Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package com.android.contacts.util.concurrent; |
| 17 | |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 18 | import android.content.BroadcastReceiver; |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 19 | import android.content.Context; |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 20 | import android.content.Intent; |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 21 | import android.content.IntentFilter; |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 22 | import android.content.Loader; |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 23 | import android.support.v4.content.LocalBroadcastManager; |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 24 | import android.util.Log; |
| 25 | |
| 26 | import com.google.common.util.concurrent.FutureCallback; |
| 27 | import com.google.common.util.concurrent.Futures; |
| 28 | import com.google.common.util.concurrent.ListenableFuture; |
| 29 | |
| 30 | import java.util.concurrent.CancellationException; |
| 31 | import java.util.concurrent.Executor; |
| 32 | |
| 33 | /** |
| 34 | * Wraps a ListenableFuture for integration with {@link android.app.LoaderManager} |
| 35 | * |
| 36 | * <p>Using a loader ensures that the result is delivered while the receiving component (activity |
| 37 | * or fragment) is resumed and also prevents leaking references these components |
| 38 | * </p> |
| 39 | */ |
| 40 | public abstract class ListenableFutureLoader<D> extends Loader<D> { |
| 41 | private static final String TAG = "FutureLoader"; |
| 42 | |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 43 | private final IntentFilter mReloadFilter; |
| 44 | private final Executor mUiExecutor; |
| 45 | private final LocalBroadcastManager mLocalBroadcastManager; |
| 46 | |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 47 | private ListenableFuture<D> mFuture; |
| 48 | private D mLoadedData; |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 49 | |
| 50 | private BroadcastReceiver mReceiver; |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 51 | |
| 52 | /** |
| 53 | * Stores away the application context associated with context. |
| 54 | * Since Loaders can be used across multiple activities it's dangerous to |
| 55 | * store the context directly; always use {@link #getContext()} to retrieve |
| 56 | * the Loader's Context, don't use the constructor argument directly. |
| 57 | * The Context returned by {@link #getContext} is safe to use across |
| 58 | * Activity instances. |
| 59 | * |
| 60 | * @param context used to retrieve the application context. |
| 61 | */ |
| 62 | public ListenableFutureLoader(Context context) { |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 63 | this(context, null); |
| 64 | } |
| 65 | |
| 66 | public ListenableFutureLoader(Context context, IntentFilter reloadBroadcastFilter) { |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 67 | super(context); |
| 68 | mUiExecutor = ContactsExecutors.newUiThreadExecutor(); |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 69 | mReloadFilter = reloadBroadcastFilter; |
| 70 | mLocalBroadcastManager = LocalBroadcastManager.getInstance(context); |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 71 | } |
| 72 | |
| 73 | @Override |
| 74 | protected void onStartLoading() { |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 75 | if (mReloadFilter != null && mReceiver == null) { |
| 76 | mReceiver = new ForceLoadReceiver(); |
| 77 | mLocalBroadcastManager.registerReceiver(mReceiver, mReloadFilter); |
| 78 | } |
| 79 | |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 80 | if (mLoadedData != null) { |
| 81 | deliverResult(mLoadedData); |
| 82 | } |
| 83 | if (mFuture == null) { |
| 84 | takeContentChanged(); |
| 85 | forceLoad(); |
| 86 | } else if (takeContentChanged()) { |
| 87 | forceLoad(); |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | @Override |
| 92 | protected void onForceLoad() { |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 93 | mFuture = loadData(); |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 94 | Futures.addCallback(mFuture, new FutureCallback<D>() { |
| 95 | @Override |
| 96 | public void onSuccess(D result) { |
Marcus Hagerott | 9a679e7 | 2016-12-15 09:30:17 -0800 | [diff] [blame] | 97 | if (mLoadedData == null || !isSameData(mLoadedData, result)) { |
| 98 | deliverResult(result); |
| 99 | } |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 100 | mLoadedData = result; |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 101 | commitContentChanged(); |
| 102 | } |
| 103 | |
| 104 | @Override |
| 105 | public void onFailure(Throwable t) { |
| 106 | if (t instanceof CancellationException) { |
| 107 | Log.i(TAG, "Loading cancelled", t); |
| 108 | rollbackContentChanged(); |
| 109 | } else { |
| 110 | Log.e(TAG, "Failed to load accounts", t); |
| 111 | } |
| 112 | } |
| 113 | }, mUiExecutor); |
| 114 | } |
| 115 | |
| 116 | @Override |
| 117 | protected void onStopLoading() { |
| 118 | if (mFuture != null) { |
| 119 | mFuture.cancel(false); |
| 120 | mFuture = null; |
| 121 | } |
| 122 | } |
| 123 | |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 124 | @Override |
| 125 | protected void onReset() { |
| 126 | mFuture = null; |
| 127 | mLoadedData = null; |
Marcus Hagerott | 75895e7 | 2016-12-12 17:21:57 -0800 | [diff] [blame] | 128 | if (mReceiver != null) { |
| 129 | mLocalBroadcastManager.unregisterReceiver(mReceiver); |
| 130 | } |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 131 | } |
| 132 | |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 133 | protected abstract ListenableFuture<D> loadData(); |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 134 | |
Marcus Hagerott | 9a679e7 | 2016-12-15 09:30:17 -0800 | [diff] [blame] | 135 | /** |
| 136 | * Returns whether the newly loaded data is the same as the cached value |
| 137 | * |
| 138 | * <p>This allows subclasses to suppress delivering results when the data hasn't |
| 139 | * actually changed. By default it will always return false. |
| 140 | * </p> |
| 141 | */ |
| 142 | protected boolean isSameData(D previousData, D newData) { |
| 143 | return false; |
| 144 | } |
| 145 | |
| 146 | public final D getLoadedData() { |
| 147 | return mLoadedData; |
| 148 | } |
| 149 | |
Marcus Hagerott | e7a71cb | 2016-12-09 16:26:14 -0800 | [diff] [blame] | 150 | public class ForceLoadReceiver extends BroadcastReceiver { |
| 151 | @Override |
| 152 | public void onReceive(Context context, Intent intent) { |
| 153 | onContentChanged(); |
| 154 | } |
| 155 | } |
Marcus Hagerott | 04be88c | 2016-12-07 09:55:03 -0800 | [diff] [blame] | 156 | } |