mirror of https://github.com/facebook/rocksdb.git
79 lines
2.3 KiB
C++
79 lines
2.3 KiB
C++
// Copyright (c) 2013, 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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#pragma once
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#include <stdint.h>
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#include <memory>
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namespace rocksdb {
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class WriteControllerToken;
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// WriteController is controlling write stalls in our write code-path. Write
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// stalls happen when compaction can't keep up with write rate.
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// All of the methods here (including WriteControllerToken's destructors) need
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// to be called while holding DB mutex
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class WriteController {
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public:
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WriteController() : total_stopped_(0), total_delay_us_(0) {}
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~WriteController() = default;
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// When an actor (column family) requests a stop token, all writes will be
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// stopped until the stop token is released (deleted)
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std::unique_ptr<WriteControllerToken> GetStopToken();
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// When an actor (column family) requests a delay token, total delay for all
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// writes will be increased by delay_us. The delay will last until delay token
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// is released
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std::unique_ptr<WriteControllerToken> GetDelayToken(uint64_t delay_us);
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// these two metods are querying the state of the WriteController
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bool IsStopped() const;
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uint64_t GetDelay() const;
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private:
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friend class WriteControllerToken;
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friend class StopWriteToken;
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friend class DelayWriteToken;
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int total_stopped_;
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uint64_t total_delay_us_;
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};
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class WriteControllerToken {
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public:
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explicit WriteControllerToken(WriteController* controller)
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: controller_(controller) {}
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virtual ~WriteControllerToken() {}
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protected:
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WriteController* controller_;
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private:
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// no copying allowed
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WriteControllerToken(const WriteControllerToken&) = delete;
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void operator=(const WriteControllerToken&) = delete;
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};
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class StopWriteToken : public WriteControllerToken {
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public:
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explicit StopWriteToken(WriteController* controller)
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: WriteControllerToken(controller) {}
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virtual ~StopWriteToken();
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};
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class DelayWriteToken : public WriteControllerToken {
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public:
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DelayWriteToken(WriteController* controller, uint64_t delay_us)
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: WriteControllerToken(controller), delay_us_(delay_us) {}
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virtual ~DelayWriteToken();
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private:
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uint64_t delay_us_;
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};
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} // namespace rocksdb
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