ngx_cycle_t

是结构体ngx_cycle_s的别名

typedef struct ngx_cycle_s           ngx_cycle_t;

结构体ngx_cycle_s的定义

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;
    time_t                    connections_reuse_time;

    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                 error_log;
    ngx_str_t                 lock_file;
    ngx_str_t                 hostname;
};

conf_ctx

创建

在ngx_init_cycle中创建conf_ctx，分配内存。创建ngx_max_module个void* 内存块

cycle->conf_ctx = ngx_pcalloc(pool, ngx_max_module * sizeof(void *));
    if (cycle->conf_ctx == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

第一次赋值

模块类型为CORE_MODULE，调用核心模块的create_conf方法来分配内存

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);
            if (rv == NULL) {
                ngx_destroy_pool(pool);
                return NULL;
            }
            cycle->conf_ctx[cycle->modules[i]->index] = rv;
        }
    }

核心模块中有create_conf的模块有

模块	create_conf方法
ngx_core_module	ngx_core_module_create_conf
ngx_openssl_module	ngx_openssl_create_conf
ngx_google_perftools_module	ngx_google_perftools_create_conf
ngx_regex_module	ngx_regex_create_conf
ngx_thread_pool_module	ngx_thread_pool_create_conf

解析模块类型为CORE_MODULE且命令类型为NGX_MAIN_CONF

模块	命令名	命令处理
ngx_core_module	daemon	ngx_conf_set_flag_slot
	master_process	ngx_conf_set_flag_slot
	timer_resolution	ngx_conf_set_msec_slot
	pid	ngx_conf_set_str_slot
	lock_file	ngx_conf_set_str_slot
	worker_processes	ngx_set_worker_processes
	debug_points	ngx_conf_set_enum_slot
	user	ngx_set_user
	worker_priority	ngx_set_priority
	worker_cpu_affinity	ngx_set_cpu_affinity
	worker_rlimit_nofile	ngx_conf_set_num_slot
	worker_rlimit_core	ngx_conf_set_off_slot
	worker_shutdown_timeout	ngx_conf_set_msec_slot
	working_directory	ngx_conf_set_str_slot
	env	ngx_set_env
	load_module	ngx_load_module
ngx_events_module	events	ngx_events_block
ngx_openssl_module	ssl_engine	ngx_openssl_engine
ngx_google_perftools_module	google_perftools_profiles	ngx_conf_set_str_slot
ngx_http_module	http	ngx_http_block
ngx_errlog_module	error_log	ngx_error_log
ngx_mail_module	mail	ngx_mail_block
ngx_regex_module	pcre_jit	ngx_conf_set_flag_slot
ngx_stream_module	stream	ngx_stream_block
ngx_thread_pool_module	thread_pool	ngx_thread_pool

第二次赋值

是在ngx_conf_handler中的判断命令类型是否是NGX_MAIN_CONF，此时(((void **) cf->ctx)[cf->cycle->modules[i]->index])是对应模块的配置信息的地址，其存的值是NULL。

通过命令接口的set方法来设置conf

ngx_conf_handler

if (cmd->type & NGX_DIRECT_CONF) {
                conf = ((void **) cf->ctx)[cf->cycle->modules[i]->index];

            } else if (cmd->type & NGX_MAIN_CONF) {
                conf = &(((void **) cf->ctx)[cf->cycle->modules[i]->index]);

            } else if (cf->ctx) {
                confp = *(void **) ((char *) cf->ctx + cmd->conf);

                if (confp) {
                    conf = confp[cf->cycle->modules[i]->ctx_index];
                }
            }

            rv = cmd->set(cf, cmd, conf);

根据命令类型是否是NGX_DIRECT_CONF还是NGX_MAIN_CONF，模块中有命令类型是NGX_DIRECT_CONF则其子接口中都有create_conf方法。

ngx_core_module核心模块中的命令都是NGX_DIRECT_CONF类型

ngx_events_module是如何分配conf_ctx的

其内存布局如下

事件相关模块分配结构

模块	方法	最终创建配置
ngx_event_core_module	ngx_event_core_create_conf	ngx_event_conf_t
ngx_devpoll_module	ngx_devpoll_create_conf	ngx_devpoll_conf_t
ngx_epoll_module	ngx_epoll_create_conf	ngx_epoll_conf_t
ngx_eventport_module	ngx_eventport_create_conf	ngx_eventport_conf_t
ngx_iocp_module	ngx_iocp_create_conf	ngx_iocp_conf_t
ngx_kqueue_module	ngx_kqueue_create_conf	ngx_kqueue_conf_t
ngx_poll_module	NULL	无
ngx_select_module	NULL	无
ngx_poll_module(win32)	NULL	无
ngx_select_module(win32)	NULL	无

ngx_http_module是如何分配conf_ctx的