可以将信号注册进pipe管道的写端，通过对读端的监听，来实现统一事件源。
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <netinet/in.h>
#include <arpa/inet.h> #include <assert.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <pthread.h> #define MAX_EVENT_NUMBER 1024
static int pipefd[]; int setnonblocking(int fd) {
int old_option = fcntl(fd, F_GETFL);
int new_option = old_option | O_NONBLOCK;
fcntl(fd, F_SETFL, new_option);
return old_option;
} void addfd(int epollfd, int fd) {
epoll_event event;
event.data.fd = fd;
event.events = EPOLLIN | EPOLLET;
epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
setnonblocking(fd);
} void sig_handler(int sig) {
int save_errno = errno;
int msg = sig;
send(pipefd[], (char*)&msg, , );
errno = save_errno;
} void addsig(int sig) {
struct sigaction sa;
memset(&sa, '\0', sizeof(sa));
sa.sa_handler = sig_handler;
sa.sa_flags != SA_RESTART;
sigfillset(&sa.sa_mask);
assert(sigaction(sig, &sa, NULL) != -);
} int main(int argc, char *argv[]) {
if (argc <= ) {
printf("usage: %s ip port\n", basename(argv[]));
return ;
}
const char *ip = argv[];
int port = atoi(argv[]); int ret = ;
sockaddr_in address;
bzero(&address, sizeof(address));
address.sin_family = AF_INET;
inet_pton(AF_INET, ip, &address.sin_addr);
address.sin_port = htons(port); int listenfd = socket(PF_INET, SOCK_STREAM, );
assert(listenfd >= ); ret = bind(listenfd, (sockaddr*)&address, sizeof(address));
if (ret == -) {
printf("errno is %d\n", errno);
return ;
}
ret = listen(listenfd, );
assert(ret != -); epoll_event events[MAX_EVENT_NUMBER];
int epollfd = epoll_create();
assert(epollfd != -);
addfd(epollfd, listenfd); ret = socketpair(PF_UNIX, SOCK_STREAM, , pipefd);
assert(ret != -);
setnonblocking(pipefd[]);
addfd(epollfd, pipefd[]); addsig(SIGHUP);
addsig(SIGCHLD);
addsig(SIGTERM);
addsig(SIGINT);
bool stop_server = false; while (!stop_server) {
int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -);
if ((number < ) && (errno != EINTR)) {
printf("epoll failure\n");
break;
} for (int i=; i<number; i++) {
int sockfd = events[i].data.fd;
if (sockfd == listenfd) {
printf("New connection is coming.\n");
sockaddr_in client_address;
socklen_t client_addrlen = sizeof(client_address);
int connfd = accept(listenfd, (sockaddr*)&client_address,
&client_addrlen);
printf("New connection established.\n");
addfd(epollfd, connfd);
}
else if ((sockfd == pipefd[]) && (events[i].events & EPOLLIN)) {
int sig;
char signals[];
ret = recv(pipefd[], signals, sizeof(signals), );
if (ret == -) {
continue;
}
else if (ret == ) {
continue;
}
else {
for (int i=; i<ret; ++i) {
switch(signals[i]) {
case SIGCHLD:
{
printf("SIGCHLD CONTINUE\n");
continue;
}
case SIGHUP:
{
printf("SIGHUP CONTINUE\n");
continue;
}
case SIGTERM:
{
printf("SIGTERM END PROGRAM\n");
stop_server = true;
break;
}
case SIGINT:
{
printf("SIGINT END PROGRAM\n");
stop_server = true;
break;
}
}
}
}
}
else {
// handle connected fd, ignore
}
}
} printf("close fds\n");
close(listenfd);
close(pipefd[]);
close(pipefd[]);
return ; }
Makefile的文件内容：
uniserver : uniserver.cpp
g++ -o uniserver uniserver.cpp -lpthread
编译出服务器程序之后，运行服务器：
$ ./uniserver 127.0.0.1
New connection is coming.
New connection established.
SIGTERM END PROGRAM
close fds
$ ./uniserver 127.0.0.1
^CSIGINT END PROGRAM
close fds
运行客户端：
$ telnet 127.0.0.1
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
a
^C^]
telnet> quit
Connection closed.
$ ps ux | grep uniserver
work 0.0 0.0 pts/ S+ : : ./uniserver 127.0.0.1
work 0.0 0.0 pts/ S+ : : grep uniserver
$ kill
可以看出，客户端的连接请求得到服务器端的响应；发出的内容"a"在服务器端没有处理和展现。
使用向服务器发信号，得到处理；服务器端直接Ctrl+C也得到了处理。
同时可以看出，信号是int类型，但是传输的时候，采用的是char*，并且只传输了一个字节就可以了；在接收端进行switch的时候，也只针对char数据的一个元素进行比对就可以了。