rocksdb/db/writebuffer.h
Jonah Cohen a14b7873ee Enforce write buffer memory limit across column families
Summary:
Introduces a new class for managing write buffer memory across column
families.  We supplement ColumnFamilyOptions::write_buffer_size with
ColumnFamilyOptions::write_buffer, a shared pointer to a WriteBuffer
instance that enforces memory limits before flushing out to disk.

Test Plan: Added SharedWriteBuffer unit test to db_test.cc

Reviewers: sdong, rven, ljin, igor

Reviewed By: igor

Subscribers: tnovak, yhchiang, dhruba, xjin, MarkCallaghan, yoshinorim

Differential Revision: https://reviews.facebook.net/D22581
2014-12-02 12:09:20 -08:00

45 lines
1.3 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.
//
// 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.
//
// WriteBuffer is for managing memory allocation for one or more MemTables.
#pragma once
namespace rocksdb {
class WriteBuffer {
public:
explicit WriteBuffer(size_t _buffer_size)
: buffer_size_(_buffer_size), memory_used_(0) {}
~WriteBuffer() {}
size_t memory_usage() const { return memory_used_; }
size_t buffer_size() const { return buffer_size_; }
// Should only be called from write thread
bool ShouldFlush() const {
return buffer_size() > 0 && memory_usage() >= buffer_size();
}
// Should only be called from write thread
void ReserveMem(size_t mem) { memory_used_ += mem; }
void FreeMem(size_t mem) { memory_used_ -= mem; }
private:
const size_t buffer_size_;
size_t memory_used_;
// No copying allowed
WriteBuffer(const WriteBuffer&);
void operator=(const WriteBuffer&);
};
} // namespace rocksdb