Reduce memory copies when fetching and uncompressing blocks from SST files (#6689)
Summary: In https://github.com/facebook/rocksdb/pull/6455, we modified the interface of `RandomAccessFileReader::Read` to be able to get rid of memcpy in direct IO mode. This PR applies the new interface to `BlockFetcher` when reading blocks from SST files in direct IO mode. Without this PR, in direct IO mode, when fetching and uncompressing compressed blocks, `BlockFetcher` will first copy the raw compressed block into `BlockFetcher::compressed_buf_` or `BlockFetcher::stack_buf_` inside `RandomAccessFileReader::Read` depending on the block size. then during uncompressing, it will copy the uncompressed block into `BlockFetcher::heap_buf_`. In this PR, we get rid of the first memcpy and directly uncompress the block from `direct_io_buf_` to `heap_buf_`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6689 Test Plan: A new unit test `block_fetcher_test` is added. Reviewed By: anand1976 Differential Revision: D21006729 Pulled By: cheng-chang fbshipit-source-id: 2370b92c24075692423b81277415feb2aed5d980main
Cheng Chang
5 years ago
committed by
Facebook GitHub Bot
parent
1758f76f2d
commit
40497a875a
@ -0,0 +1,475 @@ |
||||
// 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 "table/block_fetcher.h" |
||||
#include "db/table_properties_collector.h" |
||||
#include "options/options_helper.h" |
||||
#include "port/port.h" |
||||
#include "port/stack_trace.h" |
||||
#include "table/block_based/binary_search_index_reader.h" |
||||
#include "table/block_based/block_based_table_builder.h" |
||||
#include "table/block_based/block_based_table_factory.h" |
||||
#include "table/block_based/block_based_table_reader.h" |
||||
#include "table/format.h" |
||||
#include "test_util/testharness.h" |
||||
#include "test_util/testutil.h" |
||||
|
||||
namespace ROCKSDB_NAMESPACE { |
||||
namespace { |
||||
|
||||
class CountedMemoryAllocator : public MemoryAllocator { |
||||
public: |
||||
const char* Name() const override { return "CountedMemoryAllocator"; } |
||||
|
||||
void* Allocate(size_t size) override { |
||||
num_allocations_++; |
||||
return static_cast<void*>(new char[size]); |
||||
} |
||||
|
||||
void Deallocate(void* p) override { |
||||
num_deallocations_++; |
||||
delete[] static_cast<char*>(p); |
||||
} |
||||
|
||||
int GetNumAllocations() const { return num_allocations_; } |
||||
int GetNumDeallocations() const { return num_deallocations_; } |
||||
|
||||
private: |
||||
int num_allocations_ = 0; |
||||
int num_deallocations_ = 0; |
||||
}; |
||||
|
||||
struct MemcpyStats { |
||||
int num_stack_buf_memcpy = 0; |
||||
int num_heap_buf_memcpy = 0; |
||||
int num_compressed_buf_memcpy = 0; |
||||
}; |
||||
|
||||
struct BufAllocationStats { |
||||
int num_heap_buf_allocations = 0; |
||||
int num_compressed_buf_allocations = 0; |
||||
}; |
||||
|
||||
struct TestStats { |
||||
MemcpyStats memcpy_stats; |
||||
BufAllocationStats buf_allocation_stats; |
||||
}; |
||||
|
||||
class BlockFetcherTest : public testing::Test { |
||||
protected: |
||||
void SetUp() override { |
||||
test::ResetTmpDirForDirectIO(); |
||||
test_dir_ = test::PerThreadDBPath("block_fetcher_test"); |
||||
env_ = Env::Default(); |
||||
fs_ = FileSystem::Default(); |
||||
ASSERT_OK(fs_->CreateDir(test_dir_, IOOptions(), nullptr)); |
||||
is_direct_io_supported_ = DetectDirectIOSupport(); |
||||
} |
||||
|
||||
void TearDown() override { EXPECT_OK(test::DestroyDir(env_, test_dir_)); } |
||||
|
||||
bool IsDirectIOSupported() const { return is_direct_io_supported_; } |
||||
|
||||
void AssertSameBlock(const BlockContents& block1, |
||||
const BlockContents& block2) { |
||||
ASSERT_EQ(block1.data.ToString(), block2.data.ToString()); |
||||
} |
||||
|
||||
// Creates a table with kv pairs (i, i) where i ranges from 0 to 9, inclusive.
