xds: deprecate flag report_load_with_rq_issued and remove legacy code paths (#41614)

## Description

This PR removes the deprecated reloadable flag
`report_load_with_rq_issued` and cleans up the legacy paths.

Fix #41509

---

**Commit Message:** router: deprecate flag report_load_with_rq_issued
and remove legacy code paths
**Additional Description:** Remove the deprecated reloadable flag
`report_load_with_rq_issued` and cleans up the legacy paths.
**Risk Level:** Low
**Testing:** CI
**Docs Changes:** N/A
**Release Notes:** Added

Signed-off-by: Rohit Agrawal <[email protected]>

Author: agrawroh

changelogs/current.yaml

@@ -60,6 +60,9 @@ removed_config_or_runtime:
 - area: http
   change: |
     Removed runtime guard ``envoy.reloadable_features.original_src_fix_port_exhaustion`` and legacy code paths.
+- area: xds
+  change: |
+    Removed runtime guard ``envoy.reloadable_features.report_load_with_rq_issued`` and legacy code paths.
 
 new_features:
 - area: http

source/common/runtime/runtime_features.cc

@@ -66,7 +66,6 @@ RUNTIME_GUARD(envoy_reloadable_features_quic_signal_headers_only_to_http1_backen
 RUNTIME_GUARD(envoy_reloadable_features_quic_upstream_reads_fixed_number_packets);
 RUNTIME_GUARD(envoy_reloadable_features_quic_upstream_socket_use_address_cache_for_read);
 RUNTIME_GUARD(envoy_reloadable_features_reject_empty_trusted_ca_file);
-RUNTIME_GUARD(envoy_reloadable_features_report_load_with_rq_issued);
 RUNTIME_GUARD(envoy_reloadable_features_router_filter_resetall_on_local_reply);
 RUNTIME_GUARD(envoy_reloadable_features_safe_http2_options);
 RUNTIME_GUARD(envoy_reloadable_features_skip_dns_lookup_for_proxied_requests);

source/common/upstream/load_stats_reporter.cc

@@ -145,11 +145,7 @@ void LoadStatsReporter::sendLoadStatsRequest() {
           }
         }
 
-        bool should_send_locality_stats = rq_success + rq_error + rq_active != 0;
-        if (Runtime::runtimeFeatureEnabled(
-                "envoy.reloadable_features.report_load_with_rq_issued")) {
-          should_send_locality_stats = rq_issued != 0;
-        }
+        bool should_send_locality_stats = rq_issued != 0;
         if (should_send_locality_stats) {
           locality_stats.set_total_successful_requests(rq_success);
           locality_stats.set_total_error_requests(rq_error);

test/common/upstream/load_stats_reporter_test.cc

@@ -271,9 +271,7 @@ HostSharedPtr makeTestHost(const std::string& hostname,
 }
 
 void addStats(const HostSharedPtr& host, double a, double b = 0, double c = 0, double d = 0) {
-  if (Runtime::runtimeFeatureEnabled("envoy.reloadable_features.report_load_with_rq_issued")) {
-    host->stats().rq_total_.inc();
-  }
+  host->stats().rq_total_.inc();
   host->stats().rq_success_.inc();
   host->loadMetricStats().add("metric_a", a);
   if (b != 0) {
@@ -426,22 +424,8 @@ TEST_F(LoadStatsReporterTest, EndpointLevelLoadStatsReportingNoUpdate) {
   response_timer_cb_();
 }
 
-class LoadStatsReporterTestWithRqTotal : public LoadStatsReporterTest,
-                                         public testing::WithParamInterface<bool> {
-public:
-  LoadStatsReporterTestWithRqTotal() {
-    scoped_runtime_.mergeValues(
-        {{"envoy.reloadable_features.report_load_with_rq_issued", GetParam() ? "true" : "false"}});
-  }
-  TestScopedRuntime scoped_runtime_;
-};
-
-INSTANTIATE_TEST_SUITE_P(LoadStatsReporterTestWithRqTotal, LoadStatsReporterTestWithRqTotal,
-                         ::testing::Bool());
-
 // Validate that per-locality metrics are aggregated across hosts and included in the load report.
-TEST_P(LoadStatsReporterTestWithRqTotal, UpstreamLocalityStats) {
-  bool expects_rq_total = GetParam();
+TEST_F(LoadStatsReporterTest, UpstreamLocalityStats) {
   EXPECT_CALL(*async_client_, startRaw(_, _, _, _)).WillOnce(Return(&async_stream_));
   expectSendMessage({});
   createLoadStatsReporter();
@@ -479,19 +463,15 @@ TEST_P(LoadStatsReporterTestWithRqTotal, UpstreamLocalityStats) {
     auto expected_locality0_stats = expected_cluster_stats.add_upstream_locality_stats();
     expected_locality0_stats->mutable_locality()->set_region("mars");
     expected_locality0_stats->set_total_successful_requests(3);
-    if (expects_rq_total) {
-      expected_locality0_stats->set_total_issued_requests(3);
-    }
+    expected_locality0_stats->set_total_issued_requests(3);
     addStatExpectation(expected_locality0_stats, "metric_a", 3, 0.88888);
     addStatExpectation(expected_locality0_stats, "metric_b", 2, 1.12345);
     addStatExpectation(expected_locality0_stats, "metric_c", 1, 3.14159);
 
     auto expected_locality1_stats = expected_cluster_stats.add_upstream_locality_stats();
     expected_locality1_stats->mutable_locality()->set_region("jupiter");
     expected_locality1_stats->set_total_successful_requests(1);
-    if (expects_rq_total) {
-      expected_locality1_stats->set_total_issued_requests(1);
-    }
+    expected_locality1_stats->set_total_issued_requests(1);
     addStatExpectation(expected_locality1_stats, "metric_a", 1, 10.01);
     addStatExpectation(expected_locality1_stats, "metric_c", 1, 20.02);
     addStatExpectation(expected_locality1_stats, "metric_d", 1, 30.03);
@@ -504,9 +484,7 @@ TEST_P(LoadStatsReporterTestWithRqTotal, UpstreamLocalityStats) {
   // Traffic between previous request and next response. Previous latched metrics are cleared.
   host1->stats().rq_success_.inc();
 
-  if (expects_rq_total) {
-    host1->stats().rq_total_.inc();
-  }
+  host1->stats().rq_total_.inc();
   host1->loadMetricStats().add("metric_a", 1.41421);
   host1->loadMetricStats().add("metric_e", 2.71828);
 
@@ -524,9 +502,7 @@ TEST_P(LoadStatsReporterTestWithRqTotal, UpstreamLocalityStats) {
     auto expected_locality0_stats = expected_cluster_stats.add_upstream_locality_stats();
     expected_locality0_stats->mutable_locality()->set_region("mars");
     expected_locality0_stats->set_total_successful_requests(1);
-    if (expects_rq_total) {
-      expected_locality0_stats->set_total_issued_requests(1);
-    }
+    expected_locality0_stats->set_total_issued_requests(1);
     addStatExpectation(expected_locality0_stats, "metric_a", 1, 1.41421);
     addStatExpectation(expected_locality0_stats, "metric_e", 1, 2.71828);