C多线程编程-互斥量

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互斥量-mutual exclusion Posix API提供了互斥量的安全函数，

#include<pthread.h>

int phread_mutex_init(phread_mutex_t * tid,void * atrr);

int pthread_mutex_lock(pthread_mutex_t *tid);

int pthread_mutex_unlock(pthread_mutex_t * tid);

int pthread_mutex_trylock(pthread_mutex_t * tid);

API 返回0为成功！一般返回一个正数的出错，在这里用----char * strerror(int errno );

返回错误消息！

测试案例：

#include "unip.h"/*  mutual exclusing controls muti-alarming requestions;*/typedef struct alarm_tag{   struct alarm_tag *link;   int seconds;   time_t times;   char message[MAX];}alarm_t;alarm_t * alarm_list=NULL;pthread_mutex_t alarm_mutex=PTHREAD_MUTEX_INITIALIZER;void * alarm_thread(void *arg){   alarm_t * alarm;   int sleep_time;   time_t now;   int status;   while(1)   {    status=pthread_mutex_lock(&alarm_mutex);    if(status!=0)    Err_quit("mutex_lock error!");    now=time(NULL);    alarm=alarm_list;    if(alarm==NULL)    sleep_time=1;    else    {    alarm_list=alarm_list->link;    if(alarm->times<=now)    {    sleep_time=0;    }    else    sleep_time=alarm->times-now;    printf("[waiting:%ld(%d)\"%s\"]\n",alarm->times,alarm->seconds,alarm->message);    }    status=pthread_mutex_unlock(&alarm_mutex);    if(status!=0)    Err_quit("mutex_lock error!");    if(sleep_time>0)    {    sleep(sleep_time);    }    else    sched_yield();    if(alarm!=NULL)    {    printf("output:%d-----%s\n",alarm->seconds,alarm->message);    free(alarm);    }   }}int main(int argc, char const *argv[]){time_t now;int seconds;int status;alarm_t *alarm,*next,**last,*head;    char line[MAX];    char message[MAX];    memset(message,0,MAX);    memset(line,0,MAX);    pthread_t tid;    status=pthread_create(&tid,NULL,alarm_thread,NULL);    if(status!=0)    {         Err_quit("here pthread_create error!");    }    while(1){    printf("alarm>");     if(fgets(line,sizeof(line),stdin)==NULL)     Err_quit("No Any data here");     if(strlen(line)<=2)     continue;     alarm=malloc(sizeof(alarm_t));     if(alarm==NULL)     Err_quit("callocate error!\n");     if(sscanf(line,"%d%64[^/n]",&seconds,message)<2)     {     free(alarm);     break;    }    status=pthread_mutex_lock(&alarm_mutex);    if(status!=0)    Err_quit("mutex_lock error!");     memcpy(&alarm->message,message,MAX);     alarm->seconds=seconds;     alarm->times=time(NULL)+seconds;     last=&alarm_list;     next=*last;     while(next!=NULL)     {     if(next->times>=alarm->times)     {     alarm->link=next;     *last=alarm;     break;     }     last=&next->link;     next=next->link;     }     if(next==NULL)     {     *last=alarm;     alarm->link=NULL;     }     for(head=alarm_list;head!=NULL;head=head->link)     {     printf("%ld(%d)[\"%s\"]\n",head->times,head->seconds,head->message );     }     status=pthread_mutex_unlock(&alarm_mutex);     if(status!=0)    Err_quit("mutex_lock error!"); }return 0;}

代码2:

#include "unip.h"/*  mutual exclusing controls muti-alarming requestions;*/#define SPIN 10000000long couters;/*this program use trylock_function to tell counters in */time_t end_time;pthread_mutex_t alarm_mutex=PTHREAD_MUTEX_INITIALIZER;//header of list must be initialized here,it inited NULL (nothing);void * threadfunc1(void *arg){int status;int spin;    while(time(NULL)

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