|
||||
void CreateTable(const std::string& table_name, |
||||
const CompressionType& compression_type) { |
||||
std::unique_ptr<WritableFileWriter> writer; |
||||
NewFileWriter(table_name, &writer); |
||||
|
||||
// Create table builder.
|
||||
Options options; |
||||
ImmutableCFOptions ioptions(options); |
||||
InternalKeyComparator comparator(options.comparator); |
||||
ColumnFamilyOptions cf_options; |
||||
MutableCFOptions moptions(cf_options); |
||||
std::vector<std::unique_ptr<IntTblPropCollectorFactory>> factories; |
||||
std::unique_ptr<TableBuilder> table_builder(table_factory_.NewTableBuilder( |
||||
TableBuilderOptions(ioptions, moptions, comparator, &factories, |
||||
compression_type, 0 /* sample_for_compression */, |
||||
CompressionOptions(), false /* skip_filters */, |
||||
kDefaultColumnFamilyName, -1 /* level */), |
||||
0 /* column_family_id */, writer.get())); |
||||
|
||||
// Build table.
|
||||
for (int i = 0; i < 9; i++) { |
||||
std::string key = ToInternalKey(std::to_string(i)); |
||||
std::string value = std::to_string(i); |
||||
table_builder->Add(key, value); |
||||
} |
||||
ASSERT_OK(table_builder->Finish()); |
||||
} |
||||
|
||||
void FetchIndexBlock(const std::string& table_name, bool use_direct_io, |
||||
CountedMemoryAllocator* heap_buf_allocator, |
||||
CountedMemoryAllocator* compressed_buf_allocator, |
||||
MemcpyStats* memcpy_stats, BlockContents* index_block) { |
||||
FileOptions fopt; |
||||
fopt.use_direct_reads = use_direct_io; |
||||
std::unique_ptr<RandomAccessFileReader> file; |
||||
NewFileReader(table_name, fopt, &file); |
||||
|
||||
// Get handle of the index block.
|
||||
Footer footer; |
||||
ReadFooter(file.get(), &footer); |
||||
const BlockHandle& index_handle = footer.index_handle(); |
||||
|
||||
CompressionType compression_type; |
||||
FetchBlock(file.get(), index_handle, BlockType::kIndex, |
||||
false /* compressed */, false /* do_uncompress */, |
||||
heap_buf_allocator, compressed_buf_allocator, index_block, |
||||
memcpy_stats, &compression_type); |
||||
ASSERT_EQ(compression_type, CompressionType::kNoCompression); |
||||
} |
||||
|
||||
// Fetches the first data block in both direct IO and non-direct IO mode.
|
||||
//
|
||||
// compressed: whether the data blocks are compressed;
|
||||
// do_uncompress: whether the data blocks should be uncompressed on fetching.
|
||||
// compression_type: the expected compression type.
|
||||
//
|
||||
// Expects:
|
||||
// Block contents are the same.
|
||||
// Bufferr allocation and memory copy statistics are expected.
|
||||
void TestFetchDataBlock(const std::string& table_name_prefix, bool compressed, |
||||
bool do_uncompress, |
||||
const TestStats& expected_non_direct_io_stats, |
||||
const TestStats& expected_direct_io_stats) { |
||||
if (!IsDirectIOSupported()) { |
||||
printf("Skip this test since direct IO is not supported\n"); |
||||
return; |
||||
} |
||||
|
||||
for (CompressionType compression_type : GetSupportedCompressions()) { |
||||
bool do_compress = compression_type != kNoCompression; |
||||
if (compressed != do_compress) continue; |
||||
std::string compression_type_str = |
||||
CompressionTypeToString(compression_type); |
||||
|
||||
std::string table_name = table_name_prefix + compression_type_str; |
||||
CreateTable(table_name, compression_type); |
||||
|
||||
CompressionType expected_compression_type_after_fetch = |
||||
(compressed && !do_uncompress) ? compression_type : kNoCompression; |
||||
|
||||
BlockContents blocks[2]; |
||||
MemcpyStats memcpy_stats[2]; |
||||
CountedMemoryAllocator heap_buf_allocators[2]; |
||||
CountedMemoryAllocator compressed_buf_allocators[2]; |
||||
for (bool use_direct_io : {false, true}) { |
||||
FetchFirstDataBlock( |
||||
table_name, use_direct_io, compressed, do_uncompress, |
||||
expected_compression_type_after_fetch, |
||||
&heap_buf_allocators[use_direct_io], |
||||
&compressed_buf_allocators[use_direct_io], &blocks[use_direct_io], |
||||
&memcpy_stats[use_direct_io]); |
||||
} |
||||
|
||||
AssertSameBlock(blocks[0], blocks[1]); |
||||
|
||||
// Check memcpy and buffer allocation statistics.
