perf: run the balancer phase in an earlier phase first to avoid alway… (#4629)

Signed-off-by: spacewander <spacewanderlzx@gmail.com>

apisix/balancer.lua

@@ -288,7 +288,6 @@ end
 
 function _M.run(route, ctx, plugin_funcs)
     local server, err
-    local header_changed
 
     if ctx.picked_server then
         -- use the server picked in the access phase
@@ -311,6 +310,7 @@ function _M.run(route, ctx, plugin_funcs)
             return core.response.exit(502)
         end
 
+        local header_changed
         local pass_host = ctx.pass_host
         if pass_host == "node" and balancer.recreate_request then
             local host = server.domain or server.host
@@ -321,13 +321,12 @@ function _M.run(route, ctx, plugin_funcs)
             end
         end
 
-    end
-
         local _, run = plugin_funcs("balancer")
         -- always recreate request as the request may be changed by plugins
         if (run or header_changed) and balancer.recreate_request then
             balancer.recreate_request()
         end
+    end
 
     core.log.info("proxy request to ", server.host, ":", server.port)
 

apisix/init.lua

@@ -321,6 +321,23 @@ local function verify_tls_client(ctx)
 end
 
 
+local function common_phase(phase_name)
+    local api_ctx = ngx.ctx.api_ctx
+    if not api_ctx then
+        return
+    end
+
+    plugin.run_global_rules(api_ctx, api_ctx.global_rules, phase_name)
+
+    if api_ctx.script_obj then
+        script.run(phase_name, api_ctx)
+        return api_ctx, true
+    end
+
+    return plugin.run_plugin(phase_name, nil, api_ctx)
+end
+
+
 function _M.http_access_phase()
     local ngx_ctx = ngx.ctx
 
@@ -501,6 +518,9 @@ function _M.http_access_phase()
 
     set_upstream_headers(api_ctx, server)
 
+    -- run the balancer phase in access phase first to avoid always reinit request
+    common_phase("balancer")
+
     local ref = ctxdump.stash_ngx_ctx()
     core.log.info("stash ngx ctx: ", ref)
     ngx_var.ctx_ref = ref
@@ -546,23 +566,6 @@ function _M.grpc_access_phase()
 end
 
 
-local function common_phase(phase_name)
-    local api_ctx = ngx.ctx.api_ctx
-    if not api_ctx then
-        return
-    end
-
-    plugin.run_global_rules(api_ctx, api_ctx.global_rules, phase_name)
-
-    if api_ctx.script_obj then
-        script.run(phase_name, api_ctx)
-        return api_ctx, true
-    end
-
-    return plugin.run_plugin(phase_name, nil, api_ctx)
-end
-
-
 local function set_resp_upstream_status(up_status)
     core.response.set_header("X-APISIX-Upstream-Status", up_status)
     core.log.info("X-APISIX-Upstream-Status: ", up_status)
@@ -909,6 +912,9 @@ function _M.stream_preread_phase()
     end
 
     api_ctx.picked_server = server
+
+    -- run the balancer phase in preread phase first to avoid always reinit request
+    common_phase("balancer")
 end