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rocksdb/file/prefetch_test.cc
akankshamahajan c77b50a4fd Add AsyncIO support for tuning readahead_size by block cache lookup (#11936) 
Summary:
Add support for tuning of readahead_size by block cache lookup for async_io.

**Design/ Implementation** -

**BlockBasedTableIterator.cc** -

`BlockCacheLookupForReadAheadSize` callback API lookups in the block cache and tries to reduce the start
and end offset passed. This function looks into the block cache for the blocks between `start_offset`
and `end_offset` and add all the handles in the queue.

It then iterates from the end in the handles to find first miss block and update the end offset to that block.
It also iterates from the start and find first miss block and update the start offset to that block.

```
_read_curr_block_ argument : True if this call was due to miss in the cache and caller wants to read that block
                             synchronously.
                             False if current call is to prefetch additional data in extra buffers
                            (due to ReadAsync call in FilePrefetchBuffer)
```
In case there is no data to be read in that callback (because of upper_bound or all blocks are in cache),
it updates start and end offset to be equal and that `FilePrefetchBuffer` interprets that as 0 length to be read.

**FilePrefetchBuffer.cc** -

FilePrefetchBuffer calls the callback - `ReadAheadSizeTuning` and pass the start and end offset to that
callback to get updated start and end offset to read based on cache hits/misses.

1. In case of Read calls (when offset passed to FilePrefetchBuffer is on cache miss and that data needs to be read), _read_curr_block_ is passed true.
2. In case of ReadAsync calls, when buffer is all consumed and can go for additional prefetching,  the start offset passed is the initial end offset of prev buffer (without any updated offset based on cache hit/miss).

Foreg. if following are the data blocks with cache hit/miss and start offset
and Read API found miss on DB1 and based on readahead_size (50)  it passes end offset to be 50.
 [DB1 - miss- 0 ] [DB2 - hit -10] [DB3 - miss -20] [DB4 - miss-30] [DB5 - hit-40]
 [DB6 - hit-50] [DB7 - miss-60] [DB8 - miss - 70] [DB9 - hit - 80] [DB6 - hit 90]

- For Read call - updated start offset remains 0 but end offset updates to DB4, as DB5 is in cache.
- Read calls saves initial end offset 50 as that was meant to be prefetched.
- Now for next ReadAsync call - the start offset will be 50 (previous buffer initial end offset) and based on readahead_size, end offset will be 100
- On callback, because of cache hits - callback will update the start offset to 60 and end offset to 80 to read only 2 data blocks (DB7 and DB8).
- And for that ReadAsync call - initial end offset will be set to 100 which will again used by next ReadAsync call as start offset.
-  `initial_end_offset_` in `BufferInfo` is used to save the initial end offset of that buffer.

- If let's say DB5 and DB6 overlaps in 2 buffers (because of alignment), `prev_buf_end_offset` is passed to make sure already prefetched data is not prefetched again in second buffer.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11936

Test Plan:
- Ran crash_test several times.
-  New unit tests added.

Reviewed By: anand1976

Differential Revision: D50906217

Pulled By: akankshamahajan15

fbshipit-source-id: 0d75d3c98274e98aa34901b201b8fb05232139cf
2023-12-06 13:48:15 -08:00

