Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> jgroups >> protocols >> [ pbcast overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

---

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 org.jgroups.stack.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.

---

Nested Class Summary
private static class	PBCAST.GossipEntry
private  class	PBCAST.GossipHandler           Handles gossip and retransmission requests.

 

Field Summary
(package private)  long	desired_avg_gossip
(package private)  java.util.Hashtable	digest
(package private)  boolean	dynamic
(package private)  int	gc_lag
(package private)  PBCAST.GossipHandler	gossip_handler
(package private)  long	gossip_interval
(package private)  org.jgroups.util.List	gossip_list
(package private)  org.jgroups.util.Queue	gossip_queue
(package private)  long	gossip_round
(package private)  java.lang.Thread	gossip_thread
(package private)  java.util.Hashtable	invalid_gossipers
(package private)  org.jgroups.Address	local_addr
(package private)  int	max_gossip_cache
(package private)  int	max_invalid_gossips
(package private)  int	max_queue
(package private)  boolean	mcast_gossip
(package private)  java.util.Vector	members
(package private)  boolean	operational
(package private)  java.util.Vector	seen_list
(package private)  long	seqno
(package private)  boolean	shun
(package private)  boolean	skip_sleep
(package private)  double	subset

 

Fields inherited from class org.jgroups.stack.Protocol

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

 

Constructor Summary

PBCAST()

 

Method Summary
(package private)  long	computeGossipInterval(int num_mbrs, double desired_avg_gossip)           Computes the gossip_interval.
void	down(org.jgroups.Event evt)           An event is to be sent down the stack.
(package private)  void	garbageCollect(Digest d)
(package private)  Digest	getDigest()           Returns for each sender the 'highest seen' seqno from the digest.
java.lang.String	getName()
(package private)  long	getRandom(long range)
(package private)  void	handleGossip(Gossip gossip)           MOST IMPORTANT METHOD IN THIS CLASS !! This guy really decides how a gossip reaches all members, or whether it will flood the network !
(package private)  void	handleUpMessage(org.jgroups.Message m, PbcastHeader hdr)           Ensures that FIFO is observed for all messages for a certain member.
(package private)  void	handleXmitRequest(org.jgroups.Address requester, java.util.Hashtable xmit_reqs)           Find the messages indicated in xmit_reqs and re-send them to requester
(package private)  void	handleXmitRsp(org.jgroups.util.List xmit_msgs)
(package private)  java.lang.String	printDigest()
(package private)  java.lang.String	printIncomingMessageQueue()
(package private)  java.lang.String	printXmitReqs(java.util.Hashtable xmit_reqs)
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.
(package private)  void	sendGossip()           Send a gossip message with a message digest of the highest seqnos seen per sender to a subset of the current membership.
(package private)  void	setDigest(Digest d)           Sets (or resets) the contents of the 'digest' table.
boolean	setProperties(java.util.Properties props)           Setup the Protocol instance acording to the configuration string
(package private)  void	shunInvalidGossiper(org.jgroups.Address invalid_gossiper)           If sender of gossip is not a member, send a NOT_MEMBER to sender (after n gossips received).
(package private)  void	startGossipHandler()
(package private)  void	startGossipThread()
void	stop()           This method is called on a Channel.disconnect()>Channel.disconnect() 55 .
(package private)  void	stopGossipHandler()
(package private)  void	stopGossipThread()
void	up(org.jgroups.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, isTrace, isWarn, passDown, passUp, printStats, providedDownServices, receiveDownEvent, receiveUpEvent, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setTrace, setUpProtocol, setWarn, start, startDownHandler, startUpHandler, statsEnabled, stopInternal, upThreadEnabled

 

Methods inherited from class java.lang.Object

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

 

