initialize block to the contents of the data block.
prev_offset = v.handle.offset();
BlockHandle handle = v.handle;
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet);
const UncompressionDict& dict = uncompression_dict.GetValue()
? *uncompression_dict.GetValue()
: UncompressionDict::GetEmptyDict();
Status s = RetrieveBlock(
nullptr, ro, handle, dict, &(results.back()), BlockType::kData,
miter->get_context, &lookup_data_block_context,
/* for_compaction */ false, /* use_cache */ true,
/* wait_for_cache */ false);
if (s.IsIncomplete()) {
s = Status::OK();
}
if (s.ok() && !results.back().IsEmpty()) {
// Since we have a valid handle, check the value. If its nullptr,
// it means the cache is waiting for the final result and we're
// supposed to call WaitAll() to wait for the result.
if (results.back().GetValue() != nullptr) {
// Found it in the cache. Add NULL handle to indicate there is
// nothing to read from disk.
if (results.back().GetCacheHandle()) {
results.back().UpdateCachedValue();
}
block_handles.emplace_back(BlockHandle::NullBlockHandle());
} else {
// We have to wait for the cache lookup to finish in the
// background, and then we may have to read the block from disk
// anyway
assert(results.back().GetCacheHandle());
wait_for_cache_results = true;
block_handles.emplace_back(handle);
cache_handles.emplace_back(results.back().GetCacheHandle());
}
} else {
block_handles.emplace_back(handle);
total_len += BlockSizeWithTrailer(handle);
}
}
if (wait_for_cache_results) {
Cache* block_cache = rep_->table_options.block_cache.get();
block_cache->WaitAll(cache_handles);
for (size_t i = 0; i < block_handles.size(); ++i) {
// If this block was a success or failure or not needed because
// the corresponding key is in the same block as a prior key, skip
if (block_handles[i] == BlockHandle::NullBlockHandle() ||
results[i].IsEmpty()) {
continue;
}
results[i].UpdateCachedValue();
void* val = results[i].GetValue();
if (!val) {
// The async cache lookup failed - could be due to an error
// or a false positive. We need to read the data block from
// the SST file
results[i].Reset();
total_len += BlockSizeWithTrailer(block_handles[i]);
} else {
block_handles[i] = BlockHandle::NullBlockHandle();
}
}
}
if (total_len) {
char* scratch = nullptr;
const UncompressionDict& dict = uncompression_dict.GetValue()
? *uncompression_dict.GetValue()
: UncompressionDict::GetEmptyDict();
assert(uncompression_dict_inited || !rep_->uncompression_dict_reader);
assert(uncompression_dict_status.ok());
// If using direct IO, then scratch is not used, so keep it nullptr.
// If the blocks need to be uncompressed and we don't need the
// compressed blocks, then we can use a contiguous block of
// memory to read in all the blocks as it will be temporary
// storage
// 1. If blocks are compressed and compressed block cache is there,
// alloc heap bufs
// 2. If blocks are uncompressed, alloc heap bufs
// 3. If blocks are compressed and no compressed block cache, use
// stack buf
if (!rep_->file->use_direct_io() &&
rep_->table_options.block_cache_compressed == nullptr &&
rep_->blocks_maybe_compressed) {
if (total_len <= kMultiGetReadStackBufSize) {
scratch = stack_buf;
} else {
scratch = new char[total_len];
block_buf.reset(scratch);
}
}
RetrieveMultipleBlocks(read_options, &data_block_range, &block_handles,
&statuses, &results, scratch, dict);
if (sst_file_range.begin()->get_context) {
++(sst_file_range.begin()
->get_context->get_context_stats_.num_sst_read);
}
}
}
DataBlockIter first_biter;
DataBlockIter next_biter;
size_t idx_in_batch = 0;
SharedCleanablePtr shared_cleanable;
for (auto miter = sst_file_range.begin(); miter != sst_file_range.end();
++miter) {
Status s;
GetContext* get_context = miter->get_context;
const Slice& key = miter->ikey;
bool matched = false; // if such user key matched a key in SST
bool done = false;
bool first_block = true;
do {
DataBlockIter* biter = nullptr;
bool reusing_prev_block;
bool later_reused;
uint64_t referenced_data_size = 0;
bool does_referenced_key_exist = false;
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet, tracing_mget_id,
/*get_from_user_specified_snapshot=*/read_options.snapshot !=
nullptr);
if (first_block) {
if (!block_handles[idx_in_batch].IsNull() ||
!results[idx_in_batch].IsEmpty()) {
first_biter.Invalidate(Status::OK());
NewDataBlockIterator<DataBlockIter>(
read_options, results[idx_in_batch], &first_biter,
statuses[idx_in_batch]);
reusing_prev_block = false;
} else {
// If handler is null and result is empty, then the status is never
// set, which should be the initial value: ok().
assert(statuses[idx_in_batch].ok());
reusing_prev_block = true;
}
biter = &first_biter;
later_reused =
(reused_mask & (MultiGetContext::Mask{1} << idx_in_batch)) != 0;
idx_in_batch++;
} else {
IndexValue v = iiter->value();
if (!v.first_internal_key.empty() && !skip_filters &&
UserComparatorWrapper(rep_->internal_comparator.user_comparator())
.CompareWithoutTimestamp(
ExtractUserKey(key),
ExtractUserKey(v.first_internal_key)) < 0) {
// The requested key falls between highest key in previous block and
// lowest key in current block.
break;
}
next_biter.Invalidate(Status::OK());
NewDataBlockIterator<DataBlockIter>(
read_options, iiter->value().handle, &next_biter,
BlockType::kData, get_context, &lookup_data_block_context,
Status(), nullptr);
biter = &next_biter;
reusing_prev_block = false;
later_reused = false;
}
if (read_options.read_tier == kBlockCacheTier &&
biter->status().IsIncomplete()) {
// couldn't get block from block_cache
// Update Saver.state to Found because we are only looking for
// whether we can guarantee the key is not there when "no_io" is set
get_context->MarkKeyMayExist();
break;
}
if (!biter->status().ok()) {
s = biter->status();
break;
}
bool may_exist = biter->SeekForGet(key);
if (!may_exist) {
// HashSeek cannot find the key this block and the the iter is not
// the end of the block, i.e. cannot be in the following blocks
// either. In this case, the seek_key cannot be found, so we break
// from the top level for-loop.
break;
}
// Reusing blocks complicates pinning/Cleanable, because the cache
// entry referenced by biter can only be released once all returned
// pinned values are released. This code previously did an extra
// block_cache Ref for each reuse, but that unnecessarily increases
// block cache contention. Instead we can use a variant of shared_ptr
// to release in block cache only once.
//
// Although the biter loop below might SaveValue multiple times for
// merges, just one value_pinner suffices, as MultiGet will merge
// the operands before returning to the API user.
Cleanable* value_pinner;
if (biter->IsValuePinned()) {
if (reusing_prev_block) {
// Note that we don't yet know if the MultiGet results will need
// to pin this block, so we might wrap a block for sharing and
// still end up with 1 (or 0) pinning ref. Not ideal but OK.
//
// Here we avoid adding redundant cleanups if we didn't end up
// delegating the cleanup from last time around.
if (!biter->HasCleanups()) {
assert(shared_cleanable.get());
if (later_reused) {
shared_cleanable.RegisterCopyWith(biter);
} else {
shared_cleanable.MoveAsCleanupTo(biter);
}
}
} else if (later_reused) {
assert(biter->HasCleanups());
// Make the existing cleanups on `biter` sharable:
shared_cleanable.Allocate();
// Move existing `biter` cleanup(s) to `shared_cleanable`
biter->DelegateCleanupsTo(&*shared_cleanable);
// Reference `shared_cleanable` as new cleanup for `biter`
shared_cleanable.RegisterCopyWith(biter);
}
assert(biter->HasCleanups());
value_pinner = biter;
} else {
value_pinner = nullptr;
}
// Call the *saver function on each entry/block until it returns false
for (; biter->Valid(); biter->Next()) {
ParsedInternalKey parsed_key;
Status pik_status = ParseInternalKey(
biter->key(), &parsed_key, false /* log_err_key */); // TODO
if (!pik_status.ok()) {
s = pik_status;
}
if (!get_context->SaveValue(parsed_key, biter->value(), &matched,
value_pinner)) {
if (get_context->State() == GetContext::GetState::kFound) {
does_referenced_key_exist = true;
referenced_data_size =
biter->key().size() + biter->value().size();
}
done = true;
break;
}
s = biter->status();
}
// Write the block cache access.
// XXX: There appear to be 'break' statements above that bypass this
// writing of the block cache trace record
if (block_cache_tracer_ && block_cache_tracer_->is_tracing_enabled() &&
!reusing_prev_block) {
// Avoid making copy of block_key, cf_name, and referenced_key when
// constructing the access record.
Slice referenced_key;
if (does_referenced_key_exist) {
referenced_key = biter->key();
} else {
referenced_key = key;
}
BlockCacheTraceRecord access_record(
rep_->ioptions.clock->NowMicros(),
/*block_key=*/"", lookup_data_block_context.block_type,
lookup_data_block_context.block_size, rep_->cf_id_for_tracing(),
/*cf_name=*/"", rep_->level_for_tracing(),
rep_->sst_number_for_tracing(), lookup_data_block_context.caller,
lookup_data_block_context.is_cache_hit,
lookup_data_block_context.no_insert,
lookup_data_block_context.get_id,
lookup_data_block_context.get_from_user_specified_snapshot,
/*referenced_key=*/"", referenced_data_size,
lookup_data_block_context.num_keys_in_block,
does_referenced_key_exist);
// TODO: Should handle status here?
block_cache_tracer_
->WriteBlockAccess(access_record,
lookup_data_block_context.block_key,
rep_->cf_name_for_tracing(), referenced_key)
.PermitUncheckedError();
}
s = biter->status();
if (done) {
// Avoid the extra Next which is expensive in two-level indexes
break;
}
if (first_block) {
iiter->Seek(key);
if (!iiter->Valid()) {
break;
}
}
first_block = false;
iiter->Next();
} while (iiter->Valid());
if (matched && filter != nullptr && !filter->IsBlockBased()) {
RecordTick(rep_->ioptions.stats, BLOOM_FILTER_FULL_TRUE_POSITIVE);
PERF_COUNTER_BY_LEVEL_ADD(bloom_filter_full_true_positive, 1,
rep_->level);
}
if (s.ok() && !iiter->status().IsNotFound()) {
s = iiter->status();
}
*(miter->s) = s;
}
#ifdef ROCKSDB_ASSERT_STATUS_CHECKED
// Not sure why we need to do it. Should investigate more.
for (auto& st : statuses) {
st.PermitUncheckedError();
}
#endif // ROCKSDB_ASSERT_STATUS_CHECKED
}
}
Status BlockBasedTable::Prefetch(const Slice* const begin,
const Slice* const end) {
auto& comparator = rep_->internal_comparator;