3507 lines
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// Copyright (c) 2011-present, Facebook, Inc. 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 "db/db_test_util.h"
#include "file/file_prefetch_buffer.h"
#include "file/file_util.h"
#include "rocksdb/file_system.h"
#include "test_util/sync_point.h"
#ifdef GFLAGS
#include "tools/io_tracer_parser_tool.h"
#endif
#include "util/random.h"
namespace {
static bool enable_io_uring = true;
extern "C" bool RocksDbIOUringEnable() { return enable_io_uring; }
} // namespace
namespace ROCKSDB_NAMESPACE {
class MockFS;
class MockRandomAccessFile : public FSRandomAccessFileOwnerWrapper {
public:
MockRandomAccessFile(std::unique_ptr<FSRandomAccessFile>& file,
bool support_prefetch, std::atomic_int& prefetch_count,
bool small_buffer_alignment = false)
: FSRandomAccessFileOwnerWrapper(std::move(file)),
support_prefetch_(support_prefetch),
prefetch_count_(prefetch_count),
small_buffer_alignment_(small_buffer_alignment) {}
IOStatus Prefetch(uint64_t offset, size_t n, const IOOptions& options,
IODebugContext* dbg) override {
if (support_prefetch_) {
prefetch_count_.fetch_add(1);
return target()->Prefetch(offset, n, options, dbg);
} else {
return IOStatus::NotSupported("Prefetch not supported");
}
}
size_t GetRequiredBufferAlignment() const override {
return small_buffer_alignment_
? 1
: FSRandomAccessFileOwnerWrapper::GetRequiredBufferAlignment();
}
private:
const bool support_prefetch_;
std::atomic_int& prefetch_count_;
const bool small_buffer_alignment_;
};
class MockFS : public FileSystemWrapper {
public:
explicit MockFS(const std::shared_ptr<FileSystem>& wrapped,
bool support_prefetch, bool small_buffer_alignment = false)
: FileSystemWrapper(wrapped),
support_prefetch_(support_prefetch),
small_buffer_alignment_(small_buffer_alignment) {}
static const char* kClassName() { return "MockFS"; }
const char* Name() const override { return kClassName(); }
IOStatus NewRandomAccessFile(const std::string& fname,
const FileOptions& opts,
std::unique_ptr<FSRandomAccessFile>* result,
IODebugContext* dbg) override {
std::unique_ptr<FSRandomAccessFile> file;
IOStatus s;
s = target()->NewRandomAccessFile(fname, opts, &file, dbg);
result->reset(new MockRandomAccessFile(
file, support_prefetch_, prefetch_count_, small_buffer_alignment_));
return s;
}
void ClearPrefetchCount() { prefetch_count_ = 0; }
bool IsPrefetchCalled() { return prefetch_count_ > 0; }
int GetPrefetchCount() {
return prefetch_count_.load(std::memory_order_relaxed);
}
private:
const bool support_prefetch_;
const bool small_buffer_alignment_;
std::atomic_int prefetch_count_{0};
};
class PrefetchTest
: public DBTestBase,
public ::testing::WithParamInterface<std::tuple<bool, bool>> {
public:
PrefetchTest() : DBTestBase("prefetch_test", true) {}
virtual void SetGenericOptions(Env* env, bool use_direct_io,
Options& options) {
options = CurrentOptions();
options.write_buffer_size = 1024;
options.create_if_missing = true;
options.compression = kNoCompression;
options.env = env;
options.disable_auto_compactions = true;
if (use_direct_io) {
options.use_direct_reads = true;
options.use_direct_io_for_flush_and_compaction = true;
}
}
void SetBlockBasedTableOptions(BlockBasedTableOptions& table_options) {
table_options.no_block_cache = true;
table_options.cache_index_and_filter_blocks = false;
table_options.metadata_block_size = 1024;
table_options.index_type =
BlockBasedTableOptions::IndexType::kTwoLevelIndexSearch;
}
};
INSTANTIATE_TEST_CASE_P(PrefetchTest, PrefetchTest,
::testing::Combine(::testing::Bool(),
::testing::Bool()));
std::string BuildKey(int num, std::string postfix = "") {
return "my_key_" + std::to_string(num) + postfix;
}
// This test verifies the following basic functionalities of prefetching:
// (1) If underline file system supports prefetch, and directIO is not enabled
// make sure prefetch() is called and FilePrefetchBuffer is not used.
// (2) If underline file system doesn't support prefetch, or directIO is
// enabled, make sure prefetch() is not called and FilePrefetchBuffer is
// used.
// (3) Measure read bytes, hit and miss of SST's tail prefetching during table
// open.
TEST_P(PrefetchTest, Basic) {
// First param is if the mockFS support_prefetch or not
bool support_prefetch =
std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), support_prefetch);
// Second param is if directIO is enabled or not
bool use_direct_io = std::get<1>(GetParam());
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
const int kNumKeys = 1100;
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
// create first key range
WriteBatch batch;
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), "v1"));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(db_->Flush(FlushOptions()));
// create second key range
batch.Clear();
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i, "key2"), "v2"));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(db_->Flush(FlushOptions()));
// delete second key range
batch.Clear();
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Delete(BuildKey(i, "key2")));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(db_->Flush(FlushOptions()));
std::vector<LiveFileMetaData> metadata;
db_->GetLiveFilesMetaData(&metadata);
const size_t num_file = metadata.size();
// To verify SST file tail prefetch (once per file) during flush output
// verification
if (support_prefetch && !use_direct_io) {
ASSERT_TRUE(fs->IsPrefetchCalled());
ASSERT_EQ(num_file, fs->GetPrefetchCount());
ASSERT_EQ(0, buff_prefetch_count);
fs->ClearPrefetchCount();
} else {
ASSERT_FALSE(fs->IsPrefetchCalled());
ASSERT_EQ(buff_prefetch_count, num_file);
buff_prefetch_count = 0;
}
// compact database
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
HistogramData prev_table_open_prefetch_tail_read;
options.statistics->histogramData(TABLE_OPEN_PREFETCH_TAIL_READ_BYTES,
&prev_table_open_prefetch_tail_read);
const uint64_t prev_table_open_prefetch_tail_miss =
options.statistics->getTickerCount(TABLE_OPEN_PREFETCH_TAIL_MISS);
const uint64_t prev_table_open_prefetch_tail_hit =
options.statistics->getTickerCount(TABLE_OPEN_PREFETCH_TAIL_HIT);
// commenting out the line below causes the example to work correctly
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
HistogramData cur_table_open_prefetch_tail_read;
options.statistics->histogramData(TABLE_OPEN_PREFETCH_TAIL_READ_BYTES,
&cur_table_open_prefetch_tail_read);
const uint64_t cur_table_open_prefetch_tail_miss =
options.statistics->getTickerCount(TABLE_OPEN_PREFETCH_TAIL_MISS);
const uint64_t cur_table_open_prefetch_tail_hit =
options.statistics->getTickerCount(TABLE_OPEN_PREFETCH_TAIL_HIT);
// To verify prefetch during compaction input read
if (support_prefetch && !use_direct_io) {
ASSERT_TRUE(fs->IsPrefetchCalled());
// To rule out false positive by the SST file tail prefetch during
// compaction output verification
ASSERT_GT(fs->GetPrefetchCount(), 1);
ASSERT_EQ(0, buff_prefetch_count);
fs->ClearPrefetchCount();
} else {
ASSERT_FALSE(fs->IsPrefetchCalled());
// To rule out false positive by the SST file tail prefetch during
// compaction output verification
ASSERT_GT(buff_prefetch_count, 1);
buff_prefetch_count = 0;
ASSERT_GT(cur_table_open_prefetch_tail_read.count,
prev_table_open_prefetch_tail_read.count);
ASSERT_GT(cur_table_open_prefetch_tail_hit,
prev_table_open_prefetch_tail_hit);
ASSERT_GE(cur_table_open_prefetch_tail_miss,
prev_table_open_prefetch_tail_miss);
}
// count the keys
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
num_keys++;
}
ASSERT_OK(iter->status());
(void)num_keys;
}
// To verify prefetch during user scan
if (support_prefetch && !use_direct_io) {
ASSERT_TRUE(fs->IsPrefetchCalled());
fs->ClearPrefetchCount();
ASSERT_EQ(0, buff_prefetch_count);
} else {
ASSERT_FALSE(fs->IsPrefetchCalled());
ASSERT_GT(buff_prefetch_count, 0);
buff_prefetch_count = 0;
}
Close();
}
class PrefetchTailTest : public PrefetchTest {
public:
bool SupportPrefetch() const {
return std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
}
bool UseDirectIO() const { return std::get<1>(GetParam()); }
bool UseFilePrefetchBuffer() const {
return !SupportPrefetch() || UseDirectIO();
}
Env* GetEnv(bool small_buffer_alignment = false) const {
std::shared_ptr<MockFS> fs = std::make_shared<MockFS>(
env_->GetFileSystem(), SupportPrefetch(), small_buffer_alignment);
return new CompositeEnvWrapper(env_, fs);
}
void SetGenericOptions(Env* env, bool use_direct_io,
Options& options) override {
PrefetchTest::SetGenericOptions(env, use_direct_io, options);
options.statistics = CreateDBStatistics();
}
void SetBlockBasedTableOptions(
BlockBasedTableOptions& table_options, bool partition_filters = true,
uint64_t metadata_block_size =
BlockBasedTableOptions().metadata_block_size,
bool use_small_cache = false) {
table_options.index_type = BlockBasedTableOptions::kTwoLevelIndexSearch;
table_options.partition_filters = partition_filters;
if (table_options.partition_filters) {
table_options.filter_policy.reset(NewBloomFilterPolicy(10, false));
}
table_options.metadata_block_size = metadata_block_size;
if (use_small_cache) {
LRUCacheOptions co;
co.capacity = 1;
std::shared_ptr<Cache> cache = NewLRUCache(co);
table_options.block_cache = cache;
}
}
int64_t GetNumIndexPartition() const {
int64_t index_partition_counts = 0;
TablePropertiesCollection all_table_props;
assert(db_->GetPropertiesOfAllTables(&all_table_props).ok());
for (const auto& name_and_table_props : all_table_props) {
const auto& table_props = name_and_table_props.second;
index_partition_counts += table_props->index_partitions;
}
return index_partition_counts;
}
};
INSTANTIATE_TEST_CASE_P(PrefetchTailTest, PrefetchTailTest,
::testing::Combine(::testing::Bool(),
::testing::Bool()));
TEST_P(PrefetchTailTest, Basic) {
std::unique_ptr<Env> env(GetEnv());
Options options;
SetGenericOptions(env.get(), UseDirectIO(), options);
BlockBasedTableOptions bbto;
SetBlockBasedTableOptions(bbto);
options.table_factory.reset(NewBlockBasedTableFactory(bbto));
Status s = TryReopen(options);
if (UseDirectIO() && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
ROCKSDB_GTEST_BYPASS("Direct IO is not supported");
return;
} else {
ASSERT_OK(s);
}
ASSERT_OK(Put("k1", "v1"));
HistogramData pre_flush_file_read;
options.statistics->histogramData(FILE_READ_FLUSH_MICROS,
&pre_flush_file_read);
ASSERT_OK(Flush());
HistogramData post_flush_file_read;
options.statistics->histogramData(FILE_READ_FLUSH_MICROS,
&post_flush_file_read);
if (UseFilePrefetchBuffer()) {
// `PartitionedFilterBlockReader/PartitionIndexReader::CacheDependencies()`
// should read from the prefetched tail in file prefetch buffer instead of
// initiating extra SST reads. Therefore `BlockBasedTable::PrefetchTail()`
// should be the only SST read in table verification during flush.
ASSERT_EQ(post_flush_file_read.count - pre_flush_file_read.count, 1);
} else {
// Without the prefetched tail in file prefetch buffer,
// `PartitionedFilterBlockReader/PartitionIndexReader::CacheDependencies()`
// will initiate extra SST reads
ASSERT_GT(post_flush_file_read.count - pre_flush_file_read.count, 1);
}
ASSERT_OK(Put("k1", "v2"));
ASSERT_OK(Put("k2", "v2"));
ASSERT_OK(Flush());
CompactRangeOptions cro;
HistogramData pre_compaction_file_read;
options.statistics->histogramData(FILE_READ_COMPACTION_MICROS,
&pre_compaction_file_read);
ASSERT_OK(db_->CompactRange(cro, nullptr, nullptr));
HistogramData post_compaction_file_read;
options.statistics->histogramData(FILE_READ_COMPACTION_MICROS,
&post_compaction_file_read);
if (UseFilePrefetchBuffer()) {
// `PartitionedFilterBlockReader/PartitionIndexReader::CacheDependencies()`
