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
4 years ago
committed by
Facebook GitHub Bot
parent
1758f76f2d
commit
40497a875a
@ -0,0 +1,475 @@ |
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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include "table/block_fetcher.h" |
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#include "db/table_properties_collector.h" |
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#include "options/options_helper.h" |
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#include "port/port.h" |
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#include "port/stack_trace.h" |
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#include "table/block_based/binary_search_index_reader.h" |
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#include "table/block_based/block_based_table_builder.h" |
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#include "table/block_based/block_based_table_factory.h" |
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#include "table/block_based/block_based_table_reader.h" |
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#include "table/format.h" |
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#include "test_util/testharness.h" |
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#include "test_util/testutil.h" |
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namespace ROCKSDB_NAMESPACE { |
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namespace { |
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class CountedMemoryAllocator : public MemoryAllocator { |
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public: |
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const char* Name() const override { return "CountedMemoryAllocator"; } |
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void* Allocate(size_t size) override { |
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num_allocations_++; |
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return static_cast<void*>(new char[size]); |
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} |
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void Deallocate(void* p) override { |
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num_deallocations_++; |
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delete[] static_cast<char*>(p); |
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} |
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int GetNumAllocations() const { return num_allocations_; } |
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int GetNumDeallocations() const { return num_deallocations_; } |
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private: |
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int num_allocations_ = 0; |
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int num_deallocations_ = 0; |
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}; |
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struct MemcpyStats { |
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int num_stack_buf_memcpy = 0; |
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int num_heap_buf_memcpy = 0; |
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int num_compressed_buf_memcpy = 0; |
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}; |
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struct BufAllocationStats { |
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int num_heap_buf_allocations = 0; |
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int num_compressed_buf_allocations = 0; |
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}; |
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struct TestStats { |
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MemcpyStats memcpy_stats; |
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BufAllocationStats buf_allocation_stats; |
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}; |
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class BlockFetcherTest : public testing::Test { |
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protected: |
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void SetUp() override { |
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test::ResetTmpDirForDirectIO(); |
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test_dir_ = test::PerThreadDBPath("block_fetcher_test"); |
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env_ = Env::Default(); |
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fs_ = FileSystem::Default(); |
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ASSERT_OK(fs_->CreateDir(test_dir_, IOOptions(), nullptr)); |
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is_direct_io_supported_ = DetectDirectIOSupport(); |
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} |
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void TearDown() override { EXPECT_OK(test::DestroyDir(env_, test_dir_)); } |
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bool IsDirectIOSupported() const { return is_direct_io_supported_; } |
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void AssertSameBlock(const BlockContents& block1, |
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const BlockContents& block2) { |
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ASSERT_EQ(block1.data.ToString(), block2.data.ToString()); |
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} |
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// Creates a table with kv pairs (i, i) where i ranges from 0 to 9, inclusive.
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void CreateTable(const std::string& table_name, |
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const CompressionType& compression_type) { |
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std::unique_ptr<WritableFileWriter> writer; |
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NewFileWriter(table_name, &writer); |
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// Create table builder.
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Options options; |
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ImmutableCFOptions ioptions(options); |
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InternalKeyComparator comparator(options.comparator); |
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ColumnFamilyOptions cf_options; |
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MutableCFOptions moptions(cf_options); |
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std::vector<std::unique_ptr<IntTblPropCollectorFactory>> factories; |
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std::unique_ptr<TableBuilder> table_builder(table_factory_.NewTableBuilder( |
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TableBuilderOptions(ioptions, moptions, comparator, &factories, |
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compression_type, 0 /* sample_for_compression */, |
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CompressionOptions(), false /* skip_filters */, |
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kDefaultColumnFamilyName, -1 /* level */), |
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0 /* column_family_id */, writer.get())); |
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// Build table.