13
table/block_based/block_based_table_reader.h
View File

@ -31,6 +31,7 @@
#include "table/table_reader.h"
#include "table/two_level_iterator.h"
#include "trace_replay/block_cache_tracer.h"
#include "util/coro_utils.h"
#include "util/hash_containers.h"
namespace ROCKSDB_NAMESPACE {
@ -141,10 +142,11 @@ class BlockBasedTable : public TableReader {
GetContext* get_context, const SliceTransform* prefix_extractor,
bool skip_filters = false) override;
void MultiGet(const ReadOptions& readOptions,
DECLARE_SYNC_AND_ASYNC_OVERRIDE(void, MultiGet,
const ReadOptions& readOptions,
const MultiGetContext::Range* mget_range,
const SliceTransform* prefix_extractor,
bool skip_filters = false) override;
bool skip_filters = false);
// Pre-fetch the disk blocks that correspond to the key range specified by
// (kbegin, kend). The call will return error status in the event of
@ -366,13 +368,14 @@ class BlockBasedTable : public TableReader {
bool for_compaction, bool use_cache,
bool wait_for_cache) const;
void RetrieveMultipleBlocks(
const ReadOptions& options, const MultiGetRange* batch,
DECLARE_SYNC_AND_ASYNC_CONST(
void, RetrieveMultipleBlocks, const ReadOptions& options,
const MultiGetRange* batch,
const autovector<BlockHandle, MultiGetContext::MAX_BATCH_SIZE>* handles,
autovector<Status, MultiGetContext::MAX_BATCH_SIZE>* statuses,
autovector<CachableEntry<Block>, MultiGetContext::MAX_BATCH_SIZE>*
results,
char* scratch, const UncompressionDict& uncompression_dict) const;
char* scratch, const UncompressionDict& uncompression_dict);
// Get the iterator from the index reader.
//

748
table/block_based/block_based_table_reader_sync_and_async.h Normal file
View File

