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C++基于reactor的服务器百万并发实现与讲解

作者：恒者走天下

这篇文章主要介绍了C++基于reactor的服务器百万并发实现与讲解，本文通过实例图文相结合给大家介绍的非常详细，对大家的学习或工作具有一定的参考借鉴价值,需要的朋友可以参考下

reactor实现的原理请参考：
https://www.jb51.net/article/253794.htm
本次百万并发的代码实现也是基于上面代码进行更改而来

并发量和承载的概念
并发量：一个服务器能同时承载客户端的数量
承载：客户端发送给服务器的请求(http或tcp等)在200ms内可以返回正确的结果

一、服务器的代码实现与讲解

结构体代码主要构建的结构如图所示
链表结构，每个eventblock结点，包括一个ntyevent数组，数组中存储fd

在这里插入图片描述

/*结构体定义链表数组*/
struct ntyevent {
	int fd;//要监听的文件描述符
	int events;//对应的监听事件，	EPOLLIN和EPOLLOUT（不同的事件，走不同的回调函数）
	void *arg;//指向自己结构体指针
	int (*callback)(int fd, int events, void *arg);
	
	int status;//是否在监听：1->在红黑树上（监听），0->不在（不监听）
	char buffer[BUFFER_LENGTH];
	int length;
	long last_active;
};

struct eventblock {

	struct eventblock *next;
	struct ntyevent *events;//数组
	
};

struct ntyreactor {
	//句柄
	int epfd;
	//结点个数
	int blkcnt;
	struct eventblock *evblk; //fd --> 100w
};

初始化fd 上树、下树代码

//nty_event_set(event, sockfd, acceptor, reactor);
//初始化sockfd
void nty_event_set(struct ntyevent *ev, int fd, NCALLBACK callback, void *arg) {

	ev->fd = fd;
	ev->callback = callback;
	ev->events = 0;
	ev->arg = arg;
	ev->last_active = time(NULL);

	return ;
	
}
//nty_event_add(reactor->epfd, EPOLLIN, event);
//对监听的epoll红黑树上的结点的修改
int nty_event_add(int epfd, int events, struct ntyevent *ev) {

	struct epoll_event ep_ev = {0, {0}};
	ep_ev.data.ptr = ev;
	ep_ev.events = ev->events = events;

	int op;
	if (ev->status == 1) {
		op = EPOLL_CTL_MOD;
	} else {
		op = EPOLL_CTL_ADD;
		ev->status = 1;
	}

	if (epoll_ctl(epfd, op, ev->fd, &ep_ev) < 0) {
		printf("event add failed [fd=%d], events[%d]\n", ev->fd, events);
		return -1;
	}

	return 0;
}

int nty_event_del(int epfd, struct ntyevent *ev) {

	struct epoll_event ep_ev = {0, {0}};

	if (ev->status != 1) {
		return -1;
	}
	ep_ev.data.ptr = ev;
	ev->status = 0;
	epoll_ctl(epfd, EPOLL_CTL_DEL, ev->fd, &ep_ev);

	return 0;
}

回调函数代码的书写
注意看recv_cb的回调函数中，recv之后，立马下树，然后又重新初始化fd，上树。这样做的目的是因为代码逻辑是recv收到数据后，立即原样send,所以需要对fd的属性进行更改，需要重新初始化赋值，然后上树

int recv_cb(int fd, int events, void *arg) {

	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	struct ntyevent *ev = ntyreactor_idx(reactor, fd);

	int len = recv(fd, ev->buffer, BUFFER_LENGTH , 0); // 
	nty_event_del(reactor->epfd, ev);

	if (len > 0) {
		
		ev->length = len;
		ev->buffer[len] = '\0';

		printf("C[%d]:%s\n", fd, ev->buffer);

		nty_event_set(ev, fd, send_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLOUT, ev);
		
		
	} else if (len == 0) {

		close(ev->fd);
		//printf("[fd=%d] pos[%ld], closed\n", fd, ev-reactor->events);
		 
	} else {

		close(ev->fd);
		printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
		
	}

	return len;
}

int send_cb(int fd, int events, void *arg) {

	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	struct ntyevent *ev = ntyreactor_idx(reactor, fd);

	int len = send(fd, ev->buffer, ev->length, 0);
	if (len > 0) {
		printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer);

		nty_event_del(reactor->epfd, ev);
		nty_event_set(ev, fd, recv_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLIN, ev);
		
