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rocksdb/file/prefetch_test.cc

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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 ROCKSDB_NAMESPACE {
class MockFS;
class MockRandomAccessFile : public FSRandomAccessFileOwnerWrapper {
public:
MockRandomAccessFile(std::unique_ptr<FSRandomAccessFile>& file,
bool support_prefetch, std::atomic_int& prefetch_count)
: FSRandomAccessFileOwnerWrapper(std::move(file)),
support_prefetch_(support_prefetch),
prefetch_count_(prefetch_count) {}
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");
}
}
private:
const bool support_prefetch_;
std::atomic_int& prefetch_count_;
};
class MockFS : public FileSystemWrapper {
public:
explicit MockFS(const std::shared_ptr<FileSystem>& wrapped,
bool support_prefetch)
: FileSystemWrapper(wrapped), support_prefetch_(support_prefetch) {}
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_));
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_;
std::atomic_int prefetch_count_{0};
};
class PrefetchTest
: public DBTestBase,
public ::testing::WithParamInterface<std::tuple<bool, bool>> {
public:
PrefetchTest() : DBTestBase("prefetch_test", true) {}
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 basic functionality of prefetching.
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);
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), "value for range 1 key"));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
// create second key range
batch.Clear();
for (int i = 0; i < kNumKeys; i++) {
ASSERT_OK(batch.Put(BuildKey(i, "key2"), "value for range 2 key"));
}
ASSERT_OK(db_->Write(WriteOptions(), &batch));
// 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));
// 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());
// commenting out the line below causes the example to work correctly
ASSERT_OK(db_->CompactRange(CompactRangeOptions(), &least, &greatest));
if (support_prefetch && !use_direct_io) {
// If underline file system supports prefetch, and directIO is not enabled
// make sure prefetch() is called and FilePrefetchBuffer is not used.
ASSERT_TRUE(fs->IsPrefetchCalled());
fs->ClearPrefetchCount();
ASSERT_EQ(0, buff_prefetch_count);
} else {
// If underline file system doesn't support prefetch, or directIO is
// enabled, make sure prefetch() is not called and FilePrefetchBuffer is
// used.
ASSERT_FALSE(fs->IsPrefetchCalled());
ASSERT_GT(buff_prefetch_count, 0);
buff_prefetch_count = 0;
}
// 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++;
}
}
// Make sure prefetch is called only if file system support prefetch.
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();
}
// 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};
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();
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();
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();
}
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();
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()) {
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()) {
}
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();
}
// 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_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) {
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_async_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::PrefetchAsyncInternal:Start",
[&](void*) { buff_async_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;
}
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_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);
}
ASSERT_GT(buff_async_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);
if (ro.async_io) {
ASSERT_GT(async_read_bytes.count, 0);
} else {
ASSERT_EQ(async_read_bytes.count, 0);
}
}
SyncPoint::GetInstance()->DisableProcessing();
SyncPoint::GetInstance()->ClearAllCallBacks();
}
Close();
}
class PrefetchTest1 : public DBTestBase,
public ::testing::WithParamInterface<bool> {
public:
PrefetchTest1() : DBTestBase("prefetch_test1", true) {}
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());
// 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) {
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));
int buff_prefetch_count = 0;
SyncPoint::GetInstance()->SetCallBack(
"FilePrefetchBuffer::PrefetchAsyncInternal:Start",
[&](void*) { buff_prefetch_count++; });
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());
ASSERT_EQ(buff_prefetch_count, 2);
// Check stats to make sure async prefetch is done.
{
HistogramData async_read_bytes;
options.statistics->histogramData(ASYNC_READ_BYTES, &async_read_bytes);
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
}
buff_prefetch_count = 0;
}
Close();
}
extern "C" bool RocksDbIOUringEnable() { return true; }
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_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);
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
if (read_async_called) {
ASSERT_GT(async_read_bytes.count, 0);
} else {
ASSERT_EQ(async_read_bytes.count, 0);
}
ASSERT_GT(prefetched_bytes_discarded.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, 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);
}
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);
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
if (read_async_called) {
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
} else {
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);
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);
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
if (read_async_called) {
ASSERT_GT(async_read_bytes.count, 0);
ASSERT_GT(get_perf_context()->number_async_seek, 0);
} else {
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(get_perf_context()->number_async_seek, 0);
}
ASSERT_GT(prefetched_bytes_discarded.count, 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());
// 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(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 {
ASSERT_EQ(async_read_bytes.count, 0);
ASSERT_EQ(get_perf_context()->number_async_seek, 0);
ASSERT_EQ(buff_prefetch_count, 1);
}
}
buff_prefetch_count = 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++;
}
// End the tracing.
ASSERT_OK(db_->EndIOTrace());
ASSERT_OK(env_->FileExists(trace_file_path));
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);
// Not all platforms support iouring. In that case, ReadAsync in posix
// won't submit async requests.
if (read_async_called) {
ASSERT_GT(async_read_bytes.count, 0);
} else {
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, 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
ASSERT_TRUE(s.IsTryAgain() || s.IsNotSupported());
// Simulate a block cache hit
fpb.UpdateReadPattern(0, 4096, false);
// Now read some data that straddles the two prefetch buffers - offset 8192 to
// 16384
ASSERT_TRUE(fpb.TryReadFromCacheAsync(IOOptions(), r.get(), 8192, 8192,
&result, &s, Env::IOPriority::IO_LOW));
}
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, 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
ASSERT_TRUE(s.IsTryAgain() || s.IsNotSupported());
ASSERT_TRUE(fpb.TryReadFromCacheAsync(IOOptions(), r.get(), /*offset=*/3000,
/*length=*/4000, &async_result, &s,
Env::IOPriority::IO_LOW));
// 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.c_str() + 3000, 4000);
ASSERT_EQ(result.size(), 4000);
ASSERT_EQ(result, async_result);
}
} // 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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