|
||||
for (bool use_direct_io : {false, true}) { |
||||
const TestStats& expected_stats = use_direct_io |
||||
? expected_direct_io_stats |
||||
: expected_non_direct_io_stats; |
||||
|
||||
ASSERT_EQ(memcpy_stats[use_direct_io].num_stack_buf_memcpy, |
||||
expected_stats.memcpy_stats.num_stack_buf_memcpy); |
||||
ASSERT_EQ(memcpy_stats[use_direct_io].num_heap_buf_memcpy, |
||||
expected_stats.memcpy_stats.num_heap_buf_memcpy); |
||||
ASSERT_EQ(memcpy_stats[use_direct_io].num_compressed_buf_memcpy, |
||||
expected_stats.memcpy_stats.num_compressed_buf_memcpy); |
||||
|
||||
ASSERT_EQ(heap_buf_allocators[use_direct_io].GetNumAllocations(), |
||||
expected_stats.buf_allocation_stats.num_heap_buf_allocations); |
||||
ASSERT_EQ( |
||||
compressed_buf_allocators[use_direct_io].GetNumAllocations(), |
||||
expected_stats.buf_allocation_stats.num_compressed_buf_allocations); |
||||
|
||||
// The allocated buffers are not deallocated until
|
||||
// the block content is deleted.
|
||||
ASSERT_EQ(heap_buf_allocators[use_direct_io].GetNumDeallocations(), 0); |
||||
ASSERT_EQ( |
||||
compressed_buf_allocators[use_direct_io].GetNumDeallocations(), 0); |
||||
blocks[use_direct_io].allocation.reset(); |
||||
ASSERT_EQ(heap_buf_allocators[use_direct_io].GetNumDeallocations(), |
||||
expected_stats.buf_allocation_stats.num_heap_buf_allocations); |
||||
ASSERT_EQ( |
||||
compressed_buf_allocators[use_direct_io].GetNumDeallocations(), |
||||
expected_stats.buf_allocation_stats.num_compressed_buf_allocations); |
||||
} |
||||
} |
||||
} |
||||
|
||||
private: |
||||
std::string test_dir_; |
||||
Env* env_; |
||||
std::shared_ptr<FileSystem> fs_; |
||||
BlockBasedTableFactory table_factory_; |
||||
bool is_direct_io_supported_; |
||||
|
||||
std::string Path(const std::string& fname) { return test_dir_ + "/" + fname; } |
||||
|
||||
void WriteToFile(const std::string& content, const std::string& filename) { |
||||
std::unique_ptr<FSWritableFile> f; |
||||
ASSERT_OK(fs_->NewWritableFile(Path(filename), FileOptions(), &f, nullptr)); |
||||
ASSERT_OK(f->Append(content, IOOptions(), nullptr)); |
||||
ASSERT_OK(f->Close(IOOptions(), nullptr)); |
||||
} |
||||
|
||||
bool DetectDirectIOSupport() { |
||||
WriteToFile("", ".direct"); |
||||
FileOptions opt; |
||||
opt.use_direct_reads = true; |
||||
std::unique_ptr<FSRandomAccessFile> f; |
||||
auto s = fs_->NewRandomAccessFile(Path(".direct"), opt, &f, nullptr); |
||||
return s.ok(); |
||||
} |
||||
|
||||
void NewFileWriter(const std::string& filename, |
||||
std::unique_ptr<WritableFileWriter>* writer) { |
||||
std::string path = Path(filename); |
||||
EnvOptions env_options; |
||||
std::unique_ptr<WritableFile> file; |
||||
ASSERT_OK(env_->NewWritableFile(path, &file, env_options)); |
||||
writer->reset(new WritableFileWriter( |
||||
NewLegacyWritableFileWrapper(std::move(file)), path, env_options)); |
||||
} |
||||
|
||||
void NewFileReader(const std::string& filename, const FileOptions& opt, |
||||
std::unique_ptr<RandomAccessFileReader>* reader) { |
||||
std::string path = Path(filename); |
||||