	} else {

		close(ev->fd);

		nty_event_del(reactor->epfd, ev);
		printf("send[fd=%d] error %s\n", fd, strerror(errno));

	}

	return len;
}

int accept_cb(int fd, int events, void *arg) {

	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	if (reactor == NULL) return -1;

	struct sockaddr_in client_addr;
	socklen_t len = sizeof(client_addr);

	int clientfd;

	if ((clientfd = accept(fd, (struct sockaddr*)&client_addr, &len)) == -1) {
		if (errno != EAGAIN && errno != EINTR) {
			
		}
		printf("accept: %s\n", strerror(errno));
		return -1;
	}
	int flag = 0;
	if ((flag = fcntl(clientfd, F_SETFL, O_NONBLOCK)) < 0) {
		printf("%s: fcntl nonblocking failed, %d\n", __func__, MAX_EPOLL_EVENTS);
		return -1;
	}
	/*存储*/
	struct ntyevent *event = ntyreactor_idx(reactor, clientfd);
	
	nty_event_set(event, clientfd, recv_cb, reactor);
	nty_event_add(reactor->epfd, EPOLLIN, event);

	
	printf("new connect [%s:%d], pos[%d]\n", 
		inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), clientfd);

	return 0;

}

链表的初始化与销毁

//初始化链表
int ntyreactor_init(struct ntyreactor *reactor) {

	if (reactor == NULL) return -1;
	memset(reactor, 0, sizeof(struct ntyreactor));

	reactor->epfd = epoll_create(1);
	if (reactor->epfd <= 0) {
		printf("create epfd in %s err %s\n", __func__, strerror(errno));
		return -2;
	}

	struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	if (evs == NULL) {
		printf("ntyreactor_alloc ntyevents failed\n");
		return -2;
	}
	memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));

	struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock));
	if (block == NULL) {
		printf("ntyreactor_alloc eventblock failed\n");
		return -2;
	}
	memset(block, 0, sizeof(struct eventblock));

	block->events = evs;
	block->next = NULL;

	reactor->evblk = block;
	reactor->blkcnt = 1;

	return 0;
}

找到fd应在链表数组中存储的位置并返回

//新增块数(eventblock结点个数)
//ntyreactor_alloc(reactor);
int ntyreactor_alloc(struct ntyreactor *reactor) {

	if (reactor == NULL) return -1;
	if (reactor->evblk == NULL) return -1;

	struct eventblock *blk = reactor->evblk;
	while (blk->next != NULL) {
		blk = blk->next;
	}

	struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	if (evs == NULL) {
		printf("ntyreactor_alloc ntyevents failed\n");
		return -2;
	}
	memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));

	struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock));
	if (block == NULL) {
		printf("ntyreactor_alloc eventblock failed\n");
		return -2;
	}
	memset(block, 0, sizeof(struct eventblock));

	block->events = evs;
	block->next = NULL;

	blk->next = block;
	reactor->blkcnt ++; //

	return 0;
}

//struct ntyevent *event = ntyreactor_idx(reactor, sockfd);
struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd) {

	int blkidx = sockfd / MAX_EPOLL_EVENTS;
	//如果块数(eventblock结点个数)不能满足新的sockfd的存放
	while (blkidx >= reactor->blkcnt) {
		//新增块数(eventblock结点个数)
		ntyreactor_alloc(reactor);
	}

	//找到存放sockfd的块(eventblock对应的结点)
	int i = 0;
	struct eventblock *blk = reactor->evblk;
	while(i ++ < blkidx && blk != NULL) {
		blk = blk->next;
	}

	//返回对应块(eventblock对应的结点)的存放sockfd数组的那个具体位置
	return &blk->events[sockfd % MAX_EPOLL_EVENTS];
}

上树，并初始化链表数组上对应的fd

//ntyreactor_addlistener(reactor, sockfds[i], accept_cb);
//上树，并初始化链表数组上对应的fd
int ntyreactor_addlistener(struct ntyreactor *reactor, int sockfd, NCALLBACK *acceptor) {

	if (reactor == NULL) return -1;
	if (reactor->evblk == NULL) return -1;

	//reactor->evblk->events[sockfd];
	//找到sock所在的具体位置
	struct ntyevent *event = ntyreactor_idx(reactor, sockfd);

