1 /* 2 * Copyright (C) 2014 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 17 package android.hardware.cts.helpers; 18 19 import java.util.HashMap; 20 import java.util.concurrent.CountDownLatch; 21 22 /** 23 * An abstraction on top of {@link CountDownLatch} to synchronize the results of Activities 24 * started by a parent activity. 25 * 26 * It holds a {@link CountDownLatch} latch for each thread that requests synchronization. 27 * 28 * Each thread requests a {@link Latch} to synchronize an Activity that will be started, by invoking 29 * {@link #bindThread()}, this guarantees that a latch is associated with the thread, and the result 30 * can be retrieved. 31 */ 32 public class ActivityResultMultiplexedLatch { 33 private static final String TAG = "ActivityResultMultiplexedLatch"; 34 35 private final HashMap<Integer, Entry> mActivityEntries = new HashMap<Integer, Entry>(); 36 37 /** 38 * A latch for a bound thread. 39 * Applications get an instance by invoking {@link ActivityResultMultiplexedLatch#bindThread()}. 40 */ 41 public class Latch { 42 private Entry mEntry; 43 Latch(Entry entry)44 private Latch(Entry entry) { 45 mEntry = entry; 46 } 47 48 /** 49 * Awaits for the Activity bound to unblock the current thread. 50 * 51 * @return The result code of the Activity executed. 52 */ await()53 public int await() throws InterruptedException { 54 mEntry.latch.await(); 55 return mEntry.resultCode; 56 } 57 58 /** 59 * @return A request code for the bound thread. It can be passed to the Activity to start. 60 */ getRequestCode()61 public int getRequestCode() { 62 return mEntry.requestCode; 63 } 64 } 65 66 /** 67 * A class that represents the state for each thread/Activity being tracked. 68 */ 69 private class Entry { 70 public final CountDownLatch latch = new CountDownLatch(1); 71 public final int requestCode; 72 73 public volatile int resultCode; 74 Entry(int requestCode)75 public Entry(int requestCode) { 76 this.requestCode = requestCode; 77 } 78 } 79 80 /** 81 * Binds a thread with this object. 82 * 83 * @return A request code (or session Id) for the bound thread. 84 */ bindThread()85 public Latch bindThread() { 86 Entry entry; 87 int requestCode = getRequestCode(); 88 89 synchronized (mActivityEntries) { 90 if (mActivityEntries.containsKey(requestCode)) { 91 throw new IllegalStateException("The thread has already been bound."); 92 } 93 entry = new Entry(requestCode); 94 mActivityEntries.put(requestCode, entry); 95 } 96 97 return new Latch(entry); 98 } 99 100 /** 101 * Used by the owner of the instance to record an Activity's result. 102 */ onActivityResult(int requestCode, int resultCode)103 public void onActivityResult(int requestCode, int resultCode) { 104 Entry entry; 105 synchronized (mActivityEntries) { 106 entry = mActivityEntries.remove(requestCode); 107 } 108 if (entry == null) { 109 return; 110 } 111 112 entry.resultCode = resultCode; 113 entry.latch.countDown(); 114 } 115 116 // there is no need for a better request Id, only one Activity can be launched at any time getRequestCode()117 private int getRequestCode() { 118 return Thread.currentThread().hashCode(); 119 } 120 } 121