| /* |
| * Copyright (C) 2016 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.contacts.util.concurrent; |
| |
| import android.content.BroadcastReceiver; |
| import android.content.Context; |
| import android.content.Intent; |
| import android.content.IntentFilter; |
| import android.content.Loader; |
| import android.support.v4.content.LocalBroadcastManager; |
| import android.util.Log; |
| |
| import com.google.common.util.concurrent.FutureCallback; |
| import com.google.common.util.concurrent.Futures; |
| import com.google.common.util.concurrent.ListenableFuture; |
| |
| import java.util.concurrent.CancellationException; |
| import java.util.concurrent.Executor; |
| |
| /** |
| * Wraps a ListenableFuture for integration with {@link android.app.LoaderManager} |
| * |
| * <p>Using a loader ensures that the result is delivered while the receiving component (activity |
| * or fragment) is resumed and also prevents leaking references these components |
| * </p> |
| */ |
| public abstract class ListenableFutureLoader<D> extends Loader<D> { |
| private static final String TAG = "FutureLoader"; |
| |
| private final IntentFilter mReloadFilter; |
| private final Executor mUiExecutor; |
| private final LocalBroadcastManager mLocalBroadcastManager; |
| |
| private ListenableFuture<D> mFuture; |
| private D mLoadedData; |
| |
| private BroadcastReceiver mReceiver; |
| |
| /** |
| * Stores away the application context associated with context. |
| * Since Loaders can be used across multiple activities it's dangerous to |
| * store the context directly; always use {@link #getContext()} to retrieve |
| * the Loader's Context, don't use the constructor argument directly. |
| * The Context returned by {@link #getContext} is safe to use across |
| * Activity instances. |
| * |
| * @param context used to retrieve the application context. |
| */ |
| public ListenableFutureLoader(Context context) { |
| this(context, null); |
| } |
| |
| public ListenableFutureLoader(Context context, IntentFilter reloadBroadcastFilter) { |
| super(context); |
| mUiExecutor = ContactsExecutors.newUiThreadExecutor(); |
| mReloadFilter = reloadBroadcastFilter; |
| mLocalBroadcastManager = LocalBroadcastManager.getInstance(context); |
| } |
| |
| @Override |
| protected void onStartLoading() { |
| if (mReloadFilter != null && mReceiver == null) { |
| mReceiver = new ForceLoadReceiver(); |
| mLocalBroadcastManager.registerReceiver(mReceiver, mReloadFilter); |
| } |
| |
| if (mLoadedData != null) { |
| deliverResult(mLoadedData); |
| } |
| if (mFuture == null) { |
| takeContentChanged(); |
| forceLoad(); |
| } else if (takeContentChanged()) { |
| forceLoad(); |
| } |
| } |
| |
| @Override |
| protected void onForceLoad() { |
| mFuture = loadData(); |
| Futures.addCallback(mFuture, new FutureCallback<D>() { |
| @Override |
| public void onSuccess(D result) { |
| if (mLoadedData == null || !isSameData(mLoadedData, result)) { |
| deliverResult(result); |
| } |
| mLoadedData = result; |
| commitContentChanged(); |
| } |
| |
| @Override |
| public void onFailure(Throwable t) { |
| if (t instanceof CancellationException) { |
| Log.i(TAG, "Loading cancelled", t); |
| rollbackContentChanged(); |
| } else { |
| Log.e(TAG, "Loading failed", t); |
| } |
| } |
| }, mUiExecutor); |
| } |
| |
| @Override |
| protected void onStopLoading() { |
| if (mFuture != null) { |
| mFuture.cancel(false); |
| mFuture = null; |
| } |
| } |
| |
| @Override |
| protected void onReset() { |
| mFuture = null; |
| mLoadedData = null; |
| if (mReceiver != null) { |
| mLocalBroadcastManager.unregisterReceiver(mReceiver); |
| } |
| } |
| |
| protected abstract ListenableFuture<D> loadData(); |
| |
| /** |
| * Returns whether the newly loaded data is the same as the cached value |
| * |
| * <p>This allows subclasses to suppress delivering results when the data hasn't |
| * actually changed. By default it will always return false. |
| * </p> |
| */ |
| protected boolean isSameData(D previousData, D newData) { |
| return false; |
| } |
| |
| public final D getLoadedData() { |
| return mLoadedData; |
| } |
| |
| public class ForceLoadReceiver extends BroadcastReceiver { |
| @Override |
| public void onReceive(Context context, Intent intent) { |
| onContentChanged(); |
| } |
| } |
| } |