Fix user-agent register timing in C++ and Unity SDK (#1217)

Change user-agent register timing in C++

Change to register user-agents before platform App creation so that
the new user-agents can be captured and logged at iOS/Android level.

Also add Android utility `CallAfterEnsureMethodsCached` which is used internally to ensure the callback
is triggered when all necessary Java classes and methods are cached.

Author: chkuang-g

app/src/app_android.cc

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "app/src/app_android.h"
+
 #include <jni.h>
 #include <string.h>
 
@@ -480,6 +482,9 @@ App* App::Create(const AppOptions& options, const char* name, JNIEnv* jni_env,
   }
   LogDebug("Creating Firebase App %s for %s", name, kFirebaseVersionString);
   if (CacheMethods(jni_env, activity)) {
+    // Register C++ user-agents before creating Android app.
+    app_common::RegisterSdkUsage(jni_env);
+
     // Try to get or create a new FirebaseApp object.
     jobject platform_app =
         CreateOrGetPlatformApp(jni_env, options, name, activity);
@@ -527,9 +532,14 @@ static void RegisterLibraryWithVersionRegistrar(JNIEnv* env,
   env->DeleteLocalRef(registrar);
 }
 
-void App::RegisterLibrary(const char* library, const char* version) {
-  RegisterLibraryWithVersionRegistrar(util::GetJNIEnvFromApp(), library,
-                                      version);
+void App::RegisterLibrary(const char* library, const char* version,
+                          void* platform_resource) {
+  FIREBASE_ASSERT(platform_resource);
+
+  // Always relies on platform_resource to get reference to JNIEnv* to reduce
+  // complexity.
+  RegisterLibraryWithVersionRegistrar(
+      reinterpret_cast<JNIEnv*>(platform_resource), library, version);
   app_common::RegisterLibrary(library, version);
 }
 
@@ -570,4 +580,12 @@ JavaVM* App::java_vm() const { return internal_->java_vm(); }
 
 jobject App::GetPlatformApp() const { return internal_->GetLocalRef(); }
 
+void CallAfterEnsureMethodsCached(JNIEnv* env, jobject activity,
+                                  std::function<void()> callback) {
+  if (CacheMethods(env, activity)) {
+    callback();
+    ReleaseClasses(env);
+  }
+}
+
 }  // namespace firebase

app/src/app_android.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FIREBASE_APP_SRC_APP_ANDROID_H_
+#define FIREBASE_APP_SRC_APP_ANDROID_H_
+
+#include <jni.h>
+
+#include <functional>
+
+namespace firebase {
+// Make sure the Java classes and methods are cached before triggering the
+// the callback. Can be slow if this is called BEFORE any Firebase App is
+// created. This is currently used by Unity SDK.
+void CallAfterEnsureMethodsCached(JNIEnv* env, jobject activity,
+                                  std::function<void()> callback);
+}  // namespace firebase
+
+#endif  // FIREBASE_APP_SRC_APP_ANDROID_H_

app/src/app_common.cc

@@ -190,7 +190,7 @@ struct AppData {
 // Tracks library registrations.
 class LibraryRegistry {
  private:
-  LibraryRegistry() {}
+  LibraryRegistry() : is_common_library_registered(false) {}
 
  public:
   // Register a library, returns true if the library version changed.
@@ -252,16 +252,30 @@ class LibraryRegistry {
     }
   }
 
+  static bool IsCommonLibraryRegistered() {
+    if (library_registry_) {
+      return library_registry_->is_common_library_registered;
+    }
+    return false;
+  }
+
+  static void SetCommonLibraryRegistered() {
+    if (library_registry_) {
+      library_registry_->is_common_library_registered = true;
+    }
+  }
+
  private:
   std::map<std::string, std::string> library_to_version_;
   std::string user_agent_;
+  bool is_common_library_registered;
 
   static LibraryRegistry* library_registry_;
 };
 
 // Guards g_apps and g_default_app.
 static Mutex* g_app_mutex = new Mutex();
-static std::map<std::string, UniquePtr<AppData>>* g_apps;
+static std::map<std::string, UniquePtr<AppData>>* g_apps = nullptr;
 static App* g_default_app = nullptr;
 LibraryRegistry* LibraryRegistry::library_registry_ = nullptr;
 
@@ -294,21 +308,6 @@ App* AddApp(App* app, std::map<std::string, InitResult>* results) {
         app_options.storage_bucket(), app_options.project_id(),
         static_cast<int>(reinterpret_cast<intptr_t>(app)));
   }
-  LibraryRegistry::Initialize();
-  if (created_first_app) {
-    // This calls the platform specific method to propagate the registration to
-    // any SDKs in use by this library.
-    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX,
-                         FIREBASE_VERSION_NUMBER_STRING);
-    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-os",
-                         kOperatingSystem);
-    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-arch",
-                         kCpuArchitecture);
-    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-stl",
-                         kCppRuntimeOrStl);
-    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-buildsrc",
-                         kBuildSource);
-  }
   callback::Initialize();
   AppCallback::NotifyAllAppCreated(app, results);
   return app;
@@ -433,6 +432,28 @@ void RegisterLibrariesFromUserAgent(const char* user_agent) {
   if (changed) registry->UpdateUserAgent();
 }
 
