com.google.appengine.tools.mapreduce.DatastorePersistingStatusReporter.java Source code

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Here is the source code for com.google.appengine.tools.mapreduce.DatastorePersistingStatusReporter.java

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/*
 * Copyright 2010 Google Inc.
 *
 * Licensed 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 com.google.appengine.tools.mapreduce;

import com.google.appengine.tools.mapreduce.v2.impl.ShardState;

import org.apache.hadoop.mapreduce.Counter;
import org.apache.hadoop.mapreduce.Counters;
import org.apache.hadoop.mapreduce.StatusReporter;

import java.util.logging.Logger;

/**
 * A Hadoop StatusReporter that saves reported data to a {@link ShardState}.
 *
 */
public class DatastorePersistingStatusReporter extends StatusReporter {
    private static final Logger log = Logger.getLogger(DatastorePersistingStatusReporter.class.getName());

    // Persists state to here.
    private final ShardState shardState;

    // Working set of Counters.
    private final Counters counters;

    // Status message to report.
    private String status;

    /**
     * Initialize the reporter with the given shard state.
     */
    public DatastorePersistingStatusReporter(ShardState shardState) {
        this.shardState = shardState;
        counters = shardState.getCounters();
        status = shardState.getStatusString();
    }

    @Override
    public Counter getCounter(Enum<?> name) {
        return counters.findCounter(name);
    }

    @Override
    public Counter getCounter(String group, String name) {
        return counters.findCounter(group, name);
    }

    // I can't seem to find anybody who quite knows what the purpose of this
    // method is.
    @Override
    public void progress() {
    }

    @Override
    public void setStatus(String status) {
        this.status = status;
    }

    /**
     * Persist the underlying state of this shard.
     */
    public void persist() {
        shardState.setCounters(counters);
        shardState.setStatusString(status);
        shardState.persist();
    }
}