PARQUET-1776: NIO wrapper for Output/Input File

[HunterL]

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[belugabehr]

@HunterL

OK, so I've been recently diving into Java NIO a bit and let me add some thoughts that relate to this task:

Please change the naming convention and drop the "Local" prefix. I think Nio is probably best. As an example of why this matters:

// This exists in the current PR
return new LocalSeekableInputStream(Files.newInputStream(path));

Well that statement Files.newInputStream(path) will provide a new InputStream, but the InputStream is totally driven by whatever the path points at. Things within the JVM could be setup to allow the provided path to point at an FTP location for example and that would be a remote read and not a local read.

I also think you will have better luck storing, internal to the Input/Output streams a SeekableByteChannel instead of an OutputStream or an InputStream. This will allow you to easily track the position aspect of the underlying stream without having to do it yourself. For example, the current OutputStream implementation does not currently implement this feature:

  @Override
  public long getPos() throws IOException {
    return 0;
  }

Thanks.

[belugabehr]

Also requires unit tests.

[belugabehr]

Here are a couple of starters:

       private final ByteBuffer oneByteBuffer = ByteBuffer.allocate(1);

	@Override
	public int read() throws IOException {
		int read = this.channel.read(this.oneByteBuffer.rewind());
		if (read < 0) {
			return read;
		}
		return (0xFF & this.oneByteBuffer.flip().get());
	}

	@Override
	public void readFully(byte[] bytes) throws IOException {
		ByteBuffer bb = ByteBuffer.allocate(bytes.length);
					while (bb.hasRemaining()) {
						int read = this.channel.read(bb);
						if (read == -1) {
							throw new EOFException();
						}
					}
					bb.flip().get(bytes);
	}