d616ebea23
Summary: Closes https://github.com/facebook/rocksdb/pull/2226 Differential Revision: D4967547 Pulled By: siying fbshipit-source-id: dd3b58ae1e7a106ab6bb6f37ab5c88575b125ab4
65 lines
2.0 KiB
C++
65 lines
2.0 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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// This source code is also licensed under the GPLv2 license found in the
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// COPYING file in the root directory of this source tree.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// WriteBufferManager is for managing memory allocation for one or more
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// MemTables.
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#pragma once
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#include <atomic>
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#include <cstddef>
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namespace rocksdb {
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class WriteBufferManager {
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public:
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// _buffer_size = 0 indicates no limit. Memory won't be tracked,
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// memory_usage() won't be valid and ShouldFlush() will always return true.
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explicit WriteBufferManager(size_t _buffer_size)
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: buffer_size_(_buffer_size), memory_used_(0) {}
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~WriteBufferManager() {}
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bool enabled() const { return buffer_size_ != 0; }
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// Only valid if enabled()
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size_t memory_usage() const {
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return memory_used_.load(std::memory_order_relaxed);
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}
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size_t buffer_size() const { return buffer_size_; }
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// Should only be called from write thread
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bool ShouldFlush() const {
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return enabled() && memory_usage() >= buffer_size();
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}
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// Should only be called from write thread
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void ReserveMem(size_t mem) {
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if (enabled()) {
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memory_used_.fetch_add(mem, std::memory_order_relaxed);
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}
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}
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void FreeMem(size_t mem) {
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if (enabled()) {
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memory_used_.fetch_sub(mem, std::memory_order_relaxed);
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}
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}
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private:
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const size_t buffer_size_;
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std::atomic<size_t> memory_used_;
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// No copying allowed
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WriteBufferManager(const WriteBufferManager&) = delete;
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WriteBufferManager& operator=(const WriteBufferManager&) = delete;
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};
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} // namespace rocksdb
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