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      1 /*
      2  * Copyright (C) 2017 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.compatibility.common.util;
     17 
     18 import android.content.BroadcastReceiver;
     19 import android.content.Context;
     20 import android.content.Intent;
     21 import android.content.IntentFilter;
     22 import android.support.annotation.Nullable;
     23 import android.util.Log;
     24 
     25 import java.util.concurrent.ArrayBlockingQueue;
     26 import java.util.concurrent.BlockingQueue;
     27 import java.util.concurrent.TimeUnit;
     28 
     29 /**
     30  * A receiver that allows caller to wait for the broadcast synchronously. Notice that you should not
     31  * reuse the instance. Usage is typically like this:
     32  * <pre>
     33  *     BlockingBroadcastReceiver receiver = new BlockingBroadcastReceiver(context, "action");
     34  *     try {
     35  *         receiver.register();
     36  *         Intent intent = receiver.awaitForBroadcast();
     37  *         // assert the intent
     38  *     } finally {
     39  *         receiver.unregisterQuietly();
     40  *     }
     41  * </pre>
     42  */
     43 public class BlockingBroadcastReceiver extends BroadcastReceiver {
     44     private static final String TAG = "BlockingBroadcast";
     45 
     46     private static final int DEFAULT_TIMEOUT_SECONDS = 10;
     47 
     48     private final BlockingQueue<Intent> mBlockingQueue;
     49     private final String mExpectedAction;
     50     private final Context mContext;
     51 
     52     public BlockingBroadcastReceiver(Context context, String expectedAction) {
     53         mContext = context;
     54         mExpectedAction = expectedAction;
     55         mBlockingQueue = new ArrayBlockingQueue<>(1);
     56     }
     57 
     58     @Override
     59     public void onReceive(Context context, Intent intent) {
     60         if (mExpectedAction.equals(intent.getAction())) {
     61             mBlockingQueue.add(intent);
     62         }
     63     }
     64 
     65     public void register() {
     66         mContext.registerReceiver(this, new IntentFilter(mExpectedAction));
     67     }
     68 
     69     /**
     70      * Wait until the broadcast and return the received broadcast intent. {@code null} is returned
     71      * if no broadcast with expected action is received within 10 seconds.
     72      */
     73     public @Nullable Intent awaitForBroadcast() {
     74         try {
     75             return mBlockingQueue.poll(DEFAULT_TIMEOUT_SECONDS, TimeUnit.SECONDS);
     76         } catch (InterruptedException e) {
     77             Log.e(TAG, "waitForBroadcast get interrupted: ", e);
     78         }
     79         return null;
     80     }
     81 
     82     public void unregisterQuietly() {
     83         try {
     84             mContext.unregisterReceiver(this);
     85         } catch (Exception ex) {
     86             Log.e(TAG, "Failed to unregister BlockingBroadcastReceiver: ", ex);
     87         }
     88     }
     89 }