com.jaeksoft.searchlib.config.ConfigFileRotation.java Source code

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Here is the source code for com.jaeksoft.searchlib.config.ConfigFileRotation.java

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/**   
 * License Agreement for OpenSearchServer
 *
 * Copyright (C) 2009-2014 Emmanuel Keller / Jaeksoft
 * 
 * http://www.open-search-server.com
 * 
 * This file is part of OpenSearchServer.
 *
 * OpenSearchServer is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 * OpenSearchServer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with OpenSearchServer. 
 *  If not, see <http://www.gnu.org/licenses/>.
 **/

package com.jaeksoft.searchlib.config;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;

import com.jaeksoft.searchlib.cluster.VersionFile;
import com.jaeksoft.searchlib.util.IOUtils;
import com.jaeksoft.searchlib.util.SimpleLock;

public class ConfigFileRotation {

    private File masterFile;
    private File tempFile;
    private PrintWriter tempPrintWriter;
    private File oldFile;

    private final SimpleLock lock = new SimpleLock();

    protected ConfigFileRotation(File directory, String masterName) {
        String ext = FilenameUtils.getExtension(masterName);
        String baseName = FilenameUtils.getBaseName(masterName);
        init(directory, masterName, baseName + "_tmp." + ext, baseName + "_old." + ext);
    }

    private void init(File directory, String masterName, String tempName, String oldName) {
        lock.rl.lock();
        try {
            this.masterFile = new File(directory, masterName);
            this.tempFile = new File(directory, tempName);
            this.oldFile = new File(directory, oldName);
            this.tempPrintWriter = null;
        } finally {
            lock.rl.unlock();
        }
    }

    private void freeTempPrintWriter() {
        if (tempPrintWriter == null)
            return;
        IOUtils.close(tempPrintWriter);
        tempPrintWriter = null;
    }

    public void abort() throws IOException {
        lock.rl.lock();
        try {
            freeTempPrintWriter();
        } finally {
            lock.rl.unlock();
        }
    }

    public void rotate(VersionFile versionFile) throws IOException {
        lock.rl.lock();
        try {
            freeTempPrintWriter();
            if (oldFile.exists())
                oldFile.delete();
            if (!tempFile.exists())
                return;
            if (masterFile.exists())
                FileUtils.moveFile(masterFile, oldFile);
            FileUtils.moveFile(tempFile, masterFile);
            versionFile.increment();
        } finally {
            lock.rl.unlock();
        }
    }

    public void delete(VersionFile versionFile) throws IOException {
        lock.rl.lock();
        try {
            freeTempPrintWriter();
            if (oldFile.exists())
                oldFile.delete();
            if (masterFile.exists())
                FileUtils.moveFile(masterFile, oldFile);
            versionFile.increment();
        } finally {
            lock.rl.unlock();
        }
    }

    public PrintWriter getTempPrintWriter(String encoding) throws IOException {
        lock.rl.lock();
        try {
            if (tempPrintWriter != null)
                return tempPrintWriter;
            if (!tempFile.exists())
                FileUtils.touch(tempFile);
            tempPrintWriter = new PrintWriter(tempFile, encoding);
            return tempPrintWriter;
        } finally {
            lock.rl.unlock();
        }
    }

}