Qt生产者消费者实验:等待条件QWaitCondition

分类： LINUX 2012-08-12 16:42 829人阅读 评论(1)收藏 举报

qtbufferclass

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1. /* 
2. 使用QWaitCondition和QMutex可以实现比信号量更精确的控制 
3. */  
4.   
5. #include <QtCore>   
6. #include <iostream>   
7.   
8. //const int DataSize = 100000;   
9. //const int BufferSize = 4096;  
10.   
11.   
12. const int DataSize = 100;  
13. const int BufferSize = 100;  
14. char buffer[BufferSize];  
15.   
16. //与信号量不同的程序   
17. QWaitCondition bufferIsNotFull; //QWaitCondition允许在一定条件下触发其它多个线程  
18. QWaitCondition bufferIsNotEmpty;  
19. QMutex mutex;  
20. int usedSpace = 0;//不是信号量，而是用来代表在缓冲器中存在多少个“用过的”字节  
21.   
22. //生产者   
23. class Producer : public QThread  
24. {  
25. public:  
26.     void run();  
27. };  
28.   
29. void Producer::run()  
30. {  
31.     for (int i = 0; i < DataSize; ++i) {  
32.         mutex.lock();//锁定：保护对usedSpace变量的访问  
33.         //如果缓冲区都是用过的字节，那么就等待   
34.         while (usedSpace == BufferSize)  
35.             bufferIsNotFull.wait(&mutex);//wait的过程：解锁－>阻塞当前线程－>满足条件－>锁定－>返回  
36.         buffer[i % BufferSize] = "ACGT"[uint(rand()) % 4];  
37.         std::cerr<<"P";//代表一次生产者线程的运行  
38.         ++usedSpace;  
39.         bufferIsNotEmpty.wakeAll();//Wakes all threads waiting on the wait condition.  
40.         mutex.unlock();//解锁   
41.     }  
42. }  
43.   
44. //消费者   
45. class Consumer : public QThread  
46. {  
47. public:  
48.     void run();  
49. };  
50.   
51. void Consumer::run()  
52. {  
53.     for (int i = 0; i < DataSize; ++i) {  
54.         mutex.lock();//   
55.         //如果缓冲区里“用过的”字节数目为0，则等待  
56.         while (usedSpace == 0)  
57.             bufferIsNotEmpty.wait(&mutex);  
58.         //std::cerr << buffer[i % BufferSize];  
59.         char Cons = buffer[i % BufferSize];  
60.         std::cerr<<"c";  
61.         --usedSpace;  
62.         bufferIsNotFull.wakeAll();  
63.         mutex.unlock();  
64.     }  
65.     std::cerr << std::endl;  
66. }  
67.   
68. int main()  
69. {  
70.     Producer producer;  
71.     Consumer consumer;  
72.     producer.start();  
73.     consumer.start();  
74.     producer.wait();  
75.     consumer.wait();  
76.     return 0;  
77. }  

/*使用QWaitCondition和QMutex可以实现比信号量更精确的控制*/#include <QtCore>#include <iostream>//const int DataSize = 100000;//const int BufferSize = 4096;const int DataSize = 100;const int BufferSize = 100;char buffer[BufferSize];//与信号量不同的程序QWaitCondition bufferIsNotFull; //QWaitCondition允许在一定条件下触发其它多个线程QWaitCondition bufferIsNotEmpty;QMutex mutex;int usedSpace = 0;//不是信号量，而是用来代表在缓冲器中存在多少个“用过的”字节//生产者class Producer : public QThread{public:    void run();};void Producer::run(){    for (int i = 0; i < DataSize; ++i) {        mutex.lock();//锁定：保护对usedSpace变量的访问        //如果缓冲区都是用过的字节，那么就等待        while (usedSpace == BufferSize)            bufferIsNotFull.wait(&mutex);//wait的过程：解锁－>阻塞当前线程－>满足条件－>锁定－>返回        buffer[i % BufferSize] = "ACGT"[uint(rand()) % 4];        std::cerr<<"P";//代表一次生产者线程的运行        ++usedSpace;        bufferIsNotEmpty.wakeAll();//Wakes all threads waiting on the wait condition.        mutex.unlock();//解锁    }}//消费者class Consumer : public QThread{public:    void run();};void Consumer::run(){    for (int i = 0; i < DataSize; ++i) {        mutex.lock();//        //如果缓冲区里“用过的”字节数目为0，则等待        while (usedSpace == 0)            bufferIsNotEmpty.wait(&mutex);        //std::cerr << buffer[i % BufferSize];        char Cons = buffer[i % BufferSize];        std::cerr<<"c";        --usedSpace;        bufferIsNotFull.wakeAll();        mutex.unlock();    }    std::cerr << std::endl;}int main(){    Producer producer;    Consumer consumer;    producer.start();    consumer.start();    producer.wait();    consumer.wait();    return 0;}

执行结果

(1)

[cpp] view plaincopyprint?

1. const int DataSize = 100;  
2. const int BufferSize = 1;  

const int DataSize = 100;const int BufferSize = 1;

PcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPc

(2)

[cpp] view plaincopyprint?

1. const int DataSize = 100;  
2. const int BufferSize = 10;  

const int DataSize = 100;const int BufferSize = 10;

结果1

PPPPPPPPPPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcPcccccccccc

结果2

PPPPPPPPPPcPcPcPcPcPcPcPcPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPcc

结果3

PPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPccccccccccPPPPPPPPPPcccccccccc

(3)

[cpp] view plaincopyprint?

1. const int DataSize = 100;  
2. const int BufferSize = 100;  

const int DataSize = 100;const int BufferSize = 100;

PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc