static ngx_int_t
ngx_event_process_init(ngx_cycle_t *cycle)
{.......//对所有NGX_EVENT_MODULE模块执行module->actions.initfor (m = 0; ngx_modules[m]; m++) {if (ngx_modules[m]->type != NGX_EVENT_MODULE) {continue;}if (ngx_modules[m]->ctx_index != ecf->use) {continue;}module = ngx_modules[m]->ctx;if (module->actions.init(cycle, ngx_timer_resolution) != NGX_OK) {/* fatal */exit(2);}break;}......cycle->connections =ngx_alloc(sizeof(ngx_connection_t) * cycle->connection_n, cycle->log);if (cycle->connections == NULL) {return NGX_ERROR;}c = cycle->connections;cycle->read_events = ngx_alloc(sizeof(ngx_event_t) * cycle->connection_n,cycle->log);if (cycle->read_events == NULL) {return NGX_ERROR;}rev = cycle->read_events;for (i = 0; i < cycle->connection_n; i++) {rev[i].closed = 1;rev[i].instance = 1;
#if (NGX_THREADS)rev[i].lock = &c[i].lock;rev[i].own_lock = &c[i].lock;
#endif}cycle->write_events = ngx_alloc(sizeof(ngx_event_t) * cycle->connection_n,cycle->log);if (cycle->write_events == NULL) {return NGX_ERROR;}wev = cycle->write_events;for (i = 0; i < cycle->connection_n; i++) {wev[i].closed = 1;
#if (NGX_THREADS)wev[i].lock = &c[i].lock;wev[i].own_lock = &c[i].lock;
#endif}i = cycle->connection_n;next = NULL;do {i--;c[i].data = next;c[i].read = &cycle->read_events[i];c[i].write = &cycle->write_events[i];c[i].fd = (ngx_socket_t) -1;next = &c[i];#if (NGX_THREADS)c[i].lock = 0;
#endif} while (i);cycle->free_connections = next;cycle->free_connection_n = cycle->connection_n;/* for each listening socket */ls = cycle->listening.elts;for (i = 0; i < cycle->listening.nelts; i++) {//获取空余连接，将服务端申请的每个socket fd占用一个连接，c = ngx_get_connection(ls[i].fd, cycle->log);......rev->handler = ngx_event_accept;if (ngx_use_accept_mutex) {continue;}if (ngx_event_flags & NGX_USE_RTSIG_EVENT) {if (ngx_add_conn(c) == NGX_ERROR) {return NGX_ERROR;}} else {//如果使用epoll模块，则在epoll上注册读事件，操作类型是EPOLL_CTL_ADD，也就是关注服务端申请的socket fd是否有新连接申请if (ngx_add_event(rev, NGX_READ_EVENT, 0) == NGX_ERROR) {return NGX_ERROR;}}}return NGX_OK;
}

static ngx_int_t
ngx_epoll_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags)
{.......//epoll_event结构体成员data的ptr指针可以用来存储用户的指针信息，这里用来存储连接信息，其中事件的instance标识主要用来显示事件是否过期
    ee.events = events | (uint32_t) flags;ee.data.ptr = (void *) ((uintptr_t) c | ev->instance); //把instance加到ee的末尾（由于内存对齐，末尾一般为0）

…….if (epoll_ctl(ep, op, c->fd, &ee) == -1) {ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno,"epoll_ctl(%d, %d) failed", op, c->fd);return NGX_ERROR;}.......return NGX_OK;
}

static void
ngx_worker_process_cycle(ngx_cycle_t *cycle, void *data)
{......ngx_worker_process_init(cycle, worker);......for ( ;; ) {......ngx_process_events_and_timers(cycle);......}
}

void
ngx_process_events_and_timers(ngx_cycle_t *cycle)
{......(void) ngx_process_events(cycle, timer, flags);......}