# Nginx 事件模块 ## 概述 Nginx 是以事件的触发来驱动的，事件驱动模型主要包括事件收集、事件发送、事件处理（即事件管理）三部分。在Nginx 的工作进程中主要关注的事件是IO 网络事件 和 定时器事件。在生成的 objs 目录文件中，其中ngx\_modules.c 文件的内容是Nginx 各种模块的执行顺序，我们可以从该文件的内容中看到事件模块的执行顺序为以下所示：注意：由于是在Linux 系统下，所以支持具体的 epoll 事件模块，接下来的文章结构按照以下顺序来写。 ``` extern ngx_module_t ngx_events_module; extern ngx_module_t ngx_event_core_module; extern ngx_module_t ngx_epoll_module; ``` ## 事件模块接口 ## ngx\_event\_module\_t 结构体 在 Nginx 中，结构体 ngx\_module\_t 是 Nginx 模块最基本的接口。对于每一种不同类型的模块，都有一个具体的结构体来描述这一类模块的通用接口，该接口由ngx\_module\_t 中的成员ctx 管理。在 Nginx 中定义了事件模块的通用接口ngx\_event\_module\_t 结构体，该结构体定义在文件[src/event/ngx\_event.h](http://lxr.nginx.org/source/src/event/ngx_event.h) 中： ``` typedef struct { ngx_str_t *name; void *(*create_conf)(ngx_cycle_t *cycle); char *(*init_conf)(ngx_cycle_t *cycle, void *conf); ngx_event_actions_t actions; } ngx_event_module_t; ``` 在 ngx\_event\_module\_t 结构体中actions 的类型是ngx\_event\_actions\_t 结构体，该成员结构实现了事件驱动模块的具体方法。该结构体定义在文件[src/event/ngx\_event.h](http://lxr.nginx.org/source/src/event/ngx_event.h) 中： ``` typedef struct { ngx_int_t (*add)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); ngx_int_t (*del)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); ngx_int_t (*enable)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); ngx_int_t (*disable)(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); ngx_int_t (*add_conn)(ngx_connection_t *c); ngx_int_t (*del_conn)(ngx_connection_t *c, ngx_uint_t flags); ngx_int_t (*process_changes)(ngx_cycle_t *cycle, ngx_uint_t nowait); ngx_int_t (*process_events)(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags); ngx_int_t (*init)(ngx_cycle_t *cycle, ngx_msec_t timer); void (*done)(ngx_cycle_t *cycle); } ngx_event_actions_t; ``` ## ngx\_event\_t 结构体 在 Nginx 中，每一个具体事件的定义由结构体ngx\_event\_t 来表示，该结构体ngx\_event\_t 用来保存具体事件。该结构体定义在文件 [src/event/ngx\_event.h](http://lxr.nginx.org/source/src/event/ngx_event.h) 中： ``` struct ngx_event_s { void *data; unsigned write:1; unsigned accept:1; unsigned instance:1; unsigned active:1; unsigned disabled:1; unsigned ready:1; unsigned oneshot:1; unsigned complete:1; unsigned eof:1; unsigned error:1; unsigned timedout:1; unsigned timer_set:1; unsigned delayed:1; unsigned deferred_accept:1; unsigned pending_eof:1; unsigned posted:1; #if (NGX_WIN32) unsigned accept_context_updated:1; #endif #if (NGX_HAVE_KQUEUE) unsigned kq_vnode:1; int kq_errno; #endif #if (NGX_HAVE_KQUEUE) || (NGX_HAVE_IOCP) int available; #else unsigned available:1; #endif ngx_event_handler_pt handler; #if (NGX_HAVE_AIO) #if (NGX_HAVE_IOCP) ngx_event_ovlp_t ovlp; #else struct aiocb aiocb; #endif #endif ngx_uint_t index; ngx_log_t *log; ngx_rbtree_node_t timer; ngx_queue_t queue; unsigned closed:1; unsigned channel:1; unsigned resolver:1; unsigned cancelable:1; #if 0 void *thr_ctx; #if (NGX_EVENT_T_PADDING) uint32_t padding[NGX_EVENT_T_PADDING]; #endif #endif }; ``` 在每个事件结构体 ngx\_event\_t 最重要的成员是handler 回调函数，该回调函数定义了当事件发生时的处理方法。