多工作线程获取工作队列简单实现

以下是APUE线程章节中，简单实现多工作线程获取工作队列源码！

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <pthread.h>/*************************** *  Define the job structure **************************/struct job {struct job *j_next;struct job *j_prev;pthread_t j_pid;};/*************************** *  Define the queue *  structure. **************************/struct queue {struct job *q_head;struct job *q_tail;pthread_rwlock_t q_rwlock;};// Initialize a queueint queue_init( struct queue *qp){int err;qp->q_head = NULL;qp->q_tail = NULL;if((err = pthread_rwlock_init(&qp->q_rwlock, NULL)) != 0){perror("pthread_rwlock_init");return err;}return (0);}// Insert a job at the head of the queue.void job_insert(struct queue *qp, struct job *jp){pthread_rwlock_wrlock(&qp->q_rwlock);jp->j_next = qp->q_head;jp->j_prev = NULL;if(qp->q_head == NULL) {qp->q_tail = jp;} else {qp->q_head->j_prev = jp;}qp->q_head = jp;pthread_rwlock_unlock(&qp->q_rwlock);return ;}// Append a job on the queuevoid job_append(struct queue *qp, struct job *jp){pthread_rwlock_wrlock(&qp->q_rwlock);jp->j_prev = qp->q_tail;jp->j_next = NULL;if(qp->q_tail == NULL) {qp->q_head = jp;} else {qp->q_tail->j_next = jp;}qp->q_tail = jp;pthread_rwlock_unlock(&qp->q_rwlock);}// Remove the given job from a queue// remind: just remove the job from queue// don't free the space of the jobvoid job_remove(struct queue *qp, struct job *jp){pthread_rwlock_wrlock(&qp->q_rwlock);if(jp == qp->q_head) {qp->q_head = jp->j_next;if(qp->q_tail == jp){qp->q_tail = NULL;}} else if(jp == qp->q_tail) {qp->q_tail = jp->j_prev;if(qp->q_head == jp){qp->q_head == NULL;}} else {jp->j_prev->j_next = jp->j_next;jp->j_next->j_prev = jp->j_prev;}pthread_rwlock_unlock(&qp->q_rwlock);}// given a known pid, find out the jobstruct job * job_find (struct queue *qp, pthread_t pid){struct job *jp = NULL;pthread_rwlock_rdlock(&qp->q_rwlock);for(jp = qp->q_head; jp != NULL; jp = jp->j_next){if(pthread_equal(pid, jp->j_pid))break;}pthread_rwlock_unlock(&qp->q_rwlock);return (jp);}