org.apache.hadoop.hbase.client.metrics.ScanMetrics.java Source code

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Here is the source code for org.apache.hadoop.hbase.client.metrics.ScanMetrics.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.hadoop.hbase.client.metrics;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicLong;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;

import com.google.common.collect.ImmutableMap;

/**
 * Provides client-side metrics related to scan operations
 * The data can be passed to mapreduce framework or other systems.
 * We use atomic longs so that one thread can increment,
 * while another atomically resets to zero after the values are reported
 * to hadoop's counters.
 *
 * Some of these metrics are general for any client operation such as put
 * However, there is no need for this. So they are defined under scan operation
 * for now.
 */
@InterfaceAudience.Private
public class ScanMetrics {

    private static final Log LOG = LogFactory.getLog(ScanMetrics.class);

    /**
     * Hash to hold the String -> Atomic Long mappings.
     */
    private final Map<String, AtomicLong> counters = new HashMap<String, AtomicLong>();

    // AtomicLongs to hold the metrics values.  These are all updated through ClientScanner and
    // ScannerCallable.  They are atomic longs so that atomic getAndSet can be used to reset the
    // values after progress is passed to hadoop's counters.

    /**
     * number of RPC calls
     */
    public final AtomicLong countOfRPCcalls = createCounter("RPC_CALLS");

    /**
     * number of remote RPC calls
     */
    public final AtomicLong countOfRemoteRPCcalls = createCounter("REMOTE_RPC_CALLS");

    /**
     * sum of milliseconds between sequential next calls
     */
    public final AtomicLong sumOfMillisSecBetweenNexts = createCounter("MILLIS_BETWEEN_NEXTS");

    /**
     * number of NotServingRegionException caught
     */
    public final AtomicLong countOfNSRE = createCounter("NOT_SERVING_REGION_EXCEPTION");

    /**
     * number of bytes in Result objects from region servers
     */
    public final AtomicLong countOfBytesInResults = createCounter("BYTES_IN_RESULTS");

    /**
     * number of bytes in Result objects from remote region servers
     */
    public final AtomicLong countOfBytesInRemoteResults = createCounter("BYTES_IN_REMOTE_RESULTS");

    /**
     * number of regions
     */
    public final AtomicLong countOfRegions = createCounter("REGIONS_SCANNED");

    /**
     * number of RPC retries
     */
    public final AtomicLong countOfRPCRetries = createCounter("RPC_RETRIES");

    /**
     * number of remote RPC retries
     */
    public final AtomicLong countOfRemoteRPCRetries = createCounter("REMOTE_RPC_RETRIES");

    /**
     * constructor
     */
    public ScanMetrics() {
    }

    private AtomicLong createCounter(String counterName) {
        AtomicLong c = new AtomicLong(0);
        counters.put(counterName, c);
        return c;
    }

    public void setCounter(String counterName, long value) {
        AtomicLong c = this.counters.get(counterName);
        if (c != null) {
            c.set(value);
        }
    }

    /**
     * Get all of the values since the last time this function was called.
     *
     * Calling this function will reset all AtomicLongs in the instance back to 0.
     *
     * @return A Map of String -> Long for metrics
     */
    public Map<String, Long> getMetricsMap() {
        //Create a builder
        ImmutableMap.Builder<String, Long> builder = ImmutableMap.builder();
        //For every entry add the value and reset the AtomicLong back to zero
        for (Map.Entry<String, AtomicLong> e : this.counters.entrySet()) {
            builder.put(e.getKey(), e.getValue().getAndSet(0));
        }
        //Build the immutable map so that people can't mess around with it.
        return builder.build();
    }

}