@ -0,0 +1,748 @@
// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "util/async_file_reader.h"
#include "util/coro_utils.h"
#if defined(WITHOUT_COROUTINES) || \
(defined(USE_COROUTINES) && defined(WITH_COROUTINES))
namespace ROCKSDB_NAMESPACE {
// This function reads multiple data blocks from disk using Env::MultiRead()
// and optionally inserts them into the block cache. It uses the scratch
// buffer provided by the caller, which is contiguous. If scratch is a nullptr
// it allocates a separate buffer for each block. Typically, if the blocks
// need to be uncompressed and there is no compressed block cache, callers
// can allocate a temporary scratch buffer in order to minimize memory
// allocations.
// If options.fill_cache is true, it inserts the blocks into cache. If its
// false and scratch is non-null and the blocks are uncompressed, it copies
// the buffers to heap. In any case, the CachableEntry<Block> returned will
// own the data bytes.
// If compression is enabled and also there is no compressed block cache,
// the adjacent blocks are read out in one IO (combined read)
// batch - A MultiGetRange with only those keys with unique data blocks not
// found in cache
// handles - A vector of block handles. Some of them me be NULL handles
// scratch - An optional contiguous buffer to read compressed blocks into
DEFINE_SYNC_AND_ASYNC(void, BlockBasedTable::RetrieveMultipleBlocks)
(const ReadOptions& options, const MultiGetRange* batch,
const autovector<BlockHandle, MultiGetContext::MAX_BATCH_SIZE>* handles,
autovector<Status, MultiGetContext::MAX_BATCH_SIZE>* statuses,
autovector<CachableEntry<Block>, MultiGetContext::MAX_BATCH_SIZE>* results,
char* scratch, const UncompressionDict& uncompression_dict) const {
RandomAccessFileReader* file = rep_->file.get();
const Footer& footer = rep_->footer;
const ImmutableOptions& ioptions = rep_->ioptions;
size_t read_amp_bytes_per_bit = rep_->table_options.read_amp_bytes_per_bit;
MemoryAllocator* memory_allocator = GetMemoryAllocator(rep_->table_options);
if (ioptions.allow_mmap_reads) {
size_t idx_in_batch = 0;
for (auto mget_iter = batch->begin(); mget_iter != batch->end();
++mget_iter, ++idx_in_batch) {
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet);
const BlockHandle& handle = (*handles)[idx_in_batch];
if (handle.IsNull()) {
continue;
}
(*statuses)[idx_in_batch] =
RetrieveBlock(nullptr, options, handle, uncompression_dict,
&(*results)[idx_in_batch], BlockType::kData,
mget_iter->get_context, &lookup_data_block_context,
/* for_compaction */ false, /* use_cache */ true,
/* wait_for_cache */ true);
}
CO_RETURN;
}
// In direct IO mode, blocks share the direct io buffer.
// Otherwise, blocks share the scratch buffer.
const bool use_shared_buffer = file->use_direct_io() || scratch != nullptr;
autovector<FSReadRequest, MultiGetContext::MAX_BATCH_SIZE> read_reqs;
size_t buf_offset = 0;
size_t idx_in_batch = 0;
uint64_t prev_offset = 0;
size_t prev_len = 0;
autovector<size_t, MultiGetContext::MAX_BATCH_SIZE> req_idx_for_block;
autovector<size_t, MultiGetContext::MAX_BATCH_SIZE> req_offset_for_block;
for (auto mget_iter = batch->begin(); mget_iter != batch->end();
++mget_iter, ++idx_in_batch) {
const BlockHandle& handle = (*handles)[idx_in_batch];
if (handle.IsNull()) {
continue;
}
size_t prev_end = static_cast<size_t>(prev_offset) + prev_len;
// If current block is adjacent to the previous one, at the same time,
// compression is enabled and there is no compressed cache, we combine
// the two block read as one.
// We don't combine block reads here in direct IO mode, because when doing
// direct IO read, the block requests will be realigned and merged when
// necessary.
if (use_shared_buffer && !file->use_direct_io() &&
prev_end == handle.offset()) {
req_offset_for_block.emplace_back(prev_len);
prev_len += BlockSizeWithTrailer(handle);
} else {
// No compression or current block and previous one is not adjacent:
// Step 1, create a new request for previous blocks
if (prev_len != 0) {
FSReadRequest req;
req.offset = prev_offset;
req.len = prev_len;
if (file->use_direct_io()) {
req.scratch = nullptr;
} else if (use_shared_buffer) {
req.scratch = scratch + buf_offset;
buf_offset += req.len;
} else {
req.scratch = new char[req.len];
}
read_reqs.emplace_back(req);
}
// Step 2, remeber the previous block info
prev_offset = handle.offset();
prev_len = BlockSizeWithTrailer(handle);
req_offset_for_block.emplace_back(0);
}
req_idx_for_block.emplace_back(read_reqs.size());
PERF_COUNTER_ADD(block_read_count, 1);
PERF_COUNTER_ADD(block_read_byte, BlockSizeWithTrailer(handle));
}
// Handle the last block and process the pending last request
if (prev_len != 0) {
FSReadRequest req;
req.offset = prev_offset;
req.len = prev_len;
if (file->use_direct_io()) {
req.scratch = nullptr;
} else if (use_shared_buffer) {
req.scratch = scratch + buf_offset;
} else {
req.scratch = new char[req.len];
}
read_reqs.emplace_back(req);
}
AlignedBuf direct_io_buf;
{
IOOptions opts;
IOStatus s = file->PrepareIOOptions(options, opts);
if (s.ok()) {
#if defined(WITHOUT_COROUTINES)
s = file->MultiRead(opts, &read_reqs[0], read_reqs.size(), &direct_io_buf,
options.rate_limiter_priority);
#else // WITH_COROUTINES
co_await batch->context()->reader().MultiReadAsync(
file, opts, &read_reqs[0], read_reqs.size(), &direct_io_buf);
#endif // WITH_COROUTINES
}
if (!s.ok()) {
// Discard all the results in this batch if there is any time out
// or overall MultiRead error
for (FSReadRequest& req : read_reqs) {
req.status = s;
}
}
}
idx_in_batch = 0;
size_t valid_batch_idx = 0;
for (auto mget_iter = batch->begin(); mget_iter != batch->end();
++mget_iter, ++idx_in_batch) {
const BlockHandle& handle = (*handles)[idx_in_batch];
if (handle.IsNull()) {
continue;
}
assert(valid_batch_idx < req_idx_for_block.size());
assert(valid_batch_idx < req_offset_for_block.size());
assert(req_idx_for_block[valid_batch_idx] < read_reqs.size());
size_t& req_idx = req_idx_for_block[valid_batch_idx];
size_t& req_offset = req_offset_for_block[valid_batch_idx];
valid_batch_idx++;
if (mget_iter->get_context) {
++(mget_iter->get_context->get_context_stats_.num_data_read);
}
FSReadRequest& req = read_reqs[req_idx];
Status s = req.status;
if (s.ok()) {
if ((req.result.size() != req.len) ||
(req_offset + BlockSizeWithTrailer(handle) > req.result.size())) {
s = Status::Corruption("truncated block read from " +
rep_->file->file_name() + " offset " +
std::to_string(handle.offset()) + ", expected " +
std::to_string(req.len) + " bytes, got " +
std::to_string(req.result.size()));
}
}
BlockContents raw_block_contents;
if (s.ok()) {
if (!use_shared_buffer) {
// We allocated a buffer for this block. Give ownership of it to
// BlockContents so it can free the memory
assert(req.result.data() == req.scratch);
assert(req.result.size() == BlockSizeWithTrailer(handle));
assert(req_offset == 0);
std::unique_ptr<char[]> raw_block(req.scratch);
raw_block_contents = BlockContents(std::move(raw_block), handle.size());
} else {
// We used the scratch buffer or direct io buffer
// which are shared by the blocks.
// raw_block_contents does not have the ownership.
raw_block_contents =
BlockContents(Slice(req.result.data() + req_offset, handle.size()));
}
#ifndef NDEBUG
raw_block_contents.is_raw_block = true;
#endif
if (options.verify_checksums) {
PERF_TIMER_GUARD(block_checksum_time);
const char* data = req.result.data();
// Since the scratch might be shared, the offset of the data block in
// the buffer might not be 0. req.result.data() only point to the
// begin address of each read request, we need to add the offset
// in each read request. Checksum is stored in the block trailer,
// beyond the payload size.
s = VerifyBlockChecksum(footer.checksum_type(), data + req_offset,
handle.size(), rep_->file->file_name(),
handle.offset());
TEST_SYNC_POINT_CALLBACK("RetrieveMultipleBlocks:VerifyChecksum", &s);
}
} else if (!use_shared_buffer) {
// Free the allocated scratch buffer.
delete[] req.scratch;
}
if (s.ok()) {
// When the blocks share the same underlying buffer (scratch or direct io
// buffer), we may need to manually copy the block into heap if the raw
// block has to be inserted into a cache. That falls into th following
// cases -
// 1. Raw block is not compressed, it needs to be inserted into the
// uncompressed block cache if there is one
// 2. If the raw block is compressed, it needs to be inserted into the
// compressed block cache if there is one
//
// In all other cases, the raw block is either uncompressed into a heap
