1.模块依赖

2. 模块的初始化

2.1 location的定义

location的定义包含以下几种

location [ = | ~ | ~* | ^~ ] uri { ... }
location @name { ... }

=:表示精确匹配，只有请求的url路径与后面的字符串完全相等时，才会命中，不支持location嵌套

~：表示使用正则定义的，区分大小写

~*：表示是使用正则定义的，不区分大小写

^~：表示该符号后面的字符是最佳匹配，采用该规则，不再进行后续的查找

@name：用于定义一个内部 Location 块，该块不能被外部 Client 所访问，只能被 NGINX 内部配置指令所访问，比如 try_files 或者error_page。其修饰的location不能嵌套到其它location,也不能再嵌套其它location，即只能是server这一层的

2.2 分配ngx_http_conf_ctx_t

2.2.1 ngx_http_block

其是在解析配置文件中的http分配

ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
ctx->main_conf = ngx_pcalloc(cf->pool,sizeof(void *) * ngx_http_max_module);
ctx->srv_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
ctx->loc_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);

2.2.2 ngx_http_core_location

其是在解析配置文件中的http块内location时分配

其中main_conf，srv_conf是延用上一层级的，loc_conf会再一次分配内存

ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
pctx = cf->ctx;
ctx->main_conf = pctx->main_conf;
ctx->srv_conf = pctx->srv_conf;
ctx->loc_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);

同时也会遍历模块调用create_loc_conf创建location的配置

for (i = 0; cf->cycle->modules[i]; i++) {if (cf->cycle->modules[i]->type != NGX_HTTP_MODULE) {continue;}module = cf->cycle->modules[i]->ctx;if (module->create_loc_conf) {ctx->loc_conf[cf->cycle->modules[i]->ctx_index] =module->create_loc_conf(cf);if (ctx->loc_conf[cf->cycle->modules[i]->ctx_index] == NULL) {return NGX_CONF_ERROR;}}}

设置http_core_module配置的loc_conf来源

clcf = ctx->loc_conf[ngx_http_core_module.ctx_index];
clcf->loc_conf = ctx->loc_conf;

2.3 ngx_http_add_location

构造ngx_http_location_queue_t，将当前ngx_http_core_loc_conf_t添加到上一层级ngx_http_core_loc_conf_t中的location队列中。如果是精确匹配，正则，有名或者是无名，构造的ngx_http_location_queue_t的exact来存放ngx_http_core_loc_conf_t配置，否则使用ngx_http_location_queue_t的inclusive来存放ngx_http_core_loc_conf_t配置

if (clcf->exact_match
#if (NGX_PCRE)|| clcf->regex
#endif|| clcf->named || clcf->noname){lq->exact = clcf;lq->inclusive = NULL;} else {lq->exact = NULL;lq->inclusive = clcf;}

将构造的队列添加到上一层级的队列中

ngx_queue_insert_tail(*locations, &lq->queue);

2.4 主配置中的server

在ngx_http_block中会分配main_conf

ctx->main_conf = ngx_pcalloc(cf->pool,sizeof(void *) * ngx_http_max_module);

在处理server时（ngx_http_core_server），当前层的ctx中的main_conf会延用上一层的main_conf

http_ctx = cf->ctx;
ctx->main_conf = http_ctx->main_conf;

将server放入cmcf->server中

cscf = ctx->srv_conf[ngx_http_core_module.ctx_index];
cscf->ctx = ctx;cmcf = ctx->main_conf[ngx_http_core_module.ctx_index];cscfp = ngx_array_push(&cmcf->servers);
if (cscfp == NULL) {return NGX_CONF_ERROR;
}*cscfp = cscf;

2.5 初始化location(ngx_http_init_locations)

处理ngx_http_core_srv_conf_t中的有名location（named_locations)以及ngx_http_core_loc_conf_t中的正则location(regex_locations),在作割裂之前，会先对ngx_http_core_loc_conf_t中的locations排序，使用的排序规则为ngx_http_cmp_locations，即按照exact(sorted) -> inclusive(sorted) -> regex -> named -> noname的原则进行排序，经过处理后，原先的location队列就只剩下经过排序后的exact以及inclusive类型的location了。这两类location对应配置文件中的定义，就是不含修饰符的location,带有=和^~前缀的location。

