ceph/src/rocksdb/util/concurrent_task_limiter_impl.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5 //
   6 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   7 // Use of this source code is governed by a BSD-style license that can be
   8 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   9
  10 #pragma once
  11 #include <atomic>
  12 #include <memory>
  13
  14 #include "rocksdb/env.h"
  15 #include "rocksdb/concurrent_task_limiter.h"
  16
  17 namespace rocksdb {
  18
  19 class TaskLimiterToken;
  20
  21 class ConcurrentTaskLimiterImpl : public ConcurrentTaskLimiter {
  22  public:
  23   explicit ConcurrentTaskLimiterImpl(const std::string& name,
  24                                      int32_t max_outstanding_task);
  25
  26   virtual ~ConcurrentTaskLimiterImpl();
  27
  28   virtual const std::string& GetName() const override;
  29
  30   virtual void SetMaxOutstandingTask(int32_t limit) override;
  31
  32   virtual void ResetMaxOutstandingTask() override;
  33
  34   virtual int32_t GetOutstandingTask() const override;
  35
  36   // Request token for adding a new task.
  37   // If force == true, it requests a token bypassing throttle.
  38   // Returns nullptr if it got throttled.
  39   virtual std::unique_ptr<TaskLimiterToken> GetToken(bool force);
  40
  41  private:
  42   friend class TaskLimiterToken;
  43
  44   std::string name_;
  45   std::atomic<int32_t> max_outstanding_tasks_;
  46   std::atomic<int32_t> outstanding_tasks_;
  47
  48   // No copying allowed
  49   ConcurrentTaskLimiterImpl(const ConcurrentTaskLimiterImpl&) = delete;
  50   ConcurrentTaskLimiterImpl& operator=(
  51       const ConcurrentTaskLimiterImpl&) = delete;
  52 };
  53
  54 class TaskLimiterToken {
  55  public:
  56   explicit TaskLimiterToken(ConcurrentTaskLimiterImpl* limiter)
  57       : limiter_(limiter) {}
  58   ~TaskLimiterToken();
  59
  60  private:
  61   ConcurrentTaskLimiterImpl* limiter_;
  62
  63   // no copying allowed
  64   TaskLimiterToken(const TaskLimiterToken&) = delete;
  65   void operator=(const TaskLimiterToken&) = delete;
  66 };
  67
  68 }  // namespace rocksdb