// buffer or there is no cache at all.
CompressionType compression_type =
GetBlockCompressionType(raw_block_contents);
if (use_shared_buffer && (compression_type == kNoCompression ||
(compression_type != kNoCompression &&
rep_->table_options.block_cache_compressed))) {
Slice raw =
Slice(req.result.data() + req_offset, BlockSizeWithTrailer(handle));
raw_block_contents = BlockContents(
CopyBufferToHeap(GetMemoryAllocator(rep_->table_options), raw),
handle.size());
#ifndef NDEBUG
raw_block_contents.is_raw_block = true;
#endif
}
}
if (s.ok()) {
if (options.fill_cache) {
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet);
CachableEntry<Block>* block_entry = &(*results)[idx_in_batch];
// MaybeReadBlockAndLoadToCache will insert into the block caches if
// necessary. Since we're passing the raw block contents, it will
// avoid looking up the block cache
s = MaybeReadBlockAndLoadToCache(
nullptr, options, handle, uncompression_dict, /*wait=*/true,
/*for_compaction=*/false, block_entry, BlockType::kData,
mget_iter->get_context, &lookup_data_block_context,
&raw_block_contents);
// block_entry value could be null if no block cache is present, i.e
// BlockBasedTableOptions::no_block_cache is true and no compressed
// block cache is configured. In that case, fall
// through and set up the block explicitly
if (block_entry->GetValue() != nullptr) {
s.PermitUncheckedError();
continue;
}
}
CompressionType compression_type =
GetBlockCompressionType(raw_block_contents);
BlockContents contents;
if (compression_type != kNoCompression) {
UncompressionContext context(compression_type);
UncompressionInfo info(context, uncompression_dict, compression_type);
s = UncompressBlockContents(
info, req.result.data() + req_offset, handle.size(), &contents,
footer.format_version(), rep_->ioptions, memory_allocator);
} else {
// There are two cases here:
// 1) caller uses the shared buffer (scratch or direct io buffer);
// 2) we use the requst buffer.
// If scratch buffer or direct io buffer is used, we ensure that
// all raw blocks are copyed to the heap as single blocks. If scratch
// buffer is not used, we also have no combined read, so the raw
// block can be used directly.
contents = std::move(raw_block_contents);
}
if (s.ok()) {
(*results)[idx_in_batch].SetOwnedValue(new Block(
std::move(contents), read_amp_bytes_per_bit, ioptions.stats));
}
}
(*statuses)[idx_in_batch] = s;
}
}
using MultiGetRange = MultiGetContext::Range;
DEFINE_SYNC_AND_ASYNC(void, BlockBasedTable::MultiGet)
(const ReadOptions& read_options, const MultiGetRange* mget_range,
const SliceTransform* prefix_extractor, bool skip_filters) {
if (mget_range->empty()) {
// Caller should ensure non-empty (performance bug)
assert(false);
CO_RETURN; // Nothing to do
}
FilterBlockReader* const filter =
!skip_filters ? rep_->filter.get() : nullptr;
MultiGetRange sst_file_range(*mget_range, mget_range->begin(),
mget_range->end());
// First check the full filter
// If full filter not useful, Then go into each block
const bool no_io = read_options.read_tier == kBlockCacheTier;
uint64_t tracing_mget_id = BlockCacheTraceHelper::kReservedGetId;
if (sst_file_range.begin()->get_context) {
tracing_mget_id = sst_file_range.begin()->get_context->get_tracing_get_id();
}
BlockCacheLookupContext lookup_context{
TableReaderCaller::kUserMultiGet, tracing_mget_id,
/*_get_from_user_specified_snapshot=*/read_options.snapshot != nullptr};
FullFilterKeysMayMatch(filter, &sst_file_range, no_io, prefix_extractor,
&lookup_context);
if (!sst_file_range.empty()) {
IndexBlockIter iiter_on_stack;
// if prefix_extractor found in block differs from options, disable
// BlockPrefixIndex. Only do this check when index_type is kHashSearch.
bool need_upper_bound_check = false;
if (rep_->index_type == BlockBasedTableOptions::kHashSearch) {
need_upper_bound_check = PrefixExtractorChanged(prefix_extractor);
}
auto iiter =
NewIndexIterator(read_options, need_upper_bound_check, &iiter_on_stack,
sst_file_range.begin()->get_context, &lookup_context);
std::unique_ptr<InternalIteratorBase<IndexValue>> iiter_unique_ptr;
if (iiter != &iiter_on_stack) {
iiter_unique_ptr.reset(iiter);
}
uint64_t prev_offset = std::numeric_limits<uint64_t>::max();
autovector<BlockHandle, MultiGetContext::MAX_BATCH_SIZE> block_handles;
autovector<CachableEntry<Block>, MultiGetContext::MAX_BATCH_SIZE> results;
autovector<Status, MultiGetContext::MAX_BATCH_SIZE> statuses;
MultiGetContext::Mask reused_mask = 0;
char stack_buf[kMultiGetReadStackBufSize];
std::unique_ptr<char[]> block_buf;
{
MultiGetRange data_block_range(sst_file_range, sst_file_range.begin(),
sst_file_range.end());
std::vector<Cache::Handle*> cache_handles;
bool wait_for_cache_results = false;
CachableEntry<UncompressionDict> uncompression_dict;
Status uncompression_dict_status;
uncompression_dict_status.PermitUncheckedError();
bool uncompression_dict_inited = false;
size_t total_len = 0;
ReadOptions ro = read_options;
ro.read_tier = kBlockCacheTier;
for (auto miter = data_block_range.begin();
miter != data_block_range.end(); ++miter) {
const Slice& key = miter->ikey;
iiter->Seek(miter->ikey);
IndexValue v;
if (iiter->Valid()) {
v = iiter->value();
}
if (!iiter->Valid() ||
(!v.first_internal_key.empty() && !skip_filters &&
UserComparatorWrapper(rep_->internal_comparator.user_comparator())
.CompareWithoutTimestamp(
ExtractUserKey(key),
ExtractUserKey(v.first_internal_key)) < 0)) {
// The requested key falls between highest key in previous block and
// lowest key in current block.
if (!iiter->status().IsNotFound()) {
*(miter->s) = iiter->status();
}
data_block_range.SkipKey(miter);
sst_file_range.SkipKey(miter);
continue;
}
if (!uncompression_dict_inited && rep_->uncompression_dict_reader) {
uncompression_dict_status =
rep_->uncompression_dict_reader->GetOrReadUncompressionDictionary(
nullptr /* prefetch_buffer */, no_io,
read_options.verify_checksums,
sst_file_range.begin()->get_context, &lookup_context,
&uncompression_dict);
uncompression_dict_inited = true;
}
if (!uncompression_dict_status.ok()) {
assert(!uncompression_dict_status.IsNotFound());
*(miter->s) = uncompression_dict_status;
data_block_range.SkipKey(miter);
sst_file_range.SkipKey(miter);
continue;
}
statuses.emplace_back();
results.emplace_back();
if (v.handle.offset() == prev_offset) {
// This key can reuse the previous block (later on).
// Mark previous as "reused"
reused_mask |= MultiGetContext::Mask{1} << (block_handles.size() - 1);
// Use null handle to indicate this one reuses same block as
// previous.
block_handles.emplace_back(BlockHandle::NullBlockHandle());
continue;
}
// Lookup the cache for the given data block referenced by an index
// iterator value (i.e BlockHandle). If it exists in the cache,
// initialize block to the contents of the data block.
prev_offset = v.handle.offset();
BlockHandle handle = v.handle;
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet);
const UncompressionDict& dict = uncompression_dict.GetValue()
? *uncompression_dict.GetValue()
: UncompressionDict::GetEmptyDict();
Status s = RetrieveBlock(
nullptr, ro, handle, dict, &(results.back()), BlockType::kData,
miter->get_context, &lookup_data_block_context,
/* for_compaction */ false, /* use_cache */ true,
/* wait_for_cache */ false);
if (s.IsIncomplete()) {
s = Status::OK();
}
if (s.ok() && !results.back().IsEmpty()) {
// Since we have a valid handle, check the value. If its nullptr,
// it means the cache is waiting for the final result and we're
// supposed to call WaitAll() to wait for the result.
if (results.back().GetValue() != nullptr) {
// Found it in the cache. Add NULL handle to indicate there is
// nothing to read from disk.
if (results.back().GetCacheHandle()) {
results.back().UpdateCachedValue();
}
block_handles.emplace_back(BlockHandle::NullBlockHandle());
} else {
// We have to wait for the cache lookup to finish in the
// background, and then we may have to read the block from disk
// anyway
assert(results.back().GetCacheHandle());
wait_for_cache_results = true;
block_handles.emplace_back(handle);
cache_handles.emplace_back(results.back().GetCacheHandle());
}
} else {
block_handles.emplace_back(handle);
total_len += BlockSizeWithTrailer(handle);
}
}
if (wait_for_cache_results) {
Cache* block_cache = rep_->table_options.block_cache.get();
block_cache->WaitAll(cache_handles);
for (size_t i = 0; i < block_handles.size(); ++i) {
// If this block was a success or failure or not needed because
// the corresponding key is in the same block as a prior key, skip