2.6 将queue转为list(ngx_http_create_locations_list)

将locations queue变成locations list

2.7 创建location的二叉查找树(ngx_http_create_locations_tree)

创建精确匹配location的二叉查找树，使用ngx_queue_middle(其时间度为O(n)）得到location_list中的中间位置，如果location_list的元素个数为奇数，则是中间的一个，否则是后半部分的第一个。

ngx_queue_t *
ngx_queue_middle(ngx_queue_t *queue)
{ngx_queue_t  *middle, *next;middle = ngx_queue_head(queue);if (middle == ngx_queue_last(queue)) {return middle;}next = ngx_queue_head(queue);for ( ;; ) {middle = ngx_queue_next(middle);next = ngx_queue_next(next);if (next == ngx_queue_last(queue)) {return middle;}next = ngx_queue_next(next);if (next == ngx_queue_last(queue)) {return middle;}}
}

使用递归来构建二叉查找树

/** to keep cache locality for left leaf nodes, allocate nodes in following* order: node, left subtree, right subtree, inclusive subtree*/static ngx_http_location_tree_node_t *
ngx_http_create_locations_tree(ngx_conf_t *cf, ngx_queue_t *locations,size_t prefix)
{size_t                          len;ngx_queue_t                    *q, tail;ngx_http_location_queue_t      *lq;ngx_http_location_tree_node_t  *node;q = ngx_queue_middle(locations);lq = (ngx_http_location_queue_t *) q;len = lq->name->len - prefix;node = ngx_palloc(cf->pool,offsetof(ngx_http_location_tree_node_t, name) + len);if (node == NULL) {return NULL;}node->left = NULL;node->right = NULL;node->tree = NULL;node->exact = lq->exact;node->inclusive = lq->inclusive;node->auto_redirect = (u_char) ((lq->exact && lq->exact->auto_redirect)|| (lq->inclusive && lq->inclusive->auto_redirect));node->len = (u_short) len;ngx_memcpy(node->name, &lq->name->data[prefix], len);ngx_queue_split(locations, q, &tail);if (ngx_queue_empty(locations)) {/** ngx_queue_split() insures that if left part is empty,* then right one is empty too*/goto inclusive;}node->left = ngx_http_create_locations_tree(cf, locations, prefix);if (node->left == NULL) {return NULL;}ngx_queue_remove(q);if (ngx_queue_empty(&tail)) {goto inclusive;}node->right = ngx_http_create_locations_tree(cf, &tail, prefix);if (node->right == NULL) {return NULL;}inclusive:if (ngx_queue_empty(&lq->list)) {return node;}node->tree = ngx_http_create_locations_tree(cf, &lq->list, prefix + len);if (node->tree == NULL) {return NULL;}return node;
}

2.8 http的处理阶段

包含11个阶段

2.9 阶段处理器的初始化

ngx_http_init_phases初始化以下阶段的handlers

• NGX_HTTP_POST_READ_PHASE

• NGX_HTTP_SERVER_REWRITE_PHASE

• NGX_HTTP_REWRITE_PHASE

• NGX_HTTP_PREACCESS_PHASE

• NGX_HTTP_ACCESS_PHASE

• NGX_HTTP_PRECONTENT_PHASE

• NGX_HTTP_CONTENT_PHASE

• NGX_HTTP_LOG_PHASE

static ngx_int_t
ngx_http_init_phases(ngx_conf_t *cf, ngx_http_core_main_conf_t *cmcf)
{if (ngx_array_init(&cmcf->phases[NGX_HTTP_POST_READ_PHASE].handlers,cf->pool, 1, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_SERVER_REWRITE_PHASE].handlers,cf->pool, 1, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_REWRITE_PHASE].handlers,cf->pool, 1, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers,cf->pool, 1, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_ACCESS_PHASE].handlers,cf->pool, 2, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_PRECONTENT_PHASE].handlers,cf->pool, 2, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers,cf->pool, 4, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}if (ngx_array_init(&cmcf->phases[NGX_HTTP_LOG_PHASE].handlers,cf->pool, 1, sizeof(ngx_http_handler_pt))!= NGX_OK){return NGX_ERROR;}return NGX_OK;
}

