content: /*
   * 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 org.apache.beam.sdk.coders;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import org.apache.beam.sdk.util.ExposedByteArrayOutputStream;
  import org.apache.beam.sdk.util.StreamUtils;
  import org.apache.beam.sdk.util.VarInt;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.io.ByteStreams;
  
  /**
   * A {@link Coder} for {@code byte[]}.
   *
   * <p>The encoding format is as follows:
   *
   * <ul>
   *   <li>If in a non-nested context (the {@code byte[]} is the only value in the stream), the bytes
   *       are read/written directly.
   *   <li>If in a nested context, the bytes are prefixed with the length of the array, encoded via a
   *       {@link VarIntCoder}.
   * </ul>
   */
  public class ByteArrayCoder extends AtomicCoder<byte[]> {
  
    public static ByteArrayCoder of() {
      return INSTANCE;
    }
  
    /////////////////////////////////////////////////////////////////////////////
  
    private static final ByteArrayCoder INSTANCE = new ByteArrayCoder();
    private static final TypeDescriptor<byte[]> TYPE_DESCRIPTOR = new TypeDescriptor<byte[]>() {};
  
    private ByteArrayCoder() {}
  
    @Override
    public void encode(byte[] value, OutputStream outStream) throws IOException, CoderException {
      encode(value, outStream, Context.NESTED);
    }
  
    @Override
    public void encode(byte[] value, OutputStream outStream, Context context)
        throws IOException, CoderException {
      if (value == null) {
        throw new CoderException("cannot encode a null byte[]");
      }
      if (!context.isWholeStream) {
        VarInt.encode(value.length, outStream);
        outStream.write(value);
      } else {
        outStream.write(value);
      }
    }
  
    /**
     * Encodes the provided {@code value} with the identical encoding to {@link #encode}, but with
     * optimizations that take ownership of the value.
     *
     * <p>Once passed to this method, {@code value} should never be observed or mutated again.
     */
    public void encodeAndOwn(byte[] value, OutputStream outStream, Context context)
        throws IOException, CoderException {
      if (!context.isWholeStream) {
        VarInt.encode(value.length, outStream);
        outStream.write(value);
      } else {
        if (outStream instanceof ExposedByteArrayOutputStream) {
          ((ExposedByteArrayOutputStream) outStream).writeAndOwn(value);
        } else {
          outStream.write(value);
        }
      }
    }
  
    @Override
    public byte[] decode(InputStream inStream) throws IOException, CoderException {
      return decode(inStream, Context.NESTED);
    }
  
    @Override
    public byte[] decode(InputStream inStream, Context context) throws IOException, CoderException {
      if (context.isWholeStream) {
        return StreamUtils.getBytesWithoutClosing(inStream);
      } else {
        int length = VarInt.decodeInt(inStream);
        if (length < 0) {
          throw new IOException("invalid length " + length);
        }
        byte[] value = new byte[length];
        ByteStreams.readFully(inStream, value);
        return value;
      }
    }
  
    @Override
    public void verifyDeterministic() {}
  
    /**
     * {@inheritDoc}
     *
     * @return objects that are equal if the two arrays contain the same bytes.
     */
    @Override
    public Object structuralValue(byte[] value) {
      return new StructuralByteArray(value);
    }
  
    /**
     * {@inheritDoc}
     *
     * @return {@code true} since {@link #getEncodedElementByteSize} runs in constant time using the
     *     {@code length} of the provided array.
     */
    @Override
    public boolean isRegisterByteSizeObserverCheap(byte[] value) {
      return true;
    }
  
    @Override
    public TypeDescriptor<byte[]> getEncodedTypeDescriptor() {
      return TYPE_DESCRIPTOR;
    }
  
    @Override
    protected long getEncodedElementByteSize(byte[] value) throws Exception {
      if (value == null) {
        throw new CoderException("cannot encode a null byte[]");
      }
      return (long) VarInt.getLength(value.length) + value.length;
    }
  }
  