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for (int i = 0; i < 9; i++) { |
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std::string key = ToInternalKey(std::to_string(i)); |
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std::string value = std::to_string(i); |
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table_builder->Add(key, value); |
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} |
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ASSERT_OK(table_builder->Finish()); |
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} |
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void FetchIndexBlock(const std::string& table_name, bool use_direct_io, |
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CountedMemoryAllocator* heap_buf_allocator, |
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CountedMemoryAllocator* compressed_buf_allocator, |
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MemcpyStats* memcpy_stats, BlockContents* index_block) { |
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FileOptions fopt; |
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fopt.use_direct_reads = use_direct_io; |
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std::unique_ptr<RandomAccessFileReader> file; |
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NewFileReader(table_name, fopt, &file); |
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// Get handle of the index block.
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Footer footer; |
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ReadFooter(file.get(), &footer); |
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const BlockHandle& index_handle = footer.index_handle(); |
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CompressionType compression_type; |
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FetchBlock(file.get(), index_handle, BlockType::kIndex, |
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false /* compressed */, false /* do_uncompress */, |
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heap_buf_allocator, compressed_buf_allocator, index_block, |
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memcpy_stats, &compression_type); |
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ASSERT_EQ(compression_type, CompressionType::kNoCompression); |
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} |
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// Fetches the first data block in both direct IO and non-direct IO mode.
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//
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// compressed: whether the data blocks are compressed;
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// do_uncompress: whether the data blocks should be uncompressed on fetching.
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// compression_type: the expected compression type.
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//
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// Expects:
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// Block contents are the same.
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// Bufferr allocation and memory copy statistics are expected.
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void TestFetchDataBlock(const std::string& table_name_prefix, bool compressed, |
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bool do_uncompress, |
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const TestStats& expected_non_direct_io_stats, |
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const TestStats& expected_direct_io_stats) { |
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if (!IsDirectIOSupported()) { |
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printf("Skip this test since direct IO is not supported\n"); |
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return; |
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} |
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for (CompressionType compression_type : GetSupportedCompressions()) { |
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bool do_compress = compression_type != kNoCompression; |
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if (compressed != do_compress) continue; |
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std::string compression_type_str = |
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CompressionTypeToString(compression_type); |
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std::string table_name = table_name_prefix + compression_type_str; |
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CreateTable(table_name, compression_type); |
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CompressionType expected_compression_type_after_fetch = |
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(compressed && !do_uncompress) ? compression_type : kNoCompression; |
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BlockContents blocks[2]; |
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MemcpyStats memcpy_stats[2]; |
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CountedMemoryAllocator heap_buf_allocators[2]; |
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CountedMemoryAllocator compressed_buf_allocators[2]; |
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for (bool use_direct_io : {false, true}) { |
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FetchFirstDataBlock( |
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table_name, use_direct_io, compressed, do_uncompress, |
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expected_compression_type_after_fetch, |
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&heap_buf_allocators[use_direct_io], |
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&compressed_buf_allocators[use_direct_io], &blocks[use_direct_io], |
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&memcpy_stats[use_direct_io]); |
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} |
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AssertSameBlock(blocks[0], blocks[1]); |
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// Check memcpy and buffer allocation statistics.
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for (bool use_direct_io : {false, true}) { |
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const TestStats& expected_stats = use_direct_io |
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? expected_direct_io_stats |
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: expected_non_direct_io_stats; |
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ASSERT_EQ(memcpy_stats[use_direct_io].num_stack_buf_memcpy, |
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expected_stats.memcpy_stats.num_stack_buf_memcpy); |
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ASSERT_EQ(memcpy_stats[use_direct_io].num_heap_buf_memcpy, |
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expected_stats.memcpy_stats.num_heap_buf_memcpy); |
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ASSERT_EQ(memcpy_stats[use_direct_io].num_compressed_buf_memcpy, |
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expected_stats.memcpy_stats.num_compressed_buf_memcpy); |
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ASSERT_EQ(heap_buf_allocators[use_direct_io].GetNumAllocations(), |
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expected_stats.buf_allocation_stats.num_heap_buf_allocations); |
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ASSERT_EQ( |
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compressed_buf_allocators[use_direct_io].GetNumAllocations(), |
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expected_stats.buf_allocation_stats.num_compressed_buf_allocations); |
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// The allocated buffers are not deallocated until
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// the block content is deleted.
