1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.harmony.jpda.tests.share; 20 21 import java.lang.ref.PhantomReference; 22 import java.lang.ref.ReferenceQueue; 23 import java.util.ArrayList; 24 25 /** 26 * A class that allows one to observe GCs and finalization. 27 */ 28 public class GcMarker { 29 30 private final ReferenceQueue mQueue; 31 private final ArrayList<PhantomReference> mList; 32 33 public GcMarker() { 34 mQueue = new ReferenceQueue(); 35 mList = new ArrayList<PhantomReference>(3); 36 } 37 38 public void add(Object referent) { 39 mList.add(new PhantomReference(referent, mQueue)); 40 } 41 42 public void waitForGc(int numberOfExpectedFinalizations) { 43 if (numberOfExpectedFinalizations > mList.size()) { 44 throw new IllegalArgumentException("wait condition will never be met"); 45 } 46 47 // Request finalization of objects, and subsequent reference enqueueing. 48 // Repeat until reference queue reaches expected size. 49 do { 50 System.runFinalization(); 51 Runtime.getRuntime().gc(); 52 try { Thread.sleep(10); } catch (Exception e) {} 53 } while (isLive(numberOfExpectedFinalizations)); 54 } 55 56 private boolean isLive(int numberOfExpectedFinalizations) { 57 int numberFinalized = 0; 58 for (int i = 0, n = mList.size(); i < n; i++) { 59 if (mList.get(i).isEnqueued()) { 60 numberFinalized++; 61 } 62 } 63 return numberFinalized < numberOfExpectedFinalizations; 64 } 65 } 66
