信号量例子
#include <stdio.h>
#include <stdlib.h>
#include <semaphore.h>
#include <errno.h>
sem_t remain, apple, pear, mutex;
static unsigned int vremain = 20, vapple = 0, vpear = 0;
void *father(void *);
void *mother(void *);
void *son(void *);
void *daughter(void *);
void print_sem();
int main()
{
pthread_t fa, ma, so, da;
sem_init(&remain, 0 , 20);
sem_init(&apple, 0, 0);
sem_init(&pear, 0, 0);
sem_init(&mutex, 0, 1);
pthread_create(&fa, NULL, &father, NULL);
pthread_create(&ma, NULL, &mother, NULL);
pthread_create(&so, NULL, &son, NULL);
pthread_create(&da, NULL, &daughter, NULL);
while(1) {
sem_wait(&mutex);
printf("apple: %u, pear: %u, left: %u\n", vapple, vpear, vremain);
sem_post(&mutex);
sleep(1);
}
}
void *father(void *arg)
{
while(1) {
sem_wait(&remain);
sem_wait(&mutex);
printf("father: put before, left = %u, apple = %u\n", vremain, vapple);
vremain --;
vapple ++;
printf("father: put after, left = %u, apple = %u\n\n", vremain, vapple);
sem_post(&mutex);
sem_post(&apple);
sleep(1);
}
}
void *son(void *arg)
{
while(1) {
sem_wait(&apple);
sem_wait(&mutex);
printf("son: take before, left = %u, apple = %u\n", vremain, vapple);
vremain ++;
vapple --;
printf("son: put after, left = %u, apple = %u\n\n", vremain, vapple);
sem_post(&mutex);
sem_post(&remain);
sleep(3);
}
}
void *mother(void *arg)
{
while(1) {
sem_wait(&remain);
sem_wait(&mutex);
printf("mother: put before, left = %u, pear = %u\n", vremain, vpear);
vremain --;
vpear ++;
printf("mother: put after, left = %u, pear = %u\n\n", vremain, vpear);
sem_post(&mutex);
sem_post(&pear);
sleep(3);
}
}
void *daughter(void *arg)
{
while(1) {
sem_wait(&pear);
sem_wait(&mutex);
printf("dau: take before, left = %u, pear = %u\n", vremain, vpear);
vremain ++;
vpear --;
printf("dau: take after, left = %u, pear = %u\n\n", vremain, vpear);
sem_post(&mutex);
sem_post(&remain);
sleep(1);
}
}
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转载请注明原文链接：信号量
转载请注明原文链接：信号量
