ActiveMQ example source code file (DataFileAccessorPool.java)

This example ActiveMQ source code file (DataFileAccessorPool.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

arraylist, asyncdatamanager, closed, datafile, datafileaccessor, datafileaccessor, datafileaccessorpool, illegalstateexception, io, ioexception, ioexception, iterator, iterator, pool, pool, util

The ActiveMQ DataFileAccessorPool.java source code

/**
 * 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.activemq.kaha.impl.async;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * Used to pool DataFileAccessors.
 * 
 * @author chirino
 */
public class DataFileAccessorPool {

    private final AsyncDataManager dataManager;
    private final Map<Integer, Pool> pools = new HashMap();
    private boolean closed;
    private int maxOpenReadersPerFile = 5;

    class Pool {

        private final DataFile file;
        private final List<DataFileAccessor> pool = new ArrayList();
        private boolean used;
        private int openCounter;
        private boolean disposed;

        public Pool(DataFile file) {
            this.file = file;
        }

        public DataFileAccessor openDataFileReader() throws IOException {
            DataFileAccessor rc = null;
            if (pool.isEmpty()) {
                rc = new DataFileAccessor(dataManager, file);
            } else {
                rc = (DataFileAccessor)pool.remove(pool.size() - 1);
            }
            used = true;
            openCounter++;
            return rc;
        }

        public synchronized void closeDataFileReader(DataFileAccessor reader) {
            openCounter--;
            if (pool.size() >= maxOpenReadersPerFile || disposed) {
                reader.dispose();
            } else {
                pool.add(reader);
            }
        }

        public synchronized void clearUsedMark() {
            used = false;
        }

        public synchronized boolean isUsed() {
            return used;
        }

        public synchronized void dispose() {
            for (DataFileAccessor reader : pool) {
                reader.dispose();
            }
            pool.clear();
            disposed = true;
        }

        public synchronized int getOpenCounter() {
            return openCounter;
        }

    }

    public DataFileAccessorPool(AsyncDataManager dataManager) {
        this.dataManager = dataManager;
    }

    synchronized void clearUsedMark() {
        for (Iterator iter = pools.values().iterator(); iter.hasNext();) {
            Pool pool = (Pool)iter.next();
            pool.clearUsedMark();
        }
    }

    synchronized void disposeUnused() {
        for (Iterator<Pool> iter = pools.values().iterator(); iter.hasNext();) {
            Pool pool = iter.next();
            if (!pool.isUsed()) {
                pool.dispose();
                iter.remove();
            }
        }
    }

    synchronized void disposeDataFileAccessors(DataFile dataFile) {
        if (closed) {
            throw new IllegalStateException("Closed.");
        }
        Pool pool = pools.get(dataFile.getDataFileId());
        if (pool != null) {
            if (pool.getOpenCounter() == 0) {
                pool.dispose();
                pools.remove(dataFile.getDataFileId());
            } else {
                throw new IllegalStateException("The data file is still in use: " + dataFile + ", use count: " + pool.getOpenCounter());
            }
        }
    }

    synchronized DataFileAccessor openDataFileAccessor(DataFile dataFile) throws IOException {
        if (closed) {
            throw new IOException("Closed.");
        }

        Pool pool = pools.get(dataFile.getDataFileId());
        if (pool == null) {
            pool = new Pool(dataFile);
            pools.put(dataFile.getDataFileId(), pool);
        }
        return pool.openDataFileReader();
    }

    synchronized void closeDataFileAccessor(DataFileAccessor reader) {
        Pool pool = pools.get(reader.getDataFile().getDataFileId());
        if (pool == null || closed) {
            reader.dispose();
        } else {
            pool.closeDataFileReader(reader);
        }
    }

    public synchronized void close() {
        if (closed) {
            return;
        }
        closed = true;
        for (Iterator<Pool> iter = pools.values().iterator(); iter.hasNext();) {
            Pool pool = iter.next();
            pool.dispose();
        }
        pools.clear();
    }

}