// should read from the prefetched tail in file prefetch buffer instead of
// initiating extra SST reads.
//
// Therefore the 3 reads are
// (1) `ProcessKeyValueCompaction()` of input file 1
// (2) `ProcessKeyValueCompaction()` of input file 2
// (3) `BlockBasedTable::PrefetchTail()` of output file during table
// verification in compaction
ASSERT_EQ(post_compaction_file_read.count - pre_compaction_file_read.count,
3);
} else {
// Without the prefetched tail in file prefetch buffer,
// `PartitionedFilterBlockReader/PartitionIndexReader::CacheDependencies()`
// as well as reading other parts of the tail (e.g, footer, table
// properties..) will initiate extra SST reads
ASSERT_GT(post_compaction_file_read.count - pre_compaction_file_read.count,
3);
}
Close();
}
TEST_P(PrefetchTailTest, UpgradeToTailSizeInManifest) {
if (!UseFilePrefetchBuffer()) {
ROCKSDB_GTEST_BYPASS(
"Upgrade to tail size in manifest is only relevant when RocksDB file "
"prefetch buffer is used.");
}
if (UseDirectIO()) {
ROCKSDB_GTEST_BYPASS(
"To simplify testing logics with setting file's buffer alignment to "
"be "
"1, direct IO is required to be disabled.");
}
std::unique_ptr<Env> env(GetEnv(true /* small_buffer_alignment */));
Options options;
SetGenericOptions(env.get(), false /* use_direct_io*/, options);
options.max_open_files = -1;
options.write_buffer_size = 1024 * 1024;
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options, false /* partition_filters */,
1 /* metadata_block_size*/,
true /* use_small_cache */);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
SyncPoint::GetInstance()->EnableProcessing();
// To simulate a pre-upgrade DB where file tail size is not recorded in
// manifest
SyncPoint::GetInstance()->SetCallBack(
"FileMetaData::FileMetaData", [&](void* arg) {
FileMetaData* meta = static_cast<FileMetaData*>(arg);
meta->tail_size = 0;
});
ASSERT_OK(TryReopen(options));
for (int i = 0; i < 10000; ++i) {
ASSERT_OK(Put("k" + std::to_string(i), "v"));
}
ASSERT_OK(Flush());
SyncPoint::GetInstance()->ClearAllCallBacks();
// To simulate a DB undergoing the upgrade where tail size to prefetch is
// inferred to be a small number for files with no tail size recorded in
// manifest.
// "1" is chosen to be such number so that with `small_buffer_alignment ==
// true` and `use_small_cache == true`, it would have caused one file read
// per index partition during db open if the upgrade is done wrong.
SyncPoint::GetInstance()->SetCallBack(
"BlockBasedTable::Open::TailPrefetchLen", [&](void* arg) {
std::pair<size_t*, size_t*>* prefetch_off_len_pair =
static_cast<std::pair<size_t*, size_t*>*>(arg);
size_t* prefetch_off = prefetch_off_len_pair->first;
size_t* tail_size = prefetch_off_len_pair->second;
const size_t file_size = *prefetch_off + *tail_size;
*tail_size = 1;
*prefetch_off = file_size - (*tail_size);
});
ASSERT_OK(TryReopen(options));
SyncPoint::GetInstance()->ClearAllCallBacks();
SyncPoint::GetInstance()->DisableProcessing();
HistogramData db_open_file_read;
options.statistics->histogramData(FILE_READ_DB_OPEN_MICROS,
&db_open_file_read);
int64_t num_index_partition = GetNumIndexPartition();
// If the upgrade is done right, db open will prefetch all the index
// partitions at once, instead of doing one read per partition.
// That is, together with `metadata_block_size == 1`, there will be more
// index partitions than number of non index partitions reads.
ASSERT_LT(db_open_file_read.count, num_index_partition);
Close();
}
// This test verifies BlockBasedTableOptions.max_auto_readahead_size is
// configured dynamically.
TEST_P(PrefetchTest, ConfigureAutoMaxReadaheadSize) {
// First param is if the mockFS support_prefetch or not
bool support_prefetch =
std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), support_prefetch);
// Second param is if directIO is enabled or not
bool use_direct_io = std::get<1>(GetParam());
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
table_options.max_auto_readahead_size = 0;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
// DB open will create table readers unless we reduce the table cache
// capacity. SanitizeOptions will set max_open_files to minimum of 20. Table
// cache is allocated with max_open_files - 10 as capacity. So override
// max_open_files to 10 so table cache capacity will become 0. This will
// prevent file open during DB open and force the file to be opened during
// Iteration.
SyncPoint::GetInstance()->SetCallBack(
"SanitizeOptions::AfterChangeMaxOpenFiles", [&](void* arg) {
int* max_open_files = (int*)arg;
*max_open_files = 11;
});
SyncPoint::GetInstance()->EnableProcessing();
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
Random rnd(309);
int key_count = 0;
const int num_keys_per_level = 100;
// Level 0 : Keys in range [0, 99], Level 1:[100, 199], Level 2:[200, 299].
for (int level = 2; level >= 0; level--) {
key_count = level * num_keys_per_level;
for (int i = 0; i < num_keys_per_level; ++i) {
ASSERT_OK(Put(Key(key_count++), rnd.RandomString(500)));
}
ASSERT_OK(Flush());
MoveFilesToLevel(level);
}
Close();
std::vector<int> buff_prefectch_level_count = {0, 0, 0};
ASSERT_OK(TryReopen(options));
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
fs->ClearPrefetchCount();
buff_prefetch_count = 0;
for (int level = 2; level >= 0; level--) {
key_count = level * num_keys_per_level;
switch (level) {
case 0:
// max_auto_readahead_size is set 0 so data and index blocks are not
// prefetched.
ASSERT_OK(db_->SetOptions(
{{"block_based_table_factory", "{max_auto_readahead_size=0;}"}}));
break;
case 1:
// max_auto_readahead_size is set less than
// initial_auto_readahead_size. So readahead_size remains equal to
// max_auto_readahead_size.
ASSERT_OK(db_->SetOptions({{"block_based_table_factory",
"{max_auto_readahead_size=4096;}"}}));
break;
case 2:
ASSERT_OK(db_->SetOptions({{"block_based_table_factory",
"{max_auto_readahead_size=65536;}"}}));
break;
default:
assert(false);
}
for (int i = 0; i < num_keys_per_level; ++i) {
iter->Seek(Key(key_count++));
iter->Next();
}
buff_prefectch_level_count[level] = buff_prefetch_count;
if (support_prefetch && !use_direct_io) {
if (level == 0) {
ASSERT_FALSE(fs->IsPrefetchCalled());
} else {
ASSERT_TRUE(fs->IsPrefetchCalled());
}
fs->ClearPrefetchCount();
} else {
ASSERT_FALSE(fs->IsPrefetchCalled());
if (level == 0) {
ASSERT_EQ(buff_prefetch_count, 0);
} else {
ASSERT_GT(buff_prefetch_count, 0);
}
buff_prefetch_count = 0;
}
}
}
if (!support_prefetch) {
ASSERT_GT(buff_prefectch_level_count[1], buff_prefectch_level_count[2]);
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
// This test verifies BlockBasedTableOptions.initial_auto_readahead_size is
// configured dynamically.
TEST_P(PrefetchTest, ConfigureInternalAutoReadaheadSize) {
// First param is if the mockFS support_prefetch or not
bool support_prefetch =
std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
// Second param is if directIO is enabled or not
bool use_direct_io = std::get<1>(GetParam());
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), support_prefetch);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
table_options.initial_auto_readahead_size = 0;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
int buff_prefetch_count = 0;
// DB open will create table readers unless we reduce the table cache
// capacity. SanitizeOptions will set max_open_files to minimum of 20.
// Table cache is allocated with max_open_files - 10 as capacity. So
// override max_open_files to 10 so table cache capacity will become 0.
// This will prevent file open during DB open and force the file to be
// opened during Iteration.
SyncPoint::GetInstance()->SetCallBack(
"SanitizeOptions::AfterChangeMaxOpenFiles", [&](void* arg) {
int* max_open_files = (int*)arg;
*max_open_files = 11;
});
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
Random rnd(309);
int key_count = 0;
const int num_keys_per_level = 100;
// Level 0 : Keys in range [0, 99], Level 1:[100, 199], Level 2:[200, 299].
for (int level = 2; level >= 0; level--) {
key_count = level * num_keys_per_level;
for (int i = 0; i < num_keys_per_level; ++i) {
ASSERT_OK(Put(Key(key_count++), rnd.RandomString(500)));
}
ASSERT_OK(Flush());
MoveFilesToLevel(level);
}
Close();
ASSERT_OK(TryReopen(options));
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
fs->ClearPrefetchCount();
buff_prefetch_count = 0;
std::vector<int> buff_prefetch_level_count = {0, 0, 0};
for (int level = 2; level >= 0; level--) {
key_count = level * num_keys_per_level;
switch (level) {
case 0:
// initial_auto_readahead_size is set 0 so data and index blocks are
// not prefetched.
ASSERT_OK(db_->SetOptions({{"block_based_table_factory",
"{initial_auto_readahead_size=0;}"}}));
break;
case 1:
// intial_auto_readahead_size and max_auto_readahead_size are set
// same so readahead_size remains same.
ASSERT_OK(db_->SetOptions({{"block_based_table_factory",
"{initial_auto_readahead_size=4096;max_"
"auto_readahead_size=4096;}"}}));
break;
case 2:
ASSERT_OK(
db_->SetOptions({{"block_based_table_factory",
"{initial_auto_readahead_size=65536;}"}}));
break;
default:
assert(false);
}
for (int i = 0; i < num_keys_per_level; ++i) {
iter->Seek(Key(key_count++));
iter->Next();
}
ASSERT_OK(iter->status());
buff_prefetch_level_count[level] = buff_prefetch_count;
if (support_prefetch && !use_direct_io) {
if (level == 0) {
ASSERT_FALSE(fs->IsPrefetchCalled());
} else {
ASSERT_TRUE(fs->IsPrefetchCalled());
}
fs->ClearPrefetchCount();
} else {
ASSERT_FALSE(fs->IsPrefetchCalled());
if (level == 0) {
ASSERT_EQ(buff_prefetch_count, 0);
} else {
ASSERT_GT(buff_prefetch_count, 0);
}
buff_prefetch_count = 0;
}
}
if (!support_prefetch) {
ASSERT_GT(buff_prefetch_level_count[1], buff_prefetch_level_count[2]);
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
// This test verifies BlockBasedTableOptions.num_file_reads_for_auto_readahead
// is configured dynamically.
TEST_P(PrefetchTest, ConfigureNumFilesReadsForReadaheadSize) {
// First param is if the mockFS support_prefetch or not
bool support_prefetch =
std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
const int kNumKeys = 2000;
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), support_prefetch);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
// Second param is if directIO is enabled or not
bool use_direct_io = std::get<1>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
table_options.num_file_reads_for_auto_readahead = 0;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
Close();
ASSERT_OK(TryReopen(options));
fs->ClearPrefetchCount();
buff_prefetch_count = 0;
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
/*
* Reseek keys from sequential Data Blocks within same partitioned
* index. It will prefetch the data block at the first seek since
* num_file_reads_for_auto_readahead = 0. Data Block size is nearly 4076
* so readahead will fetch 8 * 1024 data more initially (2 more data
* blocks).
*/
iter->Seek(BuildKey(0)); // Prefetch data + index block since
// num_file_reads_for_auto_readahead = 0.
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1000)); // In buffer
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1004)); // In buffer
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1008)); // Prefetch Data
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1011)); // In buffer
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1015)); // In buffer
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019)); // In buffer
ASSERT_TRUE(iter->Valid());
// Missed 2 blocks but they are already in buffer so no reset.
iter->Seek(BuildKey(103)); // Already in buffer.
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1033)); // Prefetch Data.
