| /* |
| * Copyright 2000-2013 JetBrains s.r.o. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package com.intellij.util; |
| |
| import com.intellij.openapi.util.LowMemoryWatcher; |
| import com.intellij.util.containers.WeakList; |
| import org.jetbrains.annotations.NotNull; |
| import org.jetbrains.annotations.Nullable; |
| |
| import java.lang.ref.Reference; |
| import java.lang.ref.SoftReference; |
| import java.lang.ref.WeakReference; |
| |
| /** |
| * A reference whose referent may be garbage-collected when there's low free memory, not only when there's none. |
| * Use for objects which retain lots of memory and whose loss is not very expensive. |
| * |
| * @author peter |
| */ |
| public class SofterReference<T> { |
| private volatile Reference<T> myRef; |
| private static final WeakList<SofterReference> ourRegistry = new WeakList<SofterReference>(); |
| |
| @SuppressWarnings("UnusedDeclaration") |
| private static final LowMemoryWatcher ourWatcher = LowMemoryWatcher.register(new Runnable() { |
| @Override |
| public void run() { |
| for (SofterReference reference : ourRegistry.copyAndClear()) { |
| reference.weaken(); |
| } |
| } |
| }); |
| |
| public SofterReference(@NotNull T referent) { |
| ourRegistry.add(this); |
| myRef = new SoftReference<T>(referent); |
| } |
| |
| private void weaken() { |
| T o = myRef.get(); |
| if (o != null) { |
| myRef = new WeakReference<T>(o); |
| } |
| } |
| |
| @Nullable |
| public T get() { |
| Reference<T> ref = myRef; |
| T referent = ref.get(); |
| if (referent != null && ref instanceof WeakReference) { |
| ourRegistry.add(this); |
| myRef = new SoftReference<T>(referent); |
| } |
| return referent; |
| } |
| } |