1 /* 2 * Copyright (C) 2011 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.ddmuilib.logcat; 17 18 import com.android.ddmlib.AndroidDebugBridge; 19 import com.android.ddmlib.AndroidDebugBridge.IDeviceChangeListener; 20 import com.android.ddmlib.IDevice; 21 22 import org.eclipse.jface.preference.IPreferenceStore; 23 24 import java.util.HashMap; 25 import java.util.Map; 26 27 /** 28 * A factory for {@link LogCatReceiver} objects. Its primary objective is to cache 29 * constructed {@link LogCatReceiver}'s per device and hand them back when requested. 30 */ 31 public class LogCatReceiverFactory { 32 /** Singleton instance. */ 33 public static final LogCatReceiverFactory INSTANCE = new LogCatReceiverFactory(); 34 35 private Map<String, LogCatReceiver> mReceiverCache = new HashMap<String, LogCatReceiver>(); 36 37 /** Private constructor: cannot instantiate. */ LogCatReceiverFactory()38 private LogCatReceiverFactory() { 39 AndroidDebugBridge.addDeviceChangeListener(new IDeviceChangeListener() { 40 @Override 41 public void deviceDisconnected(final IDevice device) { 42 // The deviceDisconnected() is called from DDMS code that holds 43 // multiple locks regarding list of clients, etc. 44 // It so happens that #newReceiver() below adds a clientChangeListener 45 // which requires those locks as well. So if we call 46 // #removeReceiverFor from a DDMS/Monitor thread, we could end up 47 // in a deadlock. As a result, we spawn a separate thread that 48 // doesn't hold any of the DDMS locks to remove the receiver. 49 Thread t = new Thread(new Runnable() { 50 @Override 51 public void run() { 52 removeReceiverFor(device); } 53 }, "Remove logcat receiver for " + device.getSerialNumber()); 54 t.start(); 55 } 56 57 @Override 58 public void deviceConnected(IDevice device) { 59 } 60 61 @Override 62 public void deviceChanged(IDevice device, int changeMask) { 63 } 64 }); 65 } 66 67 /** 68 * Remove existing logcat receivers. This method should not be called from a DDMS thread 69 * context that might be holding locks. Doing so could result in a deadlock with the following 70 * two threads locked up: <ul> 71 * <li> {@link #removeReceiverFor(IDevice)} waiting to lock {@link LogCatReceiverFactory}, 72 * while holding a DDMS monitor internal lock. </li> 73 * <li> {@link #newReceiver(IDevice, IPreferenceStore)} holding {@link LogCatReceiverFactory} 74 * while attempting to obtain a DDMS monitor lock. </li> 75 * </ul> 76 */ removeReceiverFor(IDevice device)77 private synchronized void removeReceiverFor(IDevice device) { 78 LogCatReceiver r = mReceiverCache.get(device.getSerialNumber()); 79 if (r != null) { 80 r.stop(); 81 mReceiverCache.remove(device.getSerialNumber()); 82 } 83 } 84 newReceiver(IDevice device, IPreferenceStore prefs)85 public synchronized LogCatReceiver newReceiver(IDevice device, IPreferenceStore prefs) { 86 LogCatReceiver r = mReceiverCache.get(device.getSerialNumber()); 87 if (r != null) { 88 return r; 89 } 90 91 r = new LogCatReceiver(device, prefs); 92 mReceiverCache.put(device.getSerialNumber(), r); 93 return r; 94 } 95 } 96