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linux下出产者与消费者C实现

2017-11-01 08:00 星期三 所属: C语言/C++ 教程 浏览:59

副标题#e#

最近做毕设涉及到了出产者与消费者模子,这个东东只在操纵系统课程上有点印象,于是花了点时间看了下《unix情况高级编程 》的线程部门,在此记录一下。

1.多线程的观念就不多说了,pthread.h头文件中包括的几个根基观念及函数:

pthread_t————线程ID数据范例,线程ID只在它所属的历程情况中有效;

int pthread_create(pthread_t *tidp, const pthread_attr_t *attr, func(void), arg)————建设新的线程,若乐成返回0配置tidp指向的单位为新线程的线程IDattr用来配置线程属性,一般默认为NULLfunc为新线程挪用的进口函数,该函数只能有一个无范例指针参数arg,若要向函数通报多个参数,需要将所有参数放到一个布局中,再把布局地点通报给arg

pthread_t pthread_self(void)————获取自身线程ID

void pthread_exit(void *rval_ptr)———终止本线程,用rval_ptr指向的值作为退出码

int pthread_join(pthread_t thread, void **rval_ptr)————挪用该函数的线程将阻塞,直到thread线程挪用pthread_exit、从启动例程返回或被打消,rval_ptr将包括返回码

int pthread_cancel(pthread_t tid)————该函数用来请求打消统一历程中的其他线程

2.线程同步————互斥量、读写锁,条件变量

读写锁即共享——独有锁,适合于读的次数远大于写的环境,较量好领略,就不多说了。

条件变量由互斥量掩护,线程在改变条件状态之前必需先锁定互斥量。

出产者与消费者模子用到了互斥量和条件变量,对行罗列办读写,下面直接上代码:

行列操纵(数据布局的内容),回收链式布局:

#include <stdio.h>   
#include <stdlib.h>   
#include <stdbool.h>   
#include <string.h>   
#include <time.h>   
#include <unistd.h>   
#include <pthread.h>   
       
#define MAXLENGTH 10    //the maxlength of queue   
       
typedef char * datatype;   
typedef struct node {    //define node   
    datatype name;   
    struct node *next;   
} node;   
typedef struct queue {    //define queue   
    node *front, *rear;   
    int len;   
} queue;   
       
void queue_init(queue *q)   
{   
    q->front = q->rear = NULL;   
    q->len = 0;   
}   
       
void  queue_put(queue *q, datatype new_name)  //入队   
{   
    node *mynode = (node *)malloc(sizeof(node));   
    mynode->name = new_name;   
    mynode->next = NULL;   
    if (q->rear)   
        q->rear->next = mynode;   
    q->rear = mynode;   
    if (q->front == NULL)   
        q->front = mynode;   
    q->len++;   
}   
       
datatype queue_get(queue *q)   //出队   
{   
    node *mynode;   
    datatype myname;   
    if (q->front != NULL)   
        mynode = q->front;   
    myname = mynode->name;   
    q->front = q->front->next;   
    q->len--;   
    free(mynode);   
    return myname;   
}   
       
void queue_print(queue *q)  //print queue   
{   
    node *tmp = q->front;   
    while(tmp != NULL)   
    {   
        printf("%s ", tmp->name);   
        tmp = tmp->next;   
    }   
    printf("n");   
}


#p#副标题#e#

出产者与消费者函数:

/*define mutex and condtion var*/   
pthread_cond_t q_not_full = PTHREAD_COND_INITIALIZER;   
pthread_cond_t q_not_empty = PTHREAD_COND_INITIALIZER;   
pthread_mutex_t qlock = PTHREAD_MUTEX_INITIALIZER;   
       
/*   
 * producer function   
 */   
void producer(void *q)   
{   
//    printf("start porducer:n");   
    queue *qt = q;    //传入的行列   
    while(1)   
    {   
        pthread_mutex_lock(&qlock);   
//        printf("producer has locked the qlockn");   
        if(qt->len >= MAXLENGTH)    //queue is full   
        {   
//            printf("producer is going to waitingn");   
            pthread_cond_wait(&q_not_full, &qlock);   
        }   
        queue_put(qt, "* ");   
//        printf("after producer: queue's length is %dn", qt->len);   
        pthread_mutex_unlock(&qlock);   
        pthread_cond_signal(&q_not_empty);   
       
//        printf("producer has unlocked the qlockn");   
//        sleep(1);   
    }   
}   
       
/*   
 * consumer function   
 */
void consumer(void *q)   
{   
//    printf("start consumer:n");   
    queue *qt = q;   
    while(1)   
    {   
        pthread_mutex_lock(&qlock);   
//        printf("consumer has locked the qlockn");   
        if(qt->len <= 0)    //queue is empty   
        {   
//            printf("consumer is going to waitingn");   
            pthread_cond_wait(&q_not_empty, &qlock);   
        }   
        datatype back_name = queue_get(qt);   
//        printf("after consumer, queue's length is %dn", qt->len);   
        pthread_mutex_unlock(&qlock);   
        pthread_cond_signal(&q_not_full);   
//        now process the back_name   
//        printf("cousumer has unlocked the qlockn");   
//        sleep(1);   
    }   
}

#p#分页标题#e#

主函数(测试):

//gcc编译时加上-lpthread   
int main() {   
    pthread_t tid1, tid2;   
    queue *q=(queue *)malloc(sizeof(queue));   
    queue_init(q);   
//    queue_put(q, "one");   
//    queue_put(q, "two");   
//    queue_put(q, "three");   
//    queue_get(q);   
//    printf("len = %dn", q->len);   
//    queue_print(q);   
       
    long stime = clock();   
    long etime = clock();   
       
    pthread_create(&tid1, NULL, (void *)producer, (void *)q);   
    pthread_create(&tid2, NULL, (void *)consumer, (void *)q);   
       
    while((float)(etime-stime)/CLOCKS_PER_SEC < 0.00001)   
    {   
        etime = clock();   
    }   
    return 0;   
}

From:cnblogs xfan

 

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