org.apache.hadoop.fs
Interface ByteBufferReadable

All Known Implementing Classes:

CryptoFSDataInputStream, FSDataInputStream

public interface ByteBufferReadable

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

Method Summary

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() and buf.limit() should be unchanged, and therefore any data can be immediately read from buf. buf.mark() may be cleared or updated.

In the case of an exception, the values of buf.position() and buf.limit() are undefined, and callers should be prepared to recover from this eventuality.

Many implementations will throw UnsupportedOperationException, so callers that are not confident in support for this method from the underlying filesystem should be prepared to handle that exception.

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. Up to buf.limit() - buf.position() bytes may be read.

Returns:

the number of bytes available to read from buf

Throws:

IOException - if there is some error performing the read