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 4);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 4);
buff_prefetch_count = 0;
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
// This test verifies the basic functionality of implicit autoreadahead:
// - Enable implicit autoreadahead and prefetch only if sequential blocks are
// read,
// - If data is already in buffer and few blocks are not requested to read,
// don't reset,
// - If data blocks are sequential during read after enabling implicit
// autoreadahead, reset readahead parameters.
TEST_P(PrefetchTest, PrefetchWhenReseek) {
// First param is if the mockFS support_prefetch or not
bool support_prefetch =
std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
const int kNumKeys = 2000;
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), support_prefetch);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
// Second param is if directIO is enabled or not
bool use_direct_io = std::get<1>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
fs->ClearPrefetchCount();
buff_prefetch_count = 0;
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
/*
* Reseek keys from sequential Data Blocks within same partitioned
* index. After 2 sequential reads it will prefetch the data block.
* Data Block size is nearly 4076 so readahead will fetch 8 * 1024 data
* more initially (2 more data blocks).
*/
iter->Seek(BuildKey(0));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1000));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1004)); // Prefetch Data
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1008));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1011));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1015)); // Prefetch Data
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019));
ASSERT_TRUE(iter->Valid());
// Missed 2 blocks but they are already in buffer so no reset.
iter->Seek(BuildKey(103)); // Already in buffer.
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1033)); // Prefetch Data
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 3);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 3);
buff_prefetch_count = 0;
}
}
{
/*
* Reseek keys from non sequential data blocks within same partitioned
* index. buff_prefetch_count will be 0 in that case.
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
iter->Seek(BuildKey(0));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1008));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1033));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1048));
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 0);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 0);
buff_prefetch_count = 0;
}
}
{
/*
* Reesek keys from Single Data Block.
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
iter->Seek(BuildKey(0));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(10));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(100));
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 0);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 0);
buff_prefetch_count = 0;
}
}
{
/*
* Reseek keys from sequential data blocks to set implicit auto readahead
* and prefetch data but after that iterate over different (non
* sequential) data blocks which won't prefetch any data further. So
* buff_prefetch_count will be 1 for the first one.
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
iter->Seek(BuildKey(0));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1000));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1004)); // This iteration will prefetch buffer
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1008));
ASSERT_TRUE(iter->Valid());
iter->Seek(
BuildKey(996)); // Reseek won't prefetch any data and
// readahead_size will be initiallized to 8*1024.
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(992));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(989));
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 1);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 1);
buff_prefetch_count = 0;
}
// Read sequentially to confirm readahead_size is reset to initial value
// (2 more data blocks)
iter->Seek(BuildKey(1011));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1015));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019)); // Prefetch Data
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1022));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1026));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(103)); // Prefetch Data
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 2);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 2);
buff_prefetch_count = 0;
}
}
{
/* Reseek keys from sequential partitioned index block. Since partitioned
* index fetch are sequential, buff_prefetch_count will be 1.
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
iter->Seek(BuildKey(0));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1167));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1334)); // This iteration will prefetch buffer
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1499));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1667));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1847));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1999));
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 1);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 1);
buff_prefetch_count = 0;
}
}
{
/*
* Reseek over different keys from different blocks. buff_prefetch_count
* is set 0.
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
int i = 0;
int j = 1000;
do {
iter->Seek(BuildKey(i));
if (!iter->Valid()) {
ASSERT_OK(iter->status());
break;
}
i = i + 100;
iter->Seek(BuildKey(j));
j = j + 100;
} while (i < 1000 && j < kNumKeys && iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 0);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 0);
buff_prefetch_count = 0;
}
}
{
/* Iterates sequentially over all keys. It will prefetch the buffer.*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
}
ASSERT_OK(iter->status());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 13);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 13);
buff_prefetch_count = 0;
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
// This test verifies the functionality of implicit autoreadahead when caching
// is enabled:
// - If data is already in buffer and few blocks are not requested to read,
// don't reset,
// - If block was eligible for prefetching/in buffer but found in cache, don't
// prefetch and reset.
TEST_P(PrefetchTest, PrefetchWhenReseekwithCache) {
// First param is if the mockFS support_prefetch or not
bool support_prefetch =
std::get<0>(GetParam()) &&
test::IsPrefetchSupported(env_->GetFileSystem(), dbname_);
const int kNumKeys = 2000;
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), support_prefetch);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
// Second param is if directIO is enabled or not
bool use_direct_io = std::get<1>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
std::shared_ptr<Cache> cache = NewLRUCache(4 * 1024 * 1024, 2); // 8MB
table_options.block_cache = cache;
table_options.no_block_cache = false;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
fs->ClearPrefetchCount();
buff_prefetch_count = 0;
{
/*
* Reseek keys from sequential Data Blocks within same partitioned
* index. After 2 sequential reads it will prefetch the data block.
* Data Block size is nearly 4076 so readahead will fetch 8 * 1024 data
* more initially (2 more data blocks).
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
// Warm up the cache
iter->Seek(BuildKey(1011));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1015));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019));
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 1);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 1);
buff_prefetch_count = 0;
}
}
{
// After caching, blocks will be read from cache (Sequential blocks)
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
iter->Seek(BuildKey(0));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1000));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1004)); // Prefetch data (not in cache).
ASSERT_TRUE(iter->Valid());
// Missed one sequential block but next is in already in buffer so
// readahead will not be reset.
iter->Seek(BuildKey(1011));
ASSERT_TRUE(iter->Valid());
// Prefetch data but blocks are in cache so no prefetch and reset.
iter->Seek(BuildKey(1015));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1022));
ASSERT_TRUE(iter->Valid());
// Prefetch data with readahead_size = 4 blocks.
iter->Seek(BuildKey(1026));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(103));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1033));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1037));
ASSERT_TRUE(iter->Valid());
if (support_prefetch && !use_direct_io) {
ASSERT_EQ(fs->GetPrefetchCount(), 3);
fs->ClearPrefetchCount();
} else {
ASSERT_EQ(buff_prefetch_count, 2);
buff_prefetch_count = 0;
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
TEST_P(PrefetchTest, PrefetchWithBlockLookupAutoTuneTest) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(FileSystem::Default(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), /*use_direct_io=*/false, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
ASSERT_OK(s);
Random rnd(309);
WriteBatch batch;
for (int i = 0; i < 26; i++) {
std::string key = "my_key_";
for (int j = 0; j < 10; j++) {
key += char('a' + i);
ASSERT_OK(batch.Put(key, rnd.RandomString(1000)));
}
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = "my_key_a";
std::string end_key = "my_key_";
for (int j = 0; j < 10; j++) {
end_key += char('a' + 25);
}
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
// Try with different num_file_reads_for_auto_readahead from 0 to 3.
for (size_t i = 0; i < 3; i++) {
std::shared_ptr<Cache> cache = NewLRUCache(1024 * 1024, 2);
table_options.block_cache = cache;
table_options.no_block_cache = false;
table_options.num_file_reads_for_auto_readahead = i;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
s = TryReopen(options);
ASSERT_OK(s);
// Warm up the cache.
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
iter->Seek("my_key_bbb");
ASSERT_TRUE(iter->Valid());
iter->Seek("my_key_ccccccccc");
ASSERT_TRUE(iter->Valid());
iter->Seek("my_key_ddd");
ASSERT_TRUE(iter->Valid());
iter->Seek("my_key_ddddddd");
ASSERT_TRUE(iter->Valid());
iter->Seek("my_key_e");
ASSERT_TRUE(iter->Valid());
iter->Seek("my_key_eeeee");
ASSERT_TRUE(iter->Valid());
iter->Seek("my_key_eeeeeeeee");
ASSERT_TRUE(iter->Valid());
}
ReadOptions ropts;
ropts.auto_readahead_size = true;
ReadOptions cmp_ro;
cmp_ro.auto_readahead_size = false;
if (std::get<0>(GetParam())) {
ropts.readahead_size = cmp_ro.readahead_size = 32768;
}
if (std::get<1>(GetParam())) {
ropts.async_io = true;
}
// With and without tuning readahead_size.
{
ASSERT_OK(options.statistics->Reset());
// Seek.
{
Slice ub = Slice("my_key_uuu");
Slice* ub_ptr = &ub;
cmp_ro.iterate_upper_bound = ub_ptr;
ropts.iterate_upper_bound = ub_ptr;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
auto cmp_iter = std::unique_ptr<Iterator>(db_->NewIterator(cmp_ro));
Slice seek_key = Slice("my_key_aaa");
iter->Seek(seek_key);
cmp_iter->Seek(seek_key);
while (iter->Valid() && cmp_iter->Valid()) {
if (iter->key() != cmp_iter->key()) {
// Error
ASSERT_TRUE(false);
}
iter->Next();
cmp_iter->Next();
}
uint64_t readahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
ASSERT_GT(readahead_trimmed, 0);
ASSERT_OK(cmp_iter->status());
ASSERT_OK(iter->status());
}
// Reseek with new upper_bound_iterator.
{
Slice ub = Slice("my_key_y");
