org.springframework.data.hadoop.store.strategy.naming.RollingFileNamingStrategy.java Source code

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Here is the source code for org.springframework.data.hadoop.store.strategy.naming.RollingFileNamingStrategy.java

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/*
 * Copyright 2013 the original author or authors.
 *
 * Licensed 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.springframework.data.hadoop.store.strategy.naming;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.Path;
import org.springframework.util.StringUtils;

/**
 * A {@code FileNamingStrategy} which simply uses a rolling counter to give unique file name.
 *
 * @author Janne Valkealahti
 *
 */
public class RollingFileNamingStrategy extends AbstractFileNamingStrategy {

    private final static Log log = LogFactory.getLog(RollingFileNamingStrategy.class);

    private volatile int counter = 0;

    private volatile String prefix = "-";

    @Override
    public Path resolve(Path path) {
        if (!isEnabled()) {
            return path;
        } else if (path != null) {
            return new Path(path.getParent(), path.getName() + prefix + Integer.toString(counter));
        } else {
            return new Path(Integer.toString(counter));
        }
    }

    @Override
    public void next() {
        counter++;
    }

    @Override
    public void reset() {
        counter = 0;
    }

    @Override
    public Path init(Path path) {
        path = super.init(path);
        log.debug("Initialising from path=" + path);
        if (path != null) {
            String name = path.getName();

            // find numeric part
            Pattern counterPattern = Pattern.compile(prefix + "(" + "\\d+" + ")");
            Matcher m = counterPattern.matcher(name);
            while (m.find()) {
                counter = Integer.parseInt(m.group(1)) + 1;
            }
            log.debug("Initialized counter starting from " + counter);

            // find complete part handled by this strategy
            Pattern replacePattern = Pattern.compile("(" + prefix + "\\d+" + ")(.*)");
            m = replacePattern.matcher(name);

            // remove a rolling part
            name = m.replaceFirst("$2");
            if (StringUtils.hasText(name)) {
                path = new Path(path.getParent(), name);
                log.debug("Removed handled prefix, path is now " + path);
            } else {
                path = null;
                log.debug("Removed last handled name part, returning null");
            }
        }
        return path;
    }

    /**
     * Sets the prefix preceding rolling number part.
     *
     * @param prefix the new prefix
     */
    public void setPrefix(String prefix) {
        this.prefix = prefix;
    }

    @Override
    public RollingFileNamingStrategy createInstance() {
        RollingFileNamingStrategy instance = new RollingFileNamingStrategy();
        instance.setCodecInfo(getCodecInfo());
        instance.setOrder(getOrder());
        instance.setEnabled(isEnabled());
        instance.setPrefix(prefix);
        return instance;
    }

}