2.10 配置后置处理（postconfiguration）

遍历调用http模块的postconfiguration，用来注册阶段的handler

for (m = 0; cf->cycle->modules[m]; m++) {if (cf->cycle->modules[m]->type != NGX_HTTP_MODULE) {continue;}module = cf->cycle->modules[m]->ctx;if (module->postconfiguration) {if (module->postconfiguration(cf) != NGX_OK) {return NGX_CONF_ERROR;}}}

2.11 阶段引擎handler的初始化

将各个不同阶段的handler汇聚成一个处理链表

static ngx_int_t
ngx_http_init_phase_handlers(ngx_conf_t *cf, ngx_http_core_main_conf_t *cmcf)
{ngx_int_t                   j;ngx_uint_t                  i, n;ngx_uint_t                  find_config_index, use_rewrite, use_access;ngx_http_handler_pt        *h;ngx_http_phase_handler_t   *ph;ngx_http_phase_handler_pt   checker;cmcf->phase_engine.server_rewrite_index = (ngx_uint_t) -1;cmcf->phase_engine.location_rewrite_index = (ngx_uint_t) -1;find_config_index = 0;use_rewrite = cmcf->phases[NGX_HTTP_REWRITE_PHASE].handlers.nelts ? 1 : 0;use_access = cmcf->phases[NGX_HTTP_ACCESS_PHASE].handlers.nelts ? 1 : 0;n = 1                  /* find config phase */+ use_rewrite      /* post rewrite phase */+ use_access;      /* post access phase */for (i = 0; i < NGX_HTTP_LOG_PHASE; i++) {n += cmcf->phases[i].handlers.nelts;}ph = ngx_pcalloc(cf->pool,n * sizeof(ngx_http_phase_handler_t) + sizeof(void *));if (ph == NULL) {return NGX_ERROR;}cmcf->phase_engine.handlers = ph;n = 0;for (i = 0; i < NGX_HTTP_LOG_PHASE; i++) {h = cmcf->phases[i].handlers.elts;switch (i) {case NGX_HTTP_SERVER_REWRITE_PHASE:if (cmcf->phase_engine.server_rewrite_index == (ngx_uint_t) -1) {cmcf->phase_engine.server_rewrite_index = n;}checker = ngx_http_core_rewrite_phase;break;case NGX_HTTP_FIND_CONFIG_PHASE:find_config_index = n;ph->checker = ngx_http_core_find_config_phase;n++;ph++;continue;case NGX_HTTP_REWRITE_PHASE:if (cmcf->phase_engine.location_rewrite_index == (ngx_uint_t) -1) {cmcf->phase_engine.location_rewrite_index = n;}checker = ngx_http_core_rewrite_phase;break;case NGX_HTTP_POST_REWRITE_PHASE:if (use_rewrite) {ph->checker = ngx_http_core_post_rewrite_phase;ph->next = find_config_index;n++;ph++;}continue;case NGX_HTTP_ACCESS_PHASE:checker = ngx_http_core_access_phase;n++;break;case NGX_HTTP_POST_ACCESS_PHASE:if (use_access) {ph->checker = ngx_http_core_post_access_phase;ph->next = n;ph++;}continue;case NGX_HTTP_CONTENT_PHASE:checker = ngx_http_core_content_phase;break;default:checker = ngx_http_core_generic_phase;}n += cmcf->phases[i].handlers.nelts;for (j = cmcf->phases[i].handlers.nelts - 1; j >= 0; j--) {ph->checker = checker;ph->handler = h[j];ph->next = n;ph++;}}return NGX_OK;
}

2.12 初始监听端口， 服务以及监听回调

ngx_http_optimize_servers中的ngx_http_add_listening会设置端口的回调

ls->handler = ngx_http_init_connection;

3. 运行时的处理

3.1 accept事件处理

在处理accept连接事件时，会调用ngx_listening_t的回调handler函数ngx_http_init_connection

对于新分配的连接，如果读事件的ready为1，即iocp或者延时的accept事件，在有使用accept锁情况 下，将事件放入posted_events队列中，否则直接调用事件的回调handler

if (rev->ready) {/* the deferred accept(), iocp */if (ngx_use_accept_mutex) {ngx_post_event(rev, &ngx_posted_events);return;}rev->handler(rev);return;
}