	初始化sockfd
	nty_event_set(event, sockfd, acceptor, reactor);
	//对监听的epoll红黑树上的结点的修改
	nty_event_add(reactor->epfd, EPOLLIN, event);

	return 0;
}

epollwait

//ntyreactor_run(reactor);
int ntyreactor_run(struct ntyreactor *reactor) {
	if (reactor == NULL) return -1;
	if (reactor->epfd < 0) return -1;
	if (reactor->evblk == NULL) return -1;
	
	struct epoll_event events[MAX_EPOLL_EVENTS+1];
	
	int checkpos = 0, i;

	while (1) {
/*
		long now = time(NULL);
		for (i = 0;i < 100;i ++, checkpos ++) {
			if (checkpos == MAX_EPOLL_EVENTS) {
				checkpos = 0;
			}

			if (reactor->events[checkpos].status != 1) {
				continue;
			}

			long duration = now - reactor->events[checkpos].last_active;

			if (duration >= 60) {
				close(reactor->events[checkpos].fd);
				printf("[fd=%d] timeout\n", reactor->events[checkpos].fd);
				nty_event_del(reactor->epfd, &reactor->events[checkpos]);
			}
		}
*/

		int nready = epoll_wait(reactor->epfd, events, MAX_EPOLL_EVENTS, 1000);
		if (nready < 0) {
			printf("epoll_wait error, exit\n");
			continue;
		}

		for (i = 0;i < nready;i ++) {

			struct ntyevent *ev = (struct ntyevent*)events[i].data.ptr;

			//看fd连接是否发生变化
			if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN)) {
				ev->callback(ev->fd, events[i].events, ev->arg);
			}
			if ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT)) {
				ev->callback(ev->fd, events[i].events, ev->arg);
			}
			
		}

	}
}

main函数；此服务器代码开设了100个监听的端口，目的是因为客户端测试程序也是运行在虚拟机的Ubuntu上，通过开三台来充当客户端来进行测试。有因为一台Ubuntu最多有6w个端口，3台有18w端口。如果服务器只开设一个监听端口，则最多有18w端口。因此要达到100w并发则应多开设端口

// 3, 6w, 1, 100 == 
// <remoteip, remoteport, localip, localport>
int main(int argc, char *argv[]) {

	unsigned short port = SERVER_PORT; // listen 8888
	if (argc == 2) {
		port = atoi(argv[1]);//把参数 str 所指向的字符串转换为一个整数（类型为 int 型）
	}
	struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor));
	/*初始化三个结构体，建立链表*/
	ntyreactor_init(reactor);

	int i = 0;
	int sockfds[PORT_COUNT] = {0};
	for (i = 0;i < PORT_COUNT;i ++) {
		//端口号的监听
		sockfds[i] = init_sock(port+i);
		//上树
		ntyreactor_addlistener(reactor, sockfds[i], accept_cb);
	}

	// epoll_wait
	ntyreactor_run(reactor);
	//
	ntyreactor_destory(reactor);

	for (i = 0;i < PORT_COUNT;i ++) {
		close(sockfds[i]);
	}

	free(reactor);

