com.splicemachine.hbase.SpliceZooKeeperManager.java Source code

Introduction

Here is the source code for com.splicemachine.hbase.SpliceZooKeeperManager.java

Source

/*
 * Copyright 2012 - 2016 Splice Machine, Inc.
 *
 * 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 com.splicemachine.hbase;

import java.io.Closeable;
import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper;
import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
import org.apache.log4j.Logger;
import org.apache.zookeeper.KeeperException;

import com.splicemachine.access.HConfiguration;
import com.splicemachine.access.api.SConfiguration;

/**
 * @author Scott Fines
 *         Created: 2/2/13 9:47 AM
 */
public class SpliceZooKeeperManager implements Abortable, Closeable {
    private static final Logger LOG = Logger.getLogger(SpliceZooKeeperManager.class);
    protected ZooKeeperWatcher watcher;
    protected RecoverableZooKeeper rzk;
    private volatile boolean isAborted;

    public SpliceZooKeeperManager() {
        initialize(HConfiguration.getConfiguration());
    }

    public void initialize(SConfiguration configuration) {
        try {
            watcher = new ZooKeeperWatcher((Configuration) configuration.getConfigSource().unwrapDelegate(),
                    "spliceconnection", this);
            rzk = watcher.getRecoverableZooKeeper();
        } catch (Exception e) {
            LOG.error(e);
            throw new RuntimeException(e);
        }
    }

    public ZooKeeperWatcher getZooKeeperWatcher() throws ZooKeeperConnectionException {
        return watcher;
    }

    public RecoverableZooKeeper getRecoverableZooKeeper() throws ZooKeeperConnectionException {
        return rzk;
    }

    @Override
    public void abort(String why, Throwable e) {
        if (e instanceof KeeperException.SessionExpiredException) {
            try {
                LOG.info("Lost connection with ZooKeeper, attempting reconnect");
                watcher = null;
                initialize(HConfiguration.getConfiguration());
                LOG.info("Successfully reconnected to ZooKeeper");
            } catch (RuntimeException zce) {
                LOG.error("Could not reconnect to zookeeper after session expiration, aborting");
                e = zce;
            }
        }
        if (e != null)
            LOG.error(why, e);
        else
            LOG.error(why);
        this.isAborted = true;
    }

    @Override
    public boolean isAborted() {
        return isAborted;
    }

    @Override
    public void close() throws IOException {
        if (watcher != null) {
            watcher.close();
            watcher = null;
        }
        if (rzk != null) {
            try {
                rzk.close();
                rzk = null;
            } catch (InterruptedException e) {
                throw new IOException(e);
            }
        }
    }

    public interface Command<T> {
        T execute(RecoverableZooKeeper zooKeeper) throws InterruptedException, KeeperException;
    }

    public <T> T executeUnlessExpired(Command<T> command) throws InterruptedException, KeeperException {
        /*
         * What actually happens is that, in the event of a long network partition, ZooKeeper will throw
         * ConnectionLoss exceptions, but it will NOT throw a SessionExpired exception until it reconnects, even
         * if it's been disconnected for CLEARLY longer than the session timeout.
         *
         * To deal with this, we have to basically loop through our command repeatedly until we either
         *
         * 1. Succeed.
         * 2. Get a SessionExpired event from ZooKeeper
         * 3. Spent more than 2*sessionTimeout ms attempting the request
         * 4. Get some other kind of Zk error (NoNode, etc).
         */
        RecoverableZooKeeper rzk;
        try {
            rzk = getRecoverableZooKeeper();
        } catch (ZooKeeperConnectionException e) {
            throw new KeeperException.SessionExpiredException();
        }
        //multiple by 2 to make absolutely certain we're timed out.
        int sessionTimeout = 2 * rzk.getZooKeeper().getSessionTimeout();
        long nextTime = System.currentTimeMillis();
        long startTime = System.currentTimeMillis();
        while ((int) (nextTime - startTime) < sessionTimeout) {
            try {
                return command.execute(rzk);
            } catch (KeeperException ke) {
                switch (ke.code()) {
                case CONNECTIONLOSS:
                case OPERATIONTIMEOUT:
                    LOG.warn("Detected a Connection issue(" + ke.code() + ") with ZooKeeper, retrying");
                    nextTime = System.currentTimeMillis();
                    break;
                default:
                    throw ke;
                }
            }
        }

        //we've run out of time, our session has almost certainly expired. Give up and explode
        throw new KeeperException.SessionExpiredException();
    }

    public <T> T execute(Command<T> command) throws InterruptedException, KeeperException {
        try {
            return command.execute(getRecoverableZooKeeper());
        } catch (ZooKeeperConnectionException e) {
            throw new KeeperException.SessionExpiredException();
        }
    }
}