| /* |
| * 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.Handler; |
| import android.os.IBinder; |
| import android.os.IInterface; |
| import android.os.RemoteException; |
| import android.util.Log; |
| |
| 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> { |
| protected static final int RESULT_SUCCESS = 0; |
| protected static final int RESULT_NOT_AVAILABLE = 1; |
| protected static final int RESULT_NOT_SUPPORTED = 2; |
| protected static final int RESULT_GPS_LOCATION_DISABLED = 3; |
| protected static final int RESULT_INTERNAL_ERROR = 4; |
| |
| private final Handler mHandler; |
| private final String mTag; |
| |
| private final HashMap<IBinder, LinkedListener> mListenerMap = new HashMap<>(); |
| |
| private boolean mIsRegistered; |
| private boolean mHasIsSupported; |
| private boolean mIsSupported; |
| |
| protected RemoteListenerHelper(Handler handler, String name) { |
| Preconditions.checkNotNull(name); |
| mHandler = handler; |
| mTag = name; |
| } |
| |
| public boolean addListener(@NonNull TListener listener) { |
| Preconditions.checkNotNull(listener, "Attempted to register a 'null' listener."); |
| 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 return |
| Log.v(mTag, "Remote listener already died.", e); |
| return false; |
| } |
| mListenerMap.put(binder, deathListener); |
| |
| // update statuses we already know about, starting from the ones that will never change |
| int result; |
| if (!isAvailableInPlatform()) { |
| result = RESULT_NOT_AVAILABLE; |
| } else if (mHasIsSupported && !mIsSupported) { |
| result = RESULT_NOT_SUPPORTED; |
| } else if (!isGpsEnabled()) { |
| result = RESULT_GPS_LOCATION_DISABLED; |
| } else if (!tryRegister()) { |
| // only attempt to register if GPS is enabled, otherwise we will register once GPS |
| // becomes available |
| result = RESULT_INTERNAL_ERROR; |
| } else if (mHasIsSupported && mIsSupported) { |
| result = RESULT_SUCCESS; |
| } else { |
| // at this point if the supported flag is not set, the notification will be sent |
| // asynchronously in the future |
| return true; |
| } |
| post(listener, getHandlerOperation(result)); |
| } |
| return true; |
| } |
| |
| public void removeListener(@NonNull TListener listener) { |
| Preconditions.checkNotNull(listener, "Attempted to remove a 'null' listener."); |
| IBinder binder = listener.asBinder(); |
| LinkedListener linkedListener; |
| synchronized (mListenerMap) { |
| linkedListener = mListenerMap.remove(binder); |
| if (mListenerMap.isEmpty()) { |
| tryUnregister(); |
| } |
| } |
| if (linkedListener != null) { |
| binder.unlinkToDeath(linkedListener, 0 /* flags */); |
| } |
| } |
| |
| public void onGpsEnabledChanged(boolean enabled) { |
| // handle first the sub-class implementation, so any error in registration can take |
| // precedence |
| handleGpsEnabledChanged(enabled); |
| synchronized (mListenerMap) { |
| if (!enabled) { |
| tryUnregister(); |
| return; |
| } |
| if (mListenerMap.isEmpty()) { |
| return; |
| } |
| if (tryRegister()) { |
| // registration was successful, there is no need to update the state |
| return; |
| } |
| ListenerOperation<TListener> operation = getHandlerOperation(RESULT_INTERNAL_ERROR); |
| foreachUnsafe(operation); |
| } |
| } |
| |
| protected abstract boolean isAvailableInPlatform(); |
| protected abstract boolean isGpsEnabled(); |
| protected abstract boolean registerWithService(); |
| protected abstract void unregisterFromService(); |
| protected abstract ListenerOperation<TListener> getHandlerOperation(int result); |
| protected abstract void handleGpsEnabledChanged(boolean enabled); |
| |
| protected interface ListenerOperation<TListener extends IInterface> { |
| void execute(TListener listener) throws RemoteException; |
| } |
| |
| protected void foreach(ListenerOperation<TListener> operation) { |
| synchronized (mListenerMap) { |
| foreachUnsafe(operation); |
| } |
| } |
| |
| protected void setSupported(boolean value, ListenerOperation<TListener> notifier) { |
| synchronized (mListenerMap) { |
| mHasIsSupported = true; |
| mIsSupported = value; |
| foreachUnsafe(notifier); |
| } |
| } |
| |
| private void foreachUnsafe(ListenerOperation<TListener> operation) { |
| for (LinkedListener linkedListener : mListenerMap.values()) { |
| post(linkedListener.getUnderlyingListener(), operation); |
| } |
| } |
| |
| private void post(TListener listener, ListenerOperation<TListener> operation) { |
| if (operation != null) { |
| mHandler.post(new HandlerRunnable(listener, operation)); |
| } |
| } |
| |
| private boolean tryRegister() { |
| if (!mIsRegistered) { |
| mIsRegistered = registerWithService(); |
| } |
| return mIsRegistered; |
| } |
| |
| private void tryUnregister() { |
| if (!mIsRegistered) { |
| return; |
| } |
| unregisterFromService(); |
| mIsRegistered = false; |
| } |
| |
| 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); |
| } |
| } |
| |
| private class HandlerRunnable implements Runnable { |
| private final TListener mListener; |
| private final ListenerOperation<TListener> mOperation; |
| |
| public HandlerRunnable(TListener listener, ListenerOperation<TListener> operation) { |
| mListener = listener; |
| mOperation = operation; |
| } |
| |
| @Override |
| public void run() { |
| try { |
| mOperation.execute(mListener); |
| } catch (RemoteException e) { |
| Log.v(mTag, "Error in monitored listener.", e); |
| } |
| } |
| } |
| } |