Heartbeat logging passthrough for Auth on Mobile Platforms (#846)

When GetAuth is called, guarantee that the underlying native getter for Auth is also called so that any usage logging related to the native SDK is triggered.

* Minor changes based on review feedback

* Minor syntax fixes for android and ios LogHeartbeat

* Fix related to visibility of auth_data_ in LogHeartbeat

Author: AlmostMatt

auth/src/android/auth_android.cc

@@ -309,6 +309,17 @@ void Auth::DestroyPlatformAuth(AuthData* auth_data) {
   }
 }
 
+void LogHeartbeat(Auth* auth) {
+  // Calling the native getter is sufficient to cause a Heartbeat to be logged.
+  JNIEnv* env = Env(auth->auth_data_);
+  jobject platform_app = auth->app().GetPlatformApp();
+  jobject j_auth_impl = env->CallStaticObjectMethod(
+      auth::GetClass(), auth::GetMethodId(auth::kGetInstance), platform_app);
+  util::CheckAndClearJniExceptions(env);
+  env->DeleteLocalRef(j_auth_impl);
+  env->DeleteLocalRef(platform_app);
+}
+
 JNIEXPORT void JNICALL JniAuthStateListener_nativeOnAuthStateChanged(
     JNIEnv* env, jobject clazz, jlong callback_data) {
   AuthData* auth_data = reinterpret_cast<AuthData*>(callback_data);

auth/src/auth.cc

@@ -68,6 +68,9 @@ Auth* Auth::GetAuth(App* app, InitResult* init_result_out) {
   Auth* existing_auth = FindAuth(app);
   if (existing_auth) {
     if (init_result_out != nullptr) *init_result_out = kInitResultSuccess;
+    // Log heartbeat data when instance getters are called.
+    // See go/firebase-platform-logging-design for more information.
+    LogHeartbeat(existing_auth);
     return existing_auth;
   }
 

auth/src/common.h

@@ -39,6 +39,10 @@ void InitPlatformAuth(AuthData* auth_data);
 // Platform-specific method to destroy the wrapped Auth class.
 void DestroyPlatformAuth(AuthData* auth_data);
 
+// Platform-specific method that causes a heartbeat to be logged.
+// See go/firebase-platform-logging-design for more information.
+void LogHeartbeat(Auth* auth);
+
 // All the result functions are similar.
 // Just return the local Future, cast to the proper result type.
 #define AUTH_RESULT_FN(class_name, fn_name, result_type)                  \

auth/src/desktop/auth_desktop.cc

@@ -94,6 +94,10 @@ void* CreatePlatformAuth(App* const app) {
 void InitializeFunctionRegistryListener(AuthData* auth_data);
 void DestroyFunctionRegistryListener(AuthData* auth_data);
 
+// TODO(b/211006737): This is a stub until desktop implementation supports
+// heartbeat logging.
+void LogHeartbeat(Auth* const auth) {}
+
 IdTokenRefreshListener::IdTokenRefreshListener() : token_timestamp_(0) {}
 
 IdTokenRefreshListener::~IdTokenRefreshListener() {}

auth/src/include/firebase/auth.h

@@ -532,6 +532,7 @@ class Auth {
   friend void EnableTokenAutoRefresh(AuthData* authData);
   friend void DisableTokenAutoRefresh(AuthData* authData);
   friend void ResetTokenRefreshCounter(AuthData* authData);
+  friend void LogHeartbeat(Auth* auth);
   /// @endcond
 
   // Find Auth instance using App.  Return null if the instance does not exist.

auth/src/ios/auth_ios.mm

@@ -223,6 +223,11 @@ void UpdateCurrentUser(AuthData *auth_data) {
   auth_data->auth_impl = nullptr;
 }
 
+void LogHeartbeat(Auth *auth) {
+  // Calling the native getter is sufficient to cause a Heartbeat to be logged.
+  [FIRAuth authWithApp:auth->app().GetPlatformApp()];
+}
+
 Future<Auth::FetchProvidersResult> Auth::FetchProvidersForEmail(const char *email) {
   // Create data structure to hold asynchronous results.
   FetchProvidersResult initial_data;