platform/platform-impl/src/com/intellij/util/PatchedWeakReference.java

   1 /*
   2  * Copyright 2000-2009 JetBrains s.r.o.
   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.intellij.util;
  17
  18 import com.intellij.concurrency.JobScheduler;
  19 import com.intellij.openapi.diagnostic.Logger;
  20 import org.jetbrains.annotations.TestOnly;
  21
  22 import java.lang.ref.ReferenceQueue;
  23 import java.lang.ref.WeakReference;
  24 import java.util.ArrayList;
  25 import java.util.List;
  26 import java.util.concurrent.TimeUnit;
  27
  28 public class PatchedWeakReference<T> extends WeakReference<T>{
  29   private static final Logger LOG = Logger.getInstance("#com.intellij.util.PatchedWeakReference");
  30
  31   private static List<PatchedWeakReference<?>> ourRefsList = new ArrayList<PatchedWeakReference<?>>();
  32   private static final ReferenceQueue ourQueue = new ReferenceQueue();
  33
  34   static {
  35     JobScheduler.getScheduler().scheduleAtFixedRate(new Runnable() {
  36       public void run() {
  37         processQueue();
  38       }
  39     }, (long)500, (long)500, TimeUnit.MILLISECONDS);
  40   }
  41
  42   public PatchedWeakReference(T referent) {
  43     super(referent, ourQueue);
  44     if(ourRefsList.size() % 100 == 0) {
  45       int i = 0;
  46     }
  47     synchronized(ourQueue) {
  48       ourRefsList.add(this);
  49     }
  50   }
  51
  52   /**
  53    * public for being accessible from the degenerator as timer stuff does not work.
  54    */
  55   public static void processQueue() {
  56     boolean haveClearedRefs = false;
  57     while(true){
  58       PatchedWeakReference ref = (PatchedWeakReference)ourQueue.poll();
  59       if (ref != null){
  60         haveClearedRefs = true;
  61       }
  62       else{
  63         break;
  64       }
  65     }
  66     if (!haveClearedRefs) return;
  67
  68     synchronized(ourQueue) {
  69       ArrayList<PatchedWeakReference<?>> newList = new ArrayList<PatchedWeakReference<?>>(ourRefsList.size()/2+1);
  70       for(int i = 0; i < ourRefsList.size(); i++){
  71         PatchedWeakReference<?> ref = ourRefsList.get(i);
  72         if (ref.get() != null){
  73           newList.add(ref);
  74         }
  75       }
  76
  77       if (LOG.isDebugEnabled()){
  78         LOG.info("old size:" + ourRefsList.size());
  79         LOG.info("new size:" + newList.size());
  80       }
  81       //System.out.println("old size:" + ourRefsList.size());
  82       //System.out.println("new size:" + newList.size());
  83       ourRefsList = newList;
  84     }
  85   }
  86
  87   @TestOnly
  88   public static void clearAll() {
  89     synchronized (ourQueue) {
  90       while (ourQueue.poll() != null);
  91       ourRefsList = new ArrayList<PatchedWeakReference<?>>();
  92     }
  93   }
  94 }