if (block_handles[i] == BlockHandle::NullBlockHandle() ||
results[i].IsEmpty()) {
continue;
}
results[i].UpdateCachedValue();
void* val = results[i].GetValue();
if (!val) {
// The async cache lookup failed - could be due to an error
// or a false positive. We need to read the data block from
// the SST file
results[i].Reset();
total_len += BlockSizeWithTrailer(block_handles[i]);
} else {
block_handles[i] = BlockHandle::NullBlockHandle();
}
}
}
if (total_len) {
char* scratch = nullptr;
const UncompressionDict& dict = uncompression_dict.GetValue()
? *uncompression_dict.GetValue()
: UncompressionDict::GetEmptyDict();
assert(uncompression_dict_inited || !rep_->uncompression_dict_reader);
assert(uncompression_dict_status.ok());
// If using direct IO, then scratch is not used, so keep it nullptr.
// If the blocks need to be uncompressed and we don't need the
// compressed blocks, then we can use a contiguous block of
// memory to read in all the blocks as it will be temporary
// storage
// 1. If blocks are compressed and compressed block cache is there,
// alloc heap bufs
// 2. If blocks are uncompressed, alloc heap bufs
// 3. If blocks are compressed and no compressed block cache, use
// stack buf
if (!rep_->file->use_direct_io() &&
rep_->table_options.block_cache_compressed == nullptr &&
rep_->blocks_maybe_compressed) {
if (total_len <= kMultiGetReadStackBufSize) {
scratch = stack_buf;
} else {
scratch = new char[total_len];
block_buf.reset(scratch);
}
}
CO_AWAIT(RetrieveMultipleBlocks)
(read_options, &data_block_range, &block_handles, &statuses, &results,
scratch, dict);
if (sst_file_range.begin()->get_context) {
++(sst_file_range.begin()
->get_context->get_context_stats_.num_sst_read);
}
}
}
DataBlockIter first_biter;
DataBlockIter next_biter;
size_t idx_in_batch = 0;
SharedCleanablePtr shared_cleanable;
for (auto miter = sst_file_range.begin(); miter != sst_file_range.end();
++miter) {
Status s;
GetContext* get_context = miter->get_context;
const Slice& key = miter->ikey;
bool matched = false; // if such user key matched a key in SST
bool done = false;
bool first_block = true;
do {
DataBlockIter* biter = nullptr;
bool reusing_prev_block;
bool later_reused;
uint64_t referenced_data_size = 0;
bool does_referenced_key_exist = false;
BlockCacheLookupContext lookup_data_block_context(
TableReaderCaller::kUserMultiGet, tracing_mget_id,
/*_get_from_user_specified_snapshot=*/read_options.snapshot !=
nullptr);
if (first_block) {
if (!block_handles[idx_in_batch].IsNull() ||
!results[idx_in_batch].IsEmpty()) {
first_biter.Invalidate(Status::OK());
NewDataBlockIterator<DataBlockIter>(
read_options, results[idx_in_batch], &first_biter,
statuses[idx_in_batch]);
reusing_prev_block = false;
} else {
// If handler is null and result is empty, then the status is never
// set, which should be the initial value: ok().
assert(statuses[idx_in_batch].ok());
reusing_prev_block = true;
}
biter = &first_biter;
later_reused =
(reused_mask & (MultiGetContext::Mask{1} << idx_in_batch)) != 0;
idx_in_batch++;
} else {
IndexValue v = iiter->value();
if (!v.first_internal_key.empty() && !skip_filters &&
UserComparatorWrapper(rep_->internal_comparator.user_comparator())
.CompareWithoutTimestamp(
ExtractUserKey(key),
ExtractUserKey(v.first_internal_key)) < 0) {
// The requested key falls between highest key in previous block and
// lowest key in current block.
break;
}
next_biter.Invalidate(Status::OK());
NewDataBlockIterator<DataBlockIter>(
read_options, iiter->value().handle, &next_biter,
BlockType::kData, get_context, &lookup_data_block_context,
Status(), nullptr);
biter = &next_biter;
reusing_prev_block = false;
later_reused = false;
}
if (read_options.read_tier == kBlockCacheTier &&
biter->status().IsIncomplete()) {
// couldn't get block from block_cache
// Update Saver.state to Found because we are only looking for
// whether we can guarantee the key is not there when "no_io" is set
get_context->MarkKeyMayExist();
break;
}
if (!biter->status().ok()) {
s = biter->status();
break;
}
bool may_exist = biter->SeekForGet(key);
if (!may_exist) {
// HashSeek cannot find the key this block and the the iter is not
// the end of the block, i.e. cannot be in the following blocks
// either. In this case, the seek_key cannot be found, so we break
// from the top level for-loop.
break;
}
// Reusing blocks complicates pinning/Cleanable, because the cache
// entry referenced by biter can only be released once all returned
// pinned values are released. This code previously did an extra
// block_cache Ref for each reuse, but that unnecessarily increases
// block cache contention. Instead we can use a variant of shared_ptr
// to release in block cache only once.
//
// Although the biter loop below might SaveValue multiple times for
// merges, just one value_pinner suffices, as MultiGet will merge
// the operands before returning to the API user.
Cleanable* value_pinner;
if (biter->IsValuePinned()) {
if (reusing_prev_block) {
// Note that we don't yet know if the MultiGet results will need
// to pin this block, so we might wrap a block for sharing and
// still end up with 1 (or 0) pinning ref. Not ideal but OK.
//
// Here we avoid adding redundant cleanups if we didn't end up
// delegating the cleanup from last time around.
if (!biter->HasCleanups()) {
assert(shared_cleanable.get());
if (later_reused) {
shared_cleanable.RegisterCopyWith(biter);
} else {
shared_cleanable.MoveAsCleanupTo(biter);
}
}
} else if (later_reused) {
assert(biter->HasCleanups());
// Make the existing cleanups on `biter` sharable:
shared_cleanable.Allocate();
// Move existing `biter` cleanup(s) to `shared_cleanable`
biter->DelegateCleanupsTo(&*shared_cleanable);
// Reference `shared_cleanable` as new cleanup for `biter`
shared_cleanable.RegisterCopyWith(biter);
}
assert(biter->HasCleanups());
value_pinner = biter;
} else {
value_pinner = nullptr;
}
// Call the *saver function on each entry/block until it returns false
for (; biter->Valid(); biter->Next()) {
ParsedInternalKey parsed_key;
Status pik_status = ParseInternalKey(
biter->key(), &parsed_key, false /* log_err_key */); // TODO
if (!pik_status.ok()) {
s = pik_status;
}
if (!get_context->SaveValue(parsed_key, biter->value(), &matched,
value_pinner)) {
if (get_context->State() == GetContext::GetState::kFound) {
does_referenced_key_exist = true;
referenced_data_size =
biter->key().size() + biter->value().size();
}
done = true;
break;
}
s = biter->status();
}
// Write the block cache access.
// XXX: There appear to be 'break' statements above that bypass this
// writing of the block cache trace record
if (block_cache_tracer_ && block_cache_tracer_->is_tracing_enabled() &&
!reusing_prev_block) {
// Avoid making copy of block_key, cf_name, and referenced_key when
// constructing the access record.
Slice referenced_key;
if (does_referenced_key_exist) {
referenced_key = biter->key();
} else {
referenced_key = key;
}
BlockCacheTraceRecord access_record(
rep_->ioptions.clock->NowMicros(),
/*_block_key=*/"", lookup_data_block_context.block_type,
lookup_data_block_context.block_size, rep_->cf_id_for_tracing(),
/*_cf_name=*/"", rep_->level_for_tracing(),
rep_->sst_number_for_tracing(), lookup_data_block_context.caller,
lookup_data_block_context.is_cache_hit,
lookup_data_block_context.no_insert,
lookup_data_block_context.get_id,
lookup_data_block_context.get_from_user_specified_snapshot,
/*_referenced_key=*/"", referenced_data_size,
lookup_data_block_context.num_keys_in_block,
does_referenced_key_exist);
// TODO: Should handle status here?
block_cache_tracer_
->WriteBlockAccess(access_record,
lookup_data_block_context.block_key,
rep_->cf_name_for_tracing(), referenced_key)
.PermitUncheckedError();
}
s = biter->status();
if (done) {
// Avoid the extra Next which is expensive in two-level indexes
break;
}
if (first_block) {
iiter->Seek(key);
if (!iiter->Valid()) {
break;
}
}
first_block = false;
iiter->Next();
} while (iiter->Valid());
if (matched && filter != nullptr && !filter->IsBlockBased()) {
RecordTick(rep_->ioptions.stats, BLOOM_FILTER_FULL_TRUE_POSITIVE);
PERF_COUNTER_BY_LEVEL_ADD(bloom_filter_full_true_positive, 1,
rep_->level);
}
if (s.ok() && !iiter->status().IsNotFound()) {
s = iiter->status();
}
*(miter->s) = s;
}
#ifdef ROCKSDB_ASSERT_STATUS_CHECKED
// Not sure why we need to do it. Should investigate more.
for (auto& st : statuses) {
st.PermitUncheckedError();
}
#endif // ROCKSDB_ASSERT_STATUS_CHECKED
}
}
} // namespace ROCKSDB_NAMESPACE
#endif

