### Nginx 启动过程
Nginx 的启动初始化由 main 函数完成，该函数是整个 Nginx 的入口，该函数完成 Nginx 启动初始化任务，也是所有功能模块的入口。Nginx 的初始化工作主要是一个类型为 ngx_cycle_t 类型的全局变量。main 函数定义在文件：[src/core/nginx.c](http://lxr.nginx.org/source/src/core/nginx.c)
Nginx 启动过程如下。
- 调用 ngx_get_options() 解析命令参数；
- 显示版本号与帮助信息；
- 调用 ngx_time_init() 初始化并更新时间；
- 调用 ngx_log_init() 初始化日志；
- 创建全局变量 init_cycle 的内存池 pool；
- 调用 ngx_save_argv() 保存命令行参数至全局变量ngx_os_argv、ngx_argc、ngx_argv 中；
- 调用 ngx_process_options() 初始化 init_cycle 的 prefix, conf_prefix, conf_file, conf_param 等字段；
- 调用 ngx_os_init() 初始化系统相关变量；
- 调用 ngx_crc32_table_init() 初始化CRC表；
- 调用 ngx_add_inherited_sockets() 继承 sockets；
- 通过环境变量 NGINX 完成 socket 的继承，将其保存在全局变量 init_cycle 的 listening 数组中；
- 初始化每个模块 module 的index，并计算 ngx_max_module；
- 调用 ngx_init_cycle() 进行初始化全局变量 init_cycle，这个步骤非常重要；
- 调用 ngx_signal_process() 处理进程信号；
- 调用 ngx_init_signals() 注册相关信号；
- 若无继承 sockets，则调用 ngx_daemon() 创建守护进程，并设置其标志；
- 调用 ngx_create_pidfile() 创建进程 ID 记录文件；
- 进入进程处理：
- 单进程工作模式；
- 多进程工作模式，即 master-worker 多进程工作模式；
~~~
int ngx_cdecl
main(int argc, char *const *argv)
{
ngx_int_t i;
ngx_log_t *log;
ngx_cycle_t *cycle, init_cycle;
ngx_core_conf_t *ccf;
ngx_debug_init();
if (ngx_strerror_init() != NGX_OK) {
return 1;
}
/* 解析命令行参数 */
if (ngx_get_options(argc, argv) != NGX_OK) {
return 1;
}
/* 显示版本号与帮助信息 */
if (ngx_show_version) {
ngx_write_stderr("nginx version: " NGINX_VER NGX_LINEFEED);
if (ngx_show_help) {
ngx_write_stderr(
"Usage: nginx [-?hvVtq] [-s signal] [-c filename] "
"[-p prefix] [-g directives]" NGX_LINEFEED
NGX_LINEFEED
"Options:" NGX_LINEFEED
" -?,-h : this help" NGX_LINEFEED
" -v : show version and exit" NGX_LINEFEED
" -V : show version and configure options then exit"
NGX_LINEFEED
" -t : test configuration and exit" NGX_LINEFEED
" -q : suppress non-error messages "
"during configuration testing" NGX_LINEFEED
" -s signal : send signal to a master process: "
"stop, quit, reopen, reload" NGX_LINEFEED
#ifdef NGX_PREFIX
" -p prefix : set prefix path (default: "
NGX_PREFIX ")" NGX_LINEFEED
#else
" -p prefix : set prefix path (default: NONE)" NGX_LINEFEED
#endif
" -c filename : set configuration file (default: "
NGX_CONF_PATH ")" NGX_LINEFEED
" -g directives : set global directives out of configuration "
"file" NGX_LINEFEED NGX_LINEFEED
);
}
if (ngx_show_configure) {
ngx_write_stderr(
#ifdef NGX_COMPILER
"built by " NGX_COMPILER NGX_LINEFEED
#endif
#if (NGX_SSL)
#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
"TLS SNI support enabled" NGX_LINEFEED
#else
"TLS SNI support disabled" NGX_LINEFEED
#endif
#endif
"configure arguments:" NGX_CONFIGURE NGX_LINEFEED);
}
if (!ngx_test_config) {
return 0;
}
}
/* TODO */ ngx_max_sockets = -1;
/* 初始化并更新时间 */
ngx_time_init();
#if (NGX_PCRE)
ngx_regex_init();
#endif
ngx_pid = ngx_getpid();
/* 初始化日志信息 */
log = ngx_log_init(ngx_prefix);
if (log == NULL) {
return 1;
}
/* STUB */
#if (NGX_OPENSSL)
ngx_ssl_init(log);
#endif
/*
