近期在系统学习Nginx相关源码，针对nginx进程模型、事件处理模型、配置以及扩展开发等诸多方面希望能够沉淀一些东西，故针对上述方面整理一系列博客，既然是源码分析，那就首先从main函数开始吧。
核心数据结构
- 全局变量cycle数据结构
ngx_cycle_s变量是nginx中贯穿始终的全局变量，其存储在系统运行过程中的所有信息，包括配置文件信息、模块信息、客户端连接、读写事件处理函数等信息。其结构如下所示：
struct ngx_cycle_s {
void ****conf_ctx;
ngx_pool_t *pool;
ngx_log_t *log;
ngx_log_t new_log;
ngx_uint_t log_use_stderr; /* unsigned log_use_stderr:1; */
ngx_connection_t **files;
ngx_connection_t *free_connections;
ngx_uint_t free_connection_n;
ngx_module_t **modules;
ngx_uint_t modules_n;
ngx_uint_t modules_used; /* unsigned modules_used:1; */
ngx_queue_t reusable_connections_queue;
ngx_uint_t reusable_connections_n;
ngx_array_t listening;
ngx_array_t paths;
ngx_array_t config_dump;
ngx_rbtree_t config_dump_rbtree;
ngx_rbtree_node_t config_dump_sentinel;
ngx_list_t open_files;
ngx_list_t shared_memory;
ngx_uint_t connection_n;
ngx_uint_t files_n;
ngx_connection_t *connections;
ngx_event_t *read_events;
ngx_event_t *write_events;
ngx_cycle_t *old_cycle;
ngx_str_t conf_file;
ngx_str_t conf_param;
ngx_str_t conf_prefix;
ngx_str_t prefix;
ngx_str_t lock_file;
ngx_str_t hostname;
};
- Main核心配置数据结构
//核心配置
typedef struct {
ngx_flag_t daemon;
ngx_flag_t master;
ngx_msec_t timer_resolution;
ngx_msec_t shutdown_timeout;
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_uint_t transparent; /* unsigned transparent:1; */
} ngx_core_conf_t;
- 模块数据结构
//模块数据结构
struct ngx_module_s {
ngx_uint_t ctx_index;
ngx_uint_t index;
char *name;
ngx_uint_t spare0;
ngx_uint_t spare1;
ngx_uint_t version;
const char *signature;
void *ctx;
ngx_command_t *commands;
ngx_uint_t type;
ngx_int_t (*init_master)(ngx_log_t *log);
ngx_int_t (*init_module)(ngx_cycle_t *cycle);
ngx_int_t (*init_process)(ngx_cycle_t *cycle);
ngx_int_t (*init_thread)(ngx_cycle_t *cycle);
void (*exit_thread)(ngx_cycle_t *cycle);
void (*exit_process)(ngx_cycle_t *cycle);
void (*exit_master)(ngx_cycle_t *cycle);
uintptr_t spare_hook0;
uintptr_t spare_hook1;
uintptr_t spare_hook2;
uintptr_t spare_hook3;
uintptr_t spare_hook4;
uintptr_t spare_hook5;
uintptr_t spare_hook6;
uintptr_t spare_hook7;
};
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;
主函数 main()
- 文件位置：
/src/nginx.c
int ngx_cdecl main(int argc, char *const *argv)
{
ngx_buf_t *b;
ngx_log_t *log;
ngx_uint_t i;
ngx_cycle_t *cycle, init_cycle;
ngx_conf_dump_t *cd;
ngx_core_conf_t *ccf;
ngx_debug_init();
// 1.获取命令行参数
ngx_get_options(argc, argv)
// 2.初始化本地时钟
ngx_time_init();
ngx_pid = ngx_getpid();
ngx_parent = ngx_getppid();
// 3.初始化日志
log = ngx_log_init(ngx_prefix);
// 4.初始化全局变量ngx_cycle_t
ngx_memzero(&init_cycle, sizeof(ngx_cycle_t));
init_cycle.log = log;
ngx_cycle = &init_cycle;
init_cycle.pool = ngx_create_pool(1024, log);
// 5.保存命令行参数到全局变量中
ngx_save_argv(&init_cycle, argc, argv);
// 6.处理命令行参数
ngx_process_options(&init_cycle);
// 7.初始化系统相关参数
ngx_os_init(log);
// 8.预初始化模块
ngx_preinit_modules();
// 9.
