| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * |
| * 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.android.server.location; |
| |
| import com.android.internal.util.Preconditions; |
| |
| import android.annotation.NonNull; |
| import android.os.IBinder; |
| import android.os.IInterface; |
| import android.os.RemoteException; |
| import android.util.Log; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.HashMap; |
| |
| /** |
| * A helper class, that handles operations in remote listeners, and tracks for remote process death. |
| */ |
| abstract class RemoteListenerHelper<TListener extends IInterface> { |
| private final String mTag; |
| private final HashMap<IBinder, LinkedListener> mListenerMap = |
| new HashMap<IBinder, LinkedListener>(); |
| |
| protected RemoteListenerHelper(String name) { |
| Preconditions.checkNotNull(name); |
| mTag = name; |
| } |
| |
| public boolean addListener(@NonNull TListener listener) { |
| Preconditions.checkNotNull(listener, "Attempted to register a 'null' listener."); |
| if (!isSupported()) { |
| Log.e(mTag, "Refused to add listener, the feature is not supported."); |
| return false; |
| } |
| |
| IBinder binder = listener.asBinder(); |
| LinkedListener deathListener = new LinkedListener(listener); |
| synchronized (mListenerMap) { |
| if (mListenerMap.containsKey(binder)) { |
| // listener already added |
| return true; |
| } |
| |
| try { |
| binder.linkToDeath(deathListener, 0 /* flags */); |
| } catch (RemoteException e) { |
| // if the remote process registering the listener is already death, just swallow the |
| // exception and continue |
| Log.e(mTag, "Remote listener already died.", e); |
| return false; |
| } |
| |
| mListenerMap.put(binder, deathListener); |
| if (mListenerMap.size() == 1) { |
| if (!registerWithService()) { |
| Log.e(mTag, "RegisterWithService failed, listener will be removed."); |
| removeListener(listener); |
| return false; |
| } |
| } |
| } |
| |
| return true; |
| } |
| |
| public boolean removeListener(@NonNull TListener listener) { |
| Preconditions.checkNotNull(listener, "Attempted to remove a 'null' listener."); |
| if (!isSupported()) { |
| Log.e(mTag, "Refused to remove listener, the feature is not supported."); |
| return false; |
| } |
| |
| IBinder binder = listener.asBinder(); |
| LinkedListener linkedListener; |
| synchronized (mListenerMap) { |
| linkedListener = mListenerMap.remove(binder); |
| if (mListenerMap.isEmpty() && linkedListener != null) { |
| unregisterFromService(); |
| } |
| } |
| |
| if (linkedListener != null) { |
| binder.unlinkToDeath(linkedListener, 0 /* flags */); |
| } |
| return true; |
| } |
| |
| protected abstract boolean isSupported(); |
| protected abstract boolean registerWithService(); |
| protected abstract void unregisterFromService(); |
| |
| protected interface ListenerOperation<TListener extends IInterface> { |
| void execute(TListener listener) throws RemoteException; |
| } |
| |
| protected void foreach(ListenerOperation operation) { |
| Collection<LinkedListener> linkedListeners; |
| synchronized (mListenerMap) { |
| Collection<LinkedListener> values = mListenerMap.values(); |
| linkedListeners = new ArrayList<LinkedListener>(values); |
| } |
| |
| for (LinkedListener linkedListener : linkedListeners) { |
| TListener listener = linkedListener.getUnderlyingListener(); |
| try { |
| operation.execute(listener); |
| } catch (RemoteException e) { |
| Log.e(mTag, "Error in monitored listener.", e); |
| removeListener(listener); |
| } |
| } |
| } |
| |
| private class LinkedListener implements IBinder.DeathRecipient { |
| private final TListener mListener; |
| |
| public LinkedListener(@NonNull TListener listener) { |
| mListener = listener; |
| } |
| |
| @NonNull |
| public TListener getUnderlyingListener() { |
| return mListener; |
| } |
| |
| @Override |
| public void binderDied() { |
| Log.d(mTag, "Remote Listener died: " + mListener); |
| removeListener(mListener); |
| } |
| } |
| } |