From a36961f9f9953b92e234e95b53d105c5c7d13628 Mon Sep 17 00:00:00 2001
From: WenMing <moonbingbing@gmail.com>
Date: Fri, 18 Jan 2019 11:30:30 +0800
Subject: [PATCH] used table functions of LuaJIT for better performance.

---
 rootfs/etc/nginx/lua/monitor.lua | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/rootfs/etc/nginx/lua/monitor.lua b/rootfs/etc/nginx/lua/monitor.lua
index 2eba36dc3..cefae7335 100644
--- a/rootfs/etc/nginx/lua/monitor.lua
+++ b/rootfs/etc/nginx/lua/monitor.lua
@@ -1,12 +1,16 @@
 local socket = ngx.socket.tcp
 local cjson = require("cjson.safe")
 local assert = assert
+local new_tab = require "table.new"
+local clear_tab = require "table.clear"
+local clone_tab = require "table.clone"
 
-local metrics_batch = {}
 -- if an Nginx worker processes more than (MAX_BATCH_SIZE/FLUSH_INTERVAL) RPS then it will start dropping metrics
 local MAX_BATCH_SIZE = 10000
 local FLUSH_INTERVAL = 1 -- second
 
+local metrics_batch = new_tab(MAX_BATCH_SIZE, 0)
+
 local _M = {}
 
 local function send(payload)
@@ -46,8 +50,8 @@ local function flush(premature)
     return
   end
 
-  local current_metrics_batch = metrics_batch
-  metrics_batch = {}
+  local current_metrics_batch = clone_tab(metrics_batch)
+  clear_tab(metrics_batch)
 
   local payload, err = cjson.encode(current_metrics_batch)
   if not payload then
@@ -66,12 +70,13 @@ function _M.init_worker()
 end
 
 function _M.call()
-  if #metrics_batch >= MAX_BATCH_SIZE then
+  local metrics_size = #metrics_batch
+  if metrics_size >= MAX_BATCH_SIZE then
     ngx.log(ngx.WARN, "omitting metrics for the request, current batch is full")
     return
   end
 
-  table.insert(metrics_batch, metrics())
+  metrics_batch[metrics_size + 1] = metrics()
 end
 
 if _TEST then