WEB Carrier Counters + Status

Co-Authored-By: brekotis <93345790+brekotis@users.noreply.github.com>

src/config/hot_reload/fields.rs

@@ -345,15 +345,22 @@ pub(super) fn overlay_hot_fields(old: &ProxyConfig, new: &ProxyConfig) -> ProxyC
     let process_limits = cfg.web.limits.clone();
     cfg.web = new.web.clone();
     cfg.web.limits = process_limits;
+    if cfg.web.carrier_negotiation_enabled()
+        && cfg.web.carrier_learning
+        && cfg.web.limits.max_carrier_learning_entries < WEB_CARRIER_LEARNING_MIN_ENTRIES
+    {
+        if old.web.carrier_learning != new.web.carrier_learning {
+            cfg.web.carrier_learning = old.web.carrier_learning;
+        } else {
+            cfg.web.carriers = old.web.carriers.clone();
+        }
+    }
     if !web_debug_fits_limits(&cfg.web.debug, &cfg.web.limits) {
         cfg.web.debug = old.web.debug.clone();
     }
     if cfg.rebuild_runtime_user_auth().is_err() {
         cfg.runtime_user_auth = None;
     }
-    if cfg.rebuild_runtime_web().is_err() {
-        cfg.web = old.web.clone();
-    }
 
     cfg
 }

src/config/hot_reload/tests.rs

@@ -123,6 +123,47 @@ fn web_debug_policy_is_hot_while_debug_capacity_is_process_owned() {
     );
 }
 
+#[test]
+fn hot_overlay_defers_learning_that_requires_new_process_capacity() {
+    let mut old = sample_config();
+    old.web.limits.max_carrier_learning_entries = 1;
+    old.web.carriers = crate::config::WebCarriers::Disabled;
+    old.web.carrier_learning = false;
+    let mut new = old.clone();
+    new.web.limits.max_carrier_learning_entries = 3;
+    new.web.carriers = crate::config::WebCarriers::Enabled(vec![
+        crate::config::WebCarrier::Websocket,
+        crate::config::WebCarrier::Https,
+    ]);
+    new.web.carrier_learning = true;
+
+    let applied = overlay_hot_fields(&old, &new);
+
+    assert_eq!(applied.web.limits.max_carrier_learning_entries, 1);
+    assert!(applied.web.carrier_negotiation_enabled());
+    assert!(!applied.web.carrier_learning);
+}
+
+#[test]
+fn hot_overlay_defers_carriers_for_dormant_learning_with_small_capacity() {
+    let mut old = sample_config();
+    old.web.limits.max_carrier_learning_entries = 1;
+    old.web.carriers = crate::config::WebCarriers::Disabled;
+    old.web.carrier_learning = true;
+    let mut new = old.clone();
+    new.web.limits.max_carrier_learning_entries = 3;
+    new.web.carriers = crate::config::WebCarriers::Enabled(vec![
+        crate::config::WebCarrier::Websocket,
+        crate::config::WebCarrier::Https,
+    ]);
+
+    let applied = overlay_hot_fields(&old, &new);
+
+    assert_eq!(applied.web.limits.max_carrier_learning_entries, 1);
+    assert!(!applied.web.carrier_negotiation_enabled());
+    assert!(applied.web.carrier_learning);
+}
+
 #[test]
 fn web_debug_prefix_requiring_deferred_capacity_is_not_hot_applied() {
     let old = sample_config();

src/config/hot_reload/watcher.rs

@@ -161,7 +161,17 @@ fn reload_config_with_resolver(
     }
 
     let old_cfg = config_tx.borrow().clone();
-    let applied_cfg = overlay_hot_fields(&old_cfg, &new_cfg);
+    let mut applied_cfg = overlay_hot_fields(&old_cfg, &new_cfg);
+    if let Err(error) = applied_cfg
+        .validate_effective_web()
+        .and_then(|_| applied_cfg.rebuild_runtime_web())
+    {
+        error!(
+            "config reload: effective WEB validation failed: {}; keeping old config",
+            error
+        );
+        return Some(next_manifest);
+    }
     let old_hot = HotFields::from_config(&old_cfg);
     let applied_hot = HotFields::from_config(&applied_cfg);
     let non_hot_changed = !config_equal(&applied_cfg, &new_cfg);