org.apache.ambari.servicemonitor.probes.DfsSafeModeProbe.java Source code

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Here is the source code for org.apache.ambari.servicemonitor.probes.DfsSafeModeProbe.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.ambari.servicemonitor.probes;

import org.apache.ambari.servicemonitor.reporting.ProbeStatus;
import org.apache.ambari.servicemonitor.utils.DFSUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.protocol.FSConstants;

import java.io.IOException;
import java.net.URI;

/**
 * Safe mode probe can probe the safe mode status of an NN.
 * It can be set to not care if the system re-enters safe mode after startup,
 * in which case it only checks for safe mode in startup, and can be used
 * to assert that the filesystem exits safe mode after a given period of time.
 * <p/>
 * If set to ignore the safe mode status entirely, then the result of the 
 * safemode call is ignored completely -though errors to talk to the
 * filesystem are considered errors. 
 */
public class DfsSafeModeProbe extends Probe implements SafeModeCheck {

    private final boolean ignoreSafeModeManuallyTriggered;
    private boolean safeModeExitedOnce;
    protected volatile boolean inSafeMode;

    public DfsSafeModeProbe(Configuration conf, boolean ignoreSafeModeManuallyTriggered) throws IOException {
        super("SafeModeProbe", conf);
        URI uri = DFSUtils.getHDFSUri(conf);
        setName("SafeModeProbe" + uri);
        this.ignoreSafeModeManuallyTriggered = ignoreSafeModeManuallyTriggered;

        DFSUtils.makeDfsCallsNonBlocking(conf);
    }

    @Override
    public boolean isInSafeMode() {
        return inSafeMode;
    }

    @Override
    public ProbeStatus ping(boolean livePing) {
        ProbeStatus status = new ProbeStatus();
        try {
            DistributedFileSystem hdfs = DFSUtils.createUncachedDFS(conf);
            inSafeMode = hdfs.setSafeMode(FSConstants.SafeModeAction.SAFEMODE_GET);
            boolean live = !inSafeMode;
            if (inSafeMode) {
                if (ignoreSafeModeManuallyTriggered) {
                    live = safeModeExitedOnce;
                }
            } else {
                //it's easier to always set this on a live NN than it is to track whether there's just
                //been a state transition.
                safeModeExitedOnce = true;
            }
            status.succeed(this);
            status.setSuccess(live);
            status.setMessage(hdfs.getUri() + " up - safe mode state " + inSafeMode);
        } catch (IOException e) {
            status.fail(this, e);
        }
        return status;
    }

}