如果读事件的ready不为1，则将事件加入定时器的红黑树中。定时器超时后，就会调用它的 handler ngx_http_wait_request_handler 函数。

ngx_add_timer(rev, cscf->client_header_timeout);

将连接设置为可重用，因为该连接上还没有请求到来，所以当连接池中的连接不够用时，就可以重用这个连接。将当前connection添加可重用的连接队列中，同时可重用连接数加1

ngx_reusable_connection(c, 1);void
ngx_reusable_connection(ngx_connection_t *c, ngx_uint_t reusable)
{ngx_log_debug1(NGX_LOG_DEBUG_CORE, c->log, 0,"reusable connection: %ui", reusable);if (c->reusable) {ngx_queue_remove(&c->queue);ngx_cycle->reusable_connections_n--;#if (NGX_STAT_STUB)(void) ngx_atomic_fetch_add(ngx_stat_waiting, -1);
#endif}c->reusable = reusable;if (reusable) {/* need cast as ngx_cycle is volatile */ngx_queue_insert_head((ngx_queue_t *) &ngx_cycle->reusable_connections_queue, &c->queue);ngx_cycle->reusable_connections_n++;#if (NGX_STAT_STUB)(void) ngx_atomic_fetch_add(ngx_stat_waiting, 1);
#endif}
}

ngx_handle_read_event将分配连接的事件添加到事件驱动模块中

ngx_int_t
ngx_handle_read_event(ngx_event_t *rev, ngx_uint_t flags)
{if (ngx_event_flags & NGX_USE_CLEAR_EVENT) {/* kqueue, epoll */if (!rev->active && !rev->ready) {if (ngx_add_event(rev, NGX_READ_EVENT, NGX_CLEAR_EVENT)== NGX_ERROR){return NGX_ERROR;}}return NGX_OK;} else if (ngx_event_flags & NGX_USE_LEVEL_EVENT) {/* select, poll, /dev/poll */if (!rev->active && !rev->ready) {if (ngx_add_event(rev, NGX_READ_EVENT, NGX_LEVEL_EVENT)== NGX_ERROR){return NGX_ERROR;}return NGX_OK;}if (rev->active && (rev->ready || (flags & NGX_CLOSE_EVENT))) {if (ngx_del_event(rev, NGX_READ_EVENT, NGX_LEVEL_EVENT | flags)== NGX_ERROR){return NGX_ERROR;}return NGX_OK;}} else if (ngx_event_flags & NGX_USE_EVENTPORT_EVENT) {/* event ports */if (!rev->active && !rev->ready) {if (ngx_add_event(rev, NGX_READ_EVENT, 0) == NGX_ERROR) {return NGX_ERROR;}return NGX_OK;}if (rev->oneshot && rev->ready) {if (ngx_del_event(rev, NGX_READ_EVENT, 0) == NGX_ERROR) {return NGX_ERROR;}return NGX_OK;}}/* iocp */return NGX_OK;
}

3.2 首次可读事件处理

是通过ngx_http_wait_request_handler来处理

首先从网络上读取数据到连接中的buffer

ngx_connection_t          *c;
ngx_buf_t                 *b;
c = rev->data;
b = c->buffer;
if (b == NULL) {b = ngx_create_temp_buf(c->pool, size);if (b == NULL) {ngx_http_close_connection(c);return;}c->buffer = b;} else if (b->start == NULL) {b->start = ngx_palloc(c->pool, size);if (b->start == NULL) {ngx_http_close_connection(c);return;}b->pos = b->start;b->last = b->start;b->end = b->last + size;
}
n = c->recv(c, b->last, size);
b->last += n;

在可重用连接中删除当前连接

ngx_reusable_connection(c, 0);

创建http_request,在创建请求中，会将上面读取的缓冲区放在ngx_http_request_t中的header_in用于处理请求头

c->data = ngx_http_create_request(c);

处理请求头，同时将当前连接读事件的回调函数设置为ngx_http_process_request_line，用于处理单次接收的数据不完整

rev->handler = ngx_http_process_request_line;
ngx_http_process_request_line(rev);