InMemoryQueue.java

/**
 * 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.falcon.rerun.queue;

import org.apache.commons.codec.CharEncoding;
import org.apache.falcon.FalconException;
import org.apache.commons.io.IOUtils;
import org.apache.falcon.aspect.GenericAlert;
import org.apache.falcon.rerun.event.RerunEvent;
import org.apache.falcon.rerun.event.RerunEventFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.DelayQueue;

/**
 * An in-memory implementation of a DelayedQueue.
 * @param <T>
 */
public class InMemoryQueue<T extends RerunEvent> extends DelayedQueue<T> {
    public static final Logger LOG = LoggerFactory.getLogger(DelayedQueue.class);

    protected DelayQueue<T> delayQueue = new DelayQueue<T>();
    private final File serializeFilePath;

    public InMemoryQueue(File serializeFilePath) {
        this.serializeFilePath = serializeFilePath;
    }

    @Override
    public boolean offer(T event) {
        boolean flag = delayQueue.offer(event);
        beforeRetry(event);
        LOG.debug("Enqueued Message: {}", event.toString());
        return flag;
    }

    @Override
    public T take() throws FalconException {
        T event;
        try {
            event = delayQueue.take();
            LOG.debug("Dequeued Message: {}", event.toString());
            afterRetry(event);
        } catch (InterruptedException e) {
            throw new FalconException(e);
        }
        return event;
    }

    public void populateQueue(List<T> events) {
        for (T event : events) {
            delayQueue.offer(event);
        }
    }

    @Override
    public void init() {
        List<T> events = bootstrap();
        populateQueue(events);
    }

    @Override
    public void reconnect() throws FalconException {
        //Do Nothing
    }

    private void beforeRetry(T event) {
        File retryFile = getRetryFile(serializeFilePath, event);
        BufferedWriter out = null;
        try {
            out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(retryFile, true)));
            out.write(event.toString());
            out.newLine();
            out.close();
        } catch (IOException e) {
            LOG.warn("Unable to write entry for process-instance: {}:{}",
                            event.getEntityName(), event.getInstance(), e);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    private File getRetryFile(File basePath, T event) {
        return new File(basePath, (event.getType().name()) + "-"
                + event.getEntityName() + "-"
                + event.getInstance().replaceAll(":", "-"));
    }

    private void afterRetry(T event) {
        File retryFile = getRetryFile(serializeFilePath, event);
        if (!retryFile.exists()) {
            LOG.warn("Rerun file deleted or renamed for process-instance: {}:{}",
                    event.getEntityName(), event.getInstance());
            GenericAlert.alertRetryFailed(event.getEntityType(), event.getEntityName(), event.getInstance(),
                    event.getWfId(), event.getWorkflowUser(), Integer.toString(event.getRunId()),
                    "Rerun file deleted or renamed for process-instance:");
        } else {
            if (!retryFile.delete()) {
                LOG.warn("Unable to remove rerun file {}", event.getWfId());
                retryFile.deleteOnExit();
            }
        }
    }

    private List<T> bootstrap() {
        List<T> rerunEvents = new ArrayList<T>();
        File[] files = serializeFilePath.listFiles();
        if (files != null) {
            for (File rerunFile : files) {
                BufferedReader reader = null;
                try {
                    reader = new BufferedReader(new InputStreamReader(new FileInputStream(rerunFile)
                            , CharEncoding.UTF_8));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        T event = new RerunEventFactory<T>().getRerunEvent(
                                rerunFile.getName(), line);
                        rerunEvents.add(event);
                    }
                } catch (Exception e) {
                    LOG.warn("Not able to read rerun entry {}", rerunFile.getAbsolutePath(), e);
                } finally {
                    IOUtils.closeQuietly(reader);
                }
            }
        }
        return rerunEvents;
    }
}