epoll 簡單使用實例

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服務端 server.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/epoll.h>


int main()
{
    int server_sockfd, client_sockfd;
    int server_len, client_len;
    struct sockaddr_un server_address;
    struct sockaddr_un client_address;

    //服務端移除舊socket，並建立一個socket

    unlink("server_socket");
    server_sockfd = socket(AF_UNIX, SOCK_STREAM, 0);

    server_address.sun_family = AF_UNIX;
    strcpy(server_address.sun_path, "server_socket");
    server_len = sizeof(server_address);
    bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

    listen(server_sockfd, 5);
    while(1) {
        char ch;

        printf("server: server waiting....\n");

		int epfd;
		epfd = epoll_create(1);
			struct epoll_event ev,events[5];
			ev.data.fd = server_sockfd;
			ev.events = EPOLLIN|EPOLLET;
			epoll_ctl(epfd, EPOLL_CTL_ADD,server_sockfd, &ev); //註冊epoll事件 
		
					printf("server: epoll_wait....\n");
					int epoll_re = epoll_wait(epfd,events,1,-1); //永遠阻塞等待事件發生
					printf("server: epoll_re=%d\n",epoll_re);
					int i;
					for(i = 0; i < epoll_re; i++)
					{
							if(events[i].data.fd == server_sockfd)
							//接受鏈接
							client_len = sizeof(client_address);
							client_sockfd = accept(server_sockfd, 
								(struct sockaddr *)&client_address, &client_len);
							//讀寫數據
							read(client_sockfd, &ch, 1);
							printf("server: from client get a char = %c\n", ch);
							printf("server: write to client a char = %c\n", ch++);
							write(client_sockfd, &ch, 1);
							close(client_sockfd);

					}
    }
}

客戶端 client.c

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    int sockfd;
    int len;
    struct sockaddr_un address;
    int result;
    char ch = 'A';

    if( argc == 2)
		ch = *argv[1];

    //建立一個socket

    sockfd = socket(AF_UNIX, SOCK_STREAM, 0);

    address.sun_family = AF_UNIX;
    strcpy(address.sun_path, "server_socket");
    len = sizeof(address);

    result = connect(sockfd, (struct sockaddr *)&address, len);

    if(result == -1) {
        perror("oops: client1");
        exit(1);
    }

    //讀寫數據

    write(sockfd, &ch, 1);
	printf("client: write to server a char = %c\n", ch);

    read(sockfd, &ch, 1);
	printf("client: from server get a char = %c\n", ch);

    close(sockfd);
    exit(0);
}

Makefile：

CLIENTS=client
SERVERS=server

CFLAGS=-g
LDFLAGS=-g

ALL= $(CLIENTS) $(SERVERS)

all: $(ALL)

clean:
	@rm -f $(ALL) *~ *.o

測試：

[sunbeau@localhost test]$ ll
total 12
-rw-rw-r--. 1 sunbeau sunbeau  840 Oct  9 17:25 client.c
-rw-rw-r--. 1 sunbeau sunbeau  123 Oct  9 17:25 Makefile
-rw-rw-r--. 1 sunbeau sunbeau 1693 Oct  9 17:25 server.c
[sunbeau@localhost test]$ make
cc -g  -g  client.c   -o client
cc -g  -g  server.c   -o server
[sunbeau@localhost test]$ ./server &
[13] 11727
[sunbeau@localhost test]$ server: server waiting....
server: epoll_wait....

[sunbeau@localhost test]$ ./client 
server: epoll_re=1
server: from client get a char = A
server: write to client a char = A
client: write to server a char = A
server: server waiting....
server: epoll_wait....
client: from server get a char = B
[sunbeau@localhost test]$ ./client B
server: epoll_re=1
client: write to server a char = B
server: from client get a char = B
server: write to client a char = B
server: server waiting....
server: epoll_wait....
client: from server get a char = C
[sunbeau@localhost test]$

參考：

https://www.cnblogs.com/lojunren/p/3856290.html

https://www.cnblogs.com/ypwen/p/4725532.html

https://blog.csdn.net/ljx0305/article/details/4065058