	return 0;
}

完整服务器代码展示

/*链表存储数组，把epoll变成对事件的管理,用链表数组的目的就是为了回调函数*/
/*recv写法：代码逻辑是收到数据后，立即原样返回所以才那样写*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#define BUFFER_LENGTH		4096
#define MAX_EPOLL_EVENTS	1024
#define SERVER_PORT			8888
#define PORT_COUNT			100
typedef int NCALLBACK(int ,int, void*);
//struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
struct ntyevent {
	int fd;//要监听的文件描述符
	int events;//对应的监听事件，	EPOLLIN和EPOLLOUT（不同的事件，走不同的回调函数）
	void *arg;//指向自己结构体指针
	int (*callback)(int fd, int events, void *arg);
	int status;//是否在监听：1->在红黑树上（监听），0->不在（不监听）
	char buffer[BUFFER_LENGTH];
	int length;
	long last_active;
};
struct eventblock {
	struct eventblock *next;
	struct ntyevent *events;//数组
};
struct ntyreactor {
	//句柄
	int epfd;
	//结点个数
	int blkcnt;
	struct eventblock *evblk; //fd --> 100w
};
int recv_cb(int fd, int events, void *arg);
int send_cb(int fd, int events, void *arg);
struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd);
//nty_event_set(event, sockfd, acceptor, reactor);
//初始化sockfd
void nty_event_set(struct ntyevent *ev, int fd, NCALLBACK callback, void *arg) {
	ev->fd = fd;
	ev->callback = callback;
	ev->events = 0;
	ev->arg = arg;
	ev->last_active = time(NULL);
	return ;
}
//nty_event_add(reactor->epfd, EPOLLIN, event);
//对监听的epoll红黑树上的结点的修改
int nty_event_add(int epfd, int events, struct ntyevent *ev) {
	struct epoll_event ep_ev = {0, {0}};
	ep_ev.data.ptr = ev;
	ep_ev.events = ev->events = events;
	int op;
	if (ev->status == 1) {
		op = EPOLL_CTL_MOD;
	} else {
		op = EPOLL_CTL_ADD;
		ev->status = 1;
	}
	if (epoll_ctl(epfd, op, ev->fd, &ep_ev) < 0) {
		printf("event add failed [fd=%d], events[%d]\n", ev->fd, events);
		return -1;
	}
	return 0;
}
int nty_event_del(int epfd, struct ntyevent *ev) {
	struct epoll_event ep_ev = {0, {0}};
	if (ev->status != 1) {
		return -1;
	}
	ep_ev.data.ptr = ev;
	ev->status = 0;
	epoll_ctl(epfd, EPOLL_CTL_DEL, ev->fd, &ep_ev);
	return 0;
}
int recv_cb(int fd, int events, void *arg) {
	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	struct ntyevent *ev = ntyreactor_idx(reactor, fd);
	int len = recv(fd, ev->buffer, BUFFER_LENGTH , 0); // 
	nty_event_del(reactor->epfd, ev);
	if (len > 0) {
		ev->length = len;
		ev->buffer[len] = '\0';
		printf("C[%d]:%s\n", fd, ev->buffer);
		nty_event_set(ev, fd, send_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLOUT, ev);
	} else if (len == 0) {
		close(ev->fd);
		//printf("[fd=%d] pos[%ld], closed\n", fd, ev-reactor->events);
	} else {
		close(ev->fd);
		printf("recv[fd=%d] error[%d]:%s\n", fd, errno, strerror(errno));
	}
	return len;
}
int send_cb(int fd, int events, void *arg) {
	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	struct ntyevent *ev = ntyreactor_idx(reactor, fd);
	int len = send(fd, ev->buffer, ev->length, 0);
	if (len > 0) {
		printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer);
		nty_event_del(reactor->epfd, ev);
		nty_event_set(ev, fd, recv_cb, reactor);
		nty_event_add(reactor->epfd, EPOLLIN, ev);
	} else {
		close(ev->fd);
		nty_event_del(reactor->epfd, ev);
		printf("send[fd=%d] error %s\n", fd, strerror(errno));
	}
	return len;
}
int accept_cb(int fd, int events, void *arg) {
	struct ntyreactor *reactor = (struct ntyreactor*)arg;
	if (reactor == NULL) return -1;
	struct sockaddr_in client_addr;
	socklen_t len = sizeof(client_addr);
	int clientfd;
	if ((clientfd = accept(fd, (struct sockaddr*)&client_addr, &len)) == -1) {
		if (errno != EAGAIN && errno != EINTR) {
		}
		printf("accept: %s\n", strerror(errno));
		return -1;
	}
	int flag = 0;
	if ((flag = fcntl(clientfd, F_SETFL, O_NONBLOCK)) < 0) {
		printf("%s: fcntl nonblocking failed, %d\n", __func__, MAX_EPOLL_EVENTS);
		return -1;
	}
	/*存储*/
	struct ntyevent *event = ntyreactor_idx(reactor, clientfd);
	nty_event_set(event, clientfd, recv_cb, reactor);
	nty_event_add(reactor->epfd, EPOLLIN, event);
	printf("new connect [%s:%d], pos[%d]\n", 
		inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), clientfd);
	return 0;
}
int init_sock(short port) {
	int fd = socket(AF_INET, SOCK_STREAM, 0);
	fcntl(fd, F_SETFL, O_NONBLOCK);
	struct sockaddr_in server_addr;
	memset(&server_addr, 0, sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	server_addr.sin_port = htons(port);
	bind(fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
	if (listen(fd, 20) < 0) {
		printf("listen failed : %s\n", strerror(errno));
	}
	return fd;
}
//新增块数(eventblock结点个数)
//ntyreactor_alloc(reactor);
int ntyreactor_alloc(struct ntyreactor *reactor) {
	if (reactor == NULL) return -1;
	if (reactor->evblk == NULL) return -1;
	struct eventblock *blk = reactor->evblk;
	while (blk->next != NULL) {
