spork-master/src/org/apache/pig/tools/counters/PigCounterHelper.java
/*
 * 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.pig.tools.counters;

import java.util.Map;

import org.apache.pig.impl.util.Pair;
import org.apache.pig.tools.pigstats.PigStatusReporter;

import com.google.common.collect.Maps;

/**
 * A helper class to deal with Hadoop counters in Pig.  They are stored within the singleton
 * PigStatusReporter instance, but are null for some period of time at job startup, even after
 * Pig has been invoked.  This class buffers counters, trying each time to get a valid Reporter and flushing
 * stored counters each time it does.
 */
public class PigCounterHelper {
    private final Map<Pair<String, String>, Long> counterStringMap_ = Maps.newHashMap();
    private final Map<Enum<?>, Long> counterEnumMap_ = Maps.newHashMap();

    /**
    * Mocks the Reporter.incrCounter, but adds buffering.
    * See org.apache.hadoop.mapred.Reporter's incrCounter.
    */
    public void incrCounter(String group, String counterName, long incr) {
        PigStatusReporter reporter = PigStatusReporter.getInstance();
        if (reporter != null && reporter.incrCounter(group, counterName, incr)) { // common case
            if (counterStringMap_.size() > 0) {
                for (Map.Entry<Pair<String, String>, Long> entry : counterStringMap_.entrySet()) {
                    reporter.incrCounter(entry.getKey().first, entry.getKey().second, entry.getValue());
                }
                counterStringMap_.clear();
            }
            return;
        }

        // In the case when reporter is not available, or we can't get the
        // Counter, store in the local map.
        Pair<String, String> key = new Pair<String, String>(group, counterName);
        Long currentValue = counterStringMap_.get(key);
        counterStringMap_.put(key, (currentValue == null ? 0 : currentValue) + incr);
    }

    /**
    * Mocks the Reporter.incrCounter, but adds buffering.
    * See org.apache.hadoop.mapred.Reporter's incrCounter.
    */
    public void incrCounter(Enum<?> key, long incr) {
        PigStatusReporter reporter = PigStatusReporter.getInstance();
        if (reporter != null && reporter.incrCounter(key, incr)) { // common case
            if (counterEnumMap_.size() > 0) {
                for (Map.Entry<Enum<?>, Long> entry : counterEnumMap_.entrySet()) {
                    reporter.getCounter(entry.getKey()).increment(entry.getValue());
                }
                counterEnumMap_.clear();
            }
            return;
        }

        // In the case when reporter is not available, or we can't get the
        // Counter, store in the local map.
        Long currentValue = counterEnumMap_.get(key);
        counterEnumMap_.put(key, (currentValue == null ? 0 : currentValue) + incr);
    }
}