* init_cycle->log is required for signal handlers and
* ngx_process_options()
*/
/* 全局变量init_cycle清零，并创建改变量的内存池pool */
ngx_memzero(&init_cycle, sizeof(ngx_cycle_t));
init_cycle.log = log;
ngx_cycle = &init_cycle;
init_cycle.pool = ngx_create_pool(1024, log);
if (init_cycle.pool == NULL) {
return 1;
}
/* 保存命令行参数至全局变量ngx_os_argv、ngx_argc、ngx_argv */
if (ngx_save_argv(&init_cycle, argc, argv) != NGX_OK) {
return 1;
}
/* 初始化全局变量init_cycle中的成员：prefix、conf_prefix、conf_file、conf_param 等字段 */
if (ngx_process_options(&init_cycle) != NGX_OK) {
return 1;
}
/* 初始化系统相关变量，如：内存页面大小ngx_pagesize、最大连接数ngx_max_sockets等 */
if (ngx_os_init(log) != NGX_OK) {
return 1;
}
/*
* ngx_crc32_table_init() requires ngx_cacheline_size set in ngx_os_init()
*/
/* 初始化 CRC 表（循环冗余校验表） */
if (ngx_crc32_table_init() != NGX_OK) {
return 1;
}
/* 通过环境变量NGINX完成socket的继承，将其保存在全局变量init_cycle的listening数组中 */
if (ngx_add_inherited_sockets(&init_cycle) != NGX_OK) {
return 1;
}
/* 初始化每个模块module的index，并计算ngx_max_module */
ngx_max_module = 0;
for (i = 0; ngx_modules[i]; i++) {
ngx_modules[i]->index = ngx_max_module++;
}
/* 初始化全局变量init_cycle ，这里很重要 */
cycle = ngx_init_cycle(&init_cycle);
if (cycle == NULL) {
if (ngx_test_config) {
ngx_log_stderr(0, "configuration file %s test failed",
init_cycle.conf_file.data);
}
return 1;
}
if (ngx_test_config) {
if (!ngx_quiet_mode) {
ngx_log_stderr(0, "configuration file %s test is successful",
cycle->conf_file.data);
}
return 0;
}
/* 信号处理 */
if (ngx_signal) {
return ngx_signal_process(cycle, ngx_signal);
}
ngx_os_status(cycle->log);
ngx_cycle = cycle;
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
if (ccf->master && ngx_process == NGX_PROCESS_SINGLE) {
ngx_process = NGX_PROCESS_MASTER;
}
#if !(NGX_WIN32)
/* 初始化信号，注册相关信号 */
if (ngx_init_signals(cycle->log) != NGX_OK) {
return 1;
}
/* 若无socket继承，则创建守护进程，并设置守护进程标志 */
if (!ngx_inherited && ccf->daemon) {
if (ngx_daemon(cycle->log) != NGX_OK) {
return 1;
}
ngx_daemonized = 1;
}
if (ngx_inherited) {
ngx_daemonized = 1;
}
#endif
/* 记录进程ID */
if (ngx_create_pidfile(&ccf->pid, cycle->log) != NGX_OK) {
return 1;
}
if (ngx_log_redirect_stderr(cycle) != NGX_OK) {
return 1;
}
if (log->file->fd != ngx_stderr) {
if (ngx_close_file(log->file->fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
ngx_close_file_n " built-in log failed");
}
}
ngx_use_stderr = 0;
/* 进入进程处理 */
if (ngx_process == NGX_PROCESS_SINGLE) {
/* 单进程工作模式 */
ngx_single_process_cycle(cycle);
} else {
/* master-worker 多进程模式工作 */
ngx_master_process_cycle(cycle);
}
return 0;
}
~~~
### ngx_cycle_t 变量初始化
### ngx_cycle_t 结构体初始化
在初始化过程中，ngx_cycle_t 类型的全局变量最为重要，该类型结构定义如下：[src/core/ngx_cycle.h](http://lxr.nginx.org/source/src/core/ngx_cycle.h)
~~~
/* ngx_cycle_t 全局变量数据结构 */
struct ngx_cycle_s {
/*
* 保存所有模块配置项的结构体指针，该数组每个成员又是一个指针，
* 这个指针又指向存储指针的数组
*/
void **conf_ctx; /* 所有模块配置上下文的数组 */
ngx_pool_t *pool; /* 内存池 */
ngx_log_t *log; /* 日志 */
ngx_log_t new_log;
