org.apache.flink.core.fs

Interface ByteBufferReadable

All Known Implementing Classes:

ByteBufferReadableClosingFSDataInputStream, HadoopDataInputStream

@Experimental
public interface ByteBufferReadable

An interface mark that a filesystem supports to read bytes from a ByteBuffer and its given position. The interface is borrowed from ByteBufferReadable and ByteBufferPositionedReadable in Apache Hadoop.

Method Summary

Modifier and Type	Method and Description
int	read(ByteBuffer byteBuffer) Reads up to byteBuffer.remaining() bytes into byteBuffer.
int	read(long position, ByteBuffer byteBuffer) Reads up to byteBuffer.remaining() bytes into byteBuffer from a given position in the file and returns the number of bytes read.

Method Detail

read

int read(ByteBuffer byteBuffer)
  throws IOException

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

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

In the case of an exception, the values of byteBuffer.position() and byteBuffer.limit() are undefined, and callers should be prepared to recover from this eventuality. Implementations should treat 0-length requests as legitimate, and must not signal an error upon their receipt.

Parameters:

byteBuffer - 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

read

int read(long position,
         ByteBuffer byteBuffer)
  throws IOException

Reads up to byteBuffer.remaining() bytes into byteBuffer from a given position in the file and returns the number of bytes read. Callers should use byteBuffer.limit(...) to control the size of the desired read and byteBuffer.position(...) to control the offset into the buffer the data should be written to.

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

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

Parameters:

position - position within file

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

Returns:

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

Throws:

IOException - if there is some error performing the read