com.metamx.druid.realtime.firehose.GracefulShutdownFirehose.java Source code

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Here is the source code for com.metamx.druid.realtime.firehose.GracefulShutdownFirehose.java

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/*
 * Druid - a distributed column store.
 * Copyright (C) 2012  Metamarkets Group Inc.
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package com.metamx.druid.realtime.firehose;

import com.google.common.base.Throwables;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.metamx.common.concurrent.ScheduledExecutors;
import com.metamx.common.logger.Logger;
import com.metamx.druid.index.v1.IndexGranularity;
import com.metamx.druid.input.InputRow;
import com.metamx.druid.realtime.plumber.IntervalRejectionPolicyFactory;
import com.metamx.druid.realtime.plumber.RejectionPolicy;
import org.joda.time.DateTime;
import org.joda.time.Duration;
import org.joda.time.Interval;
import org.joda.time.Period;

import java.io.IOException;
import java.util.concurrent.Callable;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 */
public class GracefulShutdownFirehose implements Firehose {
    private static final Logger log = new Logger(GracefulShutdownFirehose.class);

    private final Firehose firehose;
    private final IndexGranularity segmentGranularity;
    private final long windowMillis;
    private final ScheduledExecutorService scheduledExecutor;
    private final RejectionPolicy rejectionPolicy;

    // when this is set to false, the firehose will have no more rows
    private final AtomicBoolean valveOn = new AtomicBoolean(true);

    // when this is set to true, the firehose will begin rejecting events
    private volatile boolean beginRejectionPolicy = false;

    public GracefulShutdownFirehose(Firehose firehose, IndexGranularity segmentGranularity, Period windowPeriod) {
        this.firehose = firehose;
        this.segmentGranularity = segmentGranularity;
        this.windowMillis = windowPeriod.toStandardDuration().getMillis() * 2;
        this.scheduledExecutor = Executors.newScheduledThreadPool(1,
                new ThreadFactoryBuilder().setDaemon(true).setNameFormat("firehose_scheduled_%d").build());

        final long truncatedNow = segmentGranularity.truncate(new DateTime()).getMillis();
        final long end = segmentGranularity.increment(truncatedNow);

        this.rejectionPolicy = new IntervalRejectionPolicyFactory(new Interval(truncatedNow, end))
                .create(windowPeriod);
    }

    public void shutdown() throws IOException {
        final long truncatedNow = segmentGranularity.truncate(new DateTime()).getMillis();
        final long end = segmentGranularity.increment(truncatedNow) + windowMillis;
        final Duration timeUntilShutdown = new Duration(System.currentTimeMillis(), end);

        log.info("Shutdown at approx. %s (in %s)", new DateTime(end), timeUntilShutdown);

        ScheduledExecutors.scheduleWithFixedDelay(scheduledExecutor, timeUntilShutdown,
                new Callable<ScheduledExecutors.Signal>() {
                    @Override
                    public ScheduledExecutors.Signal call() throws Exception {
                        try {
                            valveOn.set(false);
                        } catch (Exception e) {
                            throw Throwables.propagate(e);
                        }

                        return ScheduledExecutors.Signal.STOP;
                    }
                });

        beginRejectionPolicy = true;
    }

    @Override
    public boolean hasMore() {
        return valveOn.get() && firehose.hasMore();
    }

    @Override
    public InputRow nextRow() {
        InputRow next = firehose.nextRow();

        if (!beginRejectionPolicy || rejectionPolicy.accept(next.getTimestampFromEpoch())) {
            return next;
        }

        return null;
    }

    @Override
    public Runnable commit() {
        return firehose.commit();
    }

    @Override
    public void close() throws IOException {
        firehose.close();
    }
}