APUE中文第三版11章读写锁的一个可运行的例子

我的测试环境是CentOS7(内核版本3.10.0），X86_64.

头文件： wrlock.h

#ifndef _WRLOCK_H#define _WRLOCK_H#include <stdlib.h>#include <pthread.h>#include <stdio.h>struct job {    struct job  *j_next;    struct job  *j_prev;    pthread_t   tid;    void *( *job_func)( void *);};struct queue {    struct job      *q_head;    struct job      *q_tail;    pthread_rwlock_t    q_lock; };int queue_init( struct queue *qp );void job_insert( struct queue *qp, struct job *jp );void job_append( struct queue *qp, struct job *jp );void job_remove( struct queue *qp, struct job *jp );struct job *job_find( struct queue *qp, pthread_t tid );#endif

队列的相关操作，这一部分与书上的基本一样。
11_14.c

#include "wrlock.h"intqueue_init( struct queue *qp ){    int err;    qp->q_head = qp->q_tail = NULL;    if ((err = pthread_rwlock_init(&qp->q_lock,NULL)) != 0)        return err;    return 0;}/* insert a job at the head of queue */void job_insert( struct queue *qp, struct job *jp ){    pthread_rwlock_wrlock(&qp->q_lock);    jp->j_next = qp->q_head;    jp->j_prev = NULL;    if ( qp->q_head != NULL )        qp->q_head->j_prev = jp;    else            qp->q_tail = jp;    qp->q_head = jp;    pthread_rwlock_unlock(&qp->q_lock);}/* append a job on the tail of queue */void job_append( struct queue *qp, struct job *jp ){    pthread_rwlock_wrlock(&qp->q_lock);    jp->j_next = NULL;    jp->j_prev = qp->q_tail;    if ( qp->q_tail != NULL )        qp->q_tail->j_next = jp;    else            qp->q_head = jp;    qp->q_tail = jp;    pthread_rwlock_unlock(&qp->q_lock);}voidjob_remove( struct queue *qp, struct job *jp ){    pthread_rwlock_wrlock(&qp->q_lock);    /*     ** remove the head job,maybe jp pointing the only job.    */    if (jp == qp->q_head){        qp->q_head = jp->j_next;        if (jp->j_next != NULL)            jp->j_next->j_prev = NULL;        else             qp->q_tail = NULL;    }  /*        ** remove the tail job, if jp pointing the only job,        ** then if{} statements has executed, we can't get here.       */    else if ( jp == qp->q_tail ){        qp->q_tail = jp->j_prev;        jp->j_prev->j_next = NULL;    } else{        jp->j_next->j_prev = jp->j_prev;        jp->j_prev->j_next = jp->j_next;    }    pthread_rwlock_unlock(&qp->q_lock);}struct job *job_find( struct queue *qp, pthread_t tid ){    struct job *jtmp;    if(pthread_rwlock_rdlock(&qp->q_lock) != 0)        return NULL;    for ( jtmp = qp->q_head; jtmp != NULL; jtmp = jtmp->j_next ){        if (pthread_equal(jtmp->tid,tid) != 0)            break;    }    pthread_rwlock_unlock(&qp->q_lock);    return jtmp;}

main函数部分，主线程负责初始化队列，将产生的job插入队列，job结构中有指派的线程的id，以及给出的任务（函数指针）。其他的工作线程从队列中找到属于自己的job，然后利用这个函数指针调用函数，完成任务。任务很简单，就是打印一句话。

main.c:

#include "wrlock.h"#define _GNU_SOURCEvoid *task1( void *str1 ){    printf("I am thread 1, %s\n",(char *)str1);}void *task2( void *str2 ){    printf("I am thread 2, %s\n",(char *)str2);}void *task3( void *str3 ){    printf("I am thread 3, %s\n",(char *)str3);}void *thr1_func( void *arg ) //arg points to queue.{    pthread_t   tid;    struct job  *jp1;    tid = pthread_self();    while (1){        if ((jp1 = job_find(arg,tid)) != NULL){            jp1->job_func("task completly!");            job_remove(arg,jp1);             free(jp1);        }else{            pthread_yield();        }    }}void *thr2_func( void *arg ) //arg points to queue.{    pthread_t   tid;    struct job  *jp2;    tid = pthread_self();    while (1){        if ((jp2 = job_find(arg,tid)) != NULL){            jp2->job_func("task completly!");            job_remove(arg,jp2);             free(jp2);        }else{            pthread_yield();        }    }}void *thr3_func( void *arg ) //arg points to queue.{    pthread_t   tid;    struct job  *jp3;    tid = pthread_self();    while (1){        if ((jp3 = job_find(arg,tid)) != NULL){            jp3->job_func("task completly!");            job_remove(arg,jp3);             free(jp3);        }else{            pthread_yield();        }    }}int main( void ){    unsigned long   n;    int         err;    int         foo;    struct job  *jobptr;    struct queue    *qptr;    pthread_t   tid[3];    void *(*func[3])(void *) = { task1, task2, task3 };    /* initialise the queue */    if ((qptr = malloc(sizeof( struct queue ))) == NULL)        exit(-1);    queue_init(qptr);    /* produce task in main thread */    err = pthread_create(&tid[0],NULL,thr1_func,qptr);    if (err != 0)        exit(-1);    else        printf("create thread 1 success\n");    err = pthread_create(&tid[1],NULL,thr2_func,qptr);    if (err != 0)        exit(-1);    else        printf("create thread 2 success\n");    err = pthread_create(&tid[2],NULL,thr3_func,qptr);    if (err != 0)        exit(-1);    else        printf("create thread 3 success\n");    for ( n = 1; n <= 10; n++){        if ((jobptr = malloc(sizeof(struct job))) == NULL)            exit(-1);        foo = rand()%3;        jobptr->tid = tid[foo];        jobptr->job_func = func[foo];        job_insert(qptr,jobptr);    }    sleep(10);    exit(0);}