ngx_uint_t log_use_stderr; /* unsigned log_use_stderr:1; */
ngx_connection_t **files; /* 连接文件 */
ngx_connection_t *free_connections; /* 空闲连接 */
ngx_uint_t free_connection_n;/* 空闲连接的个数 */
/* 可再利用的连接队列 */
ngx_queue_t reusable_connections_queue;
ngx_array_t listening; /* 监听数组 */
ngx_array_t paths; /* 路径数组 */
ngx_list_t open_files; /* 已打开文件的链表 */
ngx_list_t shared_memory;/* 共享内存链表 */
ngx_uint_t connection_n; /* 已连接个数 */
ngx_uint_t files_n; /* 已打开文件的个数 */
ngx_connection_t *connections; /* 连接 */
ngx_event_t *read_events; /* 读事件 */
ngx_event_t *write_events; /* 写事件 */
/* old 的 ngx_cycle_t 对象，用于引用前一个 ngx_cycle_t 对象的成员 */
ngx_cycle_t *old_cycle;
ngx_str_t conf_file; /* nginx 配置文件 */
ngx_str_t conf_param; /* nginx 处理配置文件时需要特殊处理的，在命令行携带的参数 */
ngx_str_t conf_prefix; /* nginx 配置文件的路径 */
ngx_str_t prefix; /* nginx 安装路径 */
ngx_str_t lock_file; /* 加锁文件 */
ngx_str_t hostname; /* 主机名 */
};
~~~
### ngx_init_cycle() 初始化函数
该结构的初始化是通过函数 ngx_init_cycle() 完成的，该函数定义如下：[src/core/ngx_cycle.c](http://lxr.nginx.org/source/src/core/ngx_cycle.c)
ngx_cycle_t 结构全局变量初始化过程如下：
- 更新时区与时间；
- 创建内存池；
- 分配 ngx_cycle_t 结构体内存，创建该结构的变量 cycle 并初始化；
- 遍历所有 core模块，并调用该模块的 create_conf() 函数；
- 配置文件解析；
- 遍历所有core模块，并调用core模块的init_conf()函数；
- 遍历 open_files 链表中的每一个文件并打开；
- 创建新的共享内存并初始化；
- 遍历 listening 数组并打开所有侦听；
- 提交新的 cycle 配置，并调用所有模块的init_module；
- 关闭或删除不被使用的在 old_cycle 中的资源：
- 释放多余的共享内存；
- 关闭多余的侦听 sockets；
- 关闭多余的打开文件；
~~~
ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
void *rv;
char **senv, **env;
ngx_uint_t i, n;
ngx_log_t *log;
ngx_time_t *tp;
ngx_conf_t conf;
ngx_pool_t *pool;
ngx_cycle_t *cycle, **old;
ngx_shm_zone_t *shm_zone, *oshm_zone;
ngx_list_part_t *part, *opart;
ngx_open_file_t *file;
ngx_listening_t *ls, *nls;
ngx_core_conf_t *ccf, *old_ccf;
ngx_core_module_t *module;
char hostname[NGX_MAXHOSTNAMELEN];
/* 更新时区 */
ngx_timezone_update();
/* force localtime update with a new timezone */
tp = ngx_timeofday();
tp->sec = 0;
/* 更新时间 */
ngx_time_update();
/* 创建内存池pool，并初始化 */
log = old_cycle->log;
pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
if (pool == NULL) {
return NULL;
}
pool->log = log;
/* 创建ngx_cycle_t 结构体变量 */
cycle = ngx_pcalloc(pool, sizeof(ngx_cycle_t));
if (cycle == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
/* 初始化ngx_cycle_t 结构体变量 cycle */
cycle->pool = pool;
cycle->log = log;
cycle->old_cycle = old_cycle;
cycle->conf_prefix.len = old_cycle->conf_prefix.len;
cycle->conf_prefix.data = ngx_pstrdup(pool, &old_cycle->conf_prefix);
if (cycle->conf_prefix.data == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->prefix.len = old_cycle->prefix.len;
cycle->prefix.data = ngx_pstrdup(pool, &old_cycle->prefix);
if (cycle->prefix.data == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->conf_file.len = old_cycle->conf_file.len;
cycle->conf_file.data = ngx_pnalloc(pool, old_cycle->conf_file.len + 1);
if (cycle->conf_file.data == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