3
table/block_based/block_based_table_reader_test.cc
View File

@ -259,7 +259,8 @@ TEST_P(BlockBasedTableReaderTest, MultiGet) {
for (auto& key_ctx : key_context) {
sorted_keys.emplace_back(&key_ctx);
}
MultiGetContext ctx(&sorted_keys, 0, sorted_keys.size(), 0, ReadOptions());
MultiGetContext ctx(&sorted_keys, 0, sorted_keys.size(), 0, ReadOptions(),
fs_.get(), nullptr);
// Execute MultiGet.
MultiGetContext::Range range = ctx.GetMultiGetRange();

48
table/multiget_context.h
View File

@ -14,8 +14,10 @@
#include "rocksdb/env.h"
#include "rocksdb/statistics.h"
#include "rocksdb/types.h"
#include "util/async_file_reader.h"
#include "util/autovector.h"
#include "util/math.h"
#include "util/single_thread_executor.h"
namespace ROCKSDB_NAMESPACE {
class GetContext;
@ -104,11 +106,20 @@ class MultiGetContext {
MultiGetContext(autovector<KeyContext*, MAX_BATCH_SIZE>* sorted_keys,
size_t begin, size_t num_keys, SequenceNumber snapshot,
const ReadOptions& read_opts)
const ReadOptions& read_opts, FileSystem* fs,
Statistics* stats)
: num_keys_(num_keys),
value_mask_(0),
value_size_(0),
lookup_key_ptr_(reinterpret_cast<LookupKey*>(lookup_key_stack_buf)) {
lookup_key_ptr_(reinterpret_cast<LookupKey*>(lookup_key_stack_buf))
#if USE_COROUTINES
,
reader_(fs, stats),
executor_(reader_)
#endif // USE_COROUTINES
{
(void)fs;
(void)stats;
assert(num_keys <= MAX_BATCH_SIZE);
if (num_keys > MAX_LOOKUP_KEYS_ON_STACK) {
lookup_key_heap_buf.reset(new char[sizeof(LookupKey) * num_keys]);
@ -135,6 +146,12 @@ class MultiGetContext {
}
}
#if USE_COROUTINES
SingleThreadExecutor& executor() { return executor_; }
AsyncFileReader& reader() { return reader_; }
#endif // USE_COROUTINES
private:
static const int MAX_LOOKUP_KEYS_ON_STACK = 16;
alignas(alignof(LookupKey))
@ -145,6 +162,10 @@ class MultiGetContext {
uint64_t value_size_;
std::unique_ptr<char[]> lookup_key_heap_buf;
LookupKey* lookup_key_ptr_;
#if USE_COROUTINES
AsyncFileReader reader_;
SingleThreadExecutor executor_;
#endif // USE_COROUTINES
public:
// MultiGetContext::Range - Specifies a range of keys, by start and end index,
@ -267,6 +288,20 @@ class MultiGetContext {
void AddValueSize(uint64_t value_size) { ctx_->value_size_ += value_size; }
MultiGetContext* context() const { return ctx_; }
Range Suffix(const Range& other) const {
size_t other_last = other.FindLastRemaining();
size_t my_last = FindLastRemaining();
if (my_last > other_last) {
return Range(*this, Iterator(this, other_last),
Iterator(this, my_last));
} else {
return Range(*this, begin(), begin());
}
}
private:
friend MultiGetContext;
MultiGetContext* ctx_;
@ -283,6 +318,15 @@ class MultiGetContext {
return (((Mask{1} << end_) - 1) & ~((Mask{1} << start_) - 1) &
~(ctx_->value_mask_ | skip_mask_));
}
size_t FindLastRemaining() const {
Mask mask = RemainingMask();
size_t index = (mask >>= start_) ? start_ : 0;
while (mask >>= 1) {
index++;
}
return index;
}
};
// Return the initial range that encompasses all the keys in the batch

