c++ 异步消息队列

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

struct msg {
	int data;
	struct msg* next_msg;
};
struct msg * workq;


pthread_mutex_t qlock = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t  qready =  PTHREAD_COND_INITIALIZER;

void init_queue(void){
	pthread_mutex_lock(&qlock);
	workq=NULL;
	pthread_mutex_unlock(&qlock);

}


void enqueue_msg(struct msg* mp){
	pthread_mutex_lock(&qlock);
	mp->next_msg = workq;
	workq = mp;
	pthread_mutex_unlock(&qlock);
	pthread_cond_signal(&qready);
}

struct msg *queue_msg(void){
	struct msg *mp;
	pthread_mutex_lock(&qlock);
	while(workq == NULL)
		pthread_cond_wait(&qready,&qlock);
		
	mp = workq;
	workq = mp->next_msg;
	pthread_mutex_unlock(&qlock);
	return mp;

}

void process_msg(int pid){
	struct msg *mp;

	printf("thread %d created.\n",pid);

	for(;;)
	{
		mp=queue_msg();
		printf("thread %d deal the msg.data is %d  \n",pid,mp->data);
		struct msg msgx;
		msgx.data = mp->data+1;
		msgx.next_msg = NULL;
		enqueue_msg(&msgx);
		sleep(3);
	}

}

void * thr_fn(void*arg)
{
	process_msg(*(int*)arg);
	return ((void*)1);

}

void main(){
	pthread_t  tid1, tid2;

	int err;

	int pid1 = 1, pid2 = 2;

	if(err = pthread_create(&tid1,NULL,thr_fn,&pid1))
	{
		printf("can't create thread %d \n",err);
	}


	if(err = pthread_create(&tid2,NULL,thr_fn,&pid2))
	{
		printf("can't create thread %d \n",err);
	}

	printf("create thread success.\n");

	sleep(1);

	struct msg msg1;
	msg1.data=100;
	msg1.next_msg = NULL;
	init_queue();
	enqueue_msg(&msg1);
	printf("add a  msg .\n");
	sleep(3);
	printf("OK\n");

	pthread_join(tid1,NULL);
	pthread_join(tid2,NULL);
}