[thread ]pthread_mutex_lock , pthread_cond_wait

#include <pthread.h>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;

static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

static pthread_cond_t cond_1 = PTHREAD_COND_INITIALIZER;

char tmp[100];

static void cleanup_handler(void *arg)

{

    char* ptr = (char*)arg;

    pthread_mutex_unlock(&mtx);

}

static void cleanup_handler_1(void *arg)

{

    char* ptr = (char*)arg;

   

    pthread_mutex_unlock(&mtx);

}

static void *thread_func(void *arg)

{

    pthread_cleanup_push(cleanup_handler, tmp);

  

    pthread_mutex_lock(&mtx);          

   

    pthread_cond_wait(&cond, &mtx);

                          

    pthread_mutex_unlock(&mtx);            

    pthread_cleanup_pop(0);

    return NULL;

}

static void *thread_func_1(void *arg)

{

    pthread_cleanup_push(cleanup_handler_1, tmp);

  

    printf("B: START\n");

    pthread_mutex_lock(&mtx);          

   

    pthread_cond_wait(&cond_1, &mtx);  //你會發現有cond_1 ,mtx ,在wait時 , 會將mtx release ,意味其他的thread可以做pthread_mutex_lock                                 

    pthread_mutex_unlock(&mtx);            

    pthread_cleanup_pop(0);

   

    return NULL;

}

int main(void)

{

    int i;

    pthread_t tid;

    pthread_t tid_1;

   

    pthread_create(&tid , NULL, thread_func  , NULL);

    pthread_create(&tid_1, NULL, thread_func_1, NULL);     

    pthread_mutex_lock(&mtx);

    pthread_mutex_unlock(&mtx);

   

    pthread_cond_signal(&cond);

    pthread_cancel(tid);

    pthread_cancel(tid_1);

    pthread_join(tid, NULL);

    return 0;

}

code:
https://docs.google.com/file/d/0B8hm-I2M8BD7UzQ4MzRpOFRvVXc/edit?usp=sharing