+void RegisterSdkUsage(void* platform_resource) {
+  MutexLock lock(*g_app_mutex);
+
+  // Only register libraries when no C++ apps was created before.
+  if (!LibraryRegistry::IsCommonLibraryRegistered()) {
+    LibraryRegistry::Initialize();
+    // This calls the platform specific method to propagate the registration to
+    // any SDKs in use by this library.
+    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX,
+                         FIREBASE_VERSION_NUMBER_STRING, platform_resource);
+    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-os", kOperatingSystem,
+                         platform_resource);
+    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-arch",
+                         kCpuArchitecture, platform_resource);
+    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-stl",
+                         kCppRuntimeOrStl, platform_resource);
+    App::RegisterLibrary(FIREBASE_CPP_USER_AGENT_PREFIX "-buildsrc",
+                         kBuildSource, platform_resource);
+    LibraryRegistry::SetCommonLibraryRegistered();
+  }
+}
+
 const char* GetUserAgent() {
   MutexLock lock(*g_app_mutex);
   return LibraryRegistry::Initialize()->GetUserAgent();

app/src/app_common.h

@@ -80,6 +80,10 @@ void RegisterLibrary(const char* library, const char* version);
 // This is useful when this SDK wraps other SDKs.
 void RegisterLibrariesFromUserAgent(const char* user_agent);
 
+// Register all user-agents related to C++ SDK usages.
+// platform_resource currently is only used for passing JNIEnv on Android
+void RegisterSdkUsage(void* platform_resource);
+
 // Get the user agent string for all registered libraries.
 // This is not thread safe w.r.t RegisterLibrary().
 // NOTE: This is an internal method, use App::UserAgent() instead.

app/src/app_desktop.cc

@@ -137,6 +137,9 @@ App* App::Create(const AppOptions& options, const char* name) {  // NOLINT
 
   AppOptions options_with_defaults = options;
   if (options_with_defaults.PopulateRequiredWithDefaults()) {
+    // Register C++/Unity user-agents
+    app_common::RegisterSdkUsage(nullptr);
+
     app = new App();
     app->name_ = name;
     app->options_ = options_with_defaults;
@@ -168,7 +171,8 @@ internal::FunctionRegistry* App::function_registry() {
 }
 #endif  // INTERNAL_EXPERIMENTAL
 
-void App::RegisterLibrary(const char* library, const char* version) {
+void App::RegisterLibrary(const char* library, const char* version,
+                          void* /* platform_resource */) {
   app_common::RegisterLibrary(library, version);
 }
 

app/src/app_ios.mm

@@ -252,6 +252,10 @@ static void PlatformOptionsToAppOptions(FIROptions* platform_options, AppOptions
     LogError("App %s already created, options will not be applied.", name);
     return app;
   }
+
+  // Register C++/Unity user-agents before creating iOS app.
+  app_common::RegisterSdkUsage(nullptr);
+
   LogDebug("Creating Firebase App %s for %s", name, kFirebaseVersionString);
   app = new App();
   app->options_ = options;
@@ -277,7 +281,7 @@ static void PlatformOptionsToAppOptions(FIROptions* platform_options, AppOptions
 
 App* App::GetInstance(const char* name) { return app_common::FindAppByName(name); }
 
-void App::RegisterLibrary(const char* library, const char* version) {
+void App::RegisterLibrary(const char* library, const char* version, void* /* platform_resource */) {
   [FIRApp registerLibrary:@(library) withVersion:@(version)];
   app_common::RegisterLibrariesFromUserAgent(
       util::NSStringToString([FIRApp firebaseUserAgent]).c_str());

app/src/app_stub.cc

@@ -72,7 +72,8 @@ internal::FunctionRegistry* App::function_registry() {
 }
 #endif
 
-void App::RegisterLibrary(const char* library, const char* version) {
+void App::RegisterLibrary(const char* library, const char* version,
+                          void* /* platform_resource */) {
   app_common::RegisterLibrary(library, version);
 }
 

app/src/include/firebase/app.h

@@ -697,7 +697,10 @@ class App {
   /// @param library Name of the library to register as a user of the Firebase
   /// C++ SDK.
   /// @param version Version of the library being registered.
-  static void RegisterLibrary(const char* library, const char* version);
+  /// @param platform_resource Platform specific resource. Ex. for Android, this
+  /// is JNIEnv.
+  static void RegisterLibrary(const char* library, const char* version,
+                              void* platform_resource);
 
   // Internal method to retrieve the combined string of registered libraries.
   static const char* GetUserAgent();

app/src/util_android.h

@@ -1126,7 +1126,6 @@ jint AttachCurrentThread(JavaVM* java_vm, JNIEnv** env);
 // firebase::App, either the default App (if it exists) or any valid
 // App. If there is no instantiated App, returns nullptr.
 JNIEnv* GetJNIEnvFromApp();
-
 }  // namespace util
 // NOLINTNEXTLINE - allow namespace overridden
 }  // namespace firebase

app/tests/app_test.cc

@@ -498,7 +498,12 @@ TEST_F(AppTest, TestRegisterLibrary) {
               ContainsRegex("fire-cpp-arch/[^ ]+"));
   EXPECT_THAT(std::string(App::GetUserAgent()),
               ContainsRegex("fire-cpp-stl/[^ ]+"));
-  App::RegisterLibrary("fire-testing", "1.2.3");
+#if FIREBASE_PLATFORM_ANDROID
+  App::RegisterLibrary("fire-testing", "1.2.3",
+                       firebase_app_default->GetJNIEnv());
+#else
+  App::RegisterLibrary("fire-testing", "1.2.3", nullptr);
+#endif
   EXPECT_THAT(std::string(App::GetUserAgent()),
               HasSubstr("fire-testing/1.2.3"));
   firebase_app_default.reset(nullptr);