org.apache.slider.core.zk.BlockingZKWatcher.java Source code

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Here is the source code for org.apache.slider.core.zk.BlockingZKWatcher.java

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/*
 * 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.slider.core.zk;

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.ConnectException;
import java.util.concurrent.atomic.AtomicBoolean;

public class BlockingZKWatcher implements Watcher {

    protected static final Logger log = LoggerFactory.getLogger(BlockingZKWatcher.class);
    private final AtomicBoolean connectedFlag = new AtomicBoolean(false);

    @Override
    public void process(WatchedEvent event) {
        log.info("ZK binding callback received");
        connectedFlag.set(true);
        synchronized (connectedFlag) {
            try {
                connectedFlag.notify();
            } catch (Exception e) {
                log.warn("failed while waiting for notification", e);
            }
        }
    }

    /**
     * Wait for a flag to go true
     * @param timeout timeout in millis
     */

    public void waitForZKConnection(int timeout) throws InterruptedException, ConnectException {
        synchronized (connectedFlag) {
            if (!connectedFlag.get()) {
                log.info("waiting for ZK event");
                //wait a bit
                connectedFlag.wait(timeout);
            }
        }
        if (!connectedFlag.get()) {
            throw new ConnectException("Unable to connect to ZK quorum");
        }
    }

}