Nginx 项目 ngx_module_t 接口学习
nginx中功能模块抽象接口(Interface),所有要加入到nginx项目中的功能模块必须实现此接口,实现此接口的模块实例将会初始化到全局数组ngx_modules[]中,该数组在项目编译时生成.
typedef struct ngx_module_s ngx_module_t;接口定义 :
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;
};
几个重要参数说明:
index:该模块的参数配置结构信息在ngx_cycle_t中的参数配置结构指针列表conf_ctx中的索引。
ctx:实现ngx_module_t接口的具体功能模块实例对应的私有配置参数(创建及初始化)的接口指针,具体模块具体实现自己的参数创建及解析。
commands:具体功能模块配置参数,Nginx已经实现从文件读取参数的方法,最终读出来的每个参数表示什么意义及如何解析他们对应的值,由接口指针commands(类型为ngx_command_t )提供具体实现。
type: 该模块实例的类型标识,在ngx_modules[]数组中查询具体模块时会用到。
下面是Nginx中的核心模块ngx_core_module实现此接口的示例:
全局变量ngx_core_module对ngx_module_t接口的实现:
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
};
其中 ngx_core_module的成员 ctx的值ngx_core_module_ctx的类型定义及实现如下:
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;
static ngx_core_module_t ngx_core_module_ctx = {
ngx_string("core"),
ngx_core_module_create_conf,
ngx_core_module_init_conf
};即
ngx_core_module模块是调用上面两个接口ngx_core_module_create_conf&ngx_core_module_init_conf来获取自己的配置参数,并初始化自己的配置参数结构ngx_core_conf_t.
ngx_core_conf_t参数结构定义如下(具体对应配置文件中的值):
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;
uint64_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;
#if (NGX_THREADS)
ngx_int_t worker_threads;
size_t thread_stack_size;
#endif
} ngx_core_conf_t;
其中 ngx_core_module的 成员 commands 的值ngx_core_commands的实现如下:
static ngx_command_t ngx_core_commands[] = {
{ ngx_string("daemon"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
0,
offsetof(ngx_core_conf_t, daemon),
NULL },
{ ngx_string("master_process"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_FLAG,
ngx_conf_set_flag_slot,
0,
offsetof(ngx_core_conf_t, master),
NULL },
{ ngx_string("timer_resolution"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
0,
offsetof(ngx_core_conf_t, timer_resolution),
NULL },
{ ngx_string("pid"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_str_slot,
0,
offsetof(ngx_core_conf_t, pid),
NULL },
{ ngx_string("lock_file"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_str_slot,
0,
offsetof(ngx_core_conf_t, lock_file),
NULL },
{ ngx_string("worker_processes"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_set_worker_processes,
0,
0,
NULL },
{ ngx_string("debug_points"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_enum_slot,
0,
offsetof(ngx_core_conf_t, debug_points),
&ngx_debug_points },
{ ngx_string("user"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE12,
ngx_set_user,
0,
0,
NULL },
{ ngx_string("worker_priority"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_set_priority,
0,
0,
NULL },
{ ngx_string("worker_cpu_affinity"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_1MORE,
ngx_set_cpu_affinity,
0,
0,
NULL },
{ ngx_string("worker_rlimit_nofile"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
0,
offsetof(ngx_core_conf_t, rlimit_nofile),
NULL },
{ ngx_string("worker_rlimit_core"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_off_slot,
0,
offsetof(ngx_core_conf_t, rlimit_core),
NULL },
{ ngx_string("worker_rlimit_sigpending"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
0,
offsetof(ngx_core_conf_t, rlimit_sigpending),
NULL },
{ ngx_string("working_directory"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_str_slot,
0,
offsetof(ngx_core_conf_t, working_directory),
NULL },
{ ngx_string("env"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_set_env,
0,
0,
NULL },
#if (NGX_THREADS)
{ ngx_string("worker_threads"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_num_slot,
0,
offsetof(ngx_core_conf_t, worker_threads),
NULL },
{ ngx_string("thread_stack_size"),
NGX_MAIN_CONF|NGX_DIRECT_CONF|NGX_CONF_TAKE1,
ngx_conf_set_size_slot,
0,
offsetof(ngx_core_conf_t, thread_stack_size),
NULL },
#endif
ngx_null_command
};即配置文件中的每个参数对应一个ngx_command_s 接口去获取其值(如上示例):
ngx_command_s结构定义如下:
struct ngx_command_s {
ngx_str_t name;
ngx_uint_t type;
char *(*set)(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
ngx_uint_t conf;
ngx_uint_t offset;
void *post;
};即为每个参数实现一个ngx_command_s接口即可,具体实现参看
ngx_core_commands里的各个参数解析接口实现.