org.apache.hadoop.fs

Interface ByteBufferReadable

All Known Implementing Classes:

FSDataInputStream, HdfsDataInputStream

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public interface ByteBufferReadable

Implementers of this interface provide a read API that writes to a ByteBuffer, not a byte[].

Method Summary

Modifier and Type	Method and Description
int	read(ByteBuffer buf) Reads up to buf.remaining() bytes into buf.

Method Detail

read

int read(ByteBuffer buf)
  throws IOException

Reads up to buf.remaining() bytes into buf. Callers should use buf.limit(..) to control the size of the desired read.

After a successful call, buf.position() will be advanced by the number of bytes read and buf.limit() will be unchanged.

In the case of an exception, the state of the buffer (the contents of the buffer, the buf.position(), the buf.limit(), etc.) is undefined, and callers should be prepared to recover from this eventuality.

Callers should use StreamCapabilities.hasCapability(String) with StreamCapabilities.READBYTEBUFFER to check if the underlying stream supports this interface, otherwise they might get a UnsupportedOperationException.

Implementations should treat 0-length requests as legitimate, and must not signal an error upon their receipt.

Parameters:

buf - the ByteBuffer to receive the results of the read operation.

Returns:

the number of bytes read, possibly zero, or -1 if reach end-of-stream

Throws:

IOException - if there is some error performing the read