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rocksdb

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RocksDB for Erlang

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rocksdb deps rocksdb table block_fetcher.h
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deps/rocksdb/table/block_fetcher.h 

//  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