概述：

     使用libev實現TCP伺服器，提升處理效率。原理其實都一樣，都是檔案描述符，檢查讀寫條件，使用epoll事件輪詢機制。

例項Demo:

#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <stdint.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <ev.h>

#define PORT            12100
#define BUFFER_SIZE     1024
#define MAX_LISTEN      5

/*初始化服務端*/
int server_socket_init(int *sd, char *ipaddr, uint16_t port)
{
    //建立socket
    int sock = socket(AF_INET, SOCK_STREAM, 0);
    if (-1 == sock) 
		goto err1;
	//設定立即釋放埠並可以再次使用
	int reuse = 1;
    if (-1 == setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)))
		goto err2;	
	//設定為非阻塞
	if (-1 == fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_NONBLOCK))
		goto err2;
    struct sockaddr_in addr;
	memset(&addr, 0 , sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
	if (NULL == ipaddr) {
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
	} else {
        addr.sin_addr.s_addr = inet_addr(ipaddr);
	}
	//繫結監聽
    if (-1 == bind(sock, (struct sockaddr *)&addr, sizeof(addr)))
		goto err2;
    if (-1 == listen(sock, MAX_LISTEN))
		goto err2;
	*sd = sock;
	return 0;
err2:
    close(sock);
err1:
    return -1;
}

/*讀回撥*/
void read_cb(struct ev_loop *loop, struct ev_io *watcher, int revents)
{
    char buffer[BUFFER_SIZE] = {0};
    if (EV_ERROR & revents) {
	  printf("read got invalid event...\r\n");
	  return;
	}
	int res = 0;
	int32_t bytes = read(watcher->fd, buffer, sizeof(buffer));
    if (-1 == bytes) {
        //tcp Error
        if (EINTR != errno && EAGAIN != errno) {
            res = 1;
        }
    } else if (0 == bytes) {
        //tcp Close
        res = 2;
    }
    if (0 != res) {
        //關閉事件迴圈並釋放watcher
        printf("TCP CLOSE\r\n");
        ev_io_stop(loop,watcher);
        free(watcher);
    } else {
        printf("READ:\r\n    %s\r\n", buffer);
    }
}


/*accept回撥函式*/
void accept_cb(struct ev_loop *loop, struct ev_io *watcher, int revents)
{
    struct sockaddr_in client_addr;
	socklen_t client_len = sizeof(client_addr);
	if (EV_ERROR & revents) {
	  printf("accept got invalid event...\r\n");
	  return;
	}
	//accept連線
	int sock = accept(watcher->fd, (struct sockaddr *)&client_addr, &client_len);
    if (-1 == sock) {
		return;
    }
    //設定非阻塞
	if(-1 == fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_NONBLOCK)) {
		close(sock);
		return;
	}
	printf("Successfully connected with client: %s:%u\r\n", \
	inet_ntoa(client_addr.sin_addr), client_addr.sin_port);
	//加入事件迴圈
	struct ev_io *w_client = (struct ev_io*) malloc (sizeof(struct ev_io));
	ev_io_init(w_client, read_cb, sock, EV_READ);
	ev_io_start(loop, w_client);
}

int main()
{
    int sd;
    struct ev_io w_accept;
    struct ev_loop *loop = ev_loop_new(EVBACKEND_EPOLL);
    if (NULL == loop) {
        printf("loop create failed\r\n");
        return -1;
    }
    if (server_socket_init(&sd, NULL, PORT) < 0) {
        printf("server init failed\r\n");
        return -1;
    }
    ev_io_init(&w_accept, accept_cb, sd, EV_READ);
	ev_io_start(loop, &w_accept);
	ev_run(loop, 0);
    return 0;
}

 

編譯：

//編譯
gcc -o ev_server ev_server.c -lev

執行結果：