多线程 线程队列的实现

参考他人的方法，自己做了简单修改，实现一个通用的线程队列。

#include <stdio.h>
#include <pthread.h>
#include <unistd.h>

#define POOL_SIZE 10
#define QUEUE_LEN 20
pthread_mutex_t queue_lock; //队列锁
pthread_cond_t  queue_cond; //条件变量

int head = 0, tail = 0;
int queue[QUEUE_LEN];

void delay(int x)
{
	int i,j;
	for(i = 0; i < x; i++)
		for(j = 0; j <x; j++);
}

void fun1(){
	printf("fun1 start\n");
	delay(1000);
	printf("fun1 end\n");
}

void fun2(){
	printf("fun2 start\n");
	delay(2000);
	printf("fun2 end\n");
}

void fun3(){
	printf("fun3 start\n");
	delay(3000);
	printf("fun3 end\n");
}

void fun4(){
	printf("fun4 start\n");
	delay(4000);
	printf("fun4 end\n");
}

int dequeue()//出对列函数
{
	int y;
	pthread_mutex_lock(&queue_lock);
	while(head == tail)//队列中 无情求时，等待
	{
		pthread_cond_wait(&queue_cond, &queue_lock);//自动释放锁		
	}
	y = queue[head++]; //head first element,tail points to the back of last one
	if(head >= QUEUE_LEN) //0~ QUEUE_LEN-1
		head = 0;
	pthread_mutex_unlock(&queue_lock);
	return y;
}

void * process_queue(void *arg)
{
	int x = 0;
	for(;;)
	{
		x = dequeue();
		printf("%d dequeue \n",x);
		switch(x)
		{
			case 1:
				fun1(); break;
			case 2:
				fun2(); break;
		    case 3:
				fun3(); break;
			default:
				fun4(); break;
		}		
	}
}

int enqueue(int x)//插入请求 
{
	pthread_mutex_lock(&queue_lock);
	queue[tail] = x;
	++tail;
	if(tail >= QUEUE_LEN)
		tail = 0;
	if(tail == head)
	{
	 pthread_cond_signal(&queue_cond);//
	 pthread_mutex_unlock(&queue_lock);   
	 return 0;// 表示队列已满
	}	
	pthread_cond_signal(&queue_cond);//激活
	pthread_mutex_unlock(&queue_lock);
	return 1;//入队成功		
}

int main()
{
	int i;
	int num = 0;
	pthread_t tid[POOL_SIZE];

	pthread_mutex_init(&queue_lock, NULL);
	pthread_cond_init(&queue_cond, NULL);

	for(i = 0; i < POOL_SIZE; i++)
		pthread_create(&tid[i], NULL, process_queue, NULL);

	while(1)
	{
		scanf("%d",&num);
		if(0 == num)
			break;
		printf("%d ",num);
		while(!enqueue(num))//队列满时 等待
		{
			printf("queue is full\n");
			sleep(1);
		}
	}

	for(i = 0; i < POOL_SIZE; i++)
		pthread_cancel(tid[i]);//发出请求
//	for(i = 0; i < POOL_SIZE; i++)
//		pthread_join(tid[i], NULL); // 为何不能取得退出状态？？？

	pthread_mutex_destroy(&queue_lock);
	pthread_cond_destroy(&queue_cond);

	return 0;
}

还有一些不足之处，随后补上。

测试方法：

键入 ：

4 3 2 1

结果：
4 3 2 1 4 dequeue
fun4 start
3 dequeue
fun3 start
2 dequeue
fun2 start
1 dequeue
fun1 start
fun1 end
fun2 end
fun3 end
fun4 end

键入：

0

退出函数