ropts.iterate_upper_bound = &ub;
cmp_ro.iterate_upper_bound = &ub;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
auto cmp_iter = std::unique_ptr<Iterator>(db_->NewIterator(cmp_ro));
Slice reseek_key = Slice("my_key_v");
iter->Seek(reseek_key);
cmp_iter->Seek(reseek_key);
while (iter->Valid() && cmp_iter->Valid()) {
if (iter->key() != cmp_iter->key()) {
// Error
ASSERT_TRUE(false);
}
iter->Next();
cmp_iter->Next();
}
uint64_t readahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
ASSERT_GT(readahead_trimmed, 0);
ASSERT_OK(cmp_iter->status());
ASSERT_OK(iter->status());
}
}
Close();
}
}
TEST_F(PrefetchTest, PrefetchWithBlockLookupAutoTuneWithPrev) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
// First param is if the mockFS support_prefetch or not
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(FileSystem::Default(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), /*use_direct_io=*/false, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
std::shared_ptr<Cache> cache = NewLRUCache(1024 * 1024, 2);
table_options.block_cache = cache;
table_options.no_block_cache = false;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
ASSERT_OK(s);
Random rnd(309);
WriteBatch batch;
for (int i = 0; i < 26; i++) {
std::string key = "my_key_";
for (int j = 0; j < 10; j++) {
key += char('a' + i);
ASSERT_OK(batch.Put(key, rnd.RandomString(1000)));
}
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = "my_key_a";
std::string end_key = "my_key_";
for (int j = 0; j < 10; j++) {
end_key += char('a' + 25);
}
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
ReadOptions ropts;
ropts.auto_readahead_size = true;
{
// Seek.
Slice ub = Slice("my_key_uuu");
Slice* ub_ptr = &ub;
ropts.iterate_upper_bound = ub_ptr;
ropts.auto_readahead_size = true;
ReadOptions cmp_readopts = ropts;
cmp_readopts.auto_readahead_size = false;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
auto cmp_iter = std::unique_ptr<Iterator>(db_->NewIterator(cmp_readopts));
Slice seek_key = Slice("my_key_bbb");
{
cmp_iter->Seek(seek_key);
ASSERT_TRUE(cmp_iter->Valid());
ASSERT_OK(cmp_iter->status());
iter->Seek(seek_key);
ASSERT_TRUE(iter->Valid());
ASSERT_OK(iter->status());
ASSERT_EQ(iter->key(), cmp_iter->key());
}
// Prev op should pass with auto tuning of readahead_size.
{
cmp_iter->Prev();
ASSERT_TRUE(cmp_iter->Valid());
ASSERT_OK(cmp_iter->status());
iter->Prev();
ASSERT_OK(iter->status());
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(iter->key(), cmp_iter->key());
}
// Reseek would follow as usual.
{
cmp_iter->Seek(seek_key);
ASSERT_TRUE(cmp_iter->Valid());
ASSERT_OK(cmp_iter->status());
iter->Seek(seek_key);
ASSERT_OK(iter->status());
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(iter->key(), cmp_iter->key());
}
}
Close();
}
// This test verifies the functionality of ReadOptions.adaptive_readahead.
TEST_P(PrefetchTest, DBIterLevelReadAhead) {
const int kNumKeys = 1000;
// Set options
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
bool is_adaptive_readahead = std::get<1>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
int total_keys = 0;
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
total_keys++;
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
int buff_prefetch_count = 0;
int readahead_carry_over_count = 0;
int num_sst_files = NumTableFilesAtLevel(2);
size_t current_readahead_size = 0;
// Test - Iterate over the keys sequentially.
{
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
// The callback checks, since reads are sequential, readahead_size doesn't
// start from 8KB when iterator moves to next file and its called
// num_sst_files-1 times (excluding for first file).
SyncPoint::GetInstance()->SetCallBack(
"BlockPrefetcher::SetReadaheadState", [&](void* arg) {
readahead_carry_over_count++;
size_t readahead_size = *reinterpret_cast<size_t*>(arg);
if (readahead_carry_over_count) {
ASSERT_GT(readahead_size, 8 * 1024);
}
});
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::TryReadFromCache", [&](void* arg) {
current_readahead_size = *reinterpret_cast<size_t*>(arg);
ASSERT_GT(current_readahead_size, 0);
});
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ro;
if (is_adaptive_readahead) {
ro.adaptive_readahead = true;
}
ASSERT_OK(options.statistics->Reset());
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(iter->status());
num_keys++;
}
ASSERT_OK(iter->status());
ASSERT_EQ(num_keys, total_keys);
// For index and data blocks.
if (is_adaptive_readahead) {
ASSERT_EQ(readahead_carry_over_count, 2 * (num_sst_files - 1));
} else {
ASSERT_GT(buff_prefetch_count, 0);
ASSERT_EQ(readahead_carry_over_count, 0);
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
}
Close();
}
// This test verifies the functionality of ReadOptions.adaptive_readahead when
// async_io is enabled.
TEST_P(PrefetchTest, DBIterLevelReadAheadWithAsyncIO) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_BYPASS("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 1000;
// Set options
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(FileSystem::Default(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
bool is_adaptive_readahead = std::get<1>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
int total_keys = 0;
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
total_keys++;
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
int buff_async_prefetch_count = 0;
int buff_prefetch_count = 0;
int readahead_carry_over_count = 0;
int num_sst_files = NumTableFilesAtLevel(2);
size_t current_readahead_size = 0;
bool read_async_called = false;
// Test - Iterate over the keys sequentially.
{
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_async_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
// The callback checks, since reads are sequential, readahead_size doesn't
// start from 8KB when iterator moves to next file and its called
// num_sst_files-1 times (excluding for first file).
SyncPoint::GetInstance()->SetCallBack(
"BlockPrefetcher::SetReadaheadState", [&](void* arg) {
readahead_carry_over_count++;
size_t readahead_size = *reinterpret_cast<size_t*>(arg);
if (readahead_carry_over_count) {
ASSERT_GT(readahead_size, 8 * 1024);
}
});
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::TryReadFromCache", [&](void* arg) {
current_readahead_size = *reinterpret_cast<size_t*>(arg);
ASSERT_GT(current_readahead_size, 0);
});
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ro;
if (is_adaptive_readahead) {
ro.adaptive_readahead = true;
}
ro.async_io = true;
ASSERT_OK(options.statistics->Reset());
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(iter->status());
num_keys++;
}
ASSERT_OK(iter->status());
ASSERT_EQ(num_keys, total_keys);
// For index and data blocks.
if (is_adaptive_readahead) {
ASSERT_EQ(readahead_carry_over_count, 2 * (num_sst_files - 1));
} else {
ASSERT_EQ(readahead_carry_over_count, 0);
}
// Check stats to make sure async prefetch is done.
{
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
if (read_async_called) {
ASSERT_GT(buff_async_prefetch_count, 0);
ASSERT_GT(async_read_bytes.count, 0);
} else {
ASSERT_GT(buff_prefetch_count, 0);
ASSERT_EQ(async_read_bytes.count, 0);
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
}
Close();
}
TEST_P(PrefetchTest, AvoidBlockCacheLookupTwice) {
const int kNumKeys = 1000;
// Set options
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
bool async_io = std::get<1>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
std::shared_ptr<Cache> cache = NewLRUCache(4 * 1024 * 1024, 2); // 8MB
table_options.block_cache = cache;
table_options.no_block_cache = false;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
// Write to DB.
{
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
}
ReadOptions ro;
ro.async_io = async_io;
// Iterate over the keys.
{
// Each block contains around 4 keys.
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
ASSERT_OK(options.statistics->Reset());
iter->Seek(BuildKey(99)); // Prefetch data because of seek parallelization.
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(options.statistics->getAndResetTickerCount(BLOCK_CACHE_DATA_MISS),
1);
}
Close();
}
TEST_P(PrefetchTest, DBIterAsyncIONoIOUring) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 1000;
// Set options
bool use_direct_io = std::get<0>(GetParam());
bool is_adaptive_readahead = std::get<1>(GetParam());
Options options;
SetGenericOptions(Env::Default(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
enable_io_uring = false;
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
enable_io_uring = true;
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
int total_keys = 0;
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
total_keys++;
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
// Test - Iterate over the keys sequentially.
{
ReadOptions ro;
if (is_adaptive_readahead) {
ro.adaptive_readahead = true;
}
ro.async_io = true;
ASSERT_OK(options.statistics->Reset());
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(iter->status());
num_keys++;
}
ASSERT_OK(iter->status());
ASSERT_EQ(num_keys, total_keys);
// Check stats to make sure async prefetch is done.
{
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(options.statistics->getTickerCount(READ_ASYNC_MICROS), 0);
}
}
{
ReadOptions ro;
if (is_adaptive_readahead) {
ro.adaptive_readahead = true;
}
ro.async_io = true;
ro.tailing = true;
ASSERT_OK(options.statistics->Reset());
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(iter->status());
num_keys++;
}
ASSERT_OK(iter->status());
ASSERT_EQ(num_keys, total_keys);
// Check stats to make sure async prefetch is done.
{
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(options.statistics->getTickerCount(READ_ASYNC_MICROS), 0);
}
}
Close();
enable_io_uring = true;
}
class PrefetchTest1 : public DBTestBase,
public ::testing::WithParamInterface<bool> {
public:
PrefetchTest1() : DBTestBase("prefetch_test1", true) {}
virtual void SetGenericOptions(Env* env, bool use_direct_io,
Options& options) {
options = CurrentOptions();
options.write_buffer_size = 1024;
options.create_if_missing = true;
options.compression = kNoCompression;
options.env = env;
options.disable_auto_compactions = true;
if (use_direct_io) {
options.use_direct_reads = true;
options.use_direct_io_for_flush_and_compaction = true;
}
}
void SetBlockBasedTableOptions(BlockBasedTableOptions& table_options) {
table_options.no_block_cache = true;
table_options.cache_index_and_filter_blocks = false;
table_options.metadata_block_size = 1024;
table_options.index_type =
BlockBasedTableOptions::IndexType::kTwoLevelIndexSearch;
}
};
INSTANTIATE_TEST_CASE_P(PrefetchTest1, PrefetchTest1, ::testing::Bool());
TEST_P(PrefetchTest1, SeekWithExtraPrefetchAsyncIO) {
const int kNumKeys = 2000;
// Set options
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), GetParam(), options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (GetParam() && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
Close();
for (size_t i = 0; i < 3; i++) {
table_options.num_file_reads_for_auto_readahead = i;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
s = TryReopen(options);
ASSERT_OK(s);
int buff_prefetch_count = 0;
int extra_prefetch_buff_cnt = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsync:ExtraPrefetching",
[&](void*) { extra_prefetch_buff_cnt++; });
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ro;
ro.async_io = true;
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
// First Seek
iter->Seek(BuildKey(
0)); // Prefetch data on seek because of seek parallelization.
ASSERT_TRUE(iter->Valid());
// Do extra prefetching in Seek only if
// num_file_reads_for_auto_readahead = 0.
