| /* |
| * Copyright 2000-2009 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 org.jetbrains.annotations.NonNls; |
| |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * SpinAllocator can be used for allocating short-live automatic objects of type T. |
| * Avoiding reenterable allocations, MAX_SIMULTANEOUS_ALLOCATIONS are concurrently possible. |
| */ |
| public class SpinAllocator<T> { |
| |
| public static final int MAX_SIMULTANEOUS_ALLOCATIONS = 64; |
| |
| public interface ICreator<T> { |
| T createInstance(); |
| } |
| |
| public interface IDisposer<T> { |
| void disposeInstance(T instance); |
| } |
| |
| public static class AllocatorExhaustedException extends RuntimeException { |
| public AllocatorExhaustedException() { |
| //noinspection HardCodedStringLiteral |
| super("SpinAllocator has exhausted! Too many threads or you're going to get StackOverflow."); |
| } |
| } |
| |
| public static class AllocatorDisposeException extends RuntimeException { |
| public AllocatorDisposeException(@NonNls final String message) { |
| super(message); |
| } |
| } |
| |
| private final AtomicBoolean[] myEmployed = new AtomicBoolean[MAX_SIMULTANEOUS_ALLOCATIONS]; |
| private final Object[] myObjects = new Object[MAX_SIMULTANEOUS_ALLOCATIONS]; |
| protected final ICreator<T> myCreator; |
| protected final IDisposer<T> myDisposer; |
| |
| public SpinAllocator(ICreator<T> creator, IDisposer<T> disposer) { |
| myCreator = creator; |
| myDisposer = disposer; |
| for (int i = 0; i < MAX_SIMULTANEOUS_ALLOCATIONS; ++i) { |
| myEmployed[i] = new AtomicBoolean(false); |
| } |
| } |
| |
| public T alloc() { |
| for (int i = 0; i < MAX_SIMULTANEOUS_ALLOCATIONS; ++i) { |
| if (!myEmployed[i].getAndSet(true)) { |
| T result = (T)myObjects[i]; |
| if (result == null) { |
| myObjects[i] = result = myCreator.createInstance(); |
| } |
| return result; |
| } |
| } |
| throw new AllocatorExhaustedException(); |
| } |
| |
| public void dispose(T instance) { |
| for (int i = 0; i < MAX_SIMULTANEOUS_ALLOCATIONS; ++i) { |
| if (myObjects[i] == instance) { |
| if (!myEmployed[i].get()) { |
| throw new AllocatorDisposeException("Instance is already disposed."); |
| } |
| myDisposer.disposeInstance(instance); |
| myEmployed[i].set(false); |
| return; |
| } |
| } |
| throw new AllocatorDisposeException("Attempt to dispose non-allocated instance."); |
| } |
| } |