std::unique_ptr<FSRandomAccessFile> f; |
||||
ASSERT_OK(fs_->NewRandomAccessFile(path, opt, &f, nullptr)); |
||||
reader->reset(new RandomAccessFileReader(std::move(f), path, env_)); |
||||
} |
||||
|
||||
void NewTableReader(const ImmutableCFOptions& ioptions, |
||||
const FileOptions& foptions, |
||||
const InternalKeyComparator& comparator, |
||||
const std::string& table_name, |
||||
std::unique_ptr<BlockBasedTable>* table) { |
||||
std::unique_ptr<RandomAccessFileReader> file; |
||||
NewFileReader(table_name, foptions, &file); |
||||
|
||||
uint64_t file_size = 0; |
||||
ASSERT_OK(env_->GetFileSize(Path(table_name), &file_size)); |
||||
|
||||
std::unique_ptr<TableReader> table_reader; |
||||
ASSERT_OK(BlockBasedTable::Open(ioptions, EnvOptions(), |
||||
table_factory_.table_options(), comparator, |
||||
std::move(file), file_size, &table_reader)); |
||||
|
||||
table->reset(reinterpret_cast<BlockBasedTable*>(table_reader.release())); |
||||
} |
||||
|
||||
std::string ToInternalKey(const std::string& key) { |
||||
InternalKey internal_key(key, 0, ValueType::kTypeValue); |
||||
return internal_key.Encode().ToString(); |
||||
} |
||||
|
||||
void ReadFooter(RandomAccessFileReader* file, Footer* footer) { |
||||
uint64_t file_size = 0; |
||||
ASSERT_OK(env_->GetFileSize(file->file_name(), &file_size)); |
||||
ReadFooterFromFile(file, nullptr /* prefetch_buffer */, file_size, footer, |
||||
kBlockBasedTableMagicNumber); |
||||
} |
||||
|
||||
// NOTE: compression_type returns the compression type of the fetched block
|
||||
// contents, so if the block is fetched and uncompressed, then it's
|
||||
// kNoCompression.
|
||||
void FetchBlock(RandomAccessFileReader* file, const BlockHandle& block, |
||||
BlockType block_type, bool compressed, bool do_uncompress, |
||||
MemoryAllocator* heap_buf_allocator, |
||||
MemoryAllocator* compressed_buf_allocator, |
||||
BlockContents* contents, MemcpyStats* stats, |
||||
CompressionType* compresstion_type) { |
||||
Options options; |
||||
ImmutableCFOptions ioptions(options); |
||||
ReadOptions roptions; |
||||
PersistentCacheOptions persistent_cache_options; |
||||
Footer footer; |
||||
ReadFooter(file, &footer); |
||||
std::unique_ptr<BlockFetcher> fetcher(new BlockFetcher( |
||||
file, nullptr /* prefetch_buffer */, footer, roptions, block, contents, |
||||
ioptions, do_uncompress, compressed, block_type, |
||||
UncompressionDict::GetEmptyDict(), persistent_cache_options, |
||||
heap_buf_allocator, compressed_buf_allocator)); |
||||
|
||||
ASSERT_OK(fetcher->ReadBlockContents()); |
||||
|
||||
stats->num_stack_buf_memcpy = fetcher->TEST_GetNumStackBufMemcpy(); |
||||
stats->num_heap_buf_memcpy = fetcher->TEST_GetNumHeapBufMemcpy(); |
||||
stats->num_compressed_buf_memcpy = |
||||
fetcher->TEST_GetNumCompressedBufMemcpy(); |
||||
|
||||
*compresstion_type = fetcher->get_compression_type(); |
||||
} |
||||
|
||||
// NOTE: expected_compression_type is the expected compression
|
||||
// type of the fetched block content, if the block is uncompressed,
|
||||
// then the expected compression type is kNoCompression.
