gobblin.source.extractor.extract.kafka.MultiLongWatermark.java Source code

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Here is the source code for gobblin.source.extractor.extract.kafka.MultiLongWatermark.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 gobblin.source.extractor.extract.kafka;

import java.math.RoundingMode;
import java.util.List;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.math.LongMath;
import com.google.gson.Gson;
import com.google.gson.JsonElement;

import gobblin.source.extractor.Watermark;

/**
 * A {@link gobblin.source.extractor.Watermark} that holds multiple long values.
 *
 * @author Ziyang Liu
 */
public class MultiLongWatermark implements Watermark {

    private static final Gson GSON = new Gson();

    private final List<Long> values;

    /**
     * Copy constructor.
     */
    public MultiLongWatermark(MultiLongWatermark other) {
        this.values = Lists.newArrayList(other.values);
    }

    public MultiLongWatermark(List<Long> values) {
        this.values = Lists.newArrayList(values);
    }

    /**
     * Increment the idx'th value. idx must be between 0 and size()-1.
     */
    public void increment(int idx) {
        Preconditions.checkElementIndex(idx, this.values.size());
        Preconditions.checkArgument(this.values.get(idx) < Long.MAX_VALUE);
        this.values.set(idx, this.values.get(idx) + 1);
    }

    /**
     * Serializes the MultiLongWatermark into a JsonElement.
     */
    @Override
    public JsonElement toJson() {
        return GSON.toJsonTree(this);
    }

    /**
     * Given a low watermark (starting point) and a high watermark (target), returns the percentage
     * of events pulled.
     *
     * @return a percentage value between 0 and 100.
     */
    @Override
    public short calculatePercentCompletion(Watermark lowWatermark, Watermark highWatermark) {
        Preconditions.checkArgument(
                lowWatermark instanceof MultiLongWatermark && highWatermark instanceof MultiLongWatermark,
                String.format("Arguments of %s.%s must be of type %s", MultiLongWatermark.class.getSimpleName(),
                        Thread.currentThread().getStackTrace()[1].getMethodName(),
                        MultiLongWatermark.class.getSimpleName()));

        long pulled = ((MultiLongWatermark) lowWatermark).getGap(this);
        long all = ((MultiLongWatermark) lowWatermark).getGap((MultiLongWatermark) highWatermark);
        Preconditions.checkState(all > 0);
        long percent = Math.min(100, LongMath.divide(pulled * 100, all, RoundingMode.HALF_UP));
        return (short) percent;
    }

    /**
     * Get the number of records that need to be pulled given the high watermark.
     */
    public long getGap(MultiLongWatermark highWatermark) {
        Preconditions.checkNotNull(highWatermark);
        Preconditions.checkArgument(this.values.size() == highWatermark.values.size());
        long diff = 0;
        for (int i = 0; i < this.values.size(); i++) {
            Preconditions.checkArgument(this.values.get(i) <= highWatermark.values.get(i));
            diff += highWatermark.values.get(i) - this.values.get(i);
        }
        return diff;
    }

    /**
     * @return the number of long values this watermark holds.
     */
    public int size() {
        return this.values.size();
    }

    /**
     * The idx'th value of this watermark. idx must be between 0 and size()-1.
     * @return
     */
    public long get(int idx) {
        Preconditions.checkElementIndex(idx, this.values.size());
        return this.values.get(idx);
    }

    /**
     * Set the idx'th value of this watermark. idx must be between 0 and size()-1.
     */
    public long set(int idx, long value) {
        Preconditions.checkElementIndex(idx, this.values.size());
        return this.values.set(idx, value);
    }

    @Override
    public String toString() {
        return this.values.toString();
    }
}