一个线程间同步 + FIFO顺序操作链表的例子

如题：

生产者和消费者访问链表的顺序是FIFO，创建两个线程来操作这些数据：

#include <stdlib.h>
#include <pthread.h>
#include <stdio.h>

struct msg {
struct msg *next;
int num;
};

struct msg *head;
struct msg *end;
struct msg *tmp;
pthread_cond_t has_product = PTHREAD_COND_INITIALIZER;
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

void *consumer(void *p)
{
struct msg *mp;

for (;;) {
pthread_mutex_lock(&lock);
while (head == NULL)
pthread_cond_wait(&has_product, &lock);
mp = head;
head = mp->next;
pthread_mutex_unlock(&lock);
printf("Consume %d\n", mp->num);
free(mp);
sleep(rand() % 3);
}
}

void *producer(void *p)
{
struct msg *mp;
for (;;) {
mp = malloc(sizeof(struct msg));
mp->num = rand() % 1000 + 1;
printf("Produce %d\n", mp->num);
pthread_mutex_lock(&lock);
if (head == NULL)
head = mp;
else
end->next = mp;
end = mp;
end->next = NULL;
pthread_mutex_unlock(&lock);
//Queueprint();
pthread_cond_signal(&has_product);
sleep(rand() % 3);
}
}

int main(int argc, char *argv[])
{
pthread_t pid, cid;

srand(time(NULL));
pthread_create(&pid, NULL, producer, NULL);
pthread_create(&cid, NULL, consumer, NULL);
pthread_join(pid, NULL);
pthread_join(cid, NULL);
return 0;
}

输出：

$ gcc test.c -o test
$ ./test
Produce 934
Consume 934
Produce 263
Produce 701
Consume 263
Produce 753
Consume 701
Produce 257
Produce 712
Consume 753
Produce 844
Consume 257
Consume 712
Consume 844