13
table/table_reader.h
View File

@ -10,6 +10,10 @@
#pragma once
#include <memory>
#include "db/range_tombstone_fragmenter.h"
#if USE_COROUTINES
#include "folly/experimental/coro/Coroutine.h"
#include "folly/experimental/coro/Task.h"
#endif
#include "rocksdb/slice_transform.h"
#include "table/get_context.h"
#include "table/internal_iterator.h"
@ -120,6 +124,15 @@ class TableReader {
}
}
#if USE_COROUTINES
virtual folly::coro::Task<void> MultiGetCoroutine(
const ReadOptions& readOptions, const MultiGetContext::Range* mget_range,
const SliceTransform* prefix_extractor, bool skip_filters = false) {
MultiGet(readOptions, mget_range, prefix_extractor, skip_filters);
co_return;
}
#endif // USE_COROUTINES
// Prefetch data corresponding to a give range of keys
// Typically this functionality is required for table implementations that
// persists the data on a non volatile storage medium like disk/SSD

72
util/async_file_reader.cc Normal file
View File

@ -0,0 +1,72 @@
// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#if USE_COROUTINES
#include "util/async_file_reader.h"
namespace ROCKSDB_NAMESPACE {
bool AsyncFileReader::MultiReadAsyncImpl(ReadAwaiter* awaiter) {
if (tail_) {
tail_->next_ = awaiter;
}
tail_ = awaiter;
if (!head_) {
head_ = awaiter;
}
num_reqs_ += awaiter->num_reqs_;
awaiter->io_handle_.resize(awaiter->num_reqs_);
awaiter->del_fn_.resize(awaiter->num_reqs_);
for (size_t i = 0; i < awaiter->num_reqs_; ++i) {
awaiter->file_
->ReadAsync(
awaiter->read_reqs_[i], awaiter->opts_,
[](const FSReadRequest& req, void* cb_arg) {
FSReadRequest* read_req = static_cast<FSReadRequest*>(cb_arg);
read_req->status = req.status;
read_req->result = req.result;
},
&awaiter->read_reqs_[i], &awaiter->io_handle_[i],
&awaiter->del_fn_[i], Env::IOPriority::IO_TOTAL)
.PermitUncheckedError();
}
return true;
}
void AsyncFileReader::Wait() {
if (!head_) {
return;
}
ReadAwaiter* waiter;
std::vector<void*> io_handles;
io_handles.reserve(num_reqs_);
waiter = head_;
do {
for (size_t i = 0; i < waiter->num_reqs_; ++i) {
if (waiter->io_handle_[i]) {
io_handles.push_back(waiter->io_handle_[i]);
}
}
} while (waiter != tail_ && (waiter = waiter->next_));
if (io_handles.size() > 0) {
StopWatch sw(SystemClock::Default().get(), stats_, POLL_WAIT_MICROS);
fs_->Poll(io_handles, io_handles.size()).PermitUncheckedError();
}
do {
waiter = head_;
head_ = waiter->next_;
for (size_t i = 0; i < waiter->num_reqs_; ++i) {
if (waiter->io_handle_[i] && waiter->del_fn_[i]) {
waiter->del_fn_[i](waiter->io_handle_[i]);
}
}
waiter->awaiting_coro_.resume();
} while (waiter != tail_);
head_ = tail_ = nullptr;
RecordInHistogram(stats_, MULTIGET_IO_BATCH_SIZE, num_reqs_);
num_reqs_ = 0;
}
} // namespace ROCKSDB_NAMESPACE
#endif // USE_COROUTINES

143
util/async_file_reader.h Normal file
View File

@ -0,0 +1,143 @@
// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#pragma once
#if USE_COROUTINES
#include "file/random_access_file_reader.h"
#include "folly/experimental/coro/ViaIfAsync.h"
#include "port/port.h"
#include "rocksdb/file_system.h"
#include "rocksdb/statistics.h"
#include "util/autovector.h"
#include "util/stop_watch.h"
namespace ROCKSDB_NAMESPACE {
class SingleThreadExecutor;
// AsyncFileReader implements the Awaitable concept, which allows calling
// coroutines to co_await it. When the AsyncFileReader Awaitable is
// resumed, it initiates the fie reads requested by the awaiting caller
// by calling RandomAccessFileReader's ReadAsync. It then suspends the
// awaiting coroutine. The suspended awaiter is later resumed by Wait().
class AsyncFileReader {
class ReadAwaiter;
template <typename Awaiter>
class ReadOperation;
public:
AsyncFileReader(FileSystem* fs, Statistics* stats) : fs_(fs), stats_(stats) {}
~AsyncFileReader() {}
ReadOperation<ReadAwaiter> MultiReadAsync(RandomAccessFileReader* file,
const IOOptions& opts,
FSReadRequest* read_reqs,
size_t num_reqs,
AlignedBuf* aligned_buf) noexcept {
return ReadOperation<ReadAwaiter>{*this, file, opts,
read_reqs, num_reqs, aligned_buf};
}
private:
friend SingleThreadExecutor;
// Implementation of the Awaitable concept
class ReadAwaiter {
public:
explicit ReadAwaiter(AsyncFileReader& reader, RandomAccessFileReader* file,
const IOOptions& opts, FSReadRequest* read_reqs,
size_t num_reqs, AlignedBuf* /*aligned_buf*/) noexcept
: reader_(reader),
file_(file),
opts_(opts),
read_reqs_(read_reqs),
num_reqs_(num_reqs) {}
bool await_ready() noexcept { return false; }
// A return value of true means suspend the awaiter (calling coroutine). The
// awaiting_coro parameter is the handle of the awaiter. The handle can be
// resumed later, so we cache it here.
bool await_suspend(
std::experimental::coroutine_handle<> awaiting_coro) noexcept {
awaiting_coro_ = awaiting_coro;
// MultiReadAsyncImpl always returns true, so caller will be suspended
return reader_.MultiReadAsyncImpl(this);
}
void await_resume() noexcept {}
private:
friend AsyncFileReader;
// The parameters passed to MultiReadAsync are cached here when the caller
// calls MultiReadAsync. Later, when the execution of this awaitable is
// started, these are used to do the actual IO
AsyncFileReader& reader_;
RandomAccessFileReader* file_;
const IOOptions& opts_;
FSReadRequest* read_reqs_;
size_t num_reqs_;
autovector<void*, 32> io_handle_;
autovector<IOHandleDeleter, 32> del_fn_;
std::experimental::coroutine_handle<> awaiting_coro_;
// Use this to link to the next ReadAwaiter in the suspended coroutine
// list. The head and tail of the list are tracked by AsyncFileReader.
// We use this approach rather than an STL container in order to avoid
// extra memory allocations. The coroutine call already allocates a
// ReadAwaiter object.
ReadAwaiter* next_;
};
// An instance of ReadOperation is returned to the caller of MultiGetAsync.
// This represents an awaitable that can be started later.
template <typename Awaiter>
class ReadOperation {
public:
explicit ReadOperation(AsyncFileReader& reader,
RandomAccessFileReader* file, const IOOptions& opts,
FSReadRequest* read_reqs, size_t num_reqs,
AlignedBuf* aligned_buf) noexcept
: reader_(reader),
file_(file),
opts_(opts),
read_reqs_(read_reqs),
num_reqs_(num_reqs),
aligned_buf_(aligned_buf) {}
auto viaIfAsync(folly::Executor::KeepAlive<> executor) const {
return folly::coro::co_viaIfAsync(
std::move(executor),
Awaiter{reader_, file_, opts_, read_reqs_, num_reqs_, aligned_buf_});
}
private:
AsyncFileReader& reader_;
RandomAccessFileReader* file_;
const IOOptions& opts_;
FSReadRequest* read_reqs_;
size_t num_reqs_;
AlignedBuf* aligned_buf_;
};
// This function does the actual work when this awaitable starts execution
bool MultiReadAsyncImpl(ReadAwaiter* awaiter);
// Called by the SingleThreadExecutor to poll for async IO completion.
// This also resumes the awaiting coroutines.
void Wait();
// Head of the queue of awaiters waiting for async IO completion
ReadAwaiter* head_ = nullptr;
// Tail of the awaiter queue
ReadAwaiter* tail_ = nullptr;
// Total number of pending async IOs
size_t num_reqs_ = 0;
FileSystem* fs_;
Statistics* stats_;
};
} // namespace ROCKSDB_NAMESPACE
#endif // USE_COROUTINES

