Unix 线程同步，使用读写锁

#include <stdlib.h>
#include <pthread.h>
struct job{
struct job * j_next;
struct job *j_prev;
pthread_t  j_id;
};
struct queue{
struct job *q_head;
struct job *q_tail;
pthread_rwlock_t q_lock;
};
int queue_init(struct queue *qp)
{
int err;
qp->q_head=NULL;
qp->q_tail=NULL;
err=pthread_relock_init(&qp->q_lock,NULL);
if(err!=0
return(err)
return(0);
}
 
void  job_insert(struct queue *qp, struct
{  
    pthread_rwlock_wrlock(&qp->q_lock);  
    jp->j_next = qp->q_head;  
    jp->j_prev = NULL;  
if
        qp->q_head->j_prev = jp;  
else
/* list was empty */
    qp->q_head = jp;  
    pthread_rwlock_unlock(&qp->q_lock);  
}  
  
void  job_append(struct queue *qp, struct
{  
    pthread_rwlock_wrlock(&qp->q_lock);  
    jp->j_next = NULL;  
    jp->j_prev = qp->q_tail;  
if
        qp->q_tail->j_next = jp;  
else
        qp->q_head = jp;    
    qp->q_tail = jp;  
    pthread_rwlock_unlock(&qp->q_lock);  
}  
  
void  job_remove(struct queue *qp, struct
{  
    pthread_rwlock_wrlock(&qp->q_lock);  
if
        qp->q_head = jp->j_next;  
if
            qp->q_tail = NULL;  
else if
        qp->q_tail = jp->j_prev;  
if
            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_lock);  
}  
  
struct job *  job_find(struct
{  
struct
  
if
return(NULL);  
  
for
if
break;  
  
    pthread_rwlock_unlock(&qp->q_lock);  
return(jp);  
}