From 2073087909ae527ba46cce52e186b60ba2cf2866 Mon Sep 17 00:00:00 2001
From: YuanSheng Wang <membphis@gmail.com>
Date: Tue, 4 Aug 2020 09:30:13 +0800
Subject: [PATCH] perf: used empty table if the user is not enabled any plugin.
 (#1967)

---
 apisix/core.lua   | 1 +
 apisix/init.lua   | 6 +++---
 apisix/plugin.lua | 4 ++--
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/apisix/core.lua b/apisix/core.lua
index 051dae36..1b4ebf42 100644
--- a/apisix/core.lua
+++ b/apisix/core.lua
@@ -38,4 +38,5 @@ return {
     etcd     = require("apisix.core.etcd"),
     http     = require("apisix.core.http"),
     tablepool= require("tablepool"),
+    empty_tab= {},
 }
diff --git a/apisix/init.lua b/apisix/init.lua
index 99f75e2d..da2df142 100644
--- a/apisix/init.lua
+++ b/apisix/init.lua
@@ -451,8 +451,8 @@ function _M.http_access_phase()
         api_ctx.var.upstream_connection = api_ctx.var.http_connection
     end
 
-    local plugins = core.tablepool.fetch("plugins", 32, 0)
-    api_ctx.plugins = plugin.filter(route, plugins)
+    local plugins = plugin.filter(route)
+    api_ctx.plugins = plugins
 
     run_plugin("rewrite", plugins, api_ctx)
     if api_ctx.consumer then
@@ -631,7 +631,7 @@ function _M.http_log_phase()
     end
 
     core.ctx.release_vars(api_ctx)
-    if api_ctx.plugins then
+    if api_ctx.plugins and api_ctx.plugins ~= core.empty_tab then
         core.tablepool.release("plugins", api_ctx.plugins)
     end
 
diff --git a/apisix/plugin.lua b/apisix/plugin.lua
index 2cf5296a..691860d1 100644
--- a/apisix/plugin.lua
+++ b/apisix/plugin.lua
@@ -229,16 +229,16 @@ end
 
 
 function _M.filter(user_route, plugins)
-    plugins = plugins or core.table.new(#local_plugins * 2, 0)
     local user_plugin_conf = user_route.value.plugins
     if user_plugin_conf == nil or
        core.table.nkeys(user_plugin_conf) == 0 then
         if local_conf and local_conf.apisix.enable_debug then
             core.response.set_header("Apisix-Plugins", "no plugin")
         end
-        return plugins
+        return core.empty_tab
     end
 
+    plugins = plugins or core.tablepool.fetch("plugins", 32, 0)
     for _, plugin_obj in ipairs(local_plugins) do
         local name = plugin_obj.name
         local plugin_conf = user_plugin_conf[name]