该回调方法原型在文件[src/core/ngx\_core.h](http://lxr.nginx.org/source/src/core/ngx_core.h) 中： ``` typedef void (*ngx_event_handler_pt)(ngx_event_t *ev); ``` ## ngx\_connection\_t 结构体 当客户端向 Nginx 服务器发起连接请求时，此时若Nginx 服务器被动接收该连接，则相对Nginx 服务器来说称为被动连接，被动连接的表示由基本数据结构体ngx\_connection\_t 完成。该结构体定义在文件 [src/core/ngx\_connection.h](http://lxr.nginx.org/source/src/core/ngx_connection.h) 中： ``` struct ngx_connection_s { void *data; ngx_event_t *read; ngx_event_t *write; ngx_socket_t fd; ngx_recv_pt recv; ngx_send_pt send; ngx_recv_chain_pt recv_chain; ngx_send_chain_pt send_chain; ngx_listening_t *listening; off_t sent; ngx_log_t *log; ngx_pool_t *pool; struct sockaddr *sockaddr; socklen_t socklen; ngx_str_t addr_text; ngx_str_t proxy_protocol_addr; #if (NGX_SSL) ngx_ssl_connection_t *ssl; #endif struct sockaddr *local_sockaddr; socklen_t local_socklen; ngx_buf_t *buffer; ngx_queue_t queue; ngx_atomic_uint_t number; ngx_uint_t requests; unsigned buffered:8; unsigned log_error:3; unsigned unexpected_eof:1; unsigned timedout:1; unsigned error:1; unsigned destroyed:1; unsigned idle:1; unsigned reusable:1; unsigned close:1; unsigned sendfile:1; unsigned sndlowat:1; unsigned tcp_nodelay:2; unsigned tcp_nopush:2; unsigned need_last_buf:1; #if (NGX_HAVE_IOCP) unsigned accept_context_updated:1; #endif #if (NGX_HAVE_AIO_SENDFILE) unsigned aio_sendfile:1; unsigned busy_count:2; ngx_buf_t *busy_sendfile; #endif #if (NGX_THREADS) ngx_atomic_t lock; #endif }; ``` 在处理请求的过程中，若 Nginx 服务器主动向上游服务器建立连接，完成连接建立并与之进行通信，这种相对Nginx 服务器来说是一种主动连接，主动连接由结构体ngx\_peer\_connection\_t 表示，但是该结构体 ngx\_peer\_connection\_t 也是 ngx\_connection\_t 结构体的封装。该结构体定义在文件[src/event/ngx\_event\_connect.h](http://lxr.nginx.org/source/src/event/ngx_event_connect.h) 中： ``` struct ngx_peer_connection_s { ngx_connection_t *connection; struct sockaddr *sockaddr; socklen_t socklen; ngx_str_t *name; ngx_uint_t tries; ngx_event_get_peer_pt get; ngx_event_free_peer_pt free; void *data; #if (NGX_SSL) ngx_event_set_peer_session_pt set_session; ngx_event_save_peer_session_pt save_session; #endif #if (NGX_THREADS) ngx_atomic_t *lock; #endif ngx_addr_t *local; int rcvbuf; ngx_log_t *log; unsigned cached:1; unsigned log_error:2; }; ``` ## ngx\_events\_module 核心模块 ## ngx\_events\_module 核心模块的定义 ngx\_events\_module 模块是事件的核心模块，该模块的功能是：定义新的事件类型，并为每个事件模块定义通用接口ngx\_event\_module\_t 结构体，管理事件模块生成的配置项结构体，并解析事件类配置项。首先，看下该模块在文件[src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中的定义： ``` ngx_module_t ngx_events_module = { NGX_MODULE_V1, &ngx_events_module_ctx, ngx_events_commands, NGX_CORE_MODULE, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NGX_MODULE_V1_PADDING }; ``` 其中，模块的配置项指令结构 ngx\_events\_commands 决定了该模块的功能。配置项指令结构ngx\_events\_commands 在文件[src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义如下： ``` static ngx_command_t ngx_events_commands[] = { { ngx_string("events"), NGX_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_NOARGS, ngx_events_block, 0, 0, NULL }, ngx_null_command }; ``` 从配置项结构体中可以知道，该模块只对 events{...