|
||||
void FetchFirstDataBlock(const std::string& table_name, bool use_direct_io, |
||||
bool compressed, bool do_uncompress, |
||||
CompressionType expected_compression_type, |
||||
MemoryAllocator* heap_buf_allocator, |
||||
MemoryAllocator* compressed_buf_allocator, |
||||
BlockContents* block, MemcpyStats* memcpy_stats) { |
||||
if (use_direct_io && !IsDirectIOSupported()) { |
||||
printf("Skip this test since direct IO is not supported\n"); |
||||
return; |
||||
} |
||||
|
||||
Options options; |
||||
ImmutableCFOptions ioptions(options); |
||||
InternalKeyComparator comparator(options.comparator); |
||||
|
||||
FileOptions foptions; |
||||
foptions.use_direct_reads = use_direct_io; |
||||
|
||||
// Get block handle for the first data block.
|
||||
std::unique_ptr<BlockBasedTable> table; |
||||
NewTableReader(ioptions, foptions, comparator, table_name, &table); |
||||
|
||||
std::unique_ptr<BlockBasedTable::IndexReader> index_reader; |
||||
ASSERT_OK(BinarySearchIndexReader::Create( |
||||
table.get(), nullptr /* prefetch_buffer */, false /* use_cache */, |
||||
false /* prefetch */, false /* pin */, nullptr /* lookup_context */, |
||||
&index_reader)); |
||||
|
||||
std::unique_ptr<InternalIteratorBase<IndexValue>> iter( |
||||
index_reader->NewIterator( |
||||
ReadOptions(), false /* disable_prefix_seek */, nullptr /* iter */, |
||||
nullptr /* get_context */, nullptr /* lookup_context */)); |
||||
ASSERT_OK(iter->status()); |
||||
iter->SeekToFirst(); |
||||
BlockHandle first_block_handle = iter->value().handle; |
||||
|
||||
// Fetch first data block.
|
||||
std::unique_ptr<RandomAccessFileReader> file; |
||||
NewFileReader(table_name, foptions, &file); |
||||
CompressionType compression_type; |
||||
FetchBlock(file.get(), first_block_handle, BlockType::kData, compressed, |
||||
do_uncompress, heap_buf_allocator, compressed_buf_allocator, |
||||
block, memcpy_stats, &compression_type); |
||||
ASSERT_EQ(compression_type, expected_compression_type); |
||||
} |
||||
}; |
||||
|
||||
// Fetch index block under both direct IO and non-direct IO.
|
||||
// Expects:
|
||||
// the index block contents are the same for both read modes.
|
||||
TEST_F(BlockFetcherTest, FetchIndexBlock) { |
||||
if (!IsDirectIOSupported()) { |
||||
printf("Skip this test since direct IO is not supported\n"); |
||||
return; |
||||
} |
||||
|
||||
for (CompressionType compression : GetSupportedCompressions()) { |
||||
std::string table_name = |
||||
"FetchIndexBlock" + CompressionTypeToString(compression); |
||||
CreateTable(table_name, compression); |
||||
|
||||
CountedMemoryAllocator allocator; |
||||
MemcpyStats memcpy_stats; |
||||
BlockContents indexes[2]; |
||||
for (bool use_direct_io : {false, true}) { |
||||
FetchIndexBlock(table_name, use_direct_io, &allocator, &allocator, |
||||
&memcpy_stats, &indexes[use_direct_io]); |
||||
} |
||||
AssertSameBlock(indexes[0], indexes[1]); |
||||
} |
||||
} |
||||
|
||||
// Data blocks are not compressed,
|
||||
// fetch data block under both direct IO and non-direct IO.
|
||||
// Expects:
|
||||
// 1. in non-direct IO mode, allocate a heap buffer and memcpy the block
|
||||
// into the buffer;
|
||||
// 2. in direct IO mode, allocate a heap buffer and memcpy from the
|
||||
// direct IO buffer to the heap buffer.
