BufferCache.java

/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core;

import java.util.ArrayList;

import org.eclipse.jdt.core.IBuffer;
import org.eclipse.jdt.internal.core.util.LRUCache;

/**
 * An LRU cache of <code>IBuffers</code>.
 */
public class BufferCache extends OverflowingLRUCache {

	private ThreadLocal buffersToClose= new ThreadLocal();

	/**
	 * Constructs a new buffer cache of the given size.
	 */
	public BufferCache(int size) {
		super(size);
	}

	/**
	 * Constructs a new buffer cache of the given size.
	 */
	public BufferCache(int size, int overflow) {
		super(size, overflow);
	}

	/**
	 * Returns true if the buffer is successfully closed and removed from the cache, otherwise
	 * false.
	 * 
	 * <p>
	 * NOTE: this triggers an external removal of this buffer by closing the buffer.
	 */
	protected boolean close(LRUCacheEntry entry) {
		IBuffer buffer= (IBuffer)entry.value;

		// prevent buffer that have unsaved changes or working copy buffer to be removed
		// see https://bugs.eclipse.org/bugs/show_bug.cgi?id=39311
		if (!((Openable)buffer.getOwner()).canBufferBeRemovedFromCache(buffer)) {
			return false;
		} else {
			ArrayList buffers= (ArrayList)this.buffersToClose.get();
			if (buffers == null) {
				buffers= new ArrayList();
				this.buffersToClose.set(buffers);
			}
			buffers.add(buffer);
			return true;
		}
	}

	void closeBuffers() {
		ArrayList buffers= (ArrayList)this.buffersToClose.get();
		if (buffers == null)
			return;
		this.buffersToClose.set(null);
		for (int i= 0, length= buffers.size(); i < length; i++) {
			((IBuffer)buffers.get(i)).close();
		}
	}

	/**
	 * Returns a new instance of the reciever.
	 */
	protected LRUCache newInstance(int size, int newOverflow) {
		return new BufferCache(size, newOverflow);
	}
}