C++11 之生产消费者模式

爱被打了一巴掌 2022-09-03 04:22 98阅读 0赞

#include <thread>
     #include <mutex>
     #include <condition_variable>
     #include <list>
     #include <iostream>
     
     class Task
     {
     public:
         Task(int taskID)
         {
             this->taskID = taskID;
         }
         
         void doTask()
         {
             std::cout << "handle a task, taskID: " << taskID << ", threadID: " << std::this_thread::get_id() << std::endl; 
         }
         
     private:
         int taskID;
     };
     
     std::mutex                mymutex;
     std::list<Task*>          tasks;
     std::condition_variable   mycv;
     
     void* consumer_thread()
     {   
         Task* pTask = NULL;
         while (true)
         {
             std::unique_lock<std::mutex> guard(mymutex);
             while (tasks.empty())
             {               
                 //如果获得了互斥锁，但是条件不合适的话，pthread_cond_wait会释放锁，不往下执行。
                 //当发生变化后，条件合适，pthread_cond_wait将直接获得锁。
                 mycv.wait(guard);
             }
             
             pTask = tasks.front();
             tasks.pop_front();
             
             if (pTask == NULL)
                 continue;
     
             pTask->doTask();
             delete pTask;
             pTask = NULL;       
         }
         
         return NULL;
     }
     
     void* producer_thread()
     {
         int taskID = 0;
         Task* pTask = NULL;
         
         while (true)
         {
             pTask = new Task(taskID);
                 
             //使用括号减小guard锁的作用范围
             {
                 std::lock_guard<std::mutex> guard(mymutex);
                 tasks.push_back(pTask);
                 std::cout << "produce a task, taskID: " << taskID << ", threadID: " << std::this_thread::get_id() << std::endl; 
             }
             
             //释放信号量，通知消费者线程
             mycv.notify_one();
             
             taskID ++;
     
             //休眠1秒
             std::this_thread::sleep_for(std::chrono::seconds(1));
         }
         
         return NULL;
     }
     
     int main()
     {
         //创建5个消费者线程
         std::thread consumer1(consumer_thread);
         std::thread consumer2(consumer_thread);
         std::thread consumer3(consumer_thread);
         std::thread consumer4(consumer_thread);
         std::thread consumer5(consumer_thread);
         
         //创建一个生产者线程
         std::thread producer(producer_thread);
     
         producer.join();
         consumer1.join();
         consumer2.join();
         consumer3.join();
         consumer4.join();
         consumer5.join();
     
         return 0;
     }