ASSERT_EQ(extra_prefetch_buff_cnt, (i == 0 ? 1 : 0));
// buff_prefetch_count is 2 because of index block when
// num_file_reads_for_auto_readahead = 0.
// If num_file_reads_for_auto_readahead > 0, index block isn't
// prefetched.
ASSERT_EQ(buff_prefetch_count, i == 0 ? 2 : 1);
extra_prefetch_buff_cnt = 0;
buff_prefetch_count = 0;
// Reset all values of FilePrefetchBuffer on new seek.
iter->Seek(
BuildKey(22)); // Prefetch data because of seek parallelization.
ASSERT_TRUE(iter->Valid());
// Do extra prefetching in Seek only if
// num_file_reads_for_auto_readahead = 0.
ASSERT_EQ(extra_prefetch_buff_cnt, (i == 0 ? 1 : 0));
ASSERT_EQ(buff_prefetch_count, 1);
extra_prefetch_buff_cnt = 0;
buff_prefetch_count = 0;
// Reset all values of FilePrefetchBuffer on new seek.
iter->Seek(
BuildKey(33)); // Prefetch data because of seek parallelization.
ASSERT_TRUE(iter->Valid());
// Do extra prefetching in Seek only if
// num_file_reads_for_auto_readahead = 0.
ASSERT_EQ(extra_prefetch_buff_cnt, (i == 0 ? 1 : 0));
ASSERT_EQ(buff_prefetch_count, 1);
}
Close();
}
}
// This test verifies the functionality of ReadOptions.adaptive_readahead when
// reads are not sequential.
TEST_P(PrefetchTest1, NonSequentialReadsWithAdaptiveReadahead) {
const int kNumKeys = 1000;
// Set options
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), GetParam(), options);
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (GetParam() && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
int buff_prefetch_count = 0;
int set_readahead = 0;
size_t readahead_size = 0;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"BlockPrefetcher::SetReadaheadState",
[&](void* /*arg*/) { set_readahead++; });
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::TryReadFromCache",
[&](void* arg) { readahead_size = *reinterpret_cast<size_t*>(arg); });
SyncPoint::GetInstance()->EnableProcessing();
{
// Iterate until prefetch is done.
ReadOptions ro;
ro.adaptive_readahead = true;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
iter->SeekToFirst();
ASSERT_TRUE(iter->Valid());
while (iter->Valid() && buff_prefetch_count == 0) {
iter->Next();
}
ASSERT_EQ(readahead_size, 8 * 1024);
ASSERT_EQ(buff_prefetch_count, 1);
ASSERT_EQ(set_readahead, 0);
buff_prefetch_count = 0;
// Move to last file and check readahead size fallbacks to 8KB. So next
// readahead size after prefetch should be 8 * 1024;
iter->Seek(BuildKey(4004));
ASSERT_TRUE(iter->Valid());
while (iter->Valid() && buff_prefetch_count == 0) {
iter->Next();
}
ASSERT_EQ(readahead_size, 8 * 1024);
ASSERT_EQ(set_readahead, 0);
ASSERT_EQ(buff_prefetch_count, 1);
}
Close();
}
// This test verifies the functionality of adaptive_readaheadsize with cache
// and if block is found in cache, decrease the readahead_size if
// - its enabled internally by RocksDB (implicit_auto_readahead_) and,
// - readahead_size is greater than 0 and,
// - the block would have called prefetch API if not found in cache for
// which conditions are:
// - few/no bytes are in buffer and,
// - block is sequential with the previous read and,
// - num_file_reads_ + 1 (including this read) >
// num_file_reads_for_auto_readahead_
TEST_P(PrefetchTest1, DecreaseReadAheadIfInCache) {
const int kNumKeys = 2000;
// Set options
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(env_->GetFileSystem(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), GetParam(), options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
std::shared_ptr<Cache> cache = NewLRUCache(4 * 1024 * 1024, 2); // 8MB
table_options.block_cache = cache;
table_options.no_block_cache = false;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (GetParam() && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
int buff_prefetch_count = 0;
size_t current_readahead_size = 0;
size_t expected_current_readahead_size = 8 * 1024;
size_t decrease_readahead_size = 8 * 1024;
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::TryReadFromCache", [&](void* arg) {
current_readahead_size = *reinterpret_cast<size_t*>(arg);
});
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ro;
ro.adaptive_readahead = true;
{
/*
* Reseek keys from sequential Data Blocks within same partitioned
* index. After 2 sequential reads it will prefetch the data block.
* Data Block size is nearly 4076 so readahead will fetch 8 * 1024 data
* more initially (2 more data blocks).
*/
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
// Warm up the cache
iter->Seek(BuildKey(1011));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1015));
ASSERT_TRUE(iter->Valid());
iter->Seek(BuildKey(1019));
ASSERT_TRUE(iter->Valid());
buff_prefetch_count = 0;
}
{
ASSERT_OK(options.statistics->Reset());
// After caching, blocks will be read from cache (Sequential blocks)
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
iter->Seek(
BuildKey(0)); // In cache so it will decrease the readahead_size.
ASSERT_TRUE(iter->Valid());
expected_current_readahead_size = std::max(
decrease_readahead_size,
(expected_current_readahead_size >= decrease_readahead_size
? (expected_current_readahead_size - decrease_readahead_size)
: 0));
iter->Seek(BuildKey(1000)); // Won't prefetch the block.
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(current_readahead_size, expected_current_readahead_size);
iter->Seek(BuildKey(1004)); // Prefetch the block.
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(current_readahead_size, expected_current_readahead_size);
expected_current_readahead_size *= 2;
iter->Seek(BuildKey(1011));
ASSERT_TRUE(iter->Valid());
// Eligible to Prefetch data (not in buffer) but block is in cache so no
// prefetch will happen and will result in decrease in readahead_size.
// readahead_size will be 8 * 1024
iter->Seek(BuildKey(1015));
ASSERT_TRUE(iter->Valid());
expected_current_readahead_size = std::max(
decrease_readahead_size,
(expected_current_readahead_size >= decrease_readahead_size
? (expected_current_readahead_size - decrease_readahead_size)
: 0));
// 1016 is the same block as 1015. So no change in readahead_size.
iter->Seek(BuildKey(1016));
ASSERT_TRUE(iter->Valid());
// Prefetch data (not in buffer) but found in cache. So decrease
// readahead_size. Since it will 0 after decrementing so readahead_size
// will be set to initial value.
iter->Seek(BuildKey(1019));
ASSERT_TRUE(iter->Valid());
expected_current_readahead_size = std::max(
decrease_readahead_size,
(expected_current_readahead_size >= decrease_readahead_size
? (expected_current_readahead_size - decrease_readahead_size)
: 0));
// Prefetch next sequential data.
iter->Seek(BuildKey(1022));
ASSERT_TRUE(iter->Valid());
ASSERT_EQ(current_readahead_size, expected_current_readahead_size);
ASSERT_EQ(buff_prefetch_count, 2);
buff_prefetch_count = 0;
}
Close();
}
// This test verifies the basic functionality of seek parallelization for
// async_io.
TEST_P(PrefetchTest1, SeekParallelizationTest) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_BYPASS("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 2000;
// Set options
std::shared_ptr<MockFS> fs = std::make_shared<MockFS>(
FileSystem::Default(), /*support_prefetch=*/false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), GetParam(), options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (GetParam() && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
int buff_prefetch_count = 0;
int buff_prefetch_async_count = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_async_count++; });
SyncPoint::GetInstance()->SetCallBack("FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
bool read_async_called = false;
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ro;
ro.adaptive_readahead = true;
ro.async_io = true;
{
ASSERT_OK(options.statistics->Reset());
// Each block contains around 4 keys.
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
iter->Seek(BuildKey(0)); // Prefetch data because of seek parallelization.
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
// New data block. Since num_file_reads in FilePrefetch after this read is
// 2, it won't go for prefetching.
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
// Prefetch data.
iter->Next();
ASSERT_TRUE(iter->Valid());
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
// not all platforms support io_uring. In that case it'll fallback to
// normal prefetching without async_io.
if (read_async_called) {
ASSERT_EQ(buff_prefetch_async_count, 2);
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
} else {
ASSERT_EQ(buff_prefetch_count, 1);
}
}
Close();
}
// This test checks if readahead_size is trimmed when upper_bound is reached.
// It tests with different combinations of async_io disabled/enabled,
// readahead_size (implicit and explicit), and num_file_reads_for_auto_readahead
// from 0 to 2.
TEST_P(PrefetchTest, IterReadAheadSizeWithUpperBound) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
// First param is if the mockFS support_prefetch or not
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(FileSystem::Default(), false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), /*use_direct_io=*/false, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
ASSERT_OK(s);
Random rnd(309);
WriteBatch batch;
for (int i = 0; i < 26; i++) {
std::string key = "my_key_";
for (int j = 0; j < 10; j++) {
key += char('a' + i);
ASSERT_OK(batch.Put(key, rnd.RandomString(1000)));
}
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = "my_key_a";
std::string end_key = "my_key_";
for (int j = 0; j < 10; j++) {
end_key += char('a' + 25);
}
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
int buff_prefetch_count = 0;
// Try with different num_file_reads_for_auto_readahead from 0 to 3.
for (size_t i = 0; i < 3; i++) {
table_options.num_file_reads_for_auto_readahead = i;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
s = TryReopen(options);
ASSERT_OK(s);
int buff_count_with_tuning = 0, buff_count_without_tuning = 0;
int keys_with_tuning = 0, keys_without_tuning = 0;
int reseek_keys_with_tuning = 0, reseek_keys_without_tuning = 0;
buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::Prefetch:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ropts;
if (std::get<0>(GetParam())) {
ropts.readahead_size = 32768;
}
if (std::get<1>(GetParam())) {
ropts.async_io = true;
}
// With tuning readahead_size.
{
ASSERT_OK(options.statistics->Reset());
Slice ub = Slice("my_key_uuu");
Slice* ub_ptr = &ub;
ropts.iterate_upper_bound = ub_ptr;
ropts.auto_readahead_size = true;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
// Seek.
{
Slice seek_key = Slice("my_key_aaa");
iter->Seek(seek_key);
while (iter->Valid()) {
keys_with_tuning++;
iter->Next();
}
uint64_t readahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
ASSERT_GT(readahead_trimmed, 0);
buff_count_with_tuning = buff_prefetch_count;
}
// Reseek with new upper_bound_iterator.
{
ub = Slice("my_key_y");
Slice reseek_key = Slice("my_key_v");
iter->Seek(reseek_key);
while (iter->Valid()) {
iter->Next();
reseek_keys_with_tuning++;
}
ASSERT_OK(iter->status());
uint64_t readahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
ASSERT_GT(readahead_trimmed, 0);
ASSERT_GT(reseek_keys_with_tuning, 0);
}
}
// Without tuning readahead_size
{
Slice ub = Slice("my_key_uuu");
Slice* ub_ptr = &ub;
ropts.iterate_upper_bound = ub_ptr;
buff_prefetch_count = 0;
ASSERT_OK(options.statistics->Reset());
ropts.auto_readahead_size = false;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
// Seek.
{
Slice seek_key = Slice("my_key_aaa");
iter->Seek(seek_key);
while (iter->Valid()) {
keys_without_tuning++;
iter->Next();
}
buff_count_without_tuning = buff_prefetch_count;
uint64_t readahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
