alluxio.client.block.stream

Class NettyDataReader

java.lang.Object

alluxio.client.block.stream.NettyDataReader

All Implemented Interfaces:

DataReader, Closeable, AutoCloseable

@NotThreadSafe
public final class NettyDataReader
extends Object
implements DataReader

A netty packet reader that streams a region from a netty data server. Protocol: 1. The client sends a read request (id, offset, length). 2. Once the server receives the request, it streams packets to the client. The streaming pauses if the server's buffer is full and resumes if the buffer is not full. 3. The client reads packets from the stream. Reading pauses if the client buffer is full and resumes if the buffer is not full. If the client can keep up with network speed, the buffer should have at most one packet. 4. The client stops reading if it receives an empty packet which signifies the end of the stream. 5. The client can cancel the read request at anytime. The cancel request is ignored by the server if everything has been sent to channel. 6. If the client wants to reuse the channel, the client must read all the packets in the channel before releasing the channel to the channel pool. 7. To make it simple to handle errors, the channel is closed if any error occurs.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NettyDataReader.Factory Factory class to create NettyDataReaders.

Method Summary

Modifier and Type	Method and Description
void	close()
long	pos()
DataBuffer	readChunk() Reads a chunk.

Methods inherited from class java.lang.Object

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

Method Detail

pos

public long pos()

Specified by:

pos in interface DataReader

Returns:

the current stream position

readChunk

public DataBuffer readChunk()
                     throws IOException

Description copied from interface: DataReader

Reads a chunk. The caller needs to release the chunk.

Specified by:

readChunk in interface DataReader

Returns:

the data buffer or null if EOF is reached

Throws:

IOException

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable