com.yahoo.fs4

Class Packet

java.lang.Object

com.yahoo.fs4.BasicPacket

com.yahoo.fs4.Packet

Direct Known Subclasses:

DocsumPacket, EolPacket, ErrorPacket, GetDocSumsPacket, QueryPacket, QueryResultPacket

public abstract class Packet
extends BasicPacket

Superclass of fs4 packets containing channel/query ID

Author:

bratseth

Field Summary

Fields

Modifier and Type	Field and Description
protected int	channel The channel at which this packet will be sent or was received, or -1 when this is not known
protected static int	CHANNEL_ID_OFFSET
private static Logger	log

Fields inherited from class com.yahoo.fs4.BasicPacket

CODE_MASK, encodedBody, encodingBuffer, length

Constructor Summary

Constructors

Constructor and Description
Packet()

Method Summary

Modifier and Type	Method and Description
BasicPacket	decode(ByteBuffer buffer) Fills this package from a byte buffer positioned at the first byte of the package
Packet	encode(ByteBuffer buffer, int channel) Encodes this package onto the given buffer at the current position.
int	getChannel() Get the channel id of the packet.
boolean	hasChannelId() Informs that this packets needs a channel ID.
protected void	patchChannelId(ByteBuffer buf, int channelId) Only for use with encodingBuffer magic.
void	setChannel(int channel)
String	toString()

Methods inherited from class com.yahoo.fs4.BasicPacket

allocateAndEncode, codeDecodedHook, decodeAndDecompressBody, decodeBody, encode, encodeAndCompressBody, encodeBody, getCode, getLength, getTimestamp, grantEncodingBuffer, grantEncodingBuffer, isEncoded, setCompressionLimit, setCompressionType, setEncodedBody, setTimestamp

Methods inherited from class java.lang.Object

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

Field Detail

log

private static Logger log

channel

protected int channel

The channel at which this packet will be sent or was received, or -1 when this is not known

CHANNEL_ID_OFFSET

protected static final int CHANNEL_ID_OFFSET

See Also:

Constant Field Values

Constructor Detail

Packet

public Packet()

Method Detail

decode

public BasicPacket decode(ByteBuffer buffer)

Fills this package from a byte buffer positioned at the first byte of the package

Overrides:

decode in class BasicPacket

Returns:

this Packet (as a BasicPacket) for convenience

Throws:

UnsupportedOperationException - if not implemented in the subclass

encode

public final Packet encode(ByteBuffer buffer,
                           int channel)
                    throws BufferTooSmallException

Encodes this package onto the given buffer at the current position. The position of the buffer after encoding is the byte following the last encoded byte.

This method will ensure that everything is written provided sufficient capacity regardless of the buffer limit. When returning, the limit is at the end of the package (qual to the position).

Overrides:

encode in class BasicPacket

Returns:

this for convenience

Throws:

UnsupportedOperationException - if not implemented in the subclass

BufferTooSmallException

getChannel

public int getChannel()

Get the channel id of the packet. In the FS4 transport protocol, there is the concept of a channel. This must not be confused with all the other channels we have floating around this code (aargh!).

The channel can be thought of as a way to pair up requests and responses in the FS4 protocol: A response always belongs to to a channel and it is the clients responsibility to not re-use channel ids within the same connection.

Summary: This "channel" means "session id"

Returns:

FS4 channel id

setChannel

public void setChannel(int channel)

hasChannelId

public boolean hasChannelId()

Informs that this packets needs a channel ID.

Overrides:

hasChannelId in class BasicPacket

patchChannelId

protected void patchChannelId(ByteBuffer buf,
                              int channelId)

Only for use with encodingBuffer magic. This is only called from allocateAndEncode and grantEncodingBuffer, therefore an assumption about the packet starting at the beginning of the buffer is made.

Overrides:

patchChannelId in class BasicPacket

toString

public String toString()

Overrides:

toString in class BasicPacket