com.google.cloud.dataflow.sdk.coders.DurationCoder.java Source code

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Here is the source code for com.google.cloud.dataflow.sdk.coders.DurationCoder.java

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/*
 * Copyright (C) 2015 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.cloud.dataflow.sdk.coders;

import com.google.cloud.dataflow.sdk.util.common.ElementByteSizeObserver;

import com.fasterxml.jackson.annotation.JsonCreator;

import org.joda.time.Duration;
import org.joda.time.ReadableDuration;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * A {@link Coder} that encodes a joda {@link Duration} as a {@link Long} using the format of
 * {@link VarLongCoder}.
 */
public class DurationCoder extends AtomicCoder<ReadableDuration> {

    @JsonCreator
    public static DurationCoder of() {
        return INSTANCE;
    }

    /////////////////////////////////////////////////////////////////////////////

    private static final DurationCoder INSTANCE = new DurationCoder();

    private final VarLongCoder longCoder = VarLongCoder.of();

    private DurationCoder() {
    }

    private Long toLong(ReadableDuration value) {
        return value.getMillis();
    }

    private ReadableDuration fromLong(Long decoded) {
        return Duration.millis(decoded);
    }

    @Override
    public void encode(ReadableDuration value, OutputStream outStream, Context context)
            throws CoderException, IOException {
        if (value == null) {
            throw new CoderException("cannot encode a null ReadableDuration");
        }
        longCoder.encode(toLong(value), outStream, context);
    }

    @Override
    public ReadableDuration decode(InputStream inStream, Context context) throws CoderException, IOException {
        return fromLong(longCoder.decode(inStream, context));
    }

    /**
     * {@inheritDoc}
     *
     * @return {@code true}. This coder is injective.
     */
    @Override
    public boolean consistentWithEquals() {
        return true;
    }

    /**
     * {@inheritDoc}
     *
     * @return {@code true}, because it is cheap to ascertain the byte size of a long.
     */
    @Override
    public boolean isRegisterByteSizeObserverCheap(ReadableDuration value, Context context) {
        return longCoder.isRegisterByteSizeObserverCheap(toLong(value), context);
    }

    @Override
    public void registerByteSizeObserver(ReadableDuration value, ElementByteSizeObserver observer, Context context)
            throws Exception {
        longCoder.registerByteSizeObserver(toLong(value), observer, context);
    }
}