From b74504ba725bd5842f99bd77554ae69c8efead43 Mon Sep 17 00:00:00 2001
From: Chrono <chrono_cpp@me.com>
Date: Thu, 28 Dec 2023 16:49:25 +0800
Subject: [PATCH] perf(router): reuse ATC context in router match instead of
 creating a new context (#12258)

To avoid frequent memory allocation/deallocations.

KAG-3448
---
 .requirements                                   |  2 +-
 changelog/unreleased/kong/atc_reuse_context.yml |  3 +++
 changelog/unreleased/kong/bump-atc-router.yml   |  3 +++
 kong/router/atc.lua                             | 13 +++++++++----
 kong/router/fields.lua                          |  7 +++----
 5 files changed, 19 insertions(+), 9 deletions(-)
 create mode 100644 changelog/unreleased/kong/atc_reuse_context.yml
 create mode 100644 changelog/unreleased/kong/bump-atc-router.yml

diff --git a/.requirements b/.requirements
index ef36191763a..c7388ffe885 100644
--- a/.requirements
+++ b/.requirements
@@ -10,7 +10,7 @@ LUA_KONG_NGINX_MODULE=4fbc3ddc7dcbc706ed286b95344f3cb6da17e637 # 0.8.0
 LUA_RESTY_LMDB=951926f20b674a0622236a0e331b359df1c02d9b # 1.3.0
 LUA_RESTY_EVENTS=8448a92cec36ac04ea522e78f6496ba03c9b1fd8 # 0.2.0
 LUA_RESTY_WEBSOCKET=60eafc3d7153bceb16e6327074e0afc3d94b1316 # 0.4.0
-ATC_ROUTER=b0d5e7e2a2ca59bb051959385d3e42d96c93bb98 # 1.2.0
+ATC_ROUTER=ac71b24ea5556b38b0f9903850ed666c36ad7843 # 1.4.1
 
 KONG_MANAGER=v3.5.0.0
 NGX_WASM_MODULE=388d5720293f5091ccee1f859a42683fbfd14e7d # prerelease-0.2.0
diff --git a/changelog/unreleased/kong/atc_reuse_context.yml b/changelog/unreleased/kong/atc_reuse_context.yml
new file mode 100644
index 00000000000..3af76d0a2d7
--- /dev/null
+++ b/changelog/unreleased/kong/atc_reuse_context.yml
@@ -0,0 +1,3 @@
+message: "Reuse match copntext between requests to avoid frequent memory allocation/deallocation"
+type: performance
+scope: Core
diff --git a/changelog/unreleased/kong/bump-atc-router.yml b/changelog/unreleased/kong/bump-atc-router.yml
new file mode 100644
index 00000000000..2013fd9dda6
--- /dev/null
+++ b/changelog/unreleased/kong/bump-atc-router.yml
@@ -0,0 +1,3 @@
+message: Bumped atc-router from 1.2.0 to 1.4.1
+type: dependency
+scope: Core
diff --git a/kong/router/atc.lua b/kong/router/atc.lua
index a11ccb112f0..25d95ab0e62 100644
--- a/kong/router/atc.lua
+++ b/kong/router/atc.lua
@@ -4,6 +4,7 @@ local _MT = { __index = _M, }
 
 local buffer = require("string.buffer")
 local schema = require("resty.router.schema")
+local context = require("resty.router.context")
 local router = require("resty.router.router")
 local lrucache = require("resty.lrucache")
 local tb_new = require("table.new")
@@ -35,7 +36,7 @@ local check_select_params  = utils.check_select_params
 local get_service_info     = utils.get_service_info
 local route_match_stat     = utils.route_match_stat
 local get_cache_key        = fields.get_cache_key
-local get_atc_context      = fields.get_atc_context
+local fill_atc_context      = fields.fill_atc_context
 
 
 local DEFAULT_MATCH_LRUCACHE_SIZE = utils.DEFAULT_MATCH_LRUCACHE_SIZE
@@ -223,7 +224,7 @@ local function new_from_scratch(routes, get_exp_and_priority)
   local fields = inst:get_fields()
 
   return setmetatable({
-      schema = CACHED_SCHEMA,
+      context = context.new(CACHED_SCHEMA),
       router = inst,
       routes = routes_t,
       services = services_t,
@@ -412,7 +413,9 @@ function _M:matching(params)
   params.host = host
   params.port = port
 
-  local c, err = get_atc_context(self.schema, self.fields, params)
+  self.context:reset()
+
+  local c, err = fill_atc_context(self.context, self.fields, params)
 
   if not c then
     return nil, err
@@ -552,7 +555,9 @@ function _M:matching(params)
                       params.dst_ip, params.dst_port,
                       sni)
 
-  local c, err = get_atc_context(self.schema, self.fields, params)
+  self.context:reset()
+
+  local c, err = fill_atc_context(self.context, self.fields, params)
   if not c then
     return nil, err
   end
diff --git a/kong/router/fields.lua b/kong/router/fields.lua
index 11e2a09fe95..a33b27c8fcd 100644
--- a/kong/router/fields.lua
+++ b/kong/router/fields.lua
@@ -1,5 +1,4 @@
 local buffer = require("string.buffer")
-local context = require("resty.router.context")
 
 
 local type = type
@@ -288,8 +287,8 @@ local function get_cache_key(fields, params, ctx)
 end
 
 
-local function get_atc_context(schema, fields, params)
-  local c = context.new(schema)
+local function fill_atc_context(context, fields, params)
+  local c = context
 
   local res, err =
   fields_visitor(fields, params, nil, function(field, value)
@@ -354,7 +353,7 @@ end
 
 return {
   get_cache_key = get_cache_key,
-  get_atc_context = get_atc_context,
+  fill_atc_context = fill_atc_context,
 
   _set_ngx = _set_ngx,
 }