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 17 package com.googlecode.android_scripting.trigger; 18 19 import com.google.common.collect.Maps; 20 import com.googlecode.android_scripting.facade.FacadeConfiguration; 21 import com.googlecode.android_scripting.facade.FacadeManager; 22 import com.googlecode.android_scripting.rpc.MethodDescriptor; 23 import com.googlecode.android_scripting.trigger.TriggerRepository.TriggerRepositoryObserver; 24 25 import java.util.Map; 26 27 import org.json.JSONArray; 28 29 /** 30 * A {@link TriggerRepositoryObserver} that starts and stops the monitoring of events depending on 31 * whether or not triggers for the event exist. 32 * 33 */ 34 public class EventGenerationControllingObserver implements TriggerRepositoryObserver { 35 private final FacadeManager mFacadeManager; 36 private final Map<String, MethodDescriptor> mStartEventGeneratingMethodDescriptors; 37 private final Map<String, MethodDescriptor> mStopEventGeneratingMethodDescriptors; 38 private final Map<String, Integer> mEventTriggerRefCounts = Maps.newHashMap(); 39 40 /** 41 * Creates a new StartEventMonitoringObserver for the given trigger repository. 42 * 43 * @param facadeManager 44 * @param triggerRepository 45 */ EventGenerationControllingObserver(FacadeManager facadeManager)46 public EventGenerationControllingObserver(FacadeManager facadeManager) { 47 mFacadeManager = facadeManager; 48 mStartEventGeneratingMethodDescriptors = 49 FacadeConfiguration.collectStartEventMethodDescriptors(); 50 mStopEventGeneratingMethodDescriptors = FacadeConfiguration.collectStopEventMethodDescriptors(); 51 } 52 incrementAndGetRefCount(String eventName)53 private synchronized int incrementAndGetRefCount(String eventName) { 54 int refCount = 55 (mEventTriggerRefCounts.containsKey(eventName)) ? mEventTriggerRefCounts.get(eventName) : 0; 56 refCount++; 57 mEventTriggerRefCounts.put(eventName, refCount); 58 return refCount; 59 } 60 decrementAndGetRefCount(String eventName)61 private synchronized int decrementAndGetRefCount(String eventName) { 62 int refCount = 63 (mEventTriggerRefCounts.containsKey(eventName)) ? mEventTriggerRefCounts.get(eventName) : 0; 64 refCount--; 65 mEventTriggerRefCounts.put(eventName, refCount); 66 return refCount; 67 } 68 69 @Override onPut(Trigger trigger)70 public synchronized void onPut(Trigger trigger) { 71 // If we're not already monitoring the events corresponding to this trigger, do so. 72 if (incrementAndGetRefCount(trigger.getEventName()) == 1) { 73 startMonitoring(trigger.getEventName()); 74 } 75 } 76 77 @Override onRemove(Trigger trigger)78 public synchronized void onRemove(Trigger trigger) { 79 // If there are no more triggers listening to this event, then we need to stop monitoring. 80 if (decrementAndGetRefCount(trigger.getEventName()) == 1) { 81 stopMonitoring(trigger.getEventName()); 82 } 83 } 84 startMonitoring(String eventName)85 private void startMonitoring(String eventName) { 86 MethodDescriptor startEventGeneratingMethod = 87 mStartEventGeneratingMethodDescriptors.get(eventName); 88 try { 89 startEventGeneratingMethod.invoke(mFacadeManager, new JSONArray()); 90 } catch (Throwable t) { 91 throw new RuntimeException(t); 92 } 93 } 94 stopMonitoring(String eventName)95 private void stopMonitoring(String eventName) { 96 MethodDescriptor stopEventGeneratingMethod = 97 mStopEventGeneratingMethodDescriptors.get(eventName); 98 try { 99 stopEventGeneratingMethod.invoke(mFacadeManager, new JSONArray()); 100 } catch (Throwable t) { 101 throw new RuntimeException(t); 102 } 103 } 104 } 105