ngx_cpystrn(cycle->conf_file.data, old_cycle->conf_file.data,
old_cycle->conf_file.len + 1);
cycle->conf_param.len = old_cycle->conf_param.len;
cycle->conf_param.data = ngx_pstrdup(pool, &old_cycle->conf_param);
if (cycle->conf_param.data == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
n = old_cycle->paths.nelts ? old_cycle->paths.nelts : 10;
cycle->paths.elts = ngx_pcalloc(pool, n * sizeof(ngx_path_t *));
if (cycle->paths.elts == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->paths.nelts = 0;
cycle->paths.size = sizeof(ngx_path_t *);
cycle->paths.nalloc = n;
cycle->paths.pool = pool;
if (old_cycle->open_files.part.nelts) {
n = old_cycle->open_files.part.nelts;
for (part = old_cycle->open_files.part.next; part; part = part->next) {
n += part->nelts;
}
} else {
n = 20;
}
if (ngx_list_init(&cycle->open_files, pool, n, sizeof(ngx_open_file_t))
!= NGX_OK)
{
ngx_destroy_pool(pool);
return NULL;
}
if (old_cycle->shared_memory.part.nelts) {
n = old_cycle->shared_memory.part.nelts;
for (part = old_cycle->shared_memory.part.next; part; part = part->next)
{
n += part->nelts;
}
} else {
n = 1;
}
if (ngx_list_init(&cycle->shared_memory, pool, n, sizeof(ngx_shm_zone_t))
!= NGX_OK)
{
ngx_destroy_pool(pool);
return NULL;
}
n = old_cycle->listening.nelts ? old_cycle->listening.nelts : 10;
cycle->listening.elts = ngx_pcalloc(pool, n * sizeof(ngx_listening_t));
if (cycle->listening.elts == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->listening.nelts = 0;
cycle->listening.size = sizeof(ngx_listening_t);
cycle->listening.nalloc = n;
cycle->listening.pool = pool;
ngx_queue_init(&cycle->reusable_connections_queue);
cycle->conf_ctx = ngx_pcalloc(pool, ngx_max_module * sizeof(void *));
if (cycle->conf_ctx == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
if (gethostname(hostname, NGX_MAXHOSTNAMELEN) == -1) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "gethostname() failed");
ngx_destroy_pool(pool);
return NULL;
}
/* on Linux gethostname() silently truncates name that does not fit */
hostname[NGX_MAXHOSTNAMELEN - 1] = '\0';
cycle->hostname.len = ngx_strlen(hostname);
cycle->hostname.data = ngx_pnalloc(pool, cycle->hostname.len);
if (cycle->hostname.data == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
ngx_strlow(cycle->hostname.data, (u_char *) hostname, cycle->hostname.len);
/* 遍历所有core模块 */
for (i = 0; ngx_modules[i]; i++) {
if (ngx_modules[i]->type != NGX_CORE_MODULE) {
continue;
}
module = ngx_modules[i]->ctx;
/* 若有core模块实现了create_conf()，则就调用它，并返回地址 */
if (module->create_conf) {
rv = module->create_conf(cycle);
if (rv == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->conf_ctx[ngx_modules[i]->index] = rv;
}
}
senv = environ;
ngx_memzero(&conf, sizeof(ngx_conf_t));
/* STUB: init array ? */
conf.args = ngx_array_create(pool, 10, sizeof(ngx_str_t));