} 配置块感兴趣，并定义了管理事件模块的方法ngx\_events\_block；ngx\_events\_block 方法在文件[src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义： ``` static char * ngx_events_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { char *rv; void ***ctx; ngx_uint_t i; ngx_conf_t pcf; ngx_event_module_t *m; if (*(void **) conf) { return "is duplicate"; } ngx_event_max_module = 0; for (i = 0; ngx_modules[i]; i++) { if (ngx_modules[i]->type != NGX_EVENT_MODULE) { continue; } ngx_modules[i]->ctx_index = ngx_event_max_module++; } ctx = ngx_pcalloc(cf->pool, sizeof(void *)); if (ctx == NULL) { return NGX_CONF_ERROR; } *ctx = ngx_pcalloc(cf->pool, ngx_event_max_module * sizeof(void *)); if (*ctx == NULL) { return NGX_CONF_ERROR; } *(void **) conf = ctx; for (i = 0; ngx_modules[i]; i++) { if (ngx_modules[i]->type != NGX_EVENT_MODULE) { continue; } m = ngx_modules[i]->ctx; if (m->create_conf) { (*ctx)[ngx_modules[i]->ctx_index] = m->create_conf(cf->cycle); if ((*ctx)[ngx_modules[i]->ctx_index] == NULL) { return NGX_CONF_ERROR; } } } pcf = *cf; cf->ctx = ctx; cf->module_type = NGX_EVENT_MODULE; cf->cmd_type = NGX_EVENT_CONF; rv = ngx_conf_parse(cf, NULL); *cf = pcf; if (rv != NGX_CONF_OK) return rv; for (i = 0; ngx_modules[i]; i++) { if (ngx_modules[i]->type != NGX_EVENT_MODULE) { continue; } m = ngx_modules[i]->ctx; if (m->init_conf) { rv = m->init_conf(cf->cycle, (*ctx)[ngx_modules[i]->ctx_index]); if (rv != NGX_CONF_OK) { return rv; } } } return NGX_CONF_OK; } ``` 另外，在 ngx\_events\_module 模块的定义中有一个成员ctx 指向了核心模块的通用接口结构。核心模块的通用接口结构体定义在文件[src/core/ngx\_conf\_file.h](http://lxr.nginx.org/source/src/core/ngx_conf_file.h) 中： ``` typedef struct { ngx_str_t name; void *(*create_conf)(ngx_cycle_t *cycle); char *(*init_conf)(ngx_cycle_t *cycle, void *conf); } ngx_core_module_t; ``` 因此，ngx\_events\_module 作为核心模块，必须定义核心模块的通用接口结构。ngx\_events\_module 模块的核心模块通用接口在文件[src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义： ``` static ngx_core_module_t ngx_events_module_ctx = { ngx_string("events"), NULL, ngx_event_init_conf }; ``` ## 所有事件模块的配置项管理 Nginx 服务器在结构体 ngx\_cycle\_t 中定义了一个四级指针成员 conf\_ctx，整个Nginx 模块都是使用该四级指针成员管理模块的配置项结构，以下events 模块为例对该四级指针成员进行简单的分析，如下图所示： 每个事件模块可以通过宏定义 ngx\_event\_get\_conf 获取它在create\_conf 中分配的结构体的指针；该宏中定义如下： ``` #define ngx_event_get_conf(conf_ctx, module) \ (*(ngx_get_conf(conf_ctx, ngx_events_module))) [module.ctx_index]; #define ngx_get_conf(conf_ctx, module) conf_ctx[module.index] ``` 从上面的宏定义可以知道，每个事件模块获取自己在 create\_conf 中分配的结构体的指针，只需在ngx\_event\_get\_conf 传入参数ngx\_cycle\_t 中的 conf\_ctx 成员，并且传入自己模块的名称即可获取自己分配的结构体指针。 ## ngx\_event\_core\_module 事件模块 ngx\_event\_core\_module 模块是一个事件类型的模块，它在所有事件模块中的顺序是第一，是其它事件类模块的基础。它主要完成以下任务： 1. 创建连接池； 2. 决定使用哪些事件驱动机制； 3. 初始化将要使用的事件模块； ## ngx\_event\_conf\_t 结构体 ngx\_event\_conf\_t 结构体是用来保存ngx\_event\_core\_module 事件模块配置项参数的。