rocksdb/table/get_context.h
Giuseppe Ottaviano 782a1590f9 Implement a table-level row cache
Summary:
Implementation of a table-level row cache.
It only caches point queries done through the `DB::Get` interface, queries done through the `Iterator` interface will completely skip the cache.

Supports snapshots and merge operations.

Test Plan: Ran `make valgrind_check commit-prereq`

Reviewers: igor, philipp, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D39849
2015-06-23 10:25:45 -07:00

59 lines
1.8 KiB
C++

// Copyright (c) 2014, 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.
#pragma once
#include <string>
#include "db/merge_context.h"
#include "rocksdb/env.h"
namespace rocksdb {
class MergeContext;
class GetContext {
public:
enum GetState {
kNotFound,
kFound,
kDeleted,
kCorrupt,
kMerge // saver contains the current merge result (the operands)
};
GetContext(const Comparator* ucmp, const MergeOperator* merge_operator,
Logger* logger, Statistics* statistics, GetState init_state,
const Slice& user_key, std::string* ret_value, bool* value_found,
MergeContext* merge_context, Env* env_);
void MarkKeyMayExist();
void SaveValue(const Slice& value);
bool SaveValue(const ParsedInternalKey& parsed_key, const Slice& value);
GetState State() const { return state_; }
// If a non-null string is passed, all the SaveValue calls will be
// logged into the string. The operations can then be replayed on
// another GetContext with replayGetContextLog.
void SetReplayLog(std::string* replay_log) { replay_log_ = replay_log; }
private:
const Comparator* ucmp_;
const MergeOperator* merge_operator_;
// the merge operations encountered;
Logger* logger_;
Statistics* statistics_;
GetState state_;
Slice user_key_;
std::string* value_;
bool* value_found_; // Is value set correctly? Used by KeyMayExist
MergeContext* merge_context_;
Env* env_;
std::string* replay_log_;
};
void replayGetContextLog(const Slice& replay_log, const Slice& user_key,
GetContext* get_context);
} // namespace rocksdb