线程同步之生产者消费者

#include <stdio.h> #include <stdlib.h>#include <time.h> #include <pthread.h>   #define BUFFER_SIZE 16 struct prodcons   {        int buffer[BUFFER_SIZE];   pthread_mutex_t lock;   int readpos, writepos;   pthread_cond_t notempty;   pthread_cond_t notfull;};    void init(struct prodcons *b)   {     pthread_mutex_init(&b->lock, NULL);     pthread_cond_init(&b->notempty, NULL);     pthread_cond_init(&b->notfull, NULL);   //  this not work//  b->lock = PTHREAD_MUTEX_INITIALIZER;//  b->notempty = PTHREAD_COND_INITIALIZER;//  b->notfull = PTHREAD_COND_INITIALIZER;  b->readpos = 0;     b->writepos = 0;   }   void put(struct prodcons *b, int data)   {     pthread_mutex_lock(&b->lock);     if ((b->writepos + 1) % BUFFER_SIZE == b->readpos)     {       pthread_cond_wait(&b->notfull, &b->lock);     }      b->buffer[b->writepos] = data;     b->writepos++;     if (b->writepos >= BUFFER_SIZE)     b->writepos = 0;      pthread_cond_signal(&b->notempty);     pthread_mutex_unlock(&b->lock);   }     int get(struct prodcons *b)   {     int data;     pthread_mutex_lock(&b->lock);       if (b->writepos == b->readpos)     {       pthread_cond_wait(&b->notempty, &b->lock);     }        data = b->buffer[b->readpos];     b->readpos++;     if (b->readpos >= BUFFER_SIZE)     b->readpos = 0;       pthread_cond_signal(&b->notfull);     pthread_mutex_unlock(&b->lock);     return data;   }   #define OVER ( - 1)   struct prodcons buffer;   void *producer(void *data)   {     int n;     for (n = 0; n < 100; n++)     {       printf("%d --->\n", n);       put(&buffer, n);     }      put(&buffer, OVER);     return NULL;   }   void *consumer(void *data)   {     int d;     while (1)     {       d = get(&buffer);       if (d == OVER)         break;       printf("--->%d \n", d);     }     return NULL;   }   int main(void)   {     pthread_t th_a, th_b;     void *retval;     init(&buffer);       pthread_create(&th_a, NULL, producer, 0);     pthread_create(&th_b, NULL, consumer, 0);        pthread_join(th_a, &retval);     pthread_join(th_b, &retval);     return 0;   }