最近做一個收集客戶端數據的項目, 後臺使用nginx, 通過實現nginx的模塊來處理業務. nginx的模塊編寫不難,
但寫完後對nginx的內部機制還是雲裏霧裏, 趁週末好好閱讀一下nginx的源代碼. 下面記錄一些閱讀過程中遇
到的數據結構. 關於nginx的內部實現, 等看懂了源碼再寫.
模塊四要素:
1 模塊實例, 2 模塊上下文, 3 模塊指令, 4 指令參數
模塊定義
===================================================
struct ngx_module_s {
ngx_uint_t ctx_index;
ngx_uint_t index;
ngx_uint_t spare0;
ngx_uint_t spare1;
ngx_uint_t spare2;
ngx_uint_t spare3;
ngx_uint_t version;
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;
}; (core/ngx_conf_file.h)
模塊實例定義
===================================================
1 核心模塊
ngx_module_t ngx_core_module = {
NGX_MODULE_V1,
&ngx_core_module_ctx, /* module context */
ngx_core_commands, /* module directives */
NGX_CORE_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
}; (core/nginx.c)
2 http模塊
ngx_module_t ngx_http_module = {
NGX_MODULE_V1,
&ngx_http_module_ctx, /* module context */
ngx_http_commands, /* module directives */
NGX_CORE_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
3 http核心模塊
ngx_module_t ngx_http_core_module = {
NGX_MODULE_V1,
&ngx_http_core_module_ctx, /* module context */
ngx_http_core_commands, /* module directives */
NGX_HTTP_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
}; (http/ngx_http_core_module.c)
4 日誌模塊
ngx_module_t ngx_errlog_module = {
NGX_MODULE_V1,
&ngx_errlog_module_ctx, /* module context */
ngx_errlog_commands, /* module directives */
NGX_CORE_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
5 事件模塊
ngx_module_t ngx_event_core_module = {
NGX_MODULE_V1,
&ngx_event_core_module_ctx, /* module context */
ngx_event_core_commands, /* module directives */
NGX_EVENT_MODULE, /* module type */
NULL, /* init master */
ngx_event_module_init, /* init module */
ngx_event_process_init, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
模塊上下文定義
===================================================
1 核心模塊上下文定義
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; （見src/core/ngx_conf_file.h）
2 事件模塊上下文定義
typedef struct {
ngx_str_t *name;
void *(*create_conf)(ngx_cycle_t *cycle);
char *(*init_conf)(ngx_cycle_t *cycle, void *conf);
ngx_event_actions_t actions;
} ngx_event_module_t;（見src/event/ngx_event.h）
3 http模塊上下文定義
typedef struct {
ngx_int_t (*preconfiguration)(ngx_conf_t *cf);
ngx_int_t (*postconfiguration)(ngx_conf_t *cf);
void *(*create_main_conf)(ngx_conf_t *cf);
char *(*init_main_conf)(ngx_conf_t *cf, void *conf);
void *(*create_srv_conf)(ngx_conf_t *cf);
char *(*merge_srv_conf)(ngx_conf_t *cf, void *prev, void *conf);
void *(*create_loc_conf)(ngx_conf_t *cf);
char *(*merge_loc_conf)(ngx_conf_t *cf, void *prev, void *conf);
} ngx_http_module_t; （見src/http/ngx_http_config.h）
4 事件模塊上下文定義
ngx_event_module_t ngx_event_core_module_ctx = {
&event_core_name,
ngx_event_create_conf, /* create configuration */
ngx_event_init_conf, /* init configuration */
{ NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
};
模塊上下文實例
===============================================================
1 核心模塊上下文
static ngx_core_module_t ngx_core_module_ctx = {
ngx_string("core"),
ngx_core_module_create_conf,
ngx_core_module_init_conf
}; (core/nginx.c)
2 http核心模塊上下文
static ngx_http_module_t ngx_http_core_module_ctx = {
ngx_http_core_preconfiguration, /* preconfiguration */
NULL, /* postconfiguration */
ngx_http_core_create_main_conf, /* create main configuration */
ngx_http_core_init_main_conf, /* init main configuration */
ngx_http_core_create_srv_conf, /* create server configuration */
ngx_http_core_merge_srv_conf, /* merge server configuration */
ngx_http_core_create_loc_conf, /* create location configuration */
ngx_http_core_merge_loc_conf /* merge location configuration */
}; (http/ngx_http_core_module.c)
存儲指令參數的結構體