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ASSERT_EQ(heap_buf_allocators[use_direct_io].GetNumDeallocations(), 0); |
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ASSERT_EQ( |
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compressed_buf_allocators[use_direct_io].GetNumDeallocations(), 0); |
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blocks[use_direct_io].allocation.reset(); |
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ASSERT_EQ(heap_buf_allocators[use_direct_io].GetNumDeallocations(), |
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expected_stats.buf_allocation_stats.num_heap_buf_allocations); |
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ASSERT_EQ( |
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compressed_buf_allocators[use_direct_io].GetNumDeallocations(), |
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expected_stats.buf_allocation_stats.num_compressed_buf_allocations); |
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} |
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} |
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} |
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private: |
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std::string test_dir_; |
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Env* env_; |
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std::shared_ptr<FileSystem> fs_; |
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BlockBasedTableFactory table_factory_; |
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bool is_direct_io_supported_; |
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std::string Path(const std::string& fname) { return test_dir_ + "/" + fname; } |
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void WriteToFile(const std::string& content, const std::string& filename) { |
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std::unique_ptr<FSWritableFile> f; |
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ASSERT_OK(fs_->NewWritableFile(Path(filename), FileOptions(), &f, nullptr)); |
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ASSERT_OK(f->Append(content, IOOptions(), nullptr)); |
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ASSERT_OK(f->Close(IOOptions(), nullptr)); |
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} |
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bool DetectDirectIOSupport() { |
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WriteToFile("", ".direct"); |
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FileOptions opt; |
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opt.use_direct_reads = true; |
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std::unique_ptr<FSRandomAccessFile> f; |
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auto s = fs_->NewRandomAccessFile(Path(".direct"), opt, &f, nullptr); |
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return s.ok(); |
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} |
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void NewFileWriter(const std::string& filename, |
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std::unique_ptr<WritableFileWriter>* writer) { |
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std::string path = Path(filename); |
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EnvOptions env_options; |
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std::unique_ptr<WritableFile> file; |
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ASSERT_OK(env_->NewWritableFile(path, &file, env_options)); |
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writer->reset(new WritableFileWriter( |
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NewLegacyWritableFileWrapper(std::move(file)), path, env_options)); |
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} |
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void NewFileReader(const std::string& filename, const FileOptions& opt, |
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std::unique_ptr<RandomAccessFileReader>* reader) { |
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std::string path = Path(filename); |
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std::unique_ptr<FSRandomAccessFile> f; |
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ASSERT_OK(fs_->NewRandomAccessFile(path, opt, &f, nullptr)); |
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reader->reset(new RandomAccessFileReader(std::move(f), path, env_)); |
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} |
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void NewTableReader(const ImmutableCFOptions& ioptions, |
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const FileOptions& foptions, |
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const InternalKeyComparator& comparator, |
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const std::string& table_name, |
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std::unique_ptr<BlockBasedTable>* table) { |
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std::unique_ptr<RandomAccessFileReader> file; |
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NewFileReader(table_name, foptions, &file); |
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uint64_t file_size = 0; |
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ASSERT_OK(env_->GetFileSize(Path(table_name), &file_size)); |
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std::unique_ptr<TableReader> table_reader; |
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ASSERT_OK(BlockBasedTable::Open(ioptions, EnvOptions(), |
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table_factory_.table_options(), comparator, |
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std::move(file), file_size, &table_reader)); |
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table->reset(reinterpret_cast<BlockBasedTable*>(table_reader.release())); |
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} |
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std::string ToInternalKey(const std::string& key) { |
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InternalKey internal_key(key, 0, ValueType::kTypeValue); |
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return internal_key.Encode().ToString(); |
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} |
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void ReadFooter(RandomAccessFileReader* file, Footer* footer) { |
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uint64_t file_size = 0; |
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ASSERT_OK(env_->GetFileSize(file->file_name(), &file_size)); |
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ReadFooterFromFile(file, nullptr /* prefetch_buffer */, file_size, footer, |
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kBlockBasedTableMagicNumber); |
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} |
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// NOTE: compression_type returns the compression type of the fetched block
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// contents, so if the block is fetched and uncompressed, then it's
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// kNoCompression.
