rocksdb/table/block_fetcher.h
Maysam Yabandeh 235ab9dd32 Pin mmap files in ReadOnlyDB (#4053)
Summary:
https://github.com/facebook/rocksdb/pull/3881 fixed a bug where PinnableSlice pin mmap files which could be deleted with background compaction. This is however a non-issue for ReadOnlyDB when there is no compaction running and max_open_files is -1. This patch reenables the pinning feature for that case.
Closes https://github.com/facebook/rocksdb/pull/4053

Differential Revision: D8662546

Pulled By: maysamyabandeh

fbshipit-source-id: 402962602eb0f644e17822748332999c3af029fd
2018-06-27 17:13:34 -07:00

78 lines
2.8 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 "table/block.h"
#include "table/format.h"
namespace rocksdb {
class BlockFetcher {
public:
// Read the block identified by "handle" from "file".
// The only relevant option is options.verify_checksums for now.
// On failure return non-OK.
// On success fill *result and return OK - caller owns *result
// @param compression_dict Data for presetting the compression library's
// dictionary.
BlockFetcher(RandomAccessFileReader* file,
FilePrefetchBuffer* prefetch_buffer, const Footer& footer,
const ReadOptions& read_options, const BlockHandle& handle,
BlockContents* contents, const ImmutableCFOptions& ioptions,
bool do_uncompress, const Slice& compression_dict,
const PersistentCacheOptions& cache_options,
const bool immortal_source = false)
: file_(file),
prefetch_buffer_(prefetch_buffer),
footer_(footer),
read_options_(read_options),
handle_(handle),
contents_(contents),
ioptions_(ioptions),
do_uncompress_(do_uncompress),
immortal_source_(immortal_source),
compression_dict_(compression_dict),
cache_options_(cache_options) {}
Status ReadBlockContents();
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_;
const bool immortal_source_;
const Slice& compression_dict_;
const PersistentCacheOptions& cache_options_;
Status status_;
Slice slice_;
char* used_buf_ = nullptr;
size_t block_size_;
std::unique_ptr<char[]> heap_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();
void GetBlockContents();
void InsertCompressedBlockToPersistentCacheIfNeeded();
void InsertUncompressedBlockToPersistentCacheIfNeeded();
void CheckBlockChecksum();
};
} // namespace rocksdb