ceph/src/rocksdb/util/threadpool_imp.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 #pragma once
  10
  11 #include <functional>
  12 #include <memory>
  13
  14 #include "rocksdb/env.h"
  15 #include "rocksdb/threadpool.h"
  16
  17 namespace ROCKSDB_NAMESPACE {
  18
  19 class ThreadPoolImpl : public ThreadPool {
  20  public:
  21   ThreadPoolImpl();
  22   ~ThreadPoolImpl();
  23
  24   ThreadPoolImpl(ThreadPoolImpl&&) = delete;
  25   ThreadPoolImpl& operator=(ThreadPoolImpl&&) = delete;
  26
  27   // Implement ThreadPool interfaces
  28
  29   // Wait for all threads to finish.
  30   // Discards all the jobs that did not
  31   // start executing and waits for those running
  32   // to complete
  33   void JoinAllThreads() override;
  34
  35   // Set the number of background threads that will be executing the
  36   // scheduled jobs.
  37   void SetBackgroundThreads(int num) override;
  38   int GetBackgroundThreads() override;
  39
  40   // Get the number of jobs scheduled in the ThreadPool queue.
  41   unsigned int GetQueueLen() const override;
  42
  43   // Waits for all jobs to complete those
  44   // that already started running and those that did not
  45   // start yet
  46   void WaitForJobsAndJoinAllThreads() override;
  47
  48   // Make threads to run at a lower kernel IO priority
  49   // Currently only has effect on Linux
  50   void LowerIOPriority();
  51
  52   // Make threads to run at a lower kernel CPU priority
  53   // Currently only has effect on Linux
  54   void LowerCPUPriority(CpuPriority pri);
  55
  56   // Ensure there is at aleast num threads in the pool
  57   // but do not kill threads if there are more
  58   void IncBackgroundThreadsIfNeeded(int num);
  59
  60   // Submit a fire and forget job
  61   // These jobs can not be unscheduled
  62
  63   // This allows to submit the same job multiple times
  64   void SubmitJob(const std::function<void()>&) override;
  65   // This moves the function in for efficiency
  66   void SubmitJob(std::function<void()>&&) override;
  67
  68   // Schedule a job with an unschedule tag and unschedule function
  69   // Can be used to filter and unschedule jobs by a tag
  70   // that are still in the queue and did not start running
  71   void Schedule(void (*function)(void* arg1), void* arg, void* tag,
  72                 void (*unschedFunction)(void* arg));
  73
  74   // Filter jobs that are still in a queue and match
  75   // the given tag. Remove them from a queue if any
  76   // and for each such job execute an unschedule function
  77   // if such was given at scheduling time.
  78   int UnSchedule(void* tag);
  79
  80   void SetHostEnv(Env* env);
  81
  82   Env* GetHostEnv() const;
  83
  84   // Return the thread priority.
  85   // This would allow its member-thread to know its priority.
  86   Env::Priority GetThreadPriority() const;
  87
  88   // Set the thread priority.
  89   void SetThreadPriority(Env::Priority priority);
  90
  91   // Reserve a specific number of threads, prevent them from running other
  92   // functions The number of reserved threads could be fewer than the desired
  93   // one
  94   int ReserveThreads(int threads_to_be_reserved) override;
  95
  96   // Release a specific number of threads
  97   int ReleaseThreads(int threads_to_be_released) override;
  98
  99   static void PthreadCall(const char* label, int result);
 100
 101   struct Impl;
 102
 103  private:
 104   // Current public virtual interface does not provide usable
 105   // functionality and thus can not be used internally to
 106   // facade different implementations.
 107   //
 108   // We propose a pimpl idiom in order to easily replace the thread pool impl
 109   // w/o touching the header file but providing a different .cc potentially
 110   // CMake option driven.
 111   //
 112   // Another option is to introduce a Env::MakeThreadPool() virtual interface
 113   // and override the environment. This would require refactoring ThreadPool
 114   // usage.
 115   //
 116   // We can also combine these two approaches
 117   std::unique_ptr<Impl> impl_;
 118 };
 119
 120 }  // namespace ROCKSDB_NAMESPACE