if (conf.args == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
conf.temp_pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
if (conf.temp_pool == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
conf.ctx = cycle->conf_ctx;
conf.cycle = cycle;
conf.pool = pool;
conf.log = log;
conf.module_type = NGX_CORE_MODULE;
conf.cmd_type = NGX_MAIN_CONF;
#if 0
log->log_level = NGX_LOG_DEBUG_ALL;
#endif
/* 配置文件解析 */
if (ngx_conf_param(&conf) != NGX_CONF_OK) {
environ = senv;
ngx_destroy_cycle_pools(&conf);
return NULL;
}
if (ngx_conf_parse(&conf, &cycle->conf_file) != NGX_CONF_OK) {
environ = senv;
ngx_destroy_cycle_pools(&conf);
return NULL;
}
if (ngx_test_config && !ngx_quiet_mode) {
ngx_log_stderr(0, "the configuration file %s syntax is ok",
cycle->conf_file.data);
}
/* 遍历所有core模块，并调用core模块的init_conf()函数 */
for (i = 0; ngx_modules[i]; i++) {
if (ngx_modules[i]->type != NGX_CORE_MODULE) {
continue;
}
module = ngx_modules[i]->ctx;
if (module->init_conf) {
if (module->init_conf(cycle, cycle->conf_ctx[ngx_modules[i]->index])
== NGX_CONF_ERROR)
{
environ = senv;
ngx_destroy_cycle_pools(&conf);
return NULL;
}
}
}
if (ngx_process == NGX_PROCESS_SIGNALLER) {
return cycle;
}
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
if (ngx_test_config) {
if (ngx_create_pidfile(&ccf->pid, log) != NGX_OK) {
goto failed;
}
} else if (!ngx_is_init_cycle(old_cycle)) {
/*
* we do not create the pid file in the first ngx_init_cycle() call
* because we need to write the demonized process pid
*/
old_ccf = (ngx_core_conf_t *) ngx_get_conf(old_cycle->conf_ctx,
ngx_core_module);
if (ccf->pid.len != old_ccf->pid.len
|| ngx_strcmp(ccf->pid.data, old_ccf->pid.data) != 0)
{
/* new pid file name */
if (ngx_create_pidfile(&ccf->pid, log) != NGX_OK) {
goto failed;
}
ngx_delete_pidfile(old_cycle);
}
}
if (ngx_test_lockfile(cycle->lock_file.data, log) != NGX_OK) {
goto failed;
}
/* 初始化paths 数组 */
if (ngx_create_paths(cycle, ccf->user) != NGX_OK) {
goto failed;
}
if (ngx_log_open_default(cycle) != NGX_OK) {
goto failed;
}
/* open the new files */
part = &cycle->open_files.part;
file = part->elts;
/* 遍历open_file 链表中每一个文件，并打开该文件 */
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
file = part->elts;
i = 0;
}
if (file[i].name.len == 0) {
continue;
}
file[i].fd = ngx_open_file(file[i].name.data,
NGX_FILE_APPEND,
NGX_FILE_CREATE_OR_OPEN,
NGX_FILE_DEFAULT_ACCESS);
ngx_log_debug3(NGX_LOG_DEBUG_CORE, log, 0,
"log: %p %d \"%s\"",
&file[i], file[i].fd, file[i].name.data);
if (file[i].fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
ngx_open_file_n " \"%s\" failed",
file[i].name.data);
goto failed;
}
#if !(NGX_WIN32)
if (fcntl(file[i].fd, F_SETFD, FD_CLOEXEC) == -1) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
"fcntl(FD_CLOEXEC) \"%s\" failed",
file[i].name.data);
goto failed;
}
#endif
}
cycle->log = &cycle->new_log;
pool->log = &cycle->new_log;
/* 创建共享内存并初始化 */
/* create shared memory */