ASSERT_EQ(readahead_trimmed, 0);
}
// Reseek with new upper_bound_iterator.
{
ub = Slice("my_key_y");
Slice reseek_key = Slice("my_key_v");
iter->Seek(reseek_key);
while (iter->Valid()) {
iter->Next();
reseek_keys_without_tuning++;
}
ASSERT_OK(iter->status());
uint64_t readahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
ASSERT_EQ(readahead_trimmed, 0);
ASSERT_GT(reseek_keys_without_tuning, 0);
}
}
{
// Verify results with and without tuning.
if (std::get<1>(GetParam())) {
// In case of async_io.
ASSERT_GE(buff_count_with_tuning, buff_count_without_tuning);
} else {
ASSERT_EQ(buff_count_without_tuning, buff_count_with_tuning);
}
// Prefetching should happen.
ASSERT_GT(buff_count_without_tuning, 0);
ASSERT_GT(buff_count_with_tuning, 0);
// No of keys should be equal.
ASSERT_EQ(keys_without_tuning, keys_with_tuning);
// No of keys after reseek with new upper bound should be equal.
ASSERT_EQ(reseek_keys_without_tuning, reseek_keys_with_tuning);
}
Close();
}
}
// This test checks if readahead_size is trimmed when upper_bound is reached
// during Seek in async_io and it goes for polling without any extra
// prefetching.
TEST_P(PrefetchTest, IterReadAheadSizeWithUpperBoundSeekOnly) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
// First param is if the mockFS support_prefetch or not
std::shared_ptr<MockFS> fs =
std::make_shared<MockFS>(FileSystem::Default(), false);
bool use_direct_io = false;
if (std::get<0>(GetParam())) {
use_direct_io = true;
}
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
Random rnd(309);
WriteBatch batch;
for (int i = 0; i < 26; i++) {
std::string key = "my_key_";
for (int j = 0; j < 10; j++) {
key += char('a' + i);
ASSERT_OK(batch.Put(key, rnd.RandomString(1000)));
}
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = "my_key_a";
std::string end_key = "my_key_";
for (int j = 0; j < 10; j++) {
end_key += char('a' + 25);
}
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
s = TryReopen(options);
ASSERT_OK(s);
int buff_count_with_tuning = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_count_with_tuning++; });
bool read_async_called = false;
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
SyncPoint::GetInstance()->EnableProcessing();
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ropts;
if (std::get<1>(GetParam())) {
ropts.readahead_size = 32768;
}
ropts.async_io = true;
Slice ub = Slice("my_key_aaa");
ropts.iterate_upper_bound = &ub;
Slice seek_key = Slice("my_key_aaa");
// With tuning readahead_size.
{
ASSERT_OK(options.statistics->Reset());
ropts.auto_readahead_size = true;
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ropts));
iter->Seek(seek_key);
ASSERT_OK(iter->status());
// Verify results.
uint64_t readhahead_trimmed =
options.statistics->getAndResetTickerCount(READAHEAD_TRIMMED);
// Readahead got trimmed.
if (read_async_called) {
ASSERT_GT(readhahead_trimmed, 0);
// Seek called PrefetchAsync to poll the data.
ASSERT_EQ(1, buff_count_with_tuning);
} else {
// async_io disabled.
ASSERT_GE(readhahead_trimmed, 0);
ASSERT_EQ(0, buff_count_with_tuning);
}
}
Close();
}
namespace {
#ifdef GFLAGS
const int kMaxArgCount = 100;
const size_t kArgBufferSize = 100000;
void RunIOTracerParserTool(std::string trace_file) {
std::vector<std::string> params = {"./io_tracer_parser",
"-io_trace_file=" + trace_file};
char arg_buffer[kArgBufferSize];
char* argv[kMaxArgCount];
int argc = 0;
int cursor = 0;
for (const auto& arg : params) {
ASSERT_LE(cursor + arg.size() + 1, kArgBufferSize);
ASSERT_LE(argc + 1, kMaxArgCount);
snprintf(arg_buffer + cursor, arg.size() + 1, "%s", arg.c_str());
argv[argc++] = arg_buffer + cursor;
cursor += static_cast<int>(arg.size()) + 1;
}
ASSERT_EQ(0, ROCKSDB_NAMESPACE::io_tracer_parser(argc, argv));
}
#endif // GFLAGS
} // namespace
// Tests the default implementation of ReadAsync API with PosixFileSystem during
// prefetching.
TEST_P(PrefetchTest, ReadAsyncWithPosixFS) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 1000;
std::shared_ptr<MockFS> fs = std::make_shared<MockFS>(
FileSystem::Default(), /*support_prefetch=*/false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
int total_keys = 0;
// Write the keys.
{
WriteBatch batch;
Random rnd(309);
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
total_keys++;
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
}
int buff_prefetch_count = 0;
bool read_async_called = false;
ReadOptions ro;
ro.adaptive_readahead = true;
ro.async_io = true;
if (std::get<1>(GetParam())) {
ro.readahead_size = 16 * 1024;
}
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
SyncPoint::GetInstance()->EnableProcessing();
// Read the keys.
{
ASSERT_OK(options.statistics->Reset());
get_perf_context()->Reset();
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(iter->status());
num_keys++;
}
ASSERT_OK(iter->status());
if (read_async_called) {
ASSERT_EQ(num_keys, total_keys);
ASSERT_GT(buff_prefetch_count, 0);
// Check stats to make sure async prefetch is done.
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
HistogramData prefetched_bytes_discarded;
options.statistics->histogramData(PREFETCHED_BYTES_DISCARDED,
&prefetched_bytes_discarded);
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(prefetched_bytes_discarded.count, 0);
ASSERT_EQ(get_perf_context()->number_async_seek, 0);
} else {
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
ASSERT_EQ(num_keys, total_keys);
ASSERT_EQ(buff_prefetch_count, 0);
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
// This test verifies implementation of seek parallelization with
// PosixFileSystem during prefetching.
TEST_P(PrefetchTest, MultipleSeekWithPosixFS) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 1000;
std::shared_ptr<MockFS> fs = std::make_shared<MockFS>(
FileSystem::Default(), /*support_prefetch=*/false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
int total_keys = 0;
// Write the keys.
{
WriteBatch batch;
Random rnd(309);
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
total_keys++;
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
}
(void)total_keys;
int num_keys_first_batch = 0;
int num_keys_second_batch = 0;
// Calculate number of keys without async_io for correctness validation.
{
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ReadOptions()));
// First Seek.
iter->Seek(BuildKey(450));
while (iter->Valid() && num_keys_first_batch < 100) {
ASSERT_OK(iter->status());
num_keys_first_batch++;
iter->Next();
}
ASSERT_OK(iter->status());
iter->Seek(BuildKey(942));
while (iter->Valid()) {
ASSERT_OK(iter->status());
num_keys_second_batch++;
iter->Next();
}
ASSERT_OK(iter->status());
}
int buff_prefetch_count = 0;
bool read_async_called = false;
ReadOptions ro;
ro.adaptive_readahead = true;
ro.async_io = true;
if (std::get<1>(GetParam())) {
ro.readahead_size = 16 * 1024;
}
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
SyncPoint::GetInstance()->EnableProcessing();
// Read the keys using seek.
{
ASSERT_OK(options.statistics->Reset());
get_perf_context()->Reset();
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
// First Seek.
{
iter->Seek(BuildKey(450));
while (iter->Valid() && num_keys < 100) {
ASSERT_OK(iter->status());
num_keys++;
iter->Next();
}
ASSERT_OK(iter->status());
ASSERT_EQ(num_keys, num_keys_first_batch);
// Check stats to make sure async prefetch is done.
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
if (read_async_called) {
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
} else {
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(get_perf_context()->number_async_seek, 0);
}
}
// Second Seek.
{
num_keys = 0;
ASSERT_OK(options.statistics->Reset());
get_perf_context()->Reset();
iter->Seek(BuildKey(942));
while (iter->Valid()) {
ASSERT_OK(iter->status());
num_keys++;
iter->Next();
}
ASSERT_OK(iter->status());
ASSERT_EQ(num_keys, num_keys_second_batch);
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
HistogramData prefetched_bytes_discarded;
options.statistics->histogramData(PREFETCHED_BYTES_DISCARDED,
&prefetched_bytes_discarded);
ASSERT_GT(prefetched_bytes_discarded.count, 0);
if (read_async_called) {
ASSERT_GT(buff_prefetch_count, 0);
// Check stats to make sure async prefetch is done.
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
} else {
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(get_perf_context()->number_async_seek, 0);
}
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
// This test verifies implementation of seek parallelization with
// PosixFileSystem during prefetching.
TEST_P(PrefetchTest, SeekParallelizationTestWithPosix) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 2000;
// Set options
std::shared_ptr<MockFS> fs = std::make_shared<MockFS>(
FileSystem::Default(), /*support_prefetch=*/false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
WriteBatch batch;
Random rnd(309);
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
std::string start_key = BuildKey(0);
std::string end_key = BuildKey(kNumKeys - 1);
Slice least(start_key.data(), start_key.size());
Slice greatest(end_key.data(), end_key.size());
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
bool read_async_called = false;
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
SyncPoint::GetInstance()->EnableProcessing();
SyncPoint::GetInstance()->EnableProcessing();
ReadOptions ro;
ro.adaptive_readahead = true;
ro.async_io = true;
if (std::get<1>(GetParam())) {
ro.readahead_size = 16 * 1024;
}
{
ASSERT_OK(options.statistics->Reset());
// Each block contains around 4 keys.
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
iter->Seek(BuildKey(0)); // Prefetch data because of seek parallelization.
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
// New data block. Since num_file_reads in FilePrefetch after this read is
// 2, it won't go for prefetching.
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
iter->Next();
ASSERT_TRUE(iter->Valid());
// Prefetch data.
iter->Next();
ASSERT_TRUE(iter->Valid());
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
if (read_async_called) {
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
if (std::get<1>(GetParam())) {
ASSERT_EQ(buff_prefetch_count, 1);
} else {
ASSERT_EQ(buff_prefetch_count, 2);
}
} else {
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(get_perf_context()->number_async_seek, 0);
}
}
Close();
}
#ifdef GFLAGS
// This test verifies io_tracing with PosixFileSystem during prefetching.
TEST_P(PrefetchTest, TraceReadAsyncWithCallbackWrapper) {
if (mem_env_ || encrypted_env_) {
ROCKSDB_GTEST_SKIP("Test requires non-mem or non-encrypted environment");
return;
}
const int kNumKeys = 1000;
std::shared_ptr<MockFS> fs = std::make_shared<MockFS>(
FileSystem::Default(), /*support_prefetch=*/false);
std::unique_ptr<Env> env(new CompositeEnvWrapper(env_, fs));
bool use_direct_io = std::get<0>(GetParam());
Options options;
SetGenericOptions(env.get(), use_direct_io, options);
options.statistics = CreateDBStatistics();
BlockBasedTableOptions table_options;
SetBlockBasedTableOptions(table_options);
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
Status s = TryReopen(options);
if (use_direct_io && (s.IsNotSupported() || s.IsInvalidArgument())) {
// If direct IO is not supported, skip the test
return;
} else {
ASSERT_OK(s);
}
int total_keys = 0;
// Write the keys.
{
WriteBatch batch;
Random rnd(309);
for (int j = 0; j < 5; j++) {
for (int i = j * kNumKeys; i < (j + 1) * kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i), rnd.RandomString(1000)));
total_keys++;
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
ASSERT_OK(Flush());
}
MoveFilesToLevel(2);
}
int buff_prefetch_count = 0;
bool read_async_called = false;
ReadOptions ro;
