[core] Inline api_is_connected() for hot-path callers (#15888)

esphome/core/util.cpp

@@ -1,28 +1,14 @@
 #include "esphome/core/util.h"
-#include "esphome/core/defines.h"
 #include "esphome/core/application.h"
 #include "esphome/core/version.h"
 #include "esphome/core/log.h"
 
-#ifdef USE_API
-#include "esphome/components/api/api_server.h"
-#endif
-
 #ifdef USE_MQTT
 #include "esphome/components/mqtt/mqtt_client.h"
 #endif
 
 namespace esphome {
 
-bool api_is_connected() {
-#ifdef USE_API
-  if (api::global_api_server != nullptr) {
-    return api::global_api_server->is_connected();
-  }
-#endif
-  return false;
-}
-
 bool mqtt_is_connected() {
 #ifdef USE_MQTT
   if (mqtt::global_mqtt_client != nullptr) {

esphome/core/util.h

@@ -1,10 +1,28 @@
 #pragma once
 
 #include <string>
+
+#include "esphome/core/defines.h"
+#include "esphome/core/helpers.h"
+
+#ifdef USE_API
+#include "esphome/components/api/api_server.h"
+#endif
+
 namespace esphome {
 
-/// Return whether the node has at least one client connected to the native API
-bool api_is_connected();
+/// Return whether the node has at least one client connected to the native API.
+///
+/// Inline so that hot-path callers (e.g. component loop() ticks that check connectivity every
+/// iteration) can skip the call8/return pair. With USE_API disabled this trivially returns false
+/// and collapses at compile time.
+#ifdef USE_API
+ESPHOME_ALWAYS_INLINE inline bool api_is_connected() {
+  return api::global_api_server != nullptr && api::global_api_server->is_connected();
+}
+#else
+ESPHOME_ALWAYS_INLINE inline bool api_is_connected() { return false; }
+#endif
 
 /// Return whether the node has an active connection to an MQTT broker
 bool mqtt_is_connected();