part = &cycle->shared_memory.part;
shm_zone = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
shm_zone = part->elts;
i = 0;
}
if (shm_zone[i].shm.size == 0) {
ngx_log_error(NGX_LOG_EMERG, log, 0,
"zero size shared memory zone \"%V\"",
&shm_zone[i].shm.name);
goto failed;
}
shm_zone[i].shm.log = cycle->log;
opart = &old_cycle->shared_memory.part;
oshm_zone = opart->elts;
/*
* 新的共享内存与旧的共享内存链表进行比较，
* 相同则保留，不同创建新的，旧的被释放
*/
for (n = 0; /* void */ ; n++) {
if (n >= opart->nelts) {
if (opart->next == NULL) {
break;
}
opart = opart->next;
oshm_zone = opart->elts;
n = 0;
}
if (shm_zone[i].shm.name.len != oshm_zone[n].shm.name.len) {
continue;
}
if (ngx_strncmp(shm_zone[i].shm.name.data,
oshm_zone[n].shm.name.data,
shm_zone[i].shm.name.len)
!= 0)
{
continue;
}
if (shm_zone[i].tag == oshm_zone[n].tag
&& shm_zone[i].shm.size == oshm_zone[n].shm.size)
{
shm_zone[i].shm.addr = oshm_zone[n].shm.addr;
if (shm_zone[i].init(&shm_zone[i], oshm_zone[n].data)
!= NGX_OK)
{
goto failed;
}
goto shm_zone_found;
}
ngx_shm_free(&oshm_zone[n].shm);
break;
}
if (ngx_shm_alloc(&shm_zone[i].shm) != NGX_OK) {
goto failed;
}
if (ngx_init_zone_pool(cycle, &shm_zone[i]) != NGX_OK) {
goto failed;
}
if (shm_zone[i].init(&shm_zone[i], NULL) != NGX_OK) {
goto failed;
}
shm_zone_found:
continue;
}
/* 遍历listening 数组，并打开所有监听 */
/* handle the listening sockets */
if (old_cycle->listening.nelts) {
ls = old_cycle->listening.elts;
for (i = 0; i < old_cycle->listening.nelts; i++) {
ls[i].remain = 0;
}
nls = cycle->listening.elts;
for (n = 0; n < cycle->listening.nelts; n++) {
for (i = 0; i < old_cycle->listening.nelts; i++) {
if (ls[i].ignore) {
continue;
}
if (ngx_cmp_sockaddr(nls[n].sockaddr, nls[n].socklen,
ls[i].sockaddr, ls[i].socklen, 1)
== NGX_OK)
{
nls[n].fd = ls[i].fd;
nls[n].previous = &ls[i];
ls[i].remain = 1;
if (ls[i].backlog != nls[n].backlog) {
nls[n].listen = 1;
}
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
/*
* FreeBSD, except the most recent versions,
* could not remove accept filter
*/
nls[n].deferred_accept = ls[i].deferred_accept;
if (ls[i].accept_filter && nls[n].accept_filter) {
if (ngx_strcmp(ls[i].accept_filter,
nls[n].accept_filter)
!= 0)
{
nls[n].delete_deferred = 1;
nls[n].add_deferred = 1;
}
} else if (ls[i].accept_filter) {
nls[n].delete_deferred = 1;
} else if (nls[n].accept_filter) {
nls[n].add_deferred = 1;
}
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
if (ls[i].deferred_accept && !nls[n].deferred_accept) {
nls[n].delete_deferred = 1;
} else if (ls[i].deferred_accept != nls[n].deferred_accept)
{
nls[n].add_deferred = 1;
}
#endif
break;
}
}
if (nls[n].fd == (ngx_socket_t) -1) {
nls[n].open = 1;
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
if (nls[n].accept_filter) {
nls[n].add_deferred = 1;
}
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
if (nls[n].deferred_accept) {
nls[n].add_deferred = 1;
}
#endif
}
}
} else {
