120 lines
3.7 KiB
C++
120 lines
3.7 KiB
C++
/*
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* Copyright (c) 2021-2023 Huawei Device Co., Ltd.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef THREAD_POOL_H
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#define THREAD_POOL_H
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#include "nocopyable.h"
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#include <thread>
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#include <mutex>
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#include <functional>
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#include <string>
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#include <condition_variable>
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#include <deque>
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#include <vector>
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namespace OHOS {
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/**
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* @brief Provides interfaces for thread-safe thread pool operations.
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*
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* The thread-safe is for the thread pool, but not for the threads in the pool.
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* A task queue and a thread group are under control. Users add tasks to the
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* task queue, and the thread group executes the tasks in the task queue.
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*/
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class ThreadPool : public NoCopyable {
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public:
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typedef std::function<void()> Task;
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/**
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* @brief Creates a thread pool and names the threads in the pool.
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*
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* @param name Indicates the prefix of the names of the threads in pool.
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* The names of threads in the pool are in the <b>name</b> + No format.
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* The thread name is a meaningful C language string, whose length is
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* restricted to 16 characters including the terminating null byte ('\0').
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* Pay attention to the name length when setting this parameter.
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* For example, if the number of threads in the pool is less than 10,
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* the name length cannot exceed 14 characters.
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*/
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explicit ThreadPool(const std::string &name = std::string());
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~ThreadPool() override;
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/**
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* @brief Starts a given number of threads, which will execute
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* the tasks in a task queue.
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*
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* @param threadsNum Indicates the number of threads to start.
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*/
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uint32_t Start(int threadsNum);
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/**
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* @brief Stops the thread pool.
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*/
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void Stop();
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/**
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* @brief Adds a task to the task queue.
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*
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* If <b>Start()</b> has never been called, the task will be executed
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* immediately.
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*
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* @param f Indicates the task to add.
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*/
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void AddTask(const Task& f);
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/**
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* @brief Sets the maximum number of tasks in the task queue.
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*
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* @param maxSize Indicates the maximum number of tasks to set.
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*/
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void SetMaxTaskNum(size_t maxSize) { maxTaskNum_ = maxSize; }
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// for testability
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/**
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* @brief Obtains the maximum number of tasks in the task queue.
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*/
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size_t GetMaxTaskNum() const { return maxTaskNum_; }
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/**
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* @brief Obtains the number of tasks in the task queue.
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*/
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size_t GetCurTaskNum();
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/**
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* @brief Obtains the number of threads in the pool.
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*/
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size_t GetThreadsNum() const { return threads_.size(); }
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/**
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* @brief Obtains the name of the thread pool.
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*/
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std::string GetName() const { return myName_; }
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private:
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// If the number of tasks in the queue reaches the maximum set by maxQueueSize, the thread pool is full load.
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bool Overloaded() const;
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void WorkInThread(); // main function in each thread.
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Task ScheduleTask(); // fetch a task from the queue and execute it
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private:
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std::string myName_;
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std::mutex mutex_;
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std::condition_variable hasTaskToDo_;
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std::condition_variable acceptNewTask_;
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std::vector<std::thread> threads_;
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std::deque<Task> tasks_;
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size_t maxTaskNum_;
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bool running_;
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};
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} // namespace OHOS
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#endif
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