Linux基础编程 多线程同步 pthread_cond_signal
Linux基础编程 多线程同步 pthread_cond_signal
条件变量同步锁示例
此例根据上一篇文章修改 (见 )
请包含上一篇中的两个文件(未做任何改动)
1/ pthread_mutex.h
2/ pthread_mutex.c
上一篇的thread.c文件修改如下
- /*
- 多线程同步示例,条件变量同步锁
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <unistd.h>
- #include <pthread.h>
- #include "pthread_mutex.h"
- #define __DEBUG
- #ifdef __DEBUG
- #define DBG(fmt,args...) fprintf(stdout, fmt, ##args)
- #else
- #define DBG(fmt,args...)
- #endif
- #define ERR(fmt,args...) fprintf(stderr, fmt, ##args)
- static int isThreadQuit = 0;
- SemHandl_t gHndlSem = NULL;
- /*条件变量同步锁*/
- pthread_cond_t gNoneZero;
- unsigned int gCount = 0;//条件变量
- /*
- 某设备写操作,不同同时访问,所以所以需要线程锁保护
- 1、将函数DeviceWrite中加锁
- 2、在访问DeviceWrite的线程中加锁
- 以上两种方法跟据需要选择其一。
- 本例中在访问的线程中加锁
- */
- void DeviceWrite(char *str)
- {
- /*SemWait(gHndlSem);*/
- DBG("Device Write: %s\n",str);
- /*SemRelease(gHndlSem);*/
- }
- void SetXxThreadQuit()
- {
- /*quit*/
- isThreadQuit = 1;
- }
- void *XxManageThread(void *arg)
- {
- char *cmd = (char*)arg;
- DBG("arg value=%s\n",cmd);
- while(isThreadQuit==0){
- SemWait(gHndlSem);// 1、先锁定
- while(gCount==0){// 2、判断条件变量
- pthread_cond_wait(&gNoneZero,gHndlSem);// 3、如果满足,等待
- }
- gCount = gCount-1;// 4、条件变量做相应调整
- DBG("gCount=%d\n",gCount);
- SemRelease(gHndlSem); // 5、开锁
- sleep(1);
- }
- /*arg是将指针带进来,cmd则相反,或者设置 NULL*/
- pthread_exit(cmd);
- //pthread_exit(NULL);
- }
- void *XxManageThreadMutex(void *arg)
- {
- char *cmd = (char*)arg;
- DBG("arg value=%s\n",cmd);
- while(isThreadQuit==0){
- SemWait(gHndlSem);
- if(gCount == 0){
- pthread_cond_signal(&gNoneZero);
- }
- gCount = gCount+1;
- DBG("gCount=%d\n",gCount);
- SemRelease(gHndlSem);
- sleep(1);
- }
- /*arg是将指针带进来,cmd则相反,或者设置 NULL*/
- pthread_exit(cmd);
- //pthread_exit(NULL);
- }
- int XxManageThreadInit()
- {
- pthread_t tManageThread;
- pthread_t tManageThreadMutex;
- char *any="any value";
- char *retn;
- int ret;
- /*
- 第二个参数是设置线程属性,一般很少用到(设置优先级等),第四个参数为传递到线程的指针,
- 可以为任何类型
- */
- ret = pthread_create(&tManageThread,NULL,XxManageThread,"1 thread");
- if(ret == -1){
- /*成功返回0.失败返回-1*/
- ERR("Ctreate Thread ERROR\n");
- return -1;
- }
- ret = pthread_create(&tManageThreadMutex,NULL,XxManageThreadMutex,"2 thread");
- if(ret == -1){
- /*成功返回0.失败返回-1*/
- ERR("Ctreate Thread ERROR\n");
- return -1;
- }
- /*
- 设置线程退出时资源的清理方式,如果是detach,退出时会自动清理
- 如果是join,则要等待pthread_join调用时才会清理
- */
- pthread_detach(tManageThread);
- pthread_detach(tManageThreadMutex);
- //pthread_join(tManageThread,retn);
- //DBG("retn value=%s\n",retn);
- return 0;
- }
- #define TEST_MAIN
- #ifdef TEST_MAIN
- int main()
- {
- printf("hello liuyu\n");
- int count=3;
- /*创建线程锁*/
- gHndlSem = MakeSem();
- if(gHndlSem == NULL){
- return -1;
- }
- /*条件变量同步锁初始化*/
- pthread_cond_init(&gNoneZero,NULL);
- if(XxManageThreadInit()==-1){
- exit(1);
- }
- while(count--){
- DBG("[0] main running\n");
- sleep(2);
- }
- SetXxThreadQuit();
- /*等待线程结束*/
- sleep(1);
- /*删除条件变量同步锁*/
- pthread_cond_destroy(&gNoneZero);
- /*删除线程锁*/
- DestroySem(gHndlSem);
- DBG("waitting thread exit...\n");
- return 0;
- }
- #endif
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