ls = cycle->listening.elts;
for (i = 0; i < cycle->listening.nelts; i++) {
ls[i].open = 1;
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
if (ls[i].accept_filter) {
ls[i].add_deferred = 1;
}
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
if (ls[i].deferred_accept) {
ls[i].add_deferred = 1;
}
#endif
}
}
/* 打开监听 */
if (ngx_open_listening_sockets(cycle) != NGX_OK) {
goto failed;
}
if (!ngx_test_config) {
ngx_configure_listening_sockets(cycle);
}
/* 提交新的cycle配置，并调用所有模块的 init_module */
/* commit the new cycle configuration */
if (!ngx_use_stderr) {
(void) ngx_log_redirect_stderr(cycle);
}
pool->log = cycle->log;
for (i = 0; ngx_modules[i]; i++) {
if (ngx_modules[i]->init_module) {
if (ngx_modules[i]->init_module(cycle) != NGX_OK) {
/* fatal */
exit(1);
}
}
}
/* 关闭或删除不被使用的old_cycle 资源 */
/* close and delete stuff that lefts from an old cycle */
/* free the unnecessary shared memory */
opart = &old_cycle->shared_memory.part;
oshm_zone = opart->elts;
for (i = 0; /* void */ ; i++) {
if (i >= opart->nelts) {
if (opart->next == NULL) {
goto old_shm_zone_done;
}
opart = opart->next;
oshm_zone = opart->elts;
i = 0;
}
part = &cycle->shared_memory.part;
shm_zone = part->elts;
for (n = 0; /* void */ ; n++) {
if (n >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
shm_zone = part->elts;
n = 0;
}
if (oshm_zone[i].shm.name.len == shm_zone[n].shm.name.len
&& ngx_strncmp(oshm_zone[i].shm.name.data,
shm_zone[n].shm.name.data,
oshm_zone[i].shm.name.len)
== 0)
{
goto live_shm_zone;
}
}
ngx_shm_free(&oshm_zone[i].shm);
live_shm_zone:
continue;
}
old_shm_zone_done:
/* close the unnecessary listening sockets */
ls = old_cycle->listening.elts;
for (i = 0; i < old_cycle->listening.nelts; i++) {
if (ls[i].remain || ls[i].fd == (ngx_socket_t) -1) {
continue;
}
if (ngx_close_socket(ls[i].fd) == -1) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
ngx_close_socket_n " listening socket on %V failed",
&ls[i].addr_text);
}
#if (NGX_HAVE_UNIX_DOMAIN)
if (ls[i].sockaddr->sa_family == AF_UNIX) {
u_char *name;
name = ls[i].addr_text.data + sizeof("unix:") - 1;
ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
"deleting socket %s", name);
if (ngx_delete_file(name) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,
ngx_delete_file_n " %s failed", name);
}
}
#endif
}
/* close the unnecessary open files */
part = &old_cycle->open_files.part;
file = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
file = part->elts;
i = 0;
}
if (file[i].fd == NGX_INVALID_FILE || file[i].fd == ngx_stderr) {
continue;
}
if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
}
ngx_destroy_pool(conf.temp_pool);
if (ngx_process == NGX_PROCESS_MASTER || ngx_is_init_cycle(old_cycle)) {
/*
* perl_destruct() frees environ, if it is not the same as it was at
* perl_construct() time, therefore we save the previous cycle
* environment before ngx_conf_parse() where it will be changed.
