Nginx源码分析 - 主流程篇 - 全局变量cycle初始化
Nginx的大部分初始化工作主要围绕一个类型为ngx_cycle_t类型的全局变量(cycle)展开。本文主要讲解cycle的数据结构以及初始化过程中干了什么事情。
cycle的初始化过程在/src/core/cycle.c文件中。
数据结构
ngx_cycle_t的数据结构
cycle是Nginx贯穿全局的一个全局变量。阅读Nginx的源码必须得先搞清楚cycle全局变量的初始化过程。
/**
* Nginx全局变量cycle
*/
struct ngx_cycle_s {
void ****conf_ctx; /* 配置文件 上下文的数组，每个模块的配置信息*/
ngx_pool_t *pool; /* 内存池地址 */
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; /* 连接文件句柄 */
ngx_connection_t *free_connections; /* 空闲连接 */
ngx_uint_t free_connection_n;/* 空闲连接个数 */
ngx_module_t **modules; /* 模块数组 */
ngx_uint_t modules_n; /* 模块个数 */
ngx_uint_t modules_used; /* unsigned modules_used:1; */
ngx_queue_t reusable_connections_queue;
ngx_array_t listening; /* 监听数组 */
ngx_array_t paths; /* 路径数组 */
ngx_array_t config_dump;
ngx_list_t open_files; /* 打开的文件 */
ngx_list_t shared_memory;/* 共享内存链表*/
ngx_uint_t connection_n; /* 连接的个数*/
ngx_uint_t files_n; /* 打开文件的个数 */
ngx_connection_t *connections; /* 连接事件*/
ngx_event_t *read_events; /* 读取事件*/
ngx_event_t *write_events; /* 写入事件*/
ngx_cycle_t *old_cycle;
ngx_str_t conf_file; /* 配置文件 */
ngx_str_t conf_param; /* 配置参数 */
ngx_str_t conf_prefix; /* 配置文件前缀*/
ngx_str_t prefix; /* 前缀*/
ngx_str_t lock_file; /* 锁文件*/
ngx_str_t hostname; /* 主机名称*/
};
ngx_core_conf_t的数据结构
ngx_code_conf_t的数据结构主要用于装在Nginx的nginx.conf的核心配置文件的参数。后面我们会具体讲解配置文件nginx.conf的解析过程以及和模块。
/**
* 核心配置文件信息
* 对应nginx.conf的
* #user nobody;
worker_processes 1;
#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;
#pid logs/nginx.pid;
*/
typedef struct {
ngx_flag_t daemon;
ngx_flag_t master;
ngx_msec_t timer_resolution;
ngx_int_t worker_processes;
ngx_int_t debug_points;
ngx_int_t rlimit_nofile;
off_t rlimit_core;
int priority;
ngx_uint_t cpu_affinity_auto;
ngx_uint_t cpu_affinity_n;
ngx_cpuset_t *cpu_affinity;
char *username;
ngx_uid_t user;
ngx_gid_t group;
ngx_str_t working_directory;
ngx_str_t lock_file;
ngx_str_t pid;
ngx_str_t oldpid;
ngx_array_t env;
char **environment;
} ngx_core_conf_t;
初始化过程
1. 创建一个内存池。
后续所有的内存都会被分配到这个内存池上面。
/* 创建一块内存 */
pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
if (pool == NULL) {
return NULL;
}
pool->log = log;
cycle = ngx_pcalloc(pool, sizeof(ngx_cycle_t));
if (cycle == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->pool = pool;
cycle->log = log;
cycle->old_cycle = old_cycle;
2. 拷贝配置文件的路径前缀（/usr/local/nginx）。
主要拷贝到 cycle->conf_prefix
/* 配置文件路径拷贝 /usr/local/nginx/ */
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;
}
3. Nginx的路径前缀拷贝。
拷贝到cycle->prefix
/* Nginx路径拷贝 */
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;
}
4. 拷贝配置文件信息。
/nginx/conf/nginx.conf 文件路径
/* 配置文件 信息拷贝*/
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);
5. 拷贝配置参数信息。
/* 配置参数 信息拷贝 */
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;
}
6. 路径信息初始化。
/* 路径信息 */
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 (ngx_array_init(&cycle->config_dump, pool, 1, sizeof(ngx_conf_dump_t))
!= NGX_OK)
{
ngx_destroy_pool(pool);
return NULL;
}
7. 初始化打开的文件句柄。
/* 初始化打开的文件句柄 */
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;
}
8. 初始化shared_memory链表
/* 初始化shared_memory链表 */
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;
