| /** |
| * 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.pulsar.zookeeper; |
| |
| import java.io.Closeable; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.TimeUnit; |
| |
| import org.apache.zookeeper.AsyncCallback.StatCallback; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.WatchedEvent; |
| import org.apache.zookeeper.Watcher; |
| import org.apache.zookeeper.ZooKeeper; |
| import org.apache.zookeeper.data.Stat; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import io.netty.util.concurrent.DefaultThreadFactory; |
| |
| /** |
| * A ZooKeeper watcher for the Pulsar instance. |
| * |
| * Monitor the ZK session state every few seconds. If the session is not in Connected state for a while, we will kill |
| * the process before the session is supposed to expire |
| */ |
| public class ZooKeeperSessionWatcher implements Watcher, StatCallback, Runnable, Closeable { |
| |
| public interface ShutdownService { |
| void shutdown(int exitCode); |
| } |
| |
| private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperSessionWatcher.class); |
| |
| private final ShutdownService shutdownService; |
| private final ZooKeeper zk; |
| // Maximum time to wait for ZK session to be re-connected to quorum (set to 5/6 of SessionTimeout) |
| private final long monitorTimeoutMillis; |
| // Interval at which we check the state of the zk session (set to 1/15 of SessionTimeout) |
| private final long tickTimeMillis; |
| |
| private ScheduledExecutorService scheduler = null; |
| private Watcher.Event.KeeperState keeperState = Watcher.Event.KeeperState.Disconnected; |
| private long disconnectedAt = 0; |
| private boolean shuttingDown = false; |
| private volatile boolean zkOperationCompleted = false; |
| |
| public ZooKeeperSessionWatcher(ZooKeeper zk, long zkSessionTimeoutMillis, ShutdownService shutdownService) { |
| this.zk = zk; |
| this.monitorTimeoutMillis = zkSessionTimeoutMillis * 5 / 6; |
| this.tickTimeMillis = zkSessionTimeoutMillis / 15; |
| this.shutdownService = shutdownService; |
| } |
| |
| public void start() { |
| scheduler = Executors.newSingleThreadScheduledExecutor(new DefaultThreadFactory("pulsar-zk-session-watcher")); |
| scheduler.scheduleAtFixedRate(this, tickTimeMillis, tickTimeMillis, TimeUnit.MILLISECONDS); |
| } |
| |
| public Watcher.Event.KeeperState getKeeperState() { |
| return this.keeperState; |
| } |
| |
| // It is used only for testing purposes |
| public boolean isShutdownStarted() { |
| return shuttingDown; |
| } |
| |
| @Override |
| public void process(WatchedEvent event) { |
| Watcher.Event.EventType eventType = event.getType(); |
| Watcher.Event.KeeperState eventState = event.getState(); |
| |
| LOG.info("Received zookeeper notification, eventType={}, eventState={}", eventType, eventState); |
| |
| switch (eventType) { |
| case None: |
| if (eventState == Watcher.Event.KeeperState.Expired) { |
| LOG.error("ZooKeeper session already expired, invoking shutdown"); |
| close(); |
| shuttingDown = true; |
| shutdownService.shutdown(-1); |
| } |
| break; |
| default: |
| break; |
| } |
| |
| } |
| |
| // callback for zk probing |
| @Override |
| public synchronized void processResult(int rc, String path, Object ctx, Stat stat) { |
| switch (KeeperException.Code.get(rc)) { |
| case CONNECTIONLOSS: |
| keeperState = Watcher.Event.KeeperState.Disconnected; |
| break; |
| case SESSIONEXPIRED: |
| keeperState = Watcher.Event.KeeperState.Expired; |
| break; |
| case OK: |
| default: |
| keeperState = Watcher.Event.KeeperState.SyncConnected; |
| } |
| zkOperationCompleted = true; |
| this.notify(); |
| } |
| |
| // task that runs every TICK_TIME to check zk connection |
| @Override |
| public synchronized void run() { |
| try { |
| zkOperationCompleted = false; |
| if (zk != null) { |
| zk.exists("/", false, this, null); |
| try { |
| this.wait(tickTimeMillis); |
| } catch (InterruptedException e) { |
| LOG.info("ZooKeeperSessionWatcher interrupted"); |
| return; |
| } |
| } |
| if (!zkOperationCompleted) { |
| // consider zk disconnection if zk operation takes more than TICK_TIME |
| keeperState = Watcher.Event.KeeperState.Disconnected; |
| } |
| if (keeperState == Watcher.Event.KeeperState.Expired) { |
| LOG.error("zoo keeper session expired, invoking shutdown service"); |
| close(); |
| shuttingDown = true; |
| shutdownService.shutdown(-1); |
| } else if (keeperState == Watcher.Event.KeeperState.Disconnected) { |
| if (disconnectedAt == 0) { |
| // this is the first disconnect, we should monitor the time out from now, so we record the time of |
| // disconnect |
| disconnectedAt = System.nanoTime(); |
| } |
| |
| long timeRemainingMillis = monitorTimeoutMillis |
| - TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - disconnectedAt); |
| if (timeRemainingMillis <= 0) { |
| LOG.error("timeout expired for reconnecting, invoking shutdown service"); |
| close(); |
| shuttingDown = true; |
| shutdownService.shutdown(-1); |
| } else { |
| LOG.warn("zoo keeper disconnected, waiting to reconnect, time remaining = {} seconds", |
| TimeUnit.MILLISECONDS.toSeconds(timeRemainingMillis)); |
| } |
| } else { |
| if (disconnectedAt != 0) { |
| // since it reconnected to zoo keeper, we reset the disconnected time |
| LOG.info("reconnected to zoo keeper, system is back to normal."); |
| disconnectedAt = 0; |
| } |
| } |
| } catch (Exception e) { |
| LOG.warn(e.getMessage(), e); |
| } |
| } |
| |
| public void close() { |
| if (scheduler != null) { |
| scheduler.shutdownNow(); |
| } |
| } |
| } |