rocksdb/db/table_cache.h

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same 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.
//
// Thread-safe (provides internal synchronization)
#pragma once
#include <string>
#include <stdint.h>
#include "db/dbformat.h"
#include "rocksdb/env.h"
#include "rocksdb/cache.h"
#include "port/port.h"
#include "rocksdb/table.h"
namespace rocksdb {
class Env;
struct FileMetaData;
class TableCache {
public:
TableCache(const std::string& dbname, const Options* options,
const EnvOptions& storage_options, int entries);
~TableCache();
// Return an iterator for the specified file number (the corresponding
// file length must be exactly "file_size" bytes). If "tableptr" is
// non-nullptr, also sets "*tableptr" to point to the Table object
// underlying the returned iterator, or nullptr if no Table object underlies
// the returned iterator. The returned "*tableptr" object is owned by
// the cache and should not be deleted, and is valid for as long as the
// returned iterator is live.
Iterator* NewIterator(const ReadOptions& options,
const EnvOptions& toptions,
const FileMetaData& file_meta,
TableReader** table_reader_ptr = nullptr,
bool for_compaction = false);
// If a seek to internal key "k" in specified file finds an entry,
// call (*handle_result)(arg, found_key, found_value) repeatedly until
// it returns false.
Status Get(const ReadOptions& options,
const FileMetaData& file_meta,
const Slice& k,
void* arg,
bool (*handle_result)(void*, const Slice&, const Slice&, bool),
bool* table_io,
void (*mark_key_may_exist)(void*) = nullptr);
// Determine whether the table may contain the specified prefix. If
// the table index or blooms are not in memory, this may cause an I/O
bool PrefixMayMatch(const ReadOptions& options, uint64_t file_number,
uint64_t file_size, const Slice& internal_prefix,
bool* table_io);
// Evict any entry for the specified file number
void Evict(uint64_t file_number);
// Find table reader
Status FindTable(const EnvOptions& toptions, uint64_t file_number,
uint64_t file_size, Cache::Handle**, bool* table_io=nullptr,
const bool no_io = false);
// Get TableReader from a cache handle.
TableReader* GetTableReaderFromHandle(Cache::Handle* handle);
// Release the handle from a cache
void ReleaseHandle(Cache::Handle* handle);
private:
Env* const env_;
const std::string dbname_;
const Options* options_;
const EnvOptions& storage_options_;
std::shared_ptr<Cache> cache_;
};
} // namespace rocksdb