alluxio.client.block.stream

Class NettyPacketReader

java.lang.Object

alluxio.client.block.stream.NettyPacketReader

All Implemented Interfaces:

PacketReader, Closeable, AutoCloseable

@NotThreadSafe
public final class NettyPacketReader
extends Object
implements PacketReader

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	NettyPacketReader.Factory Factory class to create NettyPacketReaders.

Method Summary

Modifier and Type	Method and Description
void	close()
long	pos()
DataBuffer	readPacket() Reads a packet.

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 PacketReader

Returns:

the current stream position

readPacket

public DataBuffer readPacket()
                      throws IOException

Description copied from interface: PacketReader

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

Specified by:

readPacket in interface PacketReader

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