ro.adaptive_readahead = true;
ro.async_io = true;
if (std::get<1>(GetParam())) {
ro.readahead_size = 16 * 1024;
}
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
SyncPoint::GetInstance()->SetCallBack(
"UpdateResults::io_uring_result",
[&](void* /*arg*/) { read_async_called = true; });
SyncPoint::GetInstance()->EnableProcessing();
// Read the keys.
{
// Start io_tracing.
WriteOptions write_opt;
TraceOptions trace_opt;
std::unique_ptr<TraceWriter> trace_writer;
std::string trace_file_path = dbname_ + "/io_trace_file";
ASSERT_OK(
NewFileTraceWriter(env_, EnvOptions(), trace_file_path, &trace_writer));
ASSERT_OK(db_->StartIOTrace(trace_opt, std::move(trace_writer)));
ASSERT_OK(options.statistics->Reset());
auto iter = std::unique_ptr<Iterator>(db_->NewIterator(ro));
int num_keys = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
ASSERT_OK(iter->status());
num_keys++;
}
ASSERT_OK(iter->status());
// End the tracing.
ASSERT_OK(db_->EndIOTrace());
ASSERT_OK(env_->FileExists(trace_file_path));
ASSERT_EQ(num_keys, total_keys);
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
if (read_async_called) {
ASSERT_GT(buff_prefetch_count, 0);
// Check stats to make sure async prefetch is done.
ASSERT_GT(async_read_bytes.count, 0);
} else {
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
ASSERT_EQ(async_read_bytes.count, 0);
}
// Check the file to see if ReadAsync is logged.
RunIOTracerParserTool(trace_file_path);
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
Close();
}
#endif // GFLAGS
class FilePrefetchBufferTest : public testing::Test {
public:
void SetUp() override {
SetupSyncPointsToMockDirectIO();
env_ = Env::Default();
fs_ = FileSystem::Default();
test_dir_ = test::PerThreadDBPath("file_prefetch_buffer_test");
ASSERT_OK(fs_->CreateDir(test_dir_, IOOptions(), nullptr));
stats_ = CreateDBStatistics();
}
void TearDown() override { EXPECT_OK(DestroyDir(env_, test_dir_)); }
void Write(const std::string& fname, const std::string& content) {
std::unique_ptr<FSWritableFile> f;
ASSERT_OK(fs_->NewWritableFile(Path(fname), FileOptions(), &f, nullptr));
ASSERT_OK(f->Append(content, IOOptions(), nullptr));
ASSERT_OK(f->Close(IOOptions(), nullptr));
}
void Read(const std::string& fname, const FileOptions& opts,
std::unique_ptr<RandomAccessFileReader>* reader) {
std::string fpath = Path(fname);
std::unique_ptr<FSRandomAccessFile> f;
ASSERT_OK(fs_->NewRandomAccessFile(fpath, opts, &f, nullptr));
reader->reset(new RandomAccessFileReader(
std::move(f), fpath, env_->GetSystemClock().get(),
/*io_tracer=*/nullptr, stats_.get()));
}
void AssertResult(const std::string& content,
const std::vector<FSReadRequest>& reqs) {
for (const auto& r : reqs) {
ASSERT_OK(r.status);
ASSERT_EQ(r.len, r.result.size());
ASSERT_EQ(content.substr(r.offset, r.len), r.result.ToString());
}
}
FileSystem* fs() { return fs_.get(); }
Statistics* stats() { return stats_.get(); }
private:
Env* env_;
std::shared_ptr<FileSystem> fs_;
std::string test_dir_;
std::shared_ptr<Statistics> stats_;
std::string Path(const std::string& fname) { return test_dir_ + "/" + fname; }
};
TEST_F(FilePrefetchBufferTest, SeekWithBlockCacheHit) {
std::string fname = "seek-with-block-cache-hit";
Random rand(0);
std::string content = rand.RandomString(32768);
Write(fname, content);
FileOptions opts;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
FilePrefetchBuffer fpb(16384, 16384, true, false, false, 0, 0, 0, fs());
Slice result;
// Simulate a seek of 4096 bytes at offset 0. Due to the readahead settings,
// it will do two reads of 4096+8192 and 8192
Status s = fpb.PrefetchAsync(IOOptions(), r.get(), 0, 4096, &result);
// Platforms that don't have IO uring may not support async IO.
if (s.IsNotSupported()) {
return;
}
ASSERT_TRUE(s.IsTryAgain());
// Simulate a block cache hit
fpb.UpdateReadPattern(0, 4096, false);
// Now read some data that straddles the two prefetch buffers - offset 8192 to
// 16384
IOOptions io_opts;
io_opts.rate_limiter_priority = Env::IOPriority::IO_LOW;
ASSERT_TRUE(
fpb.TryReadFromCacheAsync(io_opts, r.get(), 8192, 8192, &result, &s));
}
// Test to ensure when PrefetchAsync is called during seek, it doesn't do any
// alignment or prefetch extra if readahead is not enabled during seek.
TEST_F(FilePrefetchBufferTest, SeekWithoutAlignment) {
std::string fname = "seek-wwithout-alignment";
Random rand(0);
std::string content = rand.RandomString(32768);
Write(fname, content);
FileOptions opts;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
size_t alignment = r->file()->GetRequiredBufferAlignment();
size_t n = alignment / 2;
int read_async_called = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::ReadAsync",
[&](void* /*arg*/) { read_async_called++; });
SyncPoint::GetInstance()->EnableProcessing();
// Without readahead enabled, there will be no alignment and offset of buffer
// will be n.
{
FilePrefetchBuffer fpb(
/*readahead_size=*/8192, /*max_readahead_size=*/16384, /*enable=*/true,
/*track_min_offset=*/false, /*implicit_auto_readahead=*/true,
/*num_file_reads=*/0, /*num_file_reads_for_auto_readahead=*/2,
/*upper_bound_offset=*/0, fs());
Slice result;
// Simulate a seek of half of alignment bytes at offset n. Due to the
// readahead settings, it won't prefetch extra or do any alignment and
// offset of buffer will be n.
Status s = fpb.PrefetchAsync(IOOptions(), r.get(), n, n, &result);
// Platforms that don't have IO uring may not support async IO.
if (s.IsNotSupported()) {
return;
}
ASSERT_TRUE(s.IsTryAgain());
IOOptions io_opts;
io_opts.rate_limiter_priority = Env::IOPriority::IO_LOW;
ASSERT_TRUE(fpb.TryReadFromCacheAsync(io_opts, r.get(), n, n, &result, &s));
if (read_async_called) {
ASSERT_EQ(fpb.GetPrefetchOffset(), n);
}
}
// With readahead enabled, it will do the alignment and prefetch and offset of
// buffer will be 0.
{
read_async_called = false;
FilePrefetchBuffer fpb(
/*readahead_size=*/16384, /*max_readahead_size=*/16384, /*enable=*/true,
/*track_min_offset=*/false, /*implicit_auto_readahead=*/false,
/*num_file_reads=*/0, /*num_file_reads_for_auto_readahead=*/2,
/*upper_bound_offset=*/0, fs());
Slice result;
// Simulate a seek of half of alignment bytes at offset n.
Status s = fpb.PrefetchAsync(IOOptions(), r.get(), n, n, &result);
// Platforms that don't have IO uring may not support async IO.
if (s.IsNotSupported()) {
return;
}
ASSERT_TRUE(s.IsTryAgain());
IOOptions io_opts;
io_opts.rate_limiter_priority = Env::IOPriority::IO_LOW;
ASSERT_TRUE(fpb.TryReadFromCacheAsync(io_opts, r.get(), n, n, &result, &s));
if (read_async_called) {
ASSERT_EQ(fpb.GetPrefetchOffset(), 0);
}
}
}
TEST_F(FilePrefetchBufferTest, NoSyncWithAsyncIO) {
std::string fname = "seek-with-block-cache-hit";
Random rand(0);
std::string content = rand.RandomString(32768);
Write(fname, content);
FileOptions opts;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
FilePrefetchBuffer fpb(
/*readahead_size=*/8192, /*max_readahead_size=*/16384, /*enable=*/true,
/*track_min_offset=*/false, /*implicit_auto_readahead=*/false,
/*num_file_reads=*/0, /*num_file_reads_for_auto_readahead=*/0,
/*upper_bound_offset=*/0, fs());
int read_async_called = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::ReadAsync",
[&](void* /*arg*/) { read_async_called++; });
SyncPoint::GetInstance()->EnableProcessing();
Slice async_result;
// Simulate a seek of 4000 bytes at offset 3000. Due to the readahead
// settings, it will do two reads of 4000+4096 and 4096
Status s = fpb.PrefetchAsync(IOOptions(), r.get(), 3000, 4000, &async_result);
// Platforms that don't have IO uring may not support async IO
if (s.IsNotSupported()) {
return;
}
ASSERT_TRUE(s.IsTryAgain());
IOOptions io_opts;
io_opts.rate_limiter_priority = Env::IOPriority::IO_LOW;
ASSERT_TRUE(fpb.TryReadFromCacheAsync(io_opts, r.get(), /*offset=*/3000,
/*length=*/4000, &async_result, &s));
// No sync call should be made.
HistogramData sst_read_micros;
stats()->histogramData(SST_READ_MICROS, &sst_read_micros);
ASSERT_EQ(sst_read_micros.count, 0);
// Number of async calls should be.
ASSERT_EQ(read_async_called, 2);
// Length should be 4000.
ASSERT_EQ(async_result.size(), 4000);
// Data correctness.
Slice result(&content[3000], 4000);
ASSERT_EQ(result.size(), 4000);
ASSERT_EQ(result, async_result);
}
// This test checks if during seek in async_io, if first buffer already
// prefetched the data till upper_bound offset, second buffer shouldn't go for
// prefetching.
TEST_F(FilePrefetchBufferTest, IterateUpperBoundTest1) {
std::string fname = "iterate-upperbound-test1";
Random rand(0);
std::string content = rand.RandomString(32768);
Write(fname, content);
FileOptions opts;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
FilePrefetchBuffer fpb(
/*readahead_size=*/8192, /*max_readahead_size=*/16384, /*enable=*/true,
/*track_min_offset=*/false, /*implicit_auto_readahead=*/false,
/*num_file_reads=*/0, /*num_file_reads_for_auto_readahead=*/0,
/*upper_bound_offset=*/8000, fs());
int read_async_called = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::ReadAsync",
[&](void* /*arg*/) { read_async_called++; });
SyncPoint::GetInstance()->EnableProcessing();
Slice async_result;
// Simulate a seek of 4000 bytes at offset 3000. Due to the readahead
// settings, it will do 1 read of 4000+1000 (till 8000 - upper bound).
Status s = fpb.PrefetchAsync(IOOptions(), r.get(), 3000, 4000, &async_result);
// Platforms that don't have IO uring may not support async IO
if (s.IsNotSupported()) {
return;
}
ASSERT_TRUE(s.IsTryAgain());
IOOptions io_opts;
io_opts.rate_limiter_priority = Env::IOPriority::IO_LOW;
ASSERT_TRUE(fpb.TryReadFromCacheAsync(io_opts, r.get(), /*offset=*/3000,
/*length=*/4000, &async_result, &s));
// No sync call should be made.
HistogramData sst_read_micros;
stats()->histogramData(SST_READ_MICROS, &sst_read_micros);
ASSERT_EQ(sst_read_micros.count, 0);
// Number of async calls should be 1.
// No Prefetching should happen in second buffer as first buffer has already
// prefetched till offset.
ASSERT_EQ(read_async_called, 1);
// Length should be 4000.
ASSERT_EQ(async_result.size(), 4000);
// Data correctness.
Slice result(&content[3000], 4000);
ASSERT_EQ(result.size(), 4000);
ASSERT_EQ(result, async_result);
}
TEST_F(FilePrefetchBufferTest, SyncReadaheadStats) {
std::string fname = "seek-with-block-cache-hit";
Random rand(0);
std::string content = rand.RandomString(32768);
Write(fname, content);
FileOptions opts;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
std::shared_ptr<Statistics> stats = CreateDBStatistics();
FilePrefetchBuffer fpb(8192, 8192, true, false, false, 0, 0, 0, fs(), nullptr,
stats.get());
Slice result;
// Simulate a seek of 4096 bytes at offset 0. Due to the readahead settings,
// it will do two reads of 4096+8192 and 8192
Status s;
ASSERT_TRUE(fpb.TryReadFromCache(IOOptions(), r.get(), 0, 4096, &result, &s));
ASSERT_EQ(s, Status::OK());
ASSERT_EQ(stats->getTickerCount(PREFETCH_HITS), 0);
ASSERT_EQ(stats->getTickerCount(PREFETCH_BYTES_USEFUL), 0);
// Simulate a block cache hit
fpb.UpdateReadPattern(4096, 4096, false);
// Now read some data that straddles the two prefetch buffers - offset 8192 to
// 16384
ASSERT_TRUE(
fpb.TryReadFromCache(IOOptions(), r.get(), 8192, 8192, &result, &s));
ASSERT_EQ(s, Status::OK());
ASSERT_EQ(stats->getTickerCount(PREFETCH_HITS), 0);
ASSERT_EQ(stats->getTickerCount(PREFETCH_BYTES_USEFUL), 4096);
ASSERT_TRUE(
fpb.TryReadFromCache(IOOptions(), r.get(), 12288, 4096, &result, &s));
ASSERT_EQ(s, Status::OK());
ASSERT_EQ(stats->getTickerCount(PREFETCH_HITS), 1);
ASSERT_EQ(stats->getTickerCount(PREFETCH_BYTES_USEFUL), 8192);
}
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
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