org.apache.ambari.servicemonitor.jobs.ProbableFileOperation.java Source code

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Here is the source code for org.apache.ambari.servicemonitor.jobs.ProbableFileOperation.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.jobs;

import org.apache.ambari.servicemonitor.utils.OnDemandFS;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapred.Reporter;

import java.io.IOException;
import java.util.Random;

/**
 * Probable file operations. Execute FS operations based on a probability. Know
 * that the FS is fetched every operation -but is not closed.
 *
 * Probability of 1.0 implies every operation is a probe. Probability of 0.0
 * implies no operations probe the FS.
 *
 * The delay parameter allows for each operation to take a fixed period of time
 * irrespective of whether the file operation takes place. This is to aid
 * testing by simulating long-lived Mappers or Reducers.
 */
public class ProbableFileOperation extends Configured {
    public static final Log LOG = LogFactory.getLog(ProbableFileOperation.class);

    /**
     * Key for the seed: {@value}
     */
    public static final String SEED = ".seed";

    /**
     * Key suffix for the path: {@value}
     */
    public static final String PATH = ".path";

    /**
     * Probability: 0.0-1.0, double: : {@value}
     */
    public static final String PROBABILITY = ".probability";

    /**
     * Delay in milliseconds, 0 for none: : {@value}
     */
    public static final String SLEEPTIME = ".delay";
    public static final String COUNTER = "operations";
    public static final String EXECUTES = "executions";
    private final Path path;
    private final float probability;
    private final Random rng;
    private final int delay;
    public final String name;
    private OnDemandFS cachedFS;

    /**
     * Create an operation
     *
     * @param name prefix for the
     * @param conf configuration to save
     */
    public ProbableFileOperation(String name, Configuration conf) {
        super(conf);
        this.name = name;
        path = new Path(conf.get(name + PATH, "/"));
        probability = conf.getFloat(name + PROBABILITY, 0.0f);
        rng = new Random(conf.getInt(name + SEED, 0));
        delay = conf.getInt(name + SLEEPTIME, 0);
        cachedFS = new OnDemandFS(getConf());
    }

    /**
     * Look at the random number, decide whether or not to query the filestatus of
     * the target path.
     *
     * the counter name+.operations is incremented every time a file operation
     * takes place -this is primarily for testing.
     *
     * @param reporter reporter to increment on file ops
     * @return true iff the file execution took place
     * @throws IOException on any failure to talk to the filesystem.
     */
    public boolean execute(Reporter reporter) throws IOException {
        //first sleep
        if (delay > 0) {
            try {
                Thread.sleep(delay);
            } catch (InterruptedException ignored) {

            }
        }
        if (reporter != null) {
            reporter.incrCounter(name, EXECUTES, 1);
        }
        //then the operation
        float random = rng.nextFloat();
        if (random < probability) {
            //execute a file operation
            if (LOG.isDebugEnabled()) {
                LOG.debug("Reading " + path);
            }

            cachedFS.getOrCreate().getFileStatus(path);
            if (reporter != null) {
                reporter.incrCounter(name, COUNTER, 1);
            }
            return true;
        } else {
            return false;
        }
    }
}