com.spotify.scio.coders.FloatCoder.java Source code

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Here is the source code for com.spotify.scio.coders.FloatCoder.java

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/*
 * Copyright 2016 Spotify AB.
 *
 * 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.
 */

/* Ported com.google.cloud.dataflow.sdk.coders.DoubleCoder */

package com.spotify.scio.coders;

import com.fasterxml.jackson.annotation.JsonCreator;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UTFDataFormatException;

// package hack
import org.apache.beam.sdk.coders.AtomicCoder;
import org.apache.beam.sdk.coders.Coder.Context;
import org.apache.beam.sdk.coders.CoderException;

/**
 * A {@link FloatCoder} encodes {@link Float} values in 4 bytes using Java serialization.
 */
public class FloatCoder extends AtomicCoder<Float> {

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

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

    private static final FloatCoder INSTANCE = new FloatCoder();

    private FloatCoder() {
    }

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

    @Override
    public Float decode(InputStream inStream, Context context) throws IOException, CoderException {
        try {
            return new DataInputStream(inStream).readFloat();
        } catch (EOFException | UTFDataFormatException exn) {
            // These exceptions correspond to decoding problems, so change
            // what kind of exception they're branded as.
            throw new CoderException(exn);
        }
    }

    /**
     * {@inheritDoc}
     *
     * @throws NonDeterministicException always.
     *         Floating-point operations are not guaranteed to be deterministic, even
     *         if the storage format might be, so floating point representations are not
     *         recommended for use in operations that require deterministic inputs.
     */
    @Override
    public void verifyDeterministic() throws NonDeterministicException {
        throw new NonDeterministicException(this,
                "Floating point encodings are not guaranteed to be deterministic.");
    }

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

    /**
     * {@inheritDoc}
     *
     * @return {@code true}. {@link FloatCoder#getEncodedElementByteSize} returns a constant.
     */
    @Override
    public boolean isRegisterByteSizeObserverCheap(Float value, Context context) {
        return true;
    }

    /**
     * {@inheritDoc}
     *
     * @return {@code 4}, the byte size of a {@link Float} encoded using Java serialization.
     */
    @Override
    protected long getEncodedElementByteSize(Float value, Context context) throws Exception {
        if (value == null) {
            throw new CoderException("cannot encode a null Float");
        }
        return 4;
    }
}