org.jgroups.protocols

Class COMPRESS

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.COMPRESS

public class COMPRESS
extends Protocol

Compresses the payload of a message. Goal is to reduce the number of messages sent across the wire. Should ideally be layered somewhere above a fragmentation protocol (e.g. FRAG).

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	COMPRESS.CompressHeader

Field Summary

Fields

Modifier and Type	Field and Description
protected int	compression_level
protected java.util.concurrent.BlockingQueue<java.util.zip.Deflater>	deflater_pool
protected java.util.concurrent.BlockingQueue<java.util.zip.Inflater>	inflater_pool
protected long	min_size
protected int	pool_size

Fields inherited from class org.jgroups.stack.Protocol

after_creation_hook, down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

Constructors

Constructor and Description
COMPRESS()

Method Summary

Modifier and Type	Method and Description
void	destroy() This method is called on a Channel.close().
java.lang.Object	down(Event evt) We compress the payload if it is larger than min_size.
void	init() Called after instance has been created (null constructor) and before protocol is started.
protected Message	uncompress(Message msg, int original_size) Returns a new message as a result of uncompressing msg, or null if msg couldn't be uncompressed
java.lang.Object	up(Event evt) If there is no header, we pass the message up.
void	up(MessageBatch batch) Sends up a multiple messages in a MessageBatch.

Methods inherited from class org.jgroups.stack.Protocol

accept, afterCreationHook, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled, stop

Methods inherited from class java.lang.Object

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

Field Detail

compression_level

protected int compression_level

min_size

protected long min_size

pool_size

protected int pool_size

deflater_pool

protected java.util.concurrent.BlockingQueue<java.util.zip.Deflater> deflater_pool

inflater_pool

protected java.util.concurrent.BlockingQueue<java.util.zip.Inflater> inflater_pool

Constructor Detail

COMPRESS

public COMPRESS()

Method Detail

init

public void init()
          throws java.lang.Exception

Description copied from class: Protocol

Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:

init in class Protocol

Throws:

java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

destroy

public void destroy()

Description copied from class: Protocol

This method is called on a Channel.close(). Does some cleanup; after the call the VM will terminate

Overrides:

destroy in class Protocol

down

public java.lang.Object down(Event evt)

We compress the payload if it is larger than min_size. In this case we add a header containing the original size before compression. Otherwise we add no header.
Note that we compress either the entire buffer (if offset/length are not used), or a subset (if offset/length are used)

Overrides:

down in class Protocol

Parameters:

evt -

up

public java.lang.Object up(Event evt)

If there is no header, we pass the message up. Otherwise we uncompress the payload to its original size.

Overrides:

up in class Protocol

Parameters:

evt -

up

public void up(MessageBatch batch)

Description copied from class: Protocol

Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.

The default processing below sends messages up the stack individually, based on a matching criteria (calling Protocol.accept(org.jgroups.Message)), and - if true - calls Protocol.up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.

Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.getMatchingMessages(short,boolean)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.

Overrides:

up in class Protocol

Parameters:

batch - The message batch

uncompress

protected Message uncompress(Message msg,
                             int original_size)

Returns a new message as a result of uncompressing msg, or null if msg couldn't be uncompressed