===============================================================
根指令的參數
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;
ngx_int_t rlimit_sigpending;
off_t rlimit_core;
int priority;
ngx_uint_t cpu_affinity_n;
u_long *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;
http指令的參數
typedef struct {
/* 保存所有server的配置信息 */
ngx_array_t servers; /* ngx_http_core_srv_conf_t */
ngx_http_phase_engine_t phase_engine;
ngx_hash_t headers_in_hash;
ngx_hash_t variables_hash;
ngx_array_t variables; /* ngx_http_variable_t */
ngx_uint_t ncaptures;
ngx_uint_t server_names_hash_max_size;
ngx_uint_t server_names_hash_bucket_size;
ngx_uint_t variables_hash_max_size;
ngx_uint_t variables_hash_bucket_size;
ngx_hash_keys_arrays_t *variables_keys;
ngx_array_t *ports;
ngx_uint_t try_files; /* unsigned try_files:1 */
ngx_http_phase_t phases[NGX_HTTP_LOG_PHASE + 1];
} ngx_http_core_main_conf_t;
server指令的參數
typedef struct {
/* array of the ngx_http_server_name_t, "server_name" directive */
ngx_array_t server_names;
/* server ctx,初始化http請求ngx_http_init_request時用得到 */
ngx_http_conf_ctx_t *ctx;
ngx_str_t server_name;
size_t connection_pool_size;
size_t request_pool_size;
size_t client_header_buffer_size;
ngx_bufs_t large_client_header_buffers;
ngx_msec_t client_header_timeout;
ngx_flag_t ignore_invalid_headers;
ngx_flag_t merge_slashes;
ngx_flag_t underscores_in_headers;
unsigned listen:1;
ngx_http_core_loc_conf_t **named_locations;
} ngx_http_core_srv_conf_t;
location指令的參數
struct ngx_http_core_loc_conf_s {
ngx_str_t name; /* location name */
unsigned noname:1; /* "if () {}" block or limit_except */
unsigned lmt_excpt:1;
unsigned named:1;
unsigned exact_match:1;
unsigned noregex:1;
unsigned auto_redirect:1;
/* pointer to the modules' loc_conf */
void **loc_conf;
uint32_t limit_except;
void **limit_except_loc_conf;
ngx_http_handler_pt handler;
/* location name length for inclusive location with inherited alias */
size_t alias;
ngx_str_t root; /* root, alias */
ngx_str_t post_action;
ngx_array_t *root_lengths;
ngx_array_t *root_values;
ngx_array_t *types;
ngx_hash_t types_hash;
ngx_str_t default_type;
off_t client_max_body_size; /* client_max_body_size */
off_t directio; /* directio */
off_t directio_alignment; /* directio_alignment */
size_t client_body_buffer_size; /* client_body_buffer_size */
size_t send_lowat; /* send_lowat */
size_t postpone_output; /* postpone_output */
size_t limit_rate; /* limit_rate */
size_t limit_rate_after; /* limit_rate_after */
size_t sendfile_max_chunk; /* sendfile_max_chunk */
size_t read_ahead; /* read_ahead */
ngx_msec_t client_body_timeout; /* client_body_timeout */
ngx_msec_t send_timeout; /* send_timeout */
ngx_msec_t keepalive_timeout; /* keepalive_timeout */
ngx_msec_t lingering_time; /* lingering_time */
ngx_msec_t lingering_timeout; /* lingering_timeout */
ngx_msec_t resolver_timeout; /* resolver_timeout */
ngx_resolver_t *resolver; /* resolver */
time_t keepalive_header; /* keepalive_timeout */
};
指令定義
===========================================================
struct ngx_command_s {
ngx_str_t name;
ngx_uint_t type;初始化http請求: ngx_http_init_request
char *(*set)(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
ngx_uint_t conf;
ngx_uint_t offset;
void *post;
};
cycle定義
===========================================================
struct ngx_cycle_s {
void ****conf_ctx;
ngx_pool_t *pool;
ngx_log_t *log;
ngx_log_t new_log;
ngx_connection_t **files;
ngx_connection_t *free_connections;
ngx_uint_t free_connection_n;
ngx_queue_t reusable_connections_queue;
ngx_array_t listening;
ngx_array_t pathes;
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;
};
http三大配置
===========================================================
typedef struct {
void **main_conf;
