Copyright (c) 2000, 2013 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core;

import java.text.NumberFormat;
import java.util.Enumeration;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.jdt.core.IBuffer;
import org.eclipse.jdt.core.IOpenable;

The buffer manager manages the set of open buffers.
It implements an LRU cache of buffers.
/**
 * The buffer manager manages the set of open buffers.
 * It implements an LRU cache of buffers.
 */
public class BufferManager {

	protected static BufferManager DEFAULT_BUFFER_MANAGER;
	protected static boolean VERBOSE;

	
LRU cache of buffers. The key and value for an entry
in the table is the identical buffer.
/**
	 * LRU cache of buffers. The key and value for an entry
	 * in the table is the identical buffer.
	 */
	private BufferCache<IOpenable> openBuffers = new BufferCache<>(60);

	
Deprecated:
/**
	 * @deprecated
	 */
	protected org.eclipse.jdt.core.IBufferFactory defaultBufferFactory = new org.eclipse.jdt.core.IBufferFactory() {
	    
Deprecated:
/**
	     * @deprecated
	     */
		@Override
		public IBuffer createBuffer(IOpenable owner) {
			return BufferManager.createBuffer(owner);
		}
	};

Adds a buffer to the table of open buffers.
/**
 * Adds a buffer to the table of open buffers.
 */
protected void addBuffer(IBuffer buffer) {
	if (VERBOSE) {
		String owner = ((Openable)buffer.getOwner()).toStringWithAncestors();
		System.out.println("Adding buffer for " + owner); //$NON-NLS-1$
	}
	synchronized (this.openBuffers) {
		this.openBuffers.put(buffer.getOwner(), buffer);
	}
	// close buffers that were removed from the cache if space was needed
	this.openBuffers.closeBuffers();
	if (VERBOSE) {
		System.out.println("-> Buffer cache filling ratio = " + NumberFormat.getInstance().format(this.openBuffers.fillingRatio()) + "%"); //$NON-NLS-1$//$NON-NLS-2$
	}
}
public static IBuffer createBuffer(IOpenable owner) {
	JavaElement element = (JavaElement) owner;
	IResource resource = element.resource();
	return
		new Buffer(
			resource instanceof IFile ? (IFile)resource : null,
			owner,
			element.isReadOnly());
}
public static IBuffer createNullBuffer(IOpenable owner) {
	JavaElement element = (JavaElement) owner;
	IResource resource = element.resource();
	return
		new NullBuffer(
			resource instanceof IFile ? (IFile)resource : null,
			owner,
			element.isReadOnly());
}
Returns the open buffer associated with the given owner,
or null if the owner does not have an open
buffer associated with it.
/**
 * Returns the open buffer associated with the given owner,
 * or <code>null</code> if the owner does not have an open
 * buffer associated with it.
 */
public IBuffer getBuffer(IOpenable owner) {
	synchronized (this.openBuffers) {
		return this.openBuffers.get(owner);
	}
}
Returns the default buffer manager.
/**
 * Returns the default buffer manager.
 */
public synchronized static BufferManager getDefaultBufferManager() {
	if (DEFAULT_BUFFER_MANAGER == null) {
		DEFAULT_BUFFER_MANAGER = new BufferManager();
	}
	return DEFAULT_BUFFER_MANAGER;
}
Returns the default buffer factory.
Deprecated:
/**
 * Returns the default buffer factory.
 * @deprecated
 */
public org.eclipse.jdt.core.IBufferFactory getDefaultBufferFactory() {
	return this.defaultBufferFactory;
}
Returns an enumeration of all open buffers.

The Enumeration answered is thread safe.
See Also:
OverflowingLRUCache
Returns:
Enumeration of IBuffer/**
 * Returns an enumeration of all open buffers.
 * <p>
 * The <code>Enumeration</code> answered is thread safe.
 *
 * @see OverflowingLRUCache
 * @return Enumeration of IBuffer
 */
public Enumeration<IBuffer> getOpenBuffers() {
	Enumeration<IBuffer> result;
	synchronized (this.openBuffers) {
		this.openBuffers.shrink();
		result = this.openBuffers.elements();
	}
	// close buffers that were removed from the cache if space was needed
	this.openBuffers.closeBuffers();
	return result;
}

Removes a buffer from the table of open buffers.
/**
 * Removes a buffer from the table of open buffers.
 */
protected void removeBuffer(IBuffer buffer) {
	if (VERBOSE) {
		String owner = ((Openable)buffer.getOwner()).toStringWithAncestors();
		System.out.println("Removing buffer for " + owner); //$NON-NLS-1$
	}
	synchronized (this.openBuffers) {
		this.openBuffers.remove(buffer.getOwner());
	}
	// close buffers that were removed from the cache (should be only one)
	this.openBuffers.closeBuffers();
	if (VERBOSE) {
		System.out.println("-> Buffer cache filling ratio = " + NumberFormat.getInstance().format(this.openBuffers.fillingRatio()) + "%"); //$NON-NLS-1$//$NON-NLS-2$
	}
}
}