struct

ngx_str_t

struct define:

typedef struct {
    size_t      len;
    u_char     *data;
} ngx_str_t;

nginx string is not like normal C-str. Which is not end with ‘\0’. It’s controlled by len. So it can share memory sources bewteen sereval string objects.

ngx_list_t

struct define:

typedef struct ngx_list_part_s  ngx_list_part_t;

struct ngx_list_part_s {
    void             *elts;
    ngx_uint_t        nelts;
    ngx_list_part_t  *next;
};


typedef struct {
    ngx_list_part_t  *last;
    ngx_list_part_t   part;
    size_t            size;
    ngx_uint_t        nalloc;
    ngx_pool_t       *pool;     // memory pool object
} ngx_list_t;

The node of nginx list is array. It’s high performance for index item in it. The memory calloc picture like

ngx_table_elt_t

struct defined:

typedef struct {
    ngx_uint_t        hash;
    ngx_str_t         key;
    ngx_str_t         value;
    u_char           *lowcase_key;
} ngx_table_elt_t;

This struct is designed for http headers. Because header key is not case sensitive.

ngx_module_t

struct defined:

struct ngx_module_s {

    // this value represent the order of this moudle in one type of modules.
    // the value is important because it affect how proccess one request with much modules

    ngx_uint_t            ctx_index;

    // like up, but it's all modules

    ngx_uint_t            index;

    // remind and unused
    ngx_uint_t            spare0;
    ngx_uint_t            spare1;
    ngx_uint_t            spare2;
    ngx_uint_t            spare3;

    // version of this module (it always 1)
    ngx_uint_t            version;

    // this value assign to context of this type of module
    // Because the different of each type module is great. So the content this value is different
    void                 *ctx;

    // this directive process config of nginx about this module
    ngx_command_t        *commands;

    // type of this module. which have 5 value:
    //      NGX_HTTP_MODULE
    //      NGX_CORE_MODULE
    //      NGX_CONF_MODULE
    //      NGX_EVENT_MODULE
    //      NGX_MAIL_MODULE
    ngx_uint_t            type;

    // method point. it will be called by nginx in different time


    // unused. always NULL
    ngx_int_t           (*init_master)(ngx_log_t *log);

    // it will be called in init of every module.(It will be called before fork worker process)
    ngx_int_t           (*init_module)(ngx_cycle_t *cycle);

    // it will be called in init of every worker process.
    ngx_int_t           (*init_process)(ngx_cycle_t *cycle);

    // unused. always NULL. (because nginx don't support thread model)
    ngx_int_t           (*init_thread)(ngx_cycle_t *cycle);

    // like up
    void                (*exit_thread)(ngx_cycle_t *cycle);

    // it will be called before worker process exit
    void                (*exit_process)(ngx_cycle_t *cycle);

    // it will be called before master process exit
    void                (*exit_master)(ngx_cycle_t *cycle);


    // remind & unused
    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;
};

ngx_log_t

struct define:

struct ngx_log_s {
    ngx_uint_t           log_level;
    ngx_open_file_t     *file;

    ngx_atomic_uint_t    connection;

    ngx_log_handler_pt   handler;
    void                *data;

    /*
     * we declare "action" as "char *" because the actions are usually
     * the static strings and in the "u_char *" case we have to override
     * their types all the time
     */

    char                *action;
    ngx_log_t           *next;
};

ngx_pool_t

struct define:

struct ngx_pool_cleanup_s {
    ngx_pool_cleanup_pt   handler;
    void                 *data;
    ngx_pool_cleanup_t   *next;
};


typedef struct ngx_pool_large_s  ngx_pool_large_t;

struct ngx_pool_large_s {
    ngx_pool_large_t     *next;
    void                 *alloc;
};


typedef struct {
    u_char               *last;
    u_char               *end;
    ngx_pool_t           *next;
    ngx_uint_t            failed;
} ngx_pool_data_t;


struct ngx_pool_s {
    ngx_pool_data_t       d;
    size_t                max;
    ngx_pool_t           *current;
    ngx_chain_t          *chain;
    ngx_pool_large_t     *large;
    ngx_pool_cleanup_t   *cleanup;
    ngx_log_t            *log;
};

The relationship within them like that:

它的逻辑:

• 没有局部free的方法，一般使用方式都是在一个pool上一点一点palloc, 等连接关闭时，对整个pool进行destory
• 开辟内存小于max的时候，在pool->d这个内存链表里开辟(不停开辟block)
• 开辟内存大于max的时候，在pool->large 这个内存链表上开辟(同上)
• pool->cleanup 是内存池提供的回调函数，free的时候会依次调用，一般不需要处理它
• pool->chain 目前还没使用

见 例子

ngx_buf_t

TODO

ngx_chain_t

TODO

ngx_hash_t

The reduced graph of hash struct is:

The detail graph of hash struct is: