8843129ece
Summary: Move arena, allocator, and memory tools under util to a separate memory/ directory. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5382 Differential Revision: D15564655 Pulled By: siying fbshipit-source-id: 9cd6b5d0d3d52b39606e19221fa154596e5852a5
103 lines
4.1 KiB
C++
103 lines
4.1 KiB
C++
// 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).
|
|
//
|
|
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file. See the AUTHORS file for names of contributors.
|
|
|
|
#pragma once
|
|
#include "memory/memory_allocator.h"
|
|
#include "table/block_based/block.h"
|
|
#include "table/format.h"
|
|
|
|
namespace rocksdb {
|
|
|
|
// Retrieves a single block of a given file. Utilizes the prefetch buffer and/or
|
|
// persistent cache provided (if any) to try to avoid reading from the file
|
|
// directly. Note that both the prefetch buffer and the persistent cache are
|
|
// optional; also, note that the persistent cache may be configured to store either
|
|
// compressed or uncompressed blocks.
|
|
//
|
|
// If the retrieved block is compressed and the do_uncompress flag is set,
|
|
// BlockFetcher uncompresses the block (using the uncompression dictionary,
|
|
// if provided, to prime the compression algorithm), and returns the resulting
|
|
// uncompressed block data. Otherwise, it returns the original block.
|
|
//
|
|
// Two read options affect the behavior of BlockFetcher: if verify_checksums is
|
|
// true, the checksum of the (original) block is checked; if fill_cache is true,
|
|
// the block is added to the persistent cache if needed.
|
|
//
|
|
// Memory for uncompressed and compressed blocks is allocated as needed
|
|
// using memory_allocator and memory_allocator_compressed, respectively
|
|
// (if provided; otherwise, the default allocator is used).
|
|
|
|
class BlockFetcher {
|
|
public:
|
|
BlockFetcher(RandomAccessFileReader* file,
|
|
FilePrefetchBuffer* prefetch_buffer, const Footer& footer,
|
|
const ReadOptions& read_options, const BlockHandle& handle,
|
|
BlockContents* contents, const ImmutableCFOptions& ioptions,
|
|
bool do_uncompress, bool maybe_compressed,
|
|
const UncompressionDict& uncompression_dict,
|
|
const PersistentCacheOptions& cache_options,
|
|
MemoryAllocator* memory_allocator = nullptr,
|
|
MemoryAllocator* memory_allocator_compressed = nullptr)
|
|
: file_(file),
|
|
prefetch_buffer_(prefetch_buffer),
|
|
footer_(footer),
|
|
read_options_(read_options),
|
|
handle_(handle),
|
|
contents_(contents),
|
|
ioptions_(ioptions),
|
|
do_uncompress_(do_uncompress),
|
|
maybe_compressed_(maybe_compressed),
|
|
uncompression_dict_(uncompression_dict),
|
|
cache_options_(cache_options),
|
|
memory_allocator_(memory_allocator),
|
|
memory_allocator_compressed_(memory_allocator_compressed) {}
|
|
Status ReadBlockContents();
|
|
CompressionType get_compression_type() const { return compression_type_; }
|
|
|
|
private:
|
|
static const uint32_t kDefaultStackBufferSize = 5000;
|
|
|
|
RandomAccessFileReader* file_;
|
|
FilePrefetchBuffer* prefetch_buffer_;
|
|
const Footer& footer_;
|
|
const ReadOptions read_options_;
|
|
const BlockHandle& handle_;
|
|
BlockContents* contents_;
|
|
const ImmutableCFOptions& ioptions_;
|
|
bool do_uncompress_;
|
|
bool maybe_compressed_;
|
|
const UncompressionDict& uncompression_dict_;
|
|
const PersistentCacheOptions& cache_options_;
|
|
MemoryAllocator* memory_allocator_;
|
|
MemoryAllocator* memory_allocator_compressed_;
|
|
Status status_;
|
|
Slice slice_;
|
|
char* used_buf_ = nullptr;
|
|
size_t block_size_;
|
|
CacheAllocationPtr heap_buf_;
|
|
CacheAllocationPtr compressed_buf_;
|
|
char stack_buf_[kDefaultStackBufferSize];
|
|
bool got_from_prefetch_buffer_ = false;
|
|
rocksdb::CompressionType compression_type_;
|
|
|
|
// return true if found
|
|
bool TryGetUncompressBlockFromPersistentCache();
|
|
// return true if found
|
|
bool TryGetFromPrefetchBuffer();
|
|
bool TryGetCompressedBlockFromPersistentCache();
|
|
void PrepareBufferForBlockFromFile();
|
|
// Copy content from used_buf_ to new heap buffer.
|
|
void CopyBufferToHeap();
|
|
void GetBlockContents();
|
|
void InsertCompressedBlockToPersistentCacheIfNeeded();
|
|
void InsertUncompressedBlockToPersistentCacheIfNeeded();
|
|
void CheckBlockChecksum();
|
|
};
|
|
} // namespace rocksdb
|