|
||||
TEST_F(BlockFetcherTest, FetchUncompressedDataBlock) { |
||||
MemcpyStats memcpy_stats; |
||||
memcpy_stats.num_heap_buf_memcpy = 1; |
||||
|
||||
BufAllocationStats buf_allocation_stats; |
||||
buf_allocation_stats.num_heap_buf_allocations = 1; |
||||
|
||||
TestStats expected_stats{memcpy_stats, buf_allocation_stats}; |
||||
|
||||
TestFetchDataBlock("FetchUncompressedDataBlock", false, false, expected_stats, |
||||
expected_stats); |
||||
} |
||||
|
||||
// Data blocks are compressed,
|
||||
// fetch data block under both direct IO and non-direct IO,
|
||||
// but do not uncompress.
|
||||
// Expects:
|
||||
// 1. in non-direct IO mode, allocate a compressed buffer and memcpy the block
|
||||
// into the buffer;
|
||||
// 2. in direct IO mode, allocate a compressed buffer and memcpy from the
|
||||
// direct IO buffer to the compressed buffer.
|
||||
TEST_F(BlockFetcherTest, FetchCompressedDataBlock) { |
||||
MemcpyStats memcpy_stats; |
||||
memcpy_stats.num_compressed_buf_memcpy = 1; |
||||
|
||||
BufAllocationStats buf_allocation_stats; |
||||
buf_allocation_stats.num_compressed_buf_allocations = 1; |
||||
|
||||
TestStats expected_stats{memcpy_stats, buf_allocation_stats}; |
||||
|
||||
TestFetchDataBlock("FetchCompressedDataBlock", true, false, expected_stats, |
||||
expected_stats); |
||||
} |
||||
|
||||
// Data blocks are compressed,
|
||||
// fetch and uncompress data block under both direct IO and non-direct IO.
|
||||
// Expects:
|
||||
// 1. in non-direct IO mode, since the block is small, so it's first memcpyed
|
||||
// to the stack buffer, then a heap buffer is allocated and the block is
|
||||
// uncompressed into the heap.
|
||||
// 2. in direct IO mode mode, allocate a heap buffer, then directly uncompress
|
||||
// and memcpy from the direct IO buffer to the heap buffer.
|
||||
TEST_F(BlockFetcherTest, FetchAndUncompressCompressedDataBlock) { |
||||
TestStats expected_non_direct_io_stats; |
||||
{ |
||||
MemcpyStats memcpy_stats; |
||||
memcpy_stats.num_stack_buf_memcpy = 1; |
||||
memcpy_stats.num_heap_buf_memcpy = 1; |
||||
|
||||
BufAllocationStats buf_allocation_stats; |
||||
buf_allocation_stats.num_heap_buf_allocations = 1; |
||||
buf_allocation_stats.num_compressed_buf_allocations = 0; |
||||
|
||||
expected_non_direct_io_stats = {memcpy_stats, buf_allocation_stats}; |
||||
} |
||||
|
||||
TestStats expected_direct_io_stats; |
||||
{ |
||||
MemcpyStats memcpy_stats; |
||||
memcpy_stats.num_heap_buf_memcpy = 1; |
||||
|
||||
BufAllocationStats buf_allocation_stats; |
||||
buf_allocation_stats.num_heap_buf_allocations = 1; |
||||
|
||||
expected_direct_io_stats = {memcpy_stats, buf_allocation_stats}; |
||||
} |
||||
|
||||
TestFetchDataBlock("FetchAndUncompressCompressedDataBlock", true, true, |
||||
expected_non_direct_io_stats, expected_direct_io_stats); |
||||
} |
||||
|
||||
} // namespace
|
||||
} // namespace ROCKSDB_NAMESPACE
|
||||
|
||||
int main(int argc, char** argv) { |
||||
ROCKSDB_NAMESPACE::port::InstallStackTraceHandler(); |
||||
::testing::InitGoogleTest(&argc, argv); |
||||
return RUN_ALL_TESTS(); |
||||
} |
||||
Loading…
Reference in new issue