001/*
002 * ModeShape (http://www.modeshape.org)
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *       http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.modeshape.schematic.internal.io;
017
018import java.nio.ByteBuffer;
019import java.nio.CharBuffer;
020import org.modeshape.schematic.annotation.NotThreadSafe;
021
022/**
023 * A cache of ByteBuffer, used in {@link BsonDataInput}.
024 * 
025 * @author Randall Hauch <rhauch@redhat.com> (C) 2011 Red Hat Inc.
026 */
027@NotThreadSafe
028public class BufferCache {
029    /**
030     * The minimum number of bytes in each buffer.
031     */
032    public static final int MINIMUM_SIZE = 1048 * 8;
033    /**
034     * The maximum number of bytes in each cached buffer. If a buffer is too large, then using it and caching it in-memory will be
035     * too costly.
036     */
037    public static final int MAXIMUM_SIZE = 1048 * 80;
038
039    private ByteBuffer byteBuffer = ByteBuffer.allocate(MINIMUM_SIZE);
040    private CharBuffer charBuffer = CharBuffer.allocate(MINIMUM_SIZE);
041
042    public ByteBuffer getByteBuffer( int minimumSize ) {
043        minimumSize = Math.max(minimumSize, MINIMUM_SIZE);
044        ByteBuffer buffer = byteBuffer;
045        if (buffer == null || buffer.capacity() < minimumSize) {
046            // Allocate a new one ...
047            buffer = ByteBuffer.allocate(minimumSize);
048        } else {
049            // The existing one is good enough ...
050            byteBuffer = null;
051            buffer.clear();
052        }
053        return buffer;
054    }
055
056    public CharBuffer getCharBuffer( int minimumSize ) {
057        minimumSize = Math.max(minimumSize, MINIMUM_SIZE);
058        CharBuffer buffer = charBuffer;
059        if (buffer == null || buffer.capacity() < minimumSize) {
060            // Allocate a new one ...
061            buffer = CharBuffer.allocate(minimumSize);
062        } else {
063            // The existing one is good enough ...
064            charBuffer = null;
065            // But be sure to clear it out ...
066            buffer.clear();
067        }
068        return buffer;
069    }
070
071    public void checkin( ByteBuffer byteBuffer ) {
072        if (byteBuffer.capacity() < MAXIMUM_SIZE) {
073            this.byteBuffer = byteBuffer;
074        }
075    }
076
077    public void checkin( CharBuffer charBuffer ) {
078        if (charBuffer.capacity() < MAXIMUM_SIZE) {
079            this.charBuffer = charBuffer;
080        }
081    }
082}