		blk = blk->next;
	}
	struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	if (evs == NULL) {
		printf("ntyreactor_alloc ntyevents failed\n");
		return -2;
	}
	memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock));
	if (block == NULL) {
		printf("ntyreactor_alloc eventblock failed\n");
		return -2;
	}
	memset(block, 0, sizeof(struct eventblock));
	block->events = evs;
	block->next = NULL;
	blk->next = block;
	reactor->blkcnt ++; //
	return 0;
}
//struct ntyevent *event = ntyreactor_idx(reactor, sockfd);
struct ntyevent *ntyreactor_idx(struct ntyreactor *reactor, int sockfd) {
	int blkidx = sockfd / MAX_EPOLL_EVENTS;
	//如果块数(eventblock结点个数)不能满足新的sockfd的存放
	while (blkidx >= reactor->blkcnt) {
		//新增块数(eventblock结点个数)
		ntyreactor_alloc(reactor);
	}
	//找到存放sockfd的块(eventblock对应的结点)
	int i = 0;
	struct eventblock *blk = reactor->evblk;
	while(i ++ < blkidx && blk != NULL) {
		blk = blk->next;
	}
	//返回对应块(eventblock对应的结点)的存放sockfd数组的那个具体位置
	return &blk->events[sockfd % MAX_EPOLL_EVENTS];
}
//初始化链表
int ntyreactor_init(struct ntyreactor *reactor) {
	if (reactor == NULL) return -1;
	memset(reactor, 0, sizeof(struct ntyreactor));
	reactor->epfd = epoll_create(1);
	if (reactor->epfd <= 0) {
		printf("create epfd in %s err %s\n", __func__, strerror(errno));
		return -2;
	}
	struct ntyevent *evs = (struct ntyevent*)malloc((MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	if (evs == NULL) {
		printf("ntyreactor_alloc ntyevents failed\n");
		return -2;
	}
	memset(evs, 0, (MAX_EPOLL_EVENTS) * sizeof(struct ntyevent));
	struct eventblock *block = (struct eventblock *)malloc(sizeof(struct eventblock));
	if (block == NULL) {
		printf("ntyreactor_alloc eventblock failed\n");
		return -2;
	}
	memset(block, 0, sizeof(struct eventblock));
	block->events = evs;
	block->next = NULL;
	reactor->evblk = block;
	reactor->blkcnt = 1;
	return 0;
}
int ntyreactor_destory(struct ntyreactor *reactor) {
	close(reactor->epfd);
	//free(reactor->events);
	struct eventblock *blk = reactor->evblk;
	struct eventblock *blk_next = NULL;
	while (blk != NULL) {
		blk_next = blk->next;
		free(blk->events);
		free(blk);
		blk = blk_next;
	}
	return 0;
}
//ntyreactor_addlistener(reactor, sockfds[i], accept_cb);
//上树，并初始化链表数组上对应的fd
int ntyreactor_addlistener(struct ntyreactor *reactor, int sockfd, NCALLBACK *acceptor) {
	if (reactor == NULL) return -1;
	if (reactor->evblk == NULL) return -1;
	//reactor->evblk->events[sockfd];
	//找到sock所在的具体位置
	struct ntyevent *event = ntyreactor_idx(reactor, sockfd);
	初始化sockfd
	nty_event_set(event, sockfd, acceptor, reactor);
	//对监听的epoll红黑树上的结点的修改
	nty_event_add(reactor->epfd, EPOLLIN, event);
	return 0;
}
//ntyreactor_run(reactor);
int ntyreactor_run(struct ntyreactor *reactor) {
	if (reactor == NULL) return -1;
	if (reactor->epfd < 0) return -1;
	if (reactor->evblk == NULL) return -1;
	struct epoll_event events[MAX_EPOLL_EVENTS+1];
	int checkpos = 0, i;
	while (1) {
/*
		long now = time(NULL);
		for (i = 0;i < 100;i ++, checkpos ++) {
			if (checkpos == MAX_EPOLL_EVENTS) {
				checkpos = 0;
			}
			if (reactor->events[checkpos].status != 1) {
				continue;
			}
			long duration = now - reactor->events[checkpos].last_active;
			if (duration >= 60) {
				close(reactor->events[checkpos].fd);
				printf("[fd=%d] timeout\n", reactor->events[checkpos].fd);
				nty_event_del(reactor->epfd, &reactor->events[checkpos]);
			}
		}
*/
		int nready = epoll_wait(reactor->epfd, events, MAX_EPOLL_EVENTS, 1000);
		if (nready < 0) {
			printf("epoll_wait error, exit\n");
			continue;
		}
		for (i = 0;i < nready;i ++) {
			struct ntyevent *ev = (struct ntyevent*)events[i].data.ptr;
			//看fd连接是否发生变化
			if ((events[i].events & EPOLLIN) && (ev->events & EPOLLIN)) {
				ev->callback(ev->fd, events[i].events, ev->arg);
			}
			if ((events[i].events & EPOLLOUT) && (ev->events & EPOLLOUT)) {
				ev->callback(ev->fd, events[i].events, ev->arg);
			}
		}
	}
}
// 3, 6w, 1, 100 == 
// <remoteip, remoteport, localip, localport>
int main(int argc, char *argv[]) {
	unsigned short port = SERVER_PORT; // listen 8888
	if (argc == 2) {
		port = atoi(argv[1]);//把参数 str 所指向的字符串转换为一个整数（类型为 int 型）
	}
	struct ntyreactor *reactor = (struct ntyreactor*)malloc(sizeof(struct ntyreactor));
	/*初始化三个结构体，建立链表*/
	ntyreactor_init(reactor);
	int i = 0;
	int sockfds[PORT_COUNT] = {0};
	for (i = 0;i < PORT_COUNT;i ++) {
		//端口号的监听
		sockfds[i] = init_sock(port+i);
		//上树
		ntyreactor_addlistener(reactor, sockfds[i], accept_cb);
	}
	// epoll_wait
	ntyreactor_run(reactor);
	//
	ntyreactor_destory(reactor);
	for (i = 0;i < PORT_COUNT;i ++) {
		close(sockfds[i]);
	}
	free(reactor);
	return 0;
}

