Name

lua-resty-transaction-queue - Lua Transaction Queue for the ngx_lua

Status

Description

This Lua library is a Transaction Queue for the ngx_lua nginx module:

https://github.com/openresty/lua-nginx-module/#readme

This module is a priority message queue for request processing. When Nginx receives a request, the request can be assigned a priority (1 ~ 10), and it will be dispatched to the message queue with the priority correspondingly. Each Nginx worker has a timer, and the timer will fetch the request from the priority message queue regularly and call the user-defined callback function to process the request. Low priority requests are processed only after high priority requests have been processed.

Synopsis

    lua_package_path "/path/to/lua-resty-transaction-queue/lib/?.lua;;";
    init_worker_by_lua_file transaction_queue_init.lua;

    server {
      set_by_lua_file $queue_size transaction_queue_set.lua 10;

      location /test {
        set $queue_priority 9;
        set $queue_handler "xxx";
        content_by_lua_file transaction_queue_handle.lua;
      }
    }

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Usage

Transaction Queue will register a timer during initialization for each Nginx worker. When Nginx receives a requests, the request will be dispatched to the transaction queue and respond user immediately. After that, the request will be processed asynchronously by the timer with the user-defined callback function. User should configure the callback function and the priority for each request, and user can also configure the transaction queue, such as queue size, etc.

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Setting Transation Queue

Setting Package Path

syntax: lua_package_path "/path/to/lua-resty-tm/lib/?.lua;;";

context: http

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Setting Init Method

syntax: init_worker_by_lua_file transaction_queue_init.lua;

context: http

phase: starting-worker

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Setting Queue Size

syntax: set_by_lua_file $queue_size transaction_queue_set.lua 10;

context: server, server if, location, location if

phase: rewrite

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Setting Request Priority

syntax: set $queue_priority 9;

context: location, location if

phase: rewrite

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Setting Request Callback

syntax: set $queue_handler "xxx";

context: location, location if

phase: rewrite

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Setting Request Handle

syntax: content_by_lua_file transaction_queue_handle.lua;

context: location, location if

phase: content

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Developing Request Callback

The Callback Module need return a table, which mush include an execute method.

The definition of execute method is:

  function _M.execute(task)
  end

  The type of parameter task is table, which include two kv pairs, as follows:
  {
    uri：ngx.var.uri,
    args：ngx.req.get_uri_args(),
  }

The Callback Module Example:

  local _M = { VERSION = '0.0.1' }
  local log = ngx.log
  local NOTICE = ngx.NOTICE

  function _M.execute(task)
    log(NOTICE, "uri:", task.uri)
    for k, v in pairs(task.args) do
    log(NOTICE, "task args, k:", k, ", value:", v)
    end
  end

  return _M