reactor模式是对epoll的一层封装，将网络io转换成event。redis/nginx/libevent对网络io的处理，都采用了reactor模式。
参考下面的代码, 看完这段代码就会明白什么是reactor
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define BUFFER_LENGTH 4096
#define MAX_EPOLL_EVENTS 1024*512
#define LISTEN_PORT_COUNT 100
typedef int NCALLBACK(int, int, void*);
typedef struct ntyevent {
int fd;
int events;
void *arg;
int (*callback)(int fd, int events, void *arg);
int status;
char buffer[BUFFER_LENGTH];
int length;
} ntyevent;
typedef struct ntyreactor {
int epfd;
ntyevent *events;
} ntyreactor;
int recv_cb(int fd, int events, void *arg);
int send_cb(int fd, int events, void *arg);
void nty_event_set(struct ntyevent *ev, int fd, NCALLBACK callback, void *arg) {
ev->fd = fd;
ev->events = 0;
ev->arg = arg;
ev->callback = callback;
}
void nty_event_add(int epfd, int events, ntyevent *ev) {
struct epoll_event ep_ev = {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)) {
printf("fail to add fd[%d], events[%d] into epoll\n", ev->fd, events);
}
}
void nty_event_del(int epfd, ntyevent *ev) {
struct epoll_event ep_ev = {0};
if (ev->status != 1) {
return;
}
ep_ev.data.ptr = ev;
ep_ev.events = ev->events;
ev->status = 0;
epoll_ctl(epfd, EPOLL_CTL_DEL, ev->fd, &ep_ev);
}
int recv_cb(int fd, int events, void *arg) {
ntyreactor *reactor = (ntyreactor*)arg;
ntyevent *ev = reactor->events + 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("Recv from [%d]: %s, %d Bytes\n", fd, ev->buffer, len);
nty_event_set(ev, fd, send_cb, reactor);
nty_event_add(reactor->epfd, EPOLLOUT, ev);
} else if (len == 0) {
close(fd);
printf("[fd=%d] pos[%ld], closed\n", fd, ev-reactor->events);
} else {
close(fd);
perror("recv");
}
return len;
}
int send_cb(int fd, int events, void *arg) {
ntyreactor *reactor = (ntyreactor*)arg;
ntyevent *ev = reactor->events + fd;
int len = send(fd, ev->buffer, ev->length, 0);
nty_event_del(reactor->epfd, ev);
if (len > 0) {
printf("send[fd=%d], [%d]%s\n", fd, len, ev->buffer);
memset(ev->buffer, 0, BUFFER_LENGTH);
nty_event_set(ev, fd, recv_cb, reactor);
nty_event_add(reactor->epfd, EPOLLIN, ev);
} else {
close(fd);
printf("send[fd=%d] error %s\n", fd, strerror(errno));
}
return len;
}
int accept_cb(int fd, int events, void *arg) {
ntyreactor *reactor = (ntyreactor*)arg;
if (reactor == NULL) {
return -1;
}
struct sockaddr_in client_addr;
socklen_t len = sizeof(client_addr);
int client_fd = accept(fd, (struct sockaddr*)&client_addr, &len);
if (client_fd < 0) {
perror("accept");
return -1;
}
if (client_fd == MAX_EPOLL_EVENTS) {
printf("%s: max connect limit[%d]\n", __func__, MAX_EPOLL_EVENTS);
return -1;
}
fcntl(client_fd, F_SETFL, O_NONBLOCK);
nty_event_set(&reactor->events[client_fd], client_fd, recv_cb, reactor);
nty_event_add(reactor->epfd, EPOLLIN, &reactor->events[client_fd]);
return 0;
}
int init_listen_fd(short port) {
int listen_fd = socket(AF_INET, SOCK_STREAM, 0);
fcntl(listen_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(listen_fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
if (listen(listen_fd, 100) < 0) {
printf("listen failed : %s\n", strerror(errno));
}
return listen_fd;
}
int ntyreactor_init(ntyreactor *reactor) {
if (reactor == NULL) {
return -1;
}
memset(reactor, 0, sizeof(ntyreactor));
reactor->epfd = epoll_create(1);
if (reactor->epfd < 0) {
perror("epoll_create");
return -2;
}
reactor->events = (ntyevent*)malloc(MAX_EPOLL_EVENTS * sizeof(ntyevent));
if (reactor->events == NULL) {
printf("fail to malloc reactor events\n");
close(reactor->epfd);
return -3;
}
return 0;
}
void ntyreactor_destroy(ntyreactor *reactor) {
close(reactor->epfd);
free(reactor->events);
free(reactor);
}
int ntyreactor_addlistener(ntyreactor *reactor, int listen_fd, NCALLBACK *acceptor) {
if (reactor == NULL || reactor->events == NULL) {
return -1;
}
nty_event_set(&reactor->events[listen_fd], listen_fd, accept_cb, reactor);
nty_event_add(reactor->epfd, EPOLLIN, &reactor->events[listen_fd]);
return 0;
}
int ntyreactor_run(ntyreactor *reactor) {
if (reactor == NULL || reactor->epfd < 0 || reactor->events == NULL ) {
return -1;
}
struct epoll_event events[MAX_EPOLL_EVENTS];
while (1) {
int nready = epoll_wait(reactor->epfd, events, MAX_EPOLL_EVENTS, 1000);
if (nready < 0) {
perror("epoll_wait");
continue;
}
int i;
for (i = 0; i < nready; i++) {
ntyevent *ev = (ntyevent*)events[i].data.ptr;
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);
}
}
}
}
int main(int argc, char* argv[]) {
if (argc < 2) {
printf("Parameter error\n");
return -1;
}
int port = atoi(argv[1]);
ntyreactor *reactor = (ntyreactor*)malloc(sizeof(ntyreactor));
ntyreactor_init(reactor);
int listen_fd[LISTEN_PORT_COUNT] = {0};
int i = 0;
for (int i = 0; i < LISTEN_PORT_COUNT; i++) {
listen_fd[i] = init_listen_fd(port + i);
ntyreactor_addlistener(reactor, listen_fd[i], accept_cb);
}
ntyreactor_run(reactor);
ntyreactor_destroy(reactor);
for (int i = 0; i < LISTEN_PORT_COUNT; i++) {
close(listen_fd[i]);
}
return 0;
}