cycle = ngx_init_cycle(&init_cycle);
ngx_os_status(cycle->log);
ngx_cycle = cycle;
// 9.获取核心模块配置参数
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
// 10.创建pid存储文件
ngx_create_pidfile(&ccf->pid, cycle->log);
ngx_log_redirect_stderr(cycle);
// 11.单进程模式运行
if (ngx_process == NGX_PROCESS_SINGLE) {
ngx_single_process_cycle(cycle);
} else {
// 12.多进程模式运行
ngx_master_process_cycle(cycle);
}
return 0;
}
预初始化模块 ngx_preinit_modules()
- 文件位置
/src/ngx_module.c - 主要工作：配置各个模块的顺序索引
ngx_int_t ngx_preinit_modules(void)
{
ngx_uint_t i;
//ngx_modules是全局变量，定义在nginx_modules.h文件中
for (i = 0; ngx_modules[i]; i++) {
ngx_modules[i]->index = i;
ngx_modules[i]->name = ngx_module_names[i];
}
ngx_modules_n = i;
ngx_max_module = ngx_modules_n + NGX_MAX_DYNAMIC_MODULES;
return NGX_OK;
}
ngx_preinit_modules()函数主要完成模块到序号初始化，其数组ngx_modules是何时产生的呢？
ngx_modules包含所有nginx定义的模块,其初始化是由执行configure命令前定义.- 新增模块或者减少模块可以在configure命令执行前 auto/modules文件里面修改。
ngx_init_cycle
- 文件位置
/src/ngx_module.c - 主要工作：初始化系统时钟、主机名、模块配置文件、各种后续数据结构，形成全局变量cycle
ngx_cycle_t * ngx_init_cycle(ngx_cycle_t *old_cycle)
{
void *rv;
char **senv;
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];
// 1.更新时钟和时区
ngx_timezone_update();
ngx_time_update();
log = old_cycle->log;
pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
pool->log = log;
cycle = ngx_pcalloc(pool, sizeof(ngx_cycle_t));
cycle->pool = pool;
cycle->log = log;
cycle->old_cycle = old_cycle;
// 2.初始化相关数据结构
ngx_array_init(&cycle->paths, pool, n, sizeof(ngx_path_t *);
ngx_memzero(cycle->paths.elts, n * sizeof(ngx_path_t *);
ngx_array_init(&cycle->config_dump, pool, 1, sizeof(ngx_conf_dump_t);
ngx_rbtree_init(&cycle->config_dump_rbtree, &cycle->config_dump_sentinel,ngx_str_rbtree_insert_value);
ngx_list_init(&cycle->open_files, pool, n, sizeof(ngx_open_file_t);
ngx_list_init(&cycle->shared_memory, pool, n, sizeof(ngx_shm_zone_t);
ngx_array_init(&cycle->listening, pool, n, sizeof(ngx_listening_t);
ngx_memzero(cycle->listening.elts, n * sizeof(ngx_listening_t));
ngx_queue_init(&cycle->reusable_connections_queue);
cycle->conf_ctx = ngx_pcalloc(pool, ngx_max_module * sizeof(void *));
// 3.获取主机名
gethostname(hostname, NGX_MAXHOSTNAMELEN) ;
hostname[NGX_MAXHOSTNAMELEN - 1] = '\0';
cycle->hostname.len = ngx_strlen(hostname);
cycle->hostname.data = ngx_pnalloc(pool, cycle->hostname.len);
// 4.创建modules数组
ngx_cycle_modules(cycle);
// 5.创建核心模块到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);
cycle->conf_ctx[cycle->modules[i]->index] = rv;
}
}
ngx_memzero(&conf, sizeof(ngx_conf_t));
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;
ngx_conf_param(&conf);
ngx_conf_parse(&conf, &cycle->conf_file)
// 6.调用核心模块的init_conf回调函数
for (i = 0; cycle->modules[i]; i++) {
if (cycle->modules[i]->type != NGX_CORE_MODULE) {
continue;
}
module = cycle->modules[i]->ctx;
if (module->init_conf) {
module->init_conf(cycle,cycle->conf_ctx[cycle->modules[i]->index])
}
}
// 7.单进程模式则直接返回
if (ngx_process == NGX_PROCESS_SIGNALLER) {
return cycle;
}
// 8.多进程模式则创建pid文件
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
ngx_create_pidfile(&ccf->pid, log);
ngx_open_listening_sockets(cycle)
ngx_init_modules(cycle);
return cycle;
}
ngx_cycle_modules
- 文件位置：
- 主要工作：生成modules数组
ngx_int_t ngx_cycle_modules(ngx_cycle_t *cycle)
{
/*
* create a list of modules to be used for this cycle,
* copy static modules to it
*/
cycle->modules = ngx_pcalloc(cycle->pool, (ngx_max_module + 1)
* sizeof(ngx_module_t *));
if (cycle->modules == NULL) {
return NGX_ERROR;
}
ngx_memcpy(cycle->modules, ngx_modules,
ngx_modules_n * sizeof(ngx_module_t *));
cycle->modules_n = ngx_modules_n;
return NGX_OK;
}
ngx_init_modules
- 文件位置
- 主要工作：回调各个模块初始化函数
ngx_int_t ngx_init_modules(ngx_cycle_t *cycle)
{
ngx_uint_t i;
for (i = 0; cycle->modules[i]; i++) {
if (cycle->modules[i]->init_module) {
if (cycle->modules[i]->init_module(cycle) != NGX_OK) {
return NGX_ERROR;
}
}
}
return NGX_OK;
}
在完成模块创建和初始化工作后，系统进入ngx_single_process_cycle 和ngx_master_process_cycle 函数，创建主进程和工作进程，其具体的进程模型将在文章NGINX系列之进程模型中介绍。