111
util/coro_utils.h Normal file
View File

@ -0,0 +1,111 @@
// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#if defined(USE_COROUTINES)
#include "folly/experimental/coro/Coroutine.h"
#include "folly/experimental/coro/Task.h"
#endif
#include "rocksdb/rocksdb_namespace.h"
// This file has two sctions. The first section applies to all instances of
// header file inclusion and has an include guard. The second section is
// meant for multiple inclusions in the same source file, and is idempotent.
namespace ROCKSDB_NAMESPACE {
#ifndef UTIL_CORO_UTILS_H_
#define UTIL_CORO_UTILS_H_
#if defined(USE_COROUTINES)
// The follwoing macros expand to regular and coroutine function
// declarations for a given function
#define DECLARE_SYNC_AND_ASYNC(__ret_type__, __func_name__, ...) \
__ret_type__ __func_name__(__VA_ARGS__); \
folly::coro::Task<__ret_type__> __func_name__##Coroutine(__VA_ARGS__);
#define DECLARE_SYNC_AND_ASYNC_OVERRIDE(__ret_type__, __func_name__, ...) \
__ret_type__ __func_name__(__VA_ARGS__) override; \
folly::coro::Task<__ret_type__> __func_name__##Coroutine(__VA_ARGS__) \
override;
#define DECLARE_SYNC_AND_ASYNC_CONST(__ret_type__, __func_name__, ...) \
__ret_type__ __func_name__(__VA_ARGS__) const; \
folly::coro::Task<__ret_type__> __func_name__##Coroutine(__VA_ARGS__) const;
constexpr bool using_coroutines() { return true; }
#else // !USE_COROUTINES
// The follwoing macros expand to a regular function declaration for a given
// function
#define DECLARE_SYNC_AND_ASYNC(__ret_type__, __func_name__, ...) \
__ret_type__ __func_name__(__VA_ARGS__);
#define DECLARE_SYNC_AND_ASYNC_OVERRIDE(__ret_type__, __func_name__, ...) \
__ret_type__ __func_name__(__VA_ARGS__) override;
#define DECLARE_SYNC_AND_ASYNC_CONST(__ret_type__, __func_name__, ...) \
__ret_type__ __func_name__(__VA_ARGS__) const;
constexpr bool using_coroutines() { return false; }
#endif // USE_COROUTINES
#endif // UTIL_CORO_UTILS_H_
// The following section of the file is meant to be included twice in a
// source file - once defining WITH_COROUTINES and once defining
// WITHOUT_COROUTINES
#undef DEFINE_SYNC_AND_ASYNC
#undef CO_AWAIT
#undef CO_RETURN
#if defined(WITH_COROUTINES) && defined(USE_COROUTINES)
// This macro should be used in the beginning of the function
// definition. The declaration should have been done using one of the
// DECLARE_SYNC_AND_ASYNC* macros. It expands to the return type and
// the function name with the Coroutine suffix. For example -
// DEFINE_SYNC_AND_ASYNC(int, foo)(bool bar) {}
// would expand to -
// folly::coro::Task<int> fooCoroutine(bool bar) {}
#define DEFINE_SYNC_AND_ASYNC(__ret_type__, __func_name__) \
folly::coro::Task<__ret_type__> __func_name__##Coroutine
// This macro should be used to call a function that might be a
// coroutine. It expands to the correct function name and prefixes
// the co_await operator if necessary. For example -
// s = CO_AWAIT(foo)(true);
// if the code is compiled WITH_COROUTINES, would expand to
// s = co_await fooCoroutine(true);
// if compiled WITHOUT_COROUTINES, would expand to
// s = foo(true);
#define CO_AWAIT(__func_name__) co_await __func_name__##Coroutine
#define CO_RETURN co_return
#elif defined(WITHOUT_COROUTINES)
// This macro should be used in the beginning of the function
// definition. The declaration should have been done using one of the
// DECLARE_SYNC_AND_ASYNC* macros. It expands to the return type and
// the function name without the Coroutine suffix. For example -
// DEFINE_SYNC_AND_ASYNC(int, foo)(bool bar) {}
// would expand to -
// int foo(bool bar) {}
#define DEFINE_SYNC_AND_ASYNC(__ret_type__, __func_name__) \
__ret_type__ __func_name__
// This macro should be used to call a function that might be a
// coroutine. It expands to the correct function name and prefixes
// the co_await operator if necessary. For example -
// s = CO_AWAIT(foo)(true);
// if the code is compiled WITH_COROUTINES, would expand to
// s = co_await fooCoroutine(true);
// if compiled WITHOUT_COROUTINES, would expand to
// s = foo(true);
#define CO_AWAIT(__func_name__) __func_name__
#define CO_RETURN return
#endif // DO_NOT_USE_COROUTINES
} // namespace ROCKSDB_NAMESPACE

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// Copyright (c) Meta Platforms, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#pragma once
#if USE_COROUTINES
#include <atomic>
#include "folly/CPortability.h"
#include "folly/CppAttributes.h"
#include "folly/Executor.h"
#include "util/async_file_reader.h"
namespace ROCKSDB_NAMESPACE {
// Implements a simple executor that runs callback functions in the same
// thread, unlike CPUThreadExecutor which may schedule the callback on
// another thread. Runs in a tight loop calling the queued callbacks,
// and polls for async IO completions when idle. The completions will
// resume suspended coroutines and they get added to the queue, which
// will get picked up by this loop.
// Any possibility of deadlock is precluded because the file system
// guarantees that async IO completion callbacks will not be scheduled
// to run in this thread or this executor.
class SingleThreadExecutor : public folly::Executor {
public:
explicit SingleThreadExecutor(AsyncFileReader& reader)
: reader_(reader), busy_(false) {}
void add(folly::Func callback) override {
auto& q = q_;
q.push(std::move(callback));
if (q.size() == 1 && !busy_) {
while (!q.empty()) {
q.front()();
q.pop();
if (q.empty()) {
// Prevent recursion, as the Wait may queue resumed coroutines
busy_ = true;
reader_.Wait();
busy_ = false;
}
}
}
}
private:
std::queue<folly::Func> q_;
AsyncFileReader& reader_;
bool busy_;
};
} // namespace ROCKSDB_NAMESPACE
#endif // USE_COROUTINES