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void FetchBlock(RandomAccessFileReader* file, const BlockHandle& block, |
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BlockType block_type, bool compressed, bool do_uncompress, |
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MemoryAllocator* heap_buf_allocator, |
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MemoryAllocator* compressed_buf_allocator, |
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BlockContents* contents, MemcpyStats* stats, |
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CompressionType* compresstion_type) { |
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Options options; |
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ImmutableCFOptions ioptions(options); |
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ReadOptions roptions; |
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PersistentCacheOptions persistent_cache_options; |
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Footer footer; |
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ReadFooter(file, &footer); |
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std::unique_ptr<BlockFetcher> fetcher(new BlockFetcher( |
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file, nullptr /* prefetch_buffer */, footer, roptions, block, contents, |
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ioptions, do_uncompress, compressed, block_type, |
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UncompressionDict::GetEmptyDict(), persistent_cache_options, |
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heap_buf_allocator, compressed_buf_allocator)); |
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ASSERT_OK(fetcher->ReadBlockContents()); |
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stats->num_stack_buf_memcpy = fetcher->TEST_GetNumStackBufMemcpy(); |
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stats->num_heap_buf_memcpy = fetcher->TEST_GetNumHeapBufMemcpy(); |
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stats->num_compressed_buf_memcpy = |
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fetcher->TEST_GetNumCompressedBufMemcpy(); |
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*compresstion_type = fetcher->get_compression_type(); |
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} |
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// NOTE: expected_compression_type is the expected compression
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// type of the fetched block content, if the block is uncompressed,
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// then the expected compression type is kNoCompression.
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void FetchFirstDataBlock(const std::string& table_name, bool use_direct_io, |
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bool compressed, bool do_uncompress, |
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CompressionType expected_compression_type, |
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MemoryAllocator* heap_buf_allocator, |
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MemoryAllocator* compressed_buf_allocator, |
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BlockContents* block, MemcpyStats* memcpy_stats) { |
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if (use_direct_io && !IsDirectIOSupported()) { |
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printf("Skip this test since direct IO is not supported\n"); |
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return; |
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} |
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Options options; |
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ImmutableCFOptions ioptions(options); |
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InternalKeyComparator comparator(options.comparator); |
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FileOptions foptions; |
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foptions.use_direct_reads = use_direct_io; |
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// Get block handle for the first data block.
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std::unique_ptr<BlockBasedTable> table; |
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NewTableReader(ioptions, foptions, comparator, table_name, &table); |
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std::unique_ptr<BlockBasedTable::IndexReader> index_reader; |
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ASSERT_OK(BinarySearchIndexReader::Create( |
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table.get(), nullptr /* prefetch_buffer */, false /* use_cache */, |
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false /* prefetch */, false /* pin */, nullptr /* lookup_context */, |
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&index_reader)); |
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std::unique_ptr<InternalIteratorBase<IndexValue>> iter( |
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index_reader->NewIterator( |
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ReadOptions(), false /* disable_prefix_seek */, nullptr /* iter */, |
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nullptr /* get_context */, nullptr /* lookup_context */)); |
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ASSERT_OK(iter->status()); |
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iter->SeekToFirst(); |
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BlockHandle first_block_handle = iter->value().handle; |
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// Fetch first data block.
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std::unique_ptr<RandomAccessFileReader> file; |
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NewFileReader(table_name, foptions, &file); |
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CompressionType compression_type; |
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FetchBlock(file.get(), first_block_handle, BlockType::kData, compressed, |
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do_uncompress, heap_buf_allocator, compressed_buf_allocator, |
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block, memcpy_stats, &compression_type); |
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ASSERT_EQ(compression_type, expected_compression_type); |
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} |
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}; |
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// Fetch index block under both direct IO and non-direct IO.
