/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.catalina.tribes.io;


import org.apache.catalina.tribes.util.StringManager;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

public class BufferPool {
    private static final Log log = LogFactory.getLog(BufferPool.class);

    public static final int DEFAULT_POOL_SIZE = 100*1024*1024; //100 MiB

    protected static final StringManager sm = StringManager.getManager(BufferPool.class);

    protected static volatile BufferPool instance = null;
    protected final BufferPoolAPI pool;

    private BufferPool(BufferPoolAPI pool) {
        this.pool = pool;
    }

    public XByteBuffer getBuffer(int minSize, boolean discard) {
        if ( pool != null ) {
            return pool.getBuffer(minSize, discard);
        } else {
            return new XByteBuffer(minSize,discard);
        }
    }

    public void returnBuffer(XByteBuffer buffer) {
        if ( pool != null ) {
            pool.returnBuffer(buffer);
        }
    }

    public void clear() {
        if ( pool != null ) {
            pool.clear();
        }
    }


    public static BufferPool getBufferPool() {
        if (instance == null) {
            synchronized (BufferPool.class) {
                if (instance == null) {
                   BufferPoolAPI pool = new BufferPool15Impl();
                   pool.setMaxSize(DEFAULT_POOL_SIZE);
                   log.info(sm.getString("bufferPool.created",
                           Integer.toString(DEFAULT_POOL_SIZE), pool.getClass().getName()));
                   instance = new BufferPool(pool);
                }
            }
        }
        return instance;
    }


    public interface BufferPoolAPI {
        void setMaxSize(int bytes);

        XByteBuffer getBuffer(int minSize, boolean discard);

        void returnBuffer(XByteBuffer buffer);

        void clear();
    }
}