该结构体在文件[src/event/ngx\_event.h](http://lxr.nginx.org/source/src/event/ngx_event.h) 中定义： ``` typedef struct { ngx_uint_t connections; ngx_uint_t use; ngx_flag_t multi_accept; ngx_flag_t accept_mutex; ngx_msec_t accept_mutex_delay; u_char *name; #if (NGX_DEBUG) ngx_array_t debug_connection; #endif } ngx_event_conf_t; ``` ## ngx\_event\_core\_module 事件模块的定义 该模块在文件 [src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义： ``` ngx_module_t ngx_event_core_module = { NGX_MODULE_V1, &ngx_event_core_module_ctx, ngx_event_core_commands, NGX_EVENT_MODULE, NULL, ngx_event_module_init, ngx_event_process_init, NULL, NULL, NULL, NULL, NGX_MODULE_V1_PADDING }; ``` 其中，模块的配置项指令结构 ngx\_event\_core\_commands 决定了该模块的功能。配置项指令结构 ngx\_event\_core\_commands 在文件 [src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义如下： ``` static ngx_str_t event_core_name = ngx_string("event_core"); static ngx_command_t ngx_event_core_commands[] = { { ngx_string("worker_connections"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_event_connections, 0, 0, NULL }, { ngx_string("connections"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_event_connections, 0, 0, NULL }, { ngx_string("use"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_event_use, 0, 0, NULL }, { ngx_string("multi_accept"), NGX_EVENT_CONF|NGX_CONF_FLAG, ngx_conf_set_flag_slot, 0, offsetof(ngx_event_conf_t, multi_accept), NULL }, { ngx_string("accept_mutex"), NGX_EVENT_CONF|NGX_CONF_FLAG, ngx_conf_set_flag_slot, 0, offsetof(ngx_event_conf_t, accept_mutex), NULL }, { ngx_string("accept_mutex_delay"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_conf_set_msec_slot, 0, offsetof(ngx_event_conf_t, accept_mutex_delay), NULL }, { ngx_string("debug_connection"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_event_debug_connection, 0, 0, NULL }, ngx_null_command }; ``` 其中，每个事件模块都需要实现事件模块的通用接口结构 ngx\_event\_module\_t，ngx\_event\_core\_module 模块的上下文结构 ngx\_event\_core\_module\_ctx 并不真正的负责网络事件的驱动，所有不会实现ngx\_event\_module\_t 结构体中的成员 actions 中的方法。上下文结构 ngx\_event\_core\_module\_ctx 在文件 [src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义如下： ``` ngx_event_module_t ngx_event_core_module_ctx = { &event_core_name, ngx_event_core_create_conf, ngx_event_core_init_conf, { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL } }; ``` 在模块定义中，实现了两种方法分别为 ngx\_event\_module\_init 和ngx\_event\_process\_init 方法。在Nginx 启动过程中没有使用 fork 出 worker 子进程之前，先调用 ngx\_event\_core\_module 模块中的 ngx\_event\_module\_init 方法，当fork 出 worker 子进程后，每一个 worker 子进程则会调用 ngx\_event\_process\_init 方法。 ngx\_event\_module\_init 方法在文件[src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义： ``` static ngx_int_t ngx_event_module_init(ngx_cycle_t *cycle) { void ***cf; u_char *shared; size_t size, cl; ngx_shm_t shm; ngx_time_t *tp; ngx_core_conf_t *ccf; ngx_event_conf_t *ecf; cf = ngx_get_conf(cycle->conf_ctx, ngx_events_module); ecf = (*cf)[ngx_event_core_module.ctx_index]; if (!ngx_test_config && ngx_process <= NGX_PROCESS_MASTER) { ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "using the \"%s\" event method", ecf->name); } ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module); ngx_timer_resolution = ccf->timer_resolution; #if !