org.jgroups.protocols.pbcast

Class PBCAST

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.pbcast.PBCAST

All Implemented Interfaces:

java.lang.Runnable

public class PBCAST
extends Protocol
implements java.lang.Runnable

Implementation of probabilistic broadcast. Sends group messages via unreliable multicast. Gossips regularly to a random subset of group members to retransmit missing messages. Gossiping is used both for bringing all members to the same state (having received the same messages) and to garbage-collect messages seen by all members (gc is piggybacked in gossip messages). See DESIGN for more details.

Author:

Bela Ban

Field Summary

Fields inherited from class org.jgroups.stack.Protocol

down_handler, down_prot, down_queue, down_thread, down_thread_prio, log, observer, props, stack, stats, up_handler, up_prot, up_queue, up_thread, up_thread_prio

Constructor Summary

Constructors

Constructor and Description
PBCAST()

Method Summary

Methods

Modifier and Type	Method and Description
void	down(Event evt) An event is to be sent down the stack.
java.lang.String	getName()
java.util.Vector	providedUpServices() List of events that are provided to layers above (they will be handled when sent down from above).
void	run() Gossip thread.
boolean	setProperties(java.util.Properties props) Setup the Protocol instance acording to the configuration string
void	stop() This method is called on a Channel.disconnect().
void	up(Event evt) An event was received from the layer below.

Methods inherited from class org.jgroups.stack.Protocol

destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, handleSpecialDownEvent, init, passDown, passUp, printStats, providedDownServices, receiveDownEvent, receiveUpEvent, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setUpProtocol, start, startDownHandler, startUpHandler, statsEnabled, stopInternal, upThreadEnabled

Methods inherited from class java.lang.Object

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

Constructor Detail

PBCAST

public PBCAST()

Method Detail

getName

public java.lang.String getName()

Specified by:

getName in class Protocol

providedUpServices

public java.util.Vector providedUpServices()

Description copied from class: Protocol

List of events that are provided to layers above (they will be handled when sent down from above).

Overrides:

providedUpServices in class Protocol

Returns:

Vector (of Integers)

stop

public void stop()

Description copied from class: Protocol

This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed

Overrides:

stop in class Protocol

up

public void up(Event evt)

Description copied from class: Protocol

An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using passDown() or c) the event (or another event) is sent up the stack using passUp().

Overrides:

up in class Protocol

down

public void down(Event evt)

Description copied from class: Protocol

An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using passDown(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using passUp().

Overrides:

down in class Protocol

run

public void run()

Gossip thread. Sends gossips containing a message digest every gossip_interval msecs

Specified by:

run in interface java.lang.Runnable

setProperties

public boolean setProperties(java.util.Properties props)

Setup the Protocol instance acording to the configuration string

Overrides:

setProperties in class Protocol