org.apache.excalibur.mpool.VariableSizePool.java Source code

Introduction

Here is the source code for org.apache.excalibur.mpool.VariableSizePool.java

Source

/* 
 * 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.excalibur.mpool;

import org.apache.avalon.framework.activity.Disposable;
import org.apache.commons.collections.Buffer;
import org.apache.commons.collections.UnboundedFifoBuffer;

/**
 * This is an <code>Pool</code> that caches Poolable objects for reuse.
 * Please note that this pool offers no resource limiting whatsoever.
 *
 * @author <a href="mailto:dev@avalon.apache.org">Avalon Development Team</a>
 * @version CVS $Revision: 1.4 $ $Date: 2004/02/28 11:47:34 $
 * @since 4.1
 */
public final class VariableSizePool implements Pool, Disposable, ManagablePool {
    private boolean m_disposed = false;
    private final Buffer m_buffer;
    private final ObjectFactory m_factory;
    private final long m_key;

    /**
     * Constructor for an unmanaged pool
     */
    public VariableSizePool(ObjectFactory factory, int size) throws Exception {
        this(factory, size, -1);
    }

    /**
     * Constructor for a managed pool
     */
    public VariableSizePool(ObjectFactory factory, int size, long key) throws Exception {
        m_buffer = new UnboundedFifoBuffer(size);
        m_factory = factory;
        m_key = key;

        synchronized (m_factory) {
            for (int i = 0; i < size; i++) {
                m_buffer.add(newInstance());
            }
        }
    }

    public Object acquire() throws Exception {
        if (m_disposed) {
            throw new IllegalStateException("Cannot get an object from a disposed pool");
        }

        Object object = null;

        synchronized (m_buffer) {
            if (m_buffer.size() > 0) {
                object = m_buffer.remove();
            }
        }

        if (null == object) {
            object = newInstance();
        }

        return object;
    }

    public void release(Object pooledObject) {
        if (m_disposed) {
            try {
                m_factory.dispose(pooledObject);
            } catch (Exception e) {
                // We should never get here, but ignore the exception if it happens
            }
        } else {
            synchronized (m_buffer) {
                m_buffer.add(PoolUtil.recycle(pooledObject));
            }
        }
    }

    public Object newInstance() throws Exception {
        synchronized (m_factory) {
            return m_factory.newInstance();
        }
    }

    public void dispose() {
        m_disposed = true;

        synchronized (m_buffer) {
            while (!m_buffer.isEmpty()) {
                try {
                    m_factory.dispose(m_buffer.remove());
                } catch (Exception e) {
                    // We should never get here, but ignore the exception if it happens
                }
            }
        }
    }

    public void shrink(final int byNum, final long key) throws IllegalAccessException {
        if (m_key < 0 || m_key != key) {
            throw new IllegalAccessException();
        }

        synchronized (m_buffer) {
            final int num = Math.min(byNum, m_buffer.size());

            for (int i = 0; i < num; i++) {
                try {
                    m_factory.dispose(m_buffer.remove());
                } catch (Exception e) {
                    // ignore exception
                }
            }
        }
    }

    public void grow(final int byNum, final long key) throws IllegalAccessException {
        if (m_key < 0 || m_key != key) {
            throw new IllegalAccessException();
        }

        synchronized (m_buffer) {
            for (int i = 0; i < byNum; i++) {
                try {
                    m_buffer.add(newInstance());
                } catch (Exception e) {
                    // ignore exception
                }
            }
        }
    }

    public int size(final long key) throws IllegalAccessException {
        if (m_key < 0 || m_key != key) {
            throw new IllegalAccessException();
        }

        synchronized (m_buffer) {
            return m_buffer.size();
        }
    }
}