Rc realtime (#3730)

* Creates Realtime Http client file. Includes ConfigUpdate Listener & Registration. Also exposes methods to be used by public RC file.

* Creates Realtime Http client file. Includes ConfigUpdate Listener & Registration. Also exposes methods to be used by public RC file.

* Update stream name

* Add copyright info to top of file.

* Update comments

* Format file.

* Creates Realtime Http client file. Includes ConfigUpdate Listener & Registration. Also exposes methods to be used by public RC file.

* Update stream name

* Add copyright info to top of file.

* Update comments

* Format file.

* Moved ConfigUpdateListener and ConfigUpdateListenerRegistration to public level.

* Moved ConfigUpdateListener and ConfigUpdateListenerRegistration to public level.

* Format and update comments

* Uodate api.txt

* Add nonnull and nullable to params

* Change registration to interface.

* Add author

* Update api.txt

* Dependabot High severity alerts (#3734)

* Dependency updates for `smoke-tests`

* Do not attempt to parse empty json files in MetaDataStore (#3735)

* Do not attempt to parse empty json files in MetaDataStore

* Safely delete corrupt files in MetaDataStore

* Disable javadoc for undocumented sdks. (#3738)

* Creates Realtime Http client file. Includes ConfigUpdate Listener & Registration. Also exposes methods to be used by public RC file.

* Reupdate files.

* Make changes based on PR comments;
Make internal ConfigUpdateListenerRegistration non-static to access private listener removal method from outer class.
Add synchonization to listeners set.

* Remove synchronized set and add explicit synchonized to methods.

Co-authored-by: Daymon <[email protected]>
Co-authored-by: Matthew Robertson <[email protected]>
Co-authored-by: Vladimir Kryachko <[email protected]>

Author: 4 people

firebase-config/api.txt

@@ -1,6 +1,15 @@
 // Signature format: 2.0
 package com.google.firebase.remoteconfig {
 
+  public interface ConfigUpdateListener {
+    method public void onError(Exception);
+    method public void onEvent();
+  }
+
+  public interface ConfigUpdateListenerRegistration {
+    method public void remove();
+  }
+
   public class FirebaseRemoteConfig {
     method @NonNull public com.google.android.gms.tasks.Task<java.lang.Boolean> activate();
     method @NonNull public com.google.android.gms.tasks.Task<com.google.firebase.remoteconfig.FirebaseRemoteConfigInfo> ensureInitialized();

firebase-config/src/main/java/com/google/firebase/remoteconfig/ConfigUpdateListener.java

@@ -0,0 +1,37 @@
+// Copyright 2022 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.
+
+package com.google.firebase.remoteconfig;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Event Listener for Realtime config update callbacks.
+ *
+ * @author Quan Pham
+ */
+public interface ConfigUpdateListener {
+  /**
+   * Callback for when a new config has been automatically fetched from the backend. Can be used to
+   * activate the new config.
+   */
+  void onEvent();
+
+  /**
+   * Call back for when an error occurs during Realtime.
+   *
+   * @param error
+   */
+  void onError(@Nonnull Exception error);
+}

firebase-config/src/main/java/com/google/firebase/remoteconfig/ConfigUpdateListenerRegistration.java

@@ -0,0 +1,31 @@
+// Copyright 2022 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.
+
+package com.google.firebase.remoteconfig;
+
+/**
+ * Represents a listener that can be removed by calling remove. This is returned when calling
+ * addOnConfigUpdateListener and should be used when you no longer want to listen for new config
+ * updates. If this is the last listener it will close the Realtime stream.
+ *
+ * @author Quan Pham
+ */
+public interface ConfigUpdateListenerRegistration {
+
+  /**
+   * Removes the listener being tracked by this 'ConfigUpdateListenerRegistration`. After the
+   * initial call, subsequent calls have no effect.
+   */
+  public void remove();
+}

firebase-config/src/main/java/com/google/firebase/remoteconfig/internal/ConfigRealtimeHttpClient.java

@@ -0,0 +1,64 @@
+// Copyright 2022 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.
+
+package com.google.firebase.remoteconfig.internal;
+
+import androidx.annotation.GuardedBy;
+import com.google.firebase.remoteconfig.ConfigUpdateListener;
+import com.google.firebase.remoteconfig.ConfigUpdateListenerRegistration;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+public class ConfigRealtimeHttpClient {
+
+  @GuardedBy("this")
+  private final Set<ConfigUpdateListener> listeners;
+
+  public ConfigRealtimeHttpClient() {
+    listeners = new LinkedHashSet<ConfigUpdateListener>();
+  }
+
+  // Kicks off Http stream listening and autofetch
+  private void beginRealtime() {}
+
+  // Pauses Http stream listening
+  private void pauseRealtime() {}
+
+  public synchronized ConfigUpdateListenerRegistration addRealtimeConfigUpdateListener(
+      ConfigUpdateListener configUpdateListener) {
+    listeners.add(configUpdateListener);
+    beginRealtime();
+    return new ConfigUpdateListenerRegistrationInternal(configUpdateListener);
+  }
+
+  private synchronized void removeRealtimeConfigUpdateListener(ConfigUpdateListener listener) {
+    listeners.remove(listener);
+    if (listeners.isEmpty()) {
+      pauseRealtime();
+    }
+  }
+
+  public class ConfigUpdateListenerRegistrationInternal
+      implements ConfigUpdateListenerRegistration {
+    private final ConfigUpdateListener listener;
+
+    public ConfigUpdateListenerRegistrationInternal(ConfigUpdateListener listener) {
+      this.listener = listener;
+    }
+
+    public void remove() {
+      removeRealtimeConfigUpdateListener(listener);
+    }
+  }
+}