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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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.
#pragma once
#include <functional>
namespace rocksdb {
* ThreadPool is a component that will spawn N background threads that will
* be used to execute scheduled work, The number of background threads could
* be modified by calling SetBackgroundThreads().
* */
class ThreadPool {
virtual ~ThreadPool() {}
// Wait for all threads to finish.
// Discard those threads that did not start
// executing
virtual void JoinAllThreads() = 0;
// Set the number of background threads that will be executing the
// scheduled jobs.
virtual void SetBackgroundThreads(int num) = 0;
virtual int GetBackgroundThreads() = 0;
// Get the number of jobs scheduled in the ThreadPool queue.
virtual unsigned int GetQueueLen() const = 0;
// Waits for all jobs to complete those
// that already started running and those that did not
// start yet. This ensures that everything that was thrown
// on the TP runs even though
// we may not have specified enough threads for the amount
// of jobs
virtual void WaitForJobsAndJoinAllThreads() = 0;
// Submit a fire and forget jobs
// This allows to submit the same job multiple times
virtual void SubmitJob(const std::function<void()>&) = 0;
// This moves the function in for efficiency
virtual void SubmitJob(std::function<void()>&&) = 0;
// NewThreadPool() is a function that could be used to create a ThreadPool
// with `num_threads` background threads.
extern ThreadPool* NewThreadPool(int num_threads);
} // namespace rocksdb