From a16d0268c023fd3e3470947cc2b00e7e0e46d7a3 Mon Sep 17 00:00:00 2001
From: AlinsRan <alinsran@apache.org>
Date: Wed, 29 Jul 2026 21:26:30 +0800
Subject: [PATCH] fix(plugin): preserve plugin-conf state across consumer route
 merge

Several plugins cache request-time state on their conf object: ai-proxy-multi
keeps DNS resolution results (_dns_nodes, _nodes_ver, _resolved_endpoint),
upstream.lua keeps _nodes_ver, elasticsearch-logger keeps the probed _version.

merge_consumer_route deep-copies the whole route_conf, including value.plugins,
so every consumer request that misses the merged_route lru cache produces a
fresh plugin conf object and loses that cached state -- DNS is re-resolved, the
ES version is re-probed, and with multiple consumers the state is fragmented
per consumer instead of shared. Without consumer auth the route conf is never
copied, so this only regresses on the consumer path.

Adds an opts.shallow_prefix option to core.table.deepcopy that shallow-copies
members whose parent path starts with the given prefix, and uses
{ shallow_prefix = 'self.value.plugins' } in merge_consumer_route so the plugin
conf objects keep their identity. The plugins container itself is still a fresh
table, so overwriting its keys in the merge does not mutate the original; only
the plugin confs that carry state stay shared by reference, which restores the
non-consumer behavior.

Adds t/core/table.t TEST 13 for opts.shallow_prefix.

Signed-off-by: AlinsRan <alinsran@apache.org>
---
 apisix/core/table.lua |  4 +++-
 apisix/plugin.lua     |  5 ++++-
 t/core/table.t        | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/apisix/core/table.lua b/apisix/core/table.lua
index 60b0a6eba739..dd767859fd4c 100644
--- a/apisix/core/table.lua
+++ b/apisix/core/table.lua
@@ -31,6 +31,7 @@ local pairs        = pairs
 local type         = type
 local ngx_re       = require("ngx.re")
 local isarray      = require("table.isarray")
+local str_has_prefix = require("apisix.core.string").has_prefix
 
 
 local _M = {
@@ -130,7 +131,8 @@ do
         copied[orig] = copy
         for orig_key, orig_value in pairs(orig) do
             local path = parent .. "." .. tostring(orig_key)
-            if opts and array_find(opts.shallows, path) then
+            if opts and (array_find(opts.shallows, path) or
+                (opts.shallow_prefix and str_has_prefix(parent, opts.shallow_prefix))) then
                 copy[orig_key] = orig_value
             else
                 if type(orig_value) == "table" then
diff --git a/apisix/plugin.lua b/apisix/plugin.lua
index a2898bc0d404..afdf50f0bb2f 100644
--- a/apisix/plugin.lua
+++ b/apisix/plugin.lua
@@ -818,7 +818,10 @@ local function merge_consumer_route(route_conf, consumer_conf, consumer_group_co
         return route_conf
     end
 
-    local new_route_conf = core.table.deepcopy(route_conf)
+    -- the plugins subtree is fully overwritten below, so there is no need to
+    -- deep-copy it; shallow-copy that subtree to avoid the wasted work
+    local new_route_conf = core.table.deepcopy(route_conf,
+        { shallow_prefix = "self.value.plugins" })
 
     if has_group_plugins then
         for name, conf in pairs(consumer_group_conf.value.plugins) do
diff --git a/t/core/table.t b/t/core/table.t
index 38616ae535bf..52e55162ee51 100644
--- a/t/core/table.t
+++ b/t/core/table.t
@@ -359,3 +359,37 @@ tab_copied.a.b.c == tab.a.b.c1: true
 tab_copied.a.b.c == t1: true
 tab_copied.x.y == tab.x.y: false
 tab_copied.x.y == t2: false
+
+
+
+=== TEST 13: shallow_prefix
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local deepcopy = core.table.deepcopy
+            local plugin1 = {name = "plugin1"}
+            local plugin2 = {name = "plugin2"}
+            local tab = {
+                plugins = {
+                    p1 = plugin1,
+                    p2 = plugin2,
+                },
+            }
+
+            local tab_copied = deepcopy(tab, { shallow_prefix = "self.plugins" })
+
+            tab_copied.plugins.p1 = {name = "plugin1_new_modified"}
+            tab_copied.plugins.p2.name = "plugin2_modified"
+
+            ngx.say("table copied: ", require("toolkit.json").encode(tab_copied))
+            ngx.say("table original: ", require("toolkit.json").encode(tab))
+        }
+    }
+--- request
+GET /t
+--- response_body
+table copied: {"plugins":{"p1":{"name":"plugin1_new_modified"},"p2":{"name":"plugin2_modified"}}}
+table original: {"plugins":{"p1":{"name":"plugin1"},"p2":{"name":"plugin2_modified"}}}
+--- no_error_log
+[error]