alluxio.worker.page

Class PagedBlockReader

java.lang.Object

alluxio.worker.block.io.BlockClient

alluxio.worker.block.io.BlockReader

alluxio.worker.page.PagedBlockReader

All Implemented Interfaces:

Closeable, AutoCloseable

@NotThreadSafe
public class PagedBlockReader
extends BlockReader

A paged implementation of BlockReader interface. The read operations will fall back to the under storage when the requested data is not in the local storage.

Nested Class Summary

Nested classes/interfaces inherited from class alluxio.worker.block.io.BlockClient

BlockClient.Type

Constructor Summary

Constructors

Constructor and Description
PagedBlockReader(CacheManager cacheManager, UfsManager ufsManager, UfsInputStreamCache ufsInStreamCache, AlluxioConfiguration conf, long blockId, Protocol.OpenUfsBlockOptions ufsBlockOptions) Constructor for PagedBlockReader.

Method Summary

Modifier and Type	Method and Description
void	close()
ReadableByteChannel	getChannel() Returns a readable byte channel of the block.
long	getLength() Gets the length of the block in bytes.
String	getLocation()
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 class alluxio.worker.block.io.BlockClient

toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

PagedBlockReader

public PagedBlockReader(CacheManager cacheManager,
                        UfsManager ufsManager,
                        UfsInputStreamCache ufsInStreamCache,
                        AlluxioConfiguration conf,
                        long blockId,
                        Protocol.OpenUfsBlockOptions ufsBlockOptions)

Constructor for PagedBlockReader.

Parameters:

cacheManager - paging cache manager

ufsManager - under file storage manager

ufsInStreamCache - a cache for the in streams from ufs

conf - alluxio configurations

blockId - block id

ufsBlockOptions - options to open a ufs block

Method Detail

read

public ByteBuffer read(long offset,
                       long length)
                throws IOException

Description copied from class: BlockReader

Reads data from the block.

Specified by:

read in class BlockReader

Parameters:

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

length - the length of data to read in bytes

Returns:

ByteBuffer the data that was read

Throws:

IOException

getLength

public long getLength()

Description copied from class: BlockReader

Gets the length of the block in bytes.

Specified by:

getLength in class BlockReader

Returns:

the length of the block in bytes

getChannel

public ReadableByteChannel getChannel()

Description copied from class: BlockReader

Returns a readable byte channel of the block.

Specified by:

getChannel in class BlockReader

Returns:

channel

transferTo

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

Description copied from class: BlockReader

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

Specified by:

transferTo in class BlockReader

Parameters:

buf - the byte buffer

Returns:

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

Throws:

IOException

isClosed

public boolean isClosed()

Specified by:

isClosed in class BlockReader

Returns:

true if this reader is closed

getLocation

public String getLocation()

Specified by:

getLocation in class BlockReader

Returns:

an informational string of the location the reader is reading from

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class BlockClient

Throws:

IOException