Field Detail

operational

boolean operational

---

seqno

long seqno

---

gossip_round

long gossip_round

---

local_addr

org.jgroups.Address local_addr

---

digest

final java.util.Hashtable digest

---

gossip_thread

java.lang.Thread gossip_thread

---

gossip_handler

PBCAST.GossipHandler gossip_handler

---

gossip_queue

final org.jgroups.util.Queue gossip_queue

---

max_queue

int max_queue

---

gossip_interval

long gossip_interval

---

subset

double subset

---

desired_avg_gossip

long desired_avg_gossip

---

members

final java.util.Vector members

---

gossip_list

final org.jgroups.util.List gossip_list

---

max_gossip_cache

int max_gossip_cache

---

gc_lag

int gc_lag

---

invalid_gossipers

final java.util.Hashtable invalid_gossipers

---

max_invalid_gossips

final int max_invalid_gossips

See Also:

Constant Field Values

---

seen_list

java.util.Vector seen_list

---

shun

boolean shun

---

dynamic

boolean dynamic

---

skip_sleep

boolean skip_sleep

---

mcast_gossip

boolean mcast_gossip

Constructor Detail

PBCAST

public PBCAST()

Method Detail

getName

public java.lang.String getName()

---

providedUpServices

public java.util.Vector providedUpServices()

Description copied from class: org.jgroups.stack.Protocol

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

---

stop

public void stop()

Description copied from class: org.jgroups.stack.Protocol

This method is called on a Channel.disconnect()>Channel.disconnect() 55 . 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

---

up

public void up(org.jgroups.Event evt)

Description copied from class: org.jgroups.stack.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().

---

down

public void down(org.jgroups.Event evt)

Description copied from class: org.jgroups.stack.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().

---

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

---

handleUpMessage

void handleUpMessage(org.jgroups.Message m,
                     PbcastHeader hdr)

Ensures that FIFO is observed for all messages for a certain member. The NakReceiverWindow corresponding to a certain sender is looked up in a hashtable. Then, the message is added to the NakReceiverWindow. As many messages as possible are then removed from the table and passed up.

---

getDigest

Digest getDigest()

Returns for each sender the 'highest seen' seqno from the digest. Highest seen means the highest seqno without any gaps, e.g. if for a sender P the messages 2 3 4 6 7 were received, then only 2, 3 and 4 can be delivered, so 4 is the highest seen. 6 and 7 cannot because there 5 is missing. If there are no message, the highest seen seqno is -1.

---

setDigest

void setDigest(Digest d)

Sets (or resets) the contents of the 'digest' table. Its current messages will be deleted and the NakReceiverTables reset.

---

printDigest

java.lang.String printDigest()

---

printIncomingMessageQueue

java.lang.String printIncomingMessageQueue()

---

startGossipThread

void startGossipThread()

---

stopGossipThread

void stopGossipThread()

---

startGossipHandler

void startGossipHandler()

---

stopGossipHandler

void stopGossipHandler()

---

sendGossip

void sendGossip()

Send a gossip message with a message digest of the highest seqnos seen per sender to a subset of the current membership. Exclude self (I receive all mcasts sent by myself).

---

handleGossip

void handleGossip(Gossip gossip)

MOST IMPORTANT METHOD IN THIS CLASS !! This guy really decides how a gossip reaches all members, or whether it will flood the network !

Scrutinize the gossip received and request retransmission of messages that we haven't received yet. A gossip has a digest which carries for each sender the lowest and highest seqno seen. We check this range against our own digest and request retransmission of missing messages if needed.
See DESIGN for a description of this method

---

handleXmitRequest

void handleXmitRequest(org.jgroups.Address requester,
                       java.util.Hashtable xmit_reqs)

Find the messages indicated in xmit_reqs and re-send them to requester

---

handleXmitRsp

void handleXmitRsp(org.jgroups.util.List xmit_msgs)

---

printXmitReqs

java.lang.String printXmitReqs(java.util.Hashtable xmit_reqs)

---

garbageCollect

void garbageCollect(Digest d)

---

shunInvalidGossiper

void shunInvalidGossiper(org.jgroups.Address invalid_gossiper)

If sender of gossip is not a member, send a NOT_MEMBER to sender (after n gossips received). This will cause that member to leave the group and possibly re-join.

---

computeGossipInterval

long computeGossipInterval(int num_mbrs,
                           double desired_avg_gossip)

Computes the gossip_interval. See DESIGN for details

---

getRandom

long getRandom(long range)

---

Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> jgroups >> protocols >> [ pbcast overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

---