将poll程序改为epoll实现

#include "apue.h"
#include <poll.h>
#include <pthread.h>
#include <sys/msg.h>
#include <sys/socket.h>

#define NQ			3		//队列的数量
#define MAXMSZ		512		//消息的最大长度
#define KEY			0x123	//消息队列的第一个key值

struct threadinfo {
int qid;
int fd;
};

struct mymesg {
long mtype;
char mtext[MAXMSZ];
};

void *helper(void *arg)
{
int n;
struct mymesg m;
struct threadinfo *tip = arg;

for (;;) {
printf("helper qid %d, fd %d, tid %u\n", tip->qid, tip->fd, (unsigned)pthread_self());

memset(&m, 0, sizeof(m));
if ((n = msgrcv(tip->qid, &m, MAXMSZ, 0, MSG_NOERROR)) < 0) {
err_sys("msgrcv error");
}
if (write(tip->fd, m.mtext, n) < 0) {
err_sys("write error");
}
}
}
int main()
{
int i, n, err;
int fd[2];
int qid[NQ];
struct pollfd pfd[NQ];
struct threadinfo ti[NQ];
pthread_t tid[NQ];
char buf[MAXMSZ];

for (i = 0; i < NQ; ++i) {
if ((qid[i] = msgget((KEY+i), IPC_CREAT|0666)) < 0) {	//创建一个新队列
err_sys("msgget error");
}
printf("queue %d ID is %d\n", i, qid[i]);
if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fd) < 0) {	//创建UNXI域套接字（fd管道）
err_sys("socketpair error");
}
printf("fd[0]:%d\n", fd[0]);
printf("fd[1]:%d\n", fd[1]);
pfd[i].fd = fd[0];
pfd[i].events = POLLIN;
ti[i].qid = qid[i];
ti[i].fd = fd[1];
if ((err = pthread_create(&tid[i], NULL, helper, &ti[i])) != 0) {	//创建线程
err_exit(err, "pthread_create error");
}
}

for (;;) {
if (poll(pfd, NQ, -1) < 0) {	//等待事件发生
err_sys("poll error");
}
for (i = 0; i < NQ; ++i) {
//printf("i:%d\n", i);
if (pfd[i].revents & POLLIN) {
if ((n = read(pfd[i].fd, buf, sizeof(buf))) < 0) {
err_sys("read error");
}
buf
= 0;
printf("queue %d id %d, message %s\n", i, qid[i], buf);
}
}
}
exit(0);
}

gcc pollmsg.c -o pollmsg -lapue -lpthread -std=c99

#include "apue.h"
#include <pthread.h>
#include <sys/msg.h>
#include <sys/socket.h>
#include <sys/epoll.h>

#define NQ			3		//队列的数量
#define MAXMSZ		512		//消息的最大长度
#define KEY			0x123	//消息队列的第一个key值
#define FDSIZE		1000
#define EPOLLEVENTS	100

struct threadinfo {
int qid;
int fd;
};

struct mymesg {
long mtype;
char mtext[MAXMSZ];
};

void *helper(void *arg)
{
int n;
struct mymesg m;
struct threadinfo *tip = arg;

for (;;) {
printf("helper qid %d, fd %d, tid %u\n", tip->qid, tip->fd, (unsigned)pthread_self());

memset(&m, 0, sizeof(m));
if ((n = msgrcv(tip->qid, &m, MAXMSZ, 0, MSG_NOERROR)) < 0) {
err_sys("msgrcv error");
}
if (write(tip->fd, m.mtext, n) < 0) {
err_sys("write error");
}
}
}

int main()
{
int i, n, err;
int fd[2];
int qid[NQ];
int epollfd;
struct epoll_event events[EPOLLEVENTS];
struct threadinfo ti[NQ];
pthread_t tid[NQ];
char buf[MAXMSZ];

epollfd = epoll_create(FDSIZE);	//创建epoll文件描述符

for (i = 0; i < NQ; ++i) {
if ((qid[i] = msgget((KEY+i), IPC_CREAT|0666)) < 0) {	//创建一个新队列
err_sys("msgget error");
}
printf("queue %d ID is %d\n", i, qid[i]);
if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fd) < 0) {	//创建UNXI域套接字（fd管道）
err_sys("socketpair error");
}
struct epoll_event ev;
ev.events = EPOLLIN;
ev.data.fd = fd[0];
epoll_ctl(epollfd, EPOLL_CTL_ADD, fd[0], &ev);	//注册fd[0]到epoll
ti[i].qid = qid[i];
ti[i].fd = fd[1];
if ((err = pthread_create(&tid[i], NULL, helper, &ti[i])) != 0) {	//创建线程
err_exit(err, "pthread_create error");
}
}

for (;;) {
int occurred;
if ((occurred = epoll_wait(epollfd, events, EPOLLEVENTS, -1)) < 0) {	//等待事件发生
err_sys("epoll error");
}
if (occurred == 0) {
err_sys("epoll timeout");
}

for (i = 0; i < occurred; ++i) {
if (events[i].events & EPOLLIN) {
if ((n = read(events[i].data.fd, buf, sizeof(buf))) < 0) {
err_sys("read error");
}
buf
= 0;
printf("main thread %u, message %s\n", (unsigned)pthread_self(), buf);
}
}

}
exit(0);
}

gcc epollmsg.c -o epollmsg -lapue -lpthread -std=c99

#include "apue.h"
#include <sys/msg.h>

#define MAXMSZ 512

struct mymesg {
long mtype;
char mtext[MAXMSZ];
};

int main(int argc, char *argv[])
{
key_t key;
long qid;
size_t nbytes;
struct mymesg m;

if (argc != 3) {
fprintf(stderr, "usage: sendmsg KEY message\n");
exit(1);
}

key = strtol(argv[1], NULL, 0);
//printf("key:0x%08X\n", (unsigned )key);
if ((qid = msgget(key, 0)) < 0) {	//打开一个现有队列
err_sys("can't open queue key %s", argv[1]);
}
memset(&m, 0, sizeof(m));
strncpy(m.mtext, argv[2], MAXMSZ - 1);
nbytes = strlen(m.mtext);
m.mtype = 1;
//printf("qid:%ld\n", qid);
if (msgsnd(qid, &m, nbytes, 0) < 0) {	//发送消息给指定消息队列
err_sys("can't send message");
}
exit(0);
}

gcc sendmsg.c -o sendmsg -lapue -std=c99