}
9. 初始化listening数组
/* 初始化listening */
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;
10. 模块创建和核心配置结构初始化ngx_core_conf_t
1. 主要初始化cycle->modules
2. 创建核心配置结构，Nginx的核心配置会放到ngx_core_conf_t *ccf数据结构上
3. 初始化核心配置结构ngx_core_conf_t *
/* 创建模块以及创建模块的配置信息 */
if (ngx_cycle_modules(cycle) != NGX_OK) {
ngx_destroy_pool(pool);
return NULL;
}
/*
* 核心模块的配置文件创建
* 配置创建调用nginx.c 中的 ngx_core_module_create_conf
* */
for (i = 0; cycle->modules[i]; i++) {
if (cycle->modules[i]->type != NGX_CORE_MODULE) {
continue;
}
module = cycle->modules[i]->ctx;
if (module->create_conf) {
rv = module->create_conf(cycle); //模块回调函数，创建模块的配置信息
if (rv == NULL) {
ngx_destroy_pool(pool);
return NULL;
}
cycle->conf_ctx[cycle->modules[i]->index] = rv; //配置文件复制
}
}
/* 获取核心配置文件的数据结构 ngx_core_conf_t */
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
11. 配置文件nginx.conf解析
配置文件解析会在下章中详细解读。
/* 解析配置文件 */
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;
}
/* 创建一个临时的内存池，后面会清空掉;conf也主要用于解析配置文件的临时变量 */
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
/* 解析命令行中的配置参数；例如：nginx -t -c /usr/local/nginx/conf/nginx.conf */
if (ngx_conf_param(&conf) != NGX_CONF_OK) {
environ = senv;
ngx_destroy_cycle_pools(&conf);
return NULL;
}
/* 解析配置文件/usr/local/nginx/conf/nginx.conf 信息 */
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);
}
12. 创建PID文件
Nginx将PID写入文件内，/usr/local/nginx-1.4.7/nginx.pid，后续对Nginx进行重启、停止、信号操作就可以使用这个PID了。
/* 创建pid文件，/usr/local/nginx-1.4.7/nginx.pid*/
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);
}
}
13. 遍历cycle->open_files链表中的文件，并且打开
cycle->open_file主要是在ngx_conf_open_file这个方法里面放入文件路径，然后下面去打开文件。
主要是日志文件和配置文件。
/* 打开日志，并调用ngx_conf_open_file方法，会将打开的文件放到cycle->open_files链表中 主要是日志文件和配置文件*/
if (ngx_log_open_default(cycle) != NGX_OK) {
goto failed;
}
/* 遍历cycle->open_files链表中的文件，并打开 */
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].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
}
14. 创建共享内存并初始化
新旧shared_memory链表的比较，相同的共享内存保留，旧的不同的共享内存被释放，新的被创建
/* 创建共享内存并初始化 */
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;
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].noreuse)
{
shm_zone[i].shm.addr = oshm_zone[n].shm.addr;
#if (NGX_WIN32)
shm_zone[i].shm.handle = oshm_zone[n].shm.handle;
#endif
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;
}
15. 处理listening数组，并开始监听socket
/* handle the listening sockets */
/* 处理listening数组，并开始监听socket */
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 (ls[i].remain) {
continue;
}
if (ls[i].type != nls[n].type) {
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
#if (NGX_HAVE_REUSEPORT)
if (nls[n].reuseport && !ls[i].reuseport) {
nls[n].add_reuseport = 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
}
}
if (ngx_open_listening_sockets(cycle) != NGX_OK) {
goto failed;
}
if (!ngx_test_config) {
ngx_configure_listening_sockets(cycle);
}
16. 关闭或删除残留在old_cycle中的资源
1. 释放多余的共享内存;
2. 关闭多余的侦听sockets;
3. 关闭多余的打开文件
/* close and delete stuff that lefts from an old cycle */
/* free the unnecessary shared memory */
/* 关闭或删除残留在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*/
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);