void **srv_conf;
void **loc_conf;
} ngx_http_conf_ctx_t;
解析配置文件的時候, 用結構體ngx_conf_s來暫時存放指令的參數
===========================================================
struct ngx_conf_s {
char *name;
ngx_array_t *args;
ngx_cycle_t *cycle;
ngx_pool_t *pool;
ngx_pool_t *temp_pool;
ngx_conf_file_t *conf_file;
ngx_log_t *log;
void *ctx;
ngx_uint_t module_type;
ngx_uint_t cmd_type;
ngx_conf_handler_pt handler;
char *handler_conf;
};
在ngx_init_cycle中聲明一個這樣的變量
ngx_conf_t conf;
然後開始解析配置文件, 這個結構體可以反覆使用, 每次遇到一個指令, 就會改變conf的內容
閱讀痕跡
=====================================================================
* ngx_init_cycle:
* ngx_conf_t.ctx = cycle->conf_ctx;
解析配置文件
* 從ngx_init_cycle調用ngx_conf_param開始解析配置文件
* ngx_conf_param再調用ngx_conf_parse解析配置文件
* ngx_conf_parse:
* 打開配置文件
* for循環:
* 讀取文件, ngx_conf_read_token, 把指令名和參數存到ngx_conf_t結構體,
每次都一條指令便返回
* 調用ngx_conf_handler來處理這條指令:
* 尋找指令所在的模塊
* 檢驗指令在配置文件中的位置是否正確
* 檢驗指令的參數個數是否合法
* 取得指令參數要存儲的地方(比如ngx_core_conf_t,用conf指針指向),這個結構體由
模塊的create_conf來創建, 然後把它安插在 ngx_conf_t.ctx 中
* 調用指令的 set 函數, 把ngx_conf_t中的參數值轉存到conf指向的結構體
解析http block
如果ngx_conf_read_token返回"http {", 則調用ngx_http_block解析http block下面的配置
* ngx_http_block:
* 創建ngx_http_conf_ctx_t結構體, 這時conf指針不再指向ngx_core_conf_t,
而是指向ngx_http_conf_ctx_t
* 數一下有多少個http模塊, 並設置每個模塊的index
* 調用所有http模塊的create_main_conf鉤子,把返回的結構體安插在ngx_http_conf_ctx_t.main_conf表中
調用所有http模塊的create_srv_conf鉤子,把返回的結構體安插在ngx_http_conf_ctx_t.srv_conf表中
調用所有http模塊的create_loc_conf鉤子,把返回的結構體安插在ngx_http_conf_ctx_t.loc_conf表中
* ngx_conf_t.ctx不再指向cycle->conf_ctx, 而是指向ngx_http_conf_ctx_t
* 調用所有http模塊的preconfiguration鉤子
* 再次調用ngx_conf_parse來解析http block裏面的指令, 至此http block,
server block, location block都解析完畢
* 調用所有http模塊的init_main_conf鉤子
* 待續...
解析server block
解析htto block的時候, 如果遇到"server {", 則調用
server command的set方法:ngx_http_core_server, 開始解析server block
ngx_http_core_server:
* 再創建一個ngx_http_conf_ctx_t結構體, 這時ngx_conf_t.ctx不再指向
http block的ngx_http_conf_ctx_t, 而是指向這個新的ngx_http_conf_ctx_t
ctx = new ngx_http_conf_ctx_t
http_ctx = cf->ctx
cf->ctx = ctx
* server ctx的main_conf從http ctx繼承過來
ctx->main_conf = http_ctx->main_conf;
* 調用所有http模塊的create_srv_conf鉤子,把返回的結構體安插在ctx.srv_conf表中
調用所有http模塊的create_loc_conf鉤子,把返回的結構體安插在ctx.loc_conf表中
http block下面三大conf的偏移量
-----------------------------------------------------------
#define NGX_HTTP_MAIN_CONF_OFFSET offsetof(ngx_http_conf_ctx_t, main_conf)
#define NGX_HTTP_SRV_CONF_OFFSET offsetof(ngx_http_conf_ctx_t, srv_conf)
#define NGX_HTTP_LOC_CONF_OFFSET offsetof(ngx_http_conf_ctx_t, loc_conf)
根據ngx_http_request_t得到三大conf
-----------------------------------------------------------
#define ngx_http_get_module_main_conf(r, module) \
(r)->main_conf[module.ctx_index]
#define ngx_http_get_module_srv_conf(r, module) (r)->srv_conf[module.ctx_index]
#define ngx_http_get_module_loc_conf(r, module) (r)->loc_conf[module.ctx_index]
根據ngx_conf_t得到三大conf
-----------------------------------------------------------
#define ngx_http_conf_get_module_main_conf(cf, module) \
((ngx_http_conf_ctx_t *) cf->ctx)->main_conf[module.ctx_index]
#define ngx_http_conf_get_module_srv_conf(cf, module) \
((ngx_http_conf_ctx_t *) cf->ctx)->srv_conf[module.ctx_index]
#define ngx_http_conf_get_module_loc_conf(cf, module) \
((ngx_http_conf_ctx_t *) cf->ctx)->loc_conf[module.ctx_index]
根據cycyle的conf_ctx得到main conf
-----------------------------------------------------------
#define ngx_http_cycle_get_module_main_conf(cycle, module) \
(cycle->conf_ctx[ngx_http_module.index] ? \
((ngx_http_conf_ctx_t *) cycle->conf_ctx[ngx_http_module.index]) \
->main_conf[module.ctx_index]: \
NULL)
==================== ngx_http_log_module實例 ==================
ngx_http_log_create_main_conf返回的結構體
-----------------------------------------------------------