(NGX_WIN32) { ngx_int_t limit; struct rlimit rlmt; if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "getrlimit(RLIMIT_NOFILE) failed, ignored"); } else { if (ecf->connections > (ngx_uint_t) rlmt.rlim_cur && (ccf->rlimit_nofile == NGX_CONF_UNSET || ecf->connections > (ngx_uint_t) ccf->rlimit_nofile)) { limit = (ccf->rlimit_nofile == NGX_CONF_UNSET) ? (ngx_int_t) rlmt.rlim_cur : ccf->rlimit_nofile; ngx_log_error(NGX_LOG_WARN, cycle->log, 0, "%ui worker_connections exceed " "open file resource limit: %i", ecf->connections, limit); } } } #endif if (ccf->master == 0) { return NGX_OK; } if (ngx_accept_mutex_ptr) { return NGX_OK; } cl = 128; size = cl + cl + cl; #if (NGX_STAT_STUB) size += cl + cl + cl + cl + cl + cl + cl; #endif shm.size = size; shm.name.len = sizeof("nginx_shared_zone"); shm.name.data = (u_char *) "nginx_shared_zone"; shm.log = cycle->log; if (ngx_shm_alloc(&shm) != NGX_OK) { return NGX_ERROR; } shared = shm.addr; ngx_accept_mutex_ptr = (ngx_atomic_t *) shared; ngx_accept_mutex.spin = (ngx_uint_t) -1; if (ngx_shmtx_create(&ngx_accept_mutex, (ngx_shmtx_sh_t *) shared, cycle->lock_file.data) != NGX_OK) { return NGX_ERROR; } ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl); (void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1); ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "counter: %p, %d", ngx_connection_counter, *ngx_connection_counter); ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl); tp = ngx_timeofday(); ngx_random_number = (tp->msec << 16) + ngx_pid; #if (NGX_STAT_STUB) ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl); ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl); ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl); ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl); ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl); ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl); ngx_stat_waiting = (ngx_atomic_t *) (shared + 9 * cl); #endif return NGX_OK; } ``` ngx\_event\_process\_init 方法在文件[src/event/ngx\_event.c](http://lxr.nginx.org/source/src/event/ngx_event.c) 中定义： ``` static ngx_int_t ngx_event_process_init(ngx_cycle_t *cycle) { ngx_uint_t m, i; ngx_event_t *rev, *wev; ngx_listening_t *ls; ngx_connection_t *c, *next, *old; ngx_core_conf_t *ccf; ngx_event_conf_t *ecf; ngx_event_module_t *module; ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module); ecf = ngx_event_get_conf(cycle->conf_ctx, ngx_event_core_module); if (ccf->master && ccf->worker_processes > 1 && ecf->accept_mutex) { ngx_use_accept_mutex = 1; ngx_accept_mutex_held = 0; ngx_accept_mutex_delay = ecf->accept_mutex_delay; } else { ngx_use_accept_mutex = 0; } #if (NGX_WIN32) ngx_use_accept_mutex = 0; #endif ngx_queue_init(&ngx_posted_accept_events); ngx_queue_init(&ngx_posted_events); if (ngx_event_timer_init(cycle->log) == NGX_ERROR) { return NGX_ERROR; } for (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) { exit(2); } break; } #if !