*/
env = environ;
environ = senv;
ngx_destroy_pool(old_cycle->pool);
cycle->old_cycle = NULL;
environ = env;
return cycle;
}
if (ngx_temp_pool == NULL) {
ngx_temp_pool = ngx_create_pool(128, cycle->log);
if (ngx_temp_pool == NULL) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
"could not create ngx_temp_pool");
exit(1);
}
n = 10;
ngx_old_cycles.elts = ngx_pcalloc(ngx_temp_pool,
n * sizeof(ngx_cycle_t *));
if (ngx_old_cycles.elts == NULL) {
exit(1);
}
ngx_old_cycles.nelts = 0;
ngx_old_cycles.size = sizeof(ngx_cycle_t *);
ngx_old_cycles.nalloc = n;
ngx_old_cycles.pool = ngx_temp_pool;
ngx_cleaner_event.handler = ngx_clean_old_cycles;
ngx_cleaner_event.log = cycle->log;
ngx_cleaner_event.data = &dumb;
dumb.fd = (ngx_socket_t) -1;
}
ngx_temp_pool->log = cycle->log;
old = ngx_array_push(&ngx_old_cycles);
if (old == NULL) {
exit(1);
}
*old = old_cycle;
if (!ngx_cleaner_event.timer_set) {
ngx_add_timer(&ngx_cleaner_event, 30000);
ngx_cleaner_event.timer_set = 1;
}
return cycle;
failed:
if (!ngx_is_init_cycle(old_cycle)) {
old_ccf = (ngx_core_conf_t *) ngx_get_conf(old_cycle->conf_ctx,
ngx_core_module);
if (old_ccf->environment) {
environ = old_ccf->environment;
}
}
/* rollback the new cycle configuration */
part = &cycle->open_files.part;
file = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
file = part->elts;
i = 0;
}
if (file[i].fd == NGX_INVALID_FILE || file[i].fd == ngx_stderr) {
continue;
}
if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
}
if (ngx_test_config) {
ngx_destroy_cycle_pools(&conf);
return NULL;
}
ls = cycle->listening.elts;
for (i = 0; i < cycle->listening.nelts; i++) {
if (ls[i].fd == (ngx_socket_t) -1 || !ls[i].open) {
continue;
}
if (ngx_close_socket(ls[i].fd) == -1) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
ngx_close_socket_n " %V failed",
&ls[i].addr_text);
}
}
ngx_destroy_cycle_pools(&conf);
return NULL;
}
~~~
参考资料：
《 [nginx源码分析—启动流程](http://blog.csdn.net/livelylittlefish/article/details/7243718)》
《[Nginx启动初始化过程](http://www.alidata.org/archives/1148)》
- 前言
- Nginx 配置文件
- Nginx 内存池管理
- Nginx 基本数据结构
- Nginx 数组结构 ngx_array_t
- Nginx 链表结构 ngx_list_t
- Nginx 队列双向链表结构 ngx_queue_t
- Nginx 哈希表结构 ngx_hash_t
- Nginx 红黑树结构 ngx_rbtree_t
- Nginx 模块开发
- Nginx 启动初始化过程
- Nginx 配置解析
- Nginx 中的 upstream 与 subrequest 机制
- Nginx 源码结构分析
- Nginx 事件模块
- Nginx 的 epoll 事件驱动模块
- Nginx 定时器事件
- Nginx 事件驱动模块连接处理
- Nginx 中 HTTP 模块初始化
- Nginx 中处理 HTTP 请求
- Nginx 中 upstream 机制的实现
- Nginx 中 upstream 机制的负载均衡