typedef struct {
ngx_array_t formats; /* array of ngx_http_log_fmt_t */
ngx_uint_t combined_used; /* unsigned combined_used:1 */
} ngx_http_log_main_conf_t;
ngx_http_log_create_loc_conf返回的結構體
-----------------------------------------------------------
typedef struct {
ngx_array_t *logs; /* array of ngx_http_log_t */
ngx_open_file_cache_t *open_file_cache;
time_t open_file_cache_valid;
ngx_uint_t open_file_cache_min_uses;
ngx_uint_t off; /* unsigned off:1 */
} ngx_http_log_loc_conf_t;
指令
-----------------------------------------------------------
static ngx_command_t ngx_http_log_commands[] = {
{ ngx_string("log_format"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_2MORE,
ngx_http_log_set_format,
NGX_HTTP_MAIN_CONF_OFFSET,
0,
NULL },
{ ngx_string("access_log"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
|NGX_HTTP_LMT_CONF|NGX_CONF_TAKE123,
ngx_http_log_set_log,
NGX_HTTP_LOC_CONF_OFFSET,
0, /* 如果使用自定義的set方法, 而且無須知道參數在結構體中的offset,那麼offset就可以設爲0 */
NULL },
{ ngx_string("open_log_file_cache"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1234,
ngx_http_log_open_file_cache,
NGX_HTTP_LOC_CONF_OFFSET,
0,
NULL },
ngx_null_command
};
上下文
-----------------------------------------------------------
static ngx_http_module_t ngx_http_log_module_ctx = {
NULL, /* preconfiguration */
ngx_http_log_init, /* postconfiguration */
ngx_http_log_create_main_conf, /* create main configuration */
NULL, /* init main configuration */
NULL, /* create server configuration */
NULL, /* merge server configuration */
ngx_http_log_create_loc_conf, /* create location configration */
ngx_http_log_merge_loc_conf /* merge location configration */
};
模塊實例
-----------------------------------------------------------
ngx_module_t ngx_http_log_module = {
NGX_MODULE_V1,
&ngx_http_log_module_ctx, /* module context */
ngx_http_log_commands, /* module directives */
NGX_HTTP_MODULE, /* module type */
NULL, /* init master */
NULL, /* init module */
NULL, /* init process */
NULL, /* init thread */
NULL, /* exit thread */
NULL, /* exit process */
NULL, /* exit master */
NGX_MODULE_V1_PADDING
};
==================== end of ngx_http_log_module實例 ==================
注意ngx_request_s保存有http block裏面的三大conf
--------------------------------------------------------------------
struct ngx_http_request_s {
uint32_t signature; /* "HTTP" */
ngx_connection_t *connection;
void **ctx;
void **main_conf;
void **srv_conf;
void **loc_conf;
}
總共創建多少個ngx_http_conf_ctx_t結構體
----------------------------------------------------
http block下創建ngx_http_conf_ctx_t
在server block下創建ngx_http_conf_ctx_t
在location block下創建ngx_http_conf_ctx_t
在location block下創建ngx_http_conf_ctx_t
在location block下創建ngx_http_conf_ctx_t
結論: http block只創建一個, 每個server都會創建一個結構體, 每個location都會創建一個結構體
疑問:server block創建的ngx_http_conf_ctx_t會保存在ngx_http_core_srv_conf_t中
那麼location block創建的ngx_http_conf_ctx_t保存在哪裏呢?
調用 ngx_conf_parse 的時候會先保存ngx_conf_t
------------------------------------------------
ngx_conf_t save;
save = *cf;
cf->ctx = ctx;
cf->cmd_type = NGX_HTTP_LOC_CONF;
rv = ngx_conf_parse(cf, NULL);
*cf = save;
初始化http請求: ngx_http_init_request
-----------------------------------------------
ngx_http_core_srv_conf_t *cscf = addr_conf->default_server;
r->main_conf = cscf->ctx->main_conf;
r->srv_conf = cscf->ctx->srv_conf;
r->loc_conf = cscf->ctx->loc_conf;
自動收割子進程
-----------------------------------------------
在master process中, 函數 ngx_signal_handler 用來處理信號, 若
接收到 SIGCHLD 信號, 表示有一個子進程退出了, 然後把變量 ngx_reap 置爲 1
然後在 ngx_master_process_cycle 函數中, 若檢查到 ngx_reap 等於 1,則創建
一個子進程:
if (ngx_reap) {
ngx_reap = 0;
ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "reap children");
live = ngx_reap_children(cycle);
}