(NGX_WIN32) if (ngx_timer_resolution && !(ngx_event_flags & NGX_USE_TIMER_EVENT)) { struct sigaction sa; struct itimerval itv; ngx_memzero(&sa, sizeof(struct sigaction)); sa.sa_handler = ngx_timer_signal_handler; sigemptyset(&sa.sa_mask); if (sigaction(SIGALRM, &sa, NULL) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "sigaction(SIGALRM) failed"); return NGX_ERROR; } itv.it_interval.tv_sec = ngx_timer_resolution / 1000; itv.it_interval.tv_usec = (ngx_timer_resolution % 1000) * 1000; itv.it_value.tv_sec = ngx_timer_resolution / 1000; itv.it_value.tv_usec = (ngx_timer_resolution % 1000 ) * 1000; if (setitimer(ITIMER_REAL, &itv, NULL) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "setitimer() failed"); } } if (ngx_event_flags & NGX_USE_FD_EVENT) { struct rlimit rlmt; if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "getrlimit(RLIMIT_NOFILE) failed"); return NGX_ERROR; } cycle->files_n = (ngx_uint_t) rlmt.rlim_cur; cycle->files = ngx_calloc(sizeof(ngx_connection_t *) * cycle->files_n, cycle->log); if (cycle->files == NULL) { return NGX_ERROR; } } #endif 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; } 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; } 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; ls = cycle->listening.elts; for (i = 0; i < cycle->listening.nelts; i++) { c = ngx_get_connection(ls[i].fd, cycle->log); if (c == NULL) { return NGX_ERROR; } c->log = &ls[i].log; c->listening = &ls[i]; ls[i].connection = c; rev = c->read; rev->log = c->log; rev->accept = 1; #if (NGX_HAVE_DEFERRED_ACCEPT) rev->deferred_accept = ls[i].deferred_accept; #endif if (!(ngx_event_flags & NGX_USE_IOCP_EVENT)) { if (ls[i].previous) { old = ls[i].previous->connection; if (ngx_del_event(old->read, NGX_READ_EVENT, NGX_CLOSE_EVENT) == NGX_ERROR) { return NGX_ERROR; } old->fd = (ngx_socket_t) -1; } } #if (NGX_WIN32) if (ngx_event_flags & NGX_USE_IOCP_EVENT) { ngx_iocp_conf_t *iocpcf; rev->handler = ngx_event_acceptex; if (ngx_use_accept_mutex) { continue; } if (ngx_add_event(rev, 0, NGX_IOCP_ACCEPT) == NGX_ERROR) { return NGX_ERROR; } ls[i].log.handler = ngx_acceptex_log_error; iocpcf = ngx_event_get_conf(cycle->conf_ctx, ngx_iocp_module); if (ngx_event_post_acceptex(&ls[i], iocpcf->post_acceptex) == NGX_ERROR) { return NGX_ERROR; } } else { rev->handler = ngx_event_accept; if (ngx_use_accept_mutex) { continue; } if (ngx_add_event(rev, NGX_READ_EVENT, 0) == NGX_ERROR) { return NGX_ERROR; } } #else 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 { if (ngx_add_event(rev, NGX_READ_EVENT, 0) == NGX_ERROR) { return NGX_ERROR; } } #endif } return NGX_OK; } ``` 参考资料： 《深入理解 Nginx 》 《[nginx事件模块分析(二)](http://blog.csdn.net/freeinfor/article/details/16343223)》 --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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