com.spotify.scio.coders.FloatCoder Maven / Gradle / Ivy

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Scio - A Scala API for Google Cloud Dataflow
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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 com.google.cloud.dataflow.sdk.coders.AtomicCoder;
import com.google.cloud.dataflow.sdk.coders.Coder.Context;
import com.google.cloud.dataflow.sdk.coders.CoderException;

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

  @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 8}, 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 8;
  }
}