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// Expects:
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// the index block contents are the same for both read modes.
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TEST_F(BlockFetcherTest, FetchIndexBlock) { |
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if (!IsDirectIOSupported()) { |
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printf("Skip this test since direct IO is not supported\n"); |
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return; |
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} |
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for (CompressionType compression : GetSupportedCompressions()) { |
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std::string table_name = |
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"FetchIndexBlock" + CompressionTypeToString(compression); |
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CreateTable(table_name, compression); |
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CountedMemoryAllocator allocator; |
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MemcpyStats memcpy_stats; |
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BlockContents indexes[2]; |
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for (bool use_direct_io : {false, true}) { |
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FetchIndexBlock(table_name, use_direct_io, &allocator, &allocator, |
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&memcpy_stats, &indexes[use_direct_io]); |
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} |
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AssertSameBlock(indexes[0], indexes[1]); |
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} |
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} |
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// Data blocks are not compressed,
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// fetch data block under both direct IO and non-direct IO.
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// Expects:
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// 1. in non-direct IO mode, allocate a heap buffer and memcpy the block
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// into the buffer;
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// 2. in direct IO mode, allocate a heap buffer and memcpy from the
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// direct IO buffer to the heap buffer.
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TEST_F(BlockFetcherTest, FetchUncompressedDataBlock) { |
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MemcpyStats memcpy_stats; |
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memcpy_stats.num_heap_buf_memcpy = 1; |
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BufAllocationStats buf_allocation_stats; |
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buf_allocation_stats.num_heap_buf_allocations = 1; |
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TestStats expected_stats{memcpy_stats, buf_allocation_stats}; |
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TestFetchDataBlock("FetchUncompressedDataBlock", false, false, expected_stats, |
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expected_stats); |
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} |
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// Data blocks are compressed,
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// fetch data block under both direct IO and non-direct IO,
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// but do not uncompress.
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// Expects:
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// 1. in non-direct IO mode, allocate a compressed buffer and memcpy the block
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// into the buffer;
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// 2. in direct IO mode, allocate a compressed buffer and memcpy from the
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// direct IO buffer to the compressed buffer.
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TEST_F(BlockFetcherTest, FetchCompressedDataBlock) { |
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MemcpyStats memcpy_stats; |
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memcpy_stats.num_compressed_buf_memcpy = 1; |
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BufAllocationStats buf_allocation_stats; |
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buf_allocation_stats.num_compressed_buf_allocations = 1; |
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TestStats expected_stats{memcpy_stats, buf_allocation_stats}; |
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TestFetchDataBlock("FetchCompressedDataBlock", true, false, expected_stats, |
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expected_stats); |
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} |
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// Data blocks are compressed,
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// fetch and uncompress data block under both direct IO and non-direct IO.
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// Expects:
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// 1. in non-direct IO mode, since the block is small, so it's first memcpyed
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// to the stack buffer, then a heap buffer is allocated and the block is
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// uncompressed into the heap.
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// 2. in direct IO mode mode, allocate a heap buffer, then directly uncompress
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// and memcpy from the direct IO buffer to the heap buffer.
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TEST_F(BlockFetcherTest, FetchAndUncompressCompressedDataBlock) { |
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TestStats expected_non_direct_io_stats; |
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{ |
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MemcpyStats memcpy_stats; |
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memcpy_stats.num_stack_buf_memcpy = 1; |
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memcpy_stats.num_heap_buf_memcpy = 1; |
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BufAllocationStats buf_allocation_stats; |
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buf_allocation_stats.num_heap_buf_allocations = 1; |
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buf_allocation_stats.num_compressed_buf_allocations = 0; |
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expected_non_direct_io_stats = {memcpy_stats, buf_allocation_stats}; |
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} |
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TestStats expected_direct_io_stats; |
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{ |
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MemcpyStats memcpy_stats; |
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memcpy_stats.num_heap_buf_memcpy = 1; |
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BufAllocationStats buf_allocation_stats; |
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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