alluxio.worker.block.io

Interface BlockReader

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

LocalFileBlockReader, RemoteBlockReader, UnderFileSystemBlockReader

public interface BlockReader
extends Closeable

A reader interface to access the data of a block stored in managed storage.

This class does not provide thread-safety.

Method Summary

Modifier and Type	Method and Description
ReadableByteChannel	getChannel() Returns a readable byte channel of the block.
long	getLength() Gets the length of the block in bytes.
boolean	isClosed()
ByteBuffer	read(long offset, long length) Reads data from the block.
int	transferTo(io.netty.buffer.ByteBuf buf) Transfers data (up to buf.writableBytes()) from this reader to the buffer.

Methods inherited from interface java.io.Closeable

close

Method Detail

read

ByteBuffer read(long offset,
                long length)
         throws IOException

Reads data from the block.

Parameters:

offset - the offset from starting of the block file in bytes

length - the length of data to read in bytes, -1 for the rest of the block

Returns:

ByteBuffer the data that was read

Throws:

IOException

getLength

long getLength()

Gets the length of the block in bytes.

Returns:

the length of the block in bytes

getChannel

ReadableByteChannel getChannel()

Returns a readable byte channel of the block.

Returns:

channel

transferTo

int transferTo(io.netty.buffer.ByteBuf buf)
        throws IOException

Transfers data (up to buf.writableBytes()) from this reader to the buffer.

Parameters:

buf - the byte buffer

Returns:

the number of bytes transferred, -1 if the end of the block is reached

Throws:

IOException

isClosed

boolean isClosed()

Returns:

true if this reader is closed