reactor的写法感觉和epoll的普通写法，感觉差别就是reactor多了个回调函数，具体没啥优点？
epoll是针对io的管理。 reactor对针对事件的管理
不同的事件，针对不同的回调函数
性能上没啥差异，但提高了代码的复用性。具体需要自己慢慢体会体会，呜呜呜呜还有体会到，编程思想不过关。

二、环境设置

限制是fd的限制，系统默认fd最多有1024个，按照一个连接一个fd的做法，那就需要百万个fd。这里有两种修改方法，一是使用ulimit -n命令，这个命令重启就失效；二是修改/etc/security/limits.conf文件，这是永久有效的，重启或sysctl -p生效。

* hard nofile 1048576
* soft nofile 1048576

hard是硬限制，不能超过该值，soft是软限制，可以超过，超过后就开始回收。
这个文件里还有一些其他的参数可以了解一下，fs.file_max是fd可取到的最大值，注意与fd最大个数区分。
突破这两个限制后，还会遇到一个问题，客户端会报错：connection timedout。连接超时，即是客户端未收到服务器对客户端connect()的回应包。这里有两种可能，客户端为收到服务器的包或是服务器未收到客户端的connect包。事实上，是因为系统有个防火墙iotables，这个防火墙是基于网卡和协议栈之间的过滤机制netfilter实现的。netfilter当连接数到达一定程度时，会不允许再向外发送connect包。修改也是通过/etc/security/limits.conf文件

net.nf_conntrack_max=1048576

突破这些限制，就可以实现百万并发了。
这里再介绍/etc/security/limits.conf中几个参数
net.ipv4.tcp_mem=262144 524288 786432是所有TCP协议栈所占空间的大小，单位是页（4KB）。介绍一下后面写的三个值，当所占空间大小超过第二个值时，系统会进行优化，此时如果占用空间降到第一个值以下，不再优化，第三个值是上限，不允许分配超过比大小的空间。
net.ipv4.tcp_wmem=2048 2048 4096是每个socket对应的写缓冲区大小，三个值分别是最小值、默认值、最大值，单位是B。
net.ipv4.tcp_rmem=2048 2048 4096是每个socket对应的读缓冲区大小，三个值分别是最小值、默认值、最大值，单位是B。
做百万并发时，如果内存不大，可以相应调小。在实际应用中，如果传输大文件，调大；如果传输的都是字符，调小，就可以接收更多fd。

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