ngxshareddict.md

ngx.shared.DICT

语法: dict = ngx.shared.DICT

语法: dict = ngx.shared[name_var]

环境: init_by_lua*, init_worker_by_lua*, set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*

获取基于共享内存名为 DICT 的 Lua 字典对象，它是一个共享内存区块，通过 lua_shared_dict 指令定义。

所有共享内存区块均被当前 nginx 服务器实例的所有 nginx worker 进程共享。

获取的 dict 对象有如下方法：

• get
• get_stale
• set
• safe_set
• add
• safe_add
• replace
• delete
• incr
• flush_all
• flush_expired
• get_keys

例如：

 http {
     lua_shared_dict dogs 10m;
     server {
         location /set {
             content_by_lua '
                 local dogs = ngx.shared.dogs
                 dogs:set("Jim", 8)
                 ngx.say("STORED")
             ';
         }
         location /get {
             content_by_lua '
                 local dogs = ngx.shared.dogs
                 ngx.say(dogs:get("Jim"))
             ';
         }
     }
 }

测试结果如下：

 $ curl localhost/set
 STORED

 $ curl localhost/get
 8

 $ curl localhost/get
 8

当访问 /get 时，无论有多少 Nginx worker 进程，将一直输出数字 8，因为 dogs 字典存储在共享内存中，对 所有 worker 进程可见。

当服务器配置重新加载时共享内存字典内容不会丢失 (不管是通过送 HUP 信号给 Nginx 进程或使用命令行 -s reload 属性)。

但是，当 Nginx 服务器退出时，字典存储内容将丢失。

这个功能最早出现在 v0.3.1rc22 版本中。

English Source

syntax: dict = ngx.shared.DICT

syntax: dict = ngx.shared[name_var]

context: init_by_lua*, init_worker_by_lua*, set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*

Fetching the shm-based Lua dictionary object for the shared memory zone named DICT defined by the lua_shared_dict directive.

Shared memory zones are always shared by all the nginx worker processes in the current nginx server instance.

The resulting object dict has the following methods:

• get
• get_stale
• set
• safe_set
• add
• safe_add
• replace
• delete
• incr
• flush_all
• flush_expired
• get_keys

Here is an example:

 http {
     lua_shared_dict dogs 10m;
     server {
         location /set {
             content_by_lua '
                 local dogs = ngx.shared.dogs
                 dogs:set("Jim", 8)
                 ngx.say("STORED")
             ';
         }
         location /get {
             content_by_lua '
                 local dogs = ngx.shared.dogs
                 ngx.say(dogs:get("Jim"))
             ';
         }
     }
 }

Let us test it:

 $ curl localhost/set
 STORED

 $ curl localhost/get
 8

 $ curl localhost/get
 8

The number 8 will be consistently output when accessing /get regardless of how many Nginx workers there are because the dogs dictionary resides in the shared memory and visible to all of the worker processes.

The shared dictionary will retain its contents through a server config reload (either by sending the HUP signal to the Nginx process or by using the -s reload command-line option).

The contents in the dictionary storage will be lost, however, when the Nginx server quits.

This feature was first introduced in the v0.3.1rc22 release.

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