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org.jgroups.protocols
Class FD  

java.lang.Object
  org.jgroups.stack.Protocol
      org.jgroups.protocols.FD

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public class FD

extends org.jgroups.stack.Protocol

Failure detection based on simple heartbeat protocol. Regularly polls members for liveness. Multicasts SUSPECT messages when a member is not reachable. The simple algorithms works as follows: the membership is known and ordered. Each HB protocol periodically sends an 'are-you-alive' message to its *neighbor*. A neighbor is the next in rank in the membership list, which is recomputed upon a view change. When a response hasn't been received for n milliseconds and m tries, the corresponding member is suspected (and eventually excluded if faulty).

FD starts when it detects (in a view change notification) that there are at least 2 members in the group. It stops running when the membership drops below 2.

When a message is received from the monitored neighbor member, it causes the pinger thread to 'skip' sending the next are-you-alive message. Thus, traffic is reduced.

When we receive a ping from a member that's not in the membership list, we shun it by sending it a NOT_MEMBER message. That member will then leave the group (and possibly rejoin). This is only done if shun is true.

Version:

$Revision: 1.29 $

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Nested Class Summary
private  class	FD.Broadcaster           Task that periodically broadcasts a list of suspected members to the group.
private  class	FD.BroadcastTask
static class	FD.FdHeader
private  class	FD.Monitor

 

Field Summary
(package private)  FD.Broadcaster	bcast_task           Transmits SUSPECT message until view change or UNSUSPECT is received
(package private)  java.util.Hashtable	invalid_pingers
(package private)  long	last_ack
(package private)  org.jgroups.Address	local_addr
(package private)  int	max_tries
(package private)  java.util.Vector	members
(package private)  FD.Monitor	monitor
private  java.lang.Object	monitor_mutex
(package private) static java.lang.String	name
private  int	num_heartbeats
private  int	num_suspect_events
(package private)  int	num_tries
(package private)  org.jgroups.Address	ping_dest
(package private)  java.util.Vector	pingable_mbrs           Members from which we select ping_dest.
(package private)  boolean	shun
(package private)  org.jgroups.util.BoundedList	suspect_history
(package private)  long	timeout
(package private)  org.jgroups.util.TimeScheduler	timer

 

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

FD()

 

Method Summary
void	down(org.jgroups.Event evt)           An event is to be sent down the stack.
int	getCurrentNumTries()
java.lang.String	getLocalAddress()
int	getMaxTries()
java.lang.String	getMembers()
java.lang.String	getName()
int	getNumberOfHeartbeatsSent()
int	getNumSuspectEventsGenerated()
java.lang.String	getPingableMembers()
java.lang.String	getPingDest()
(package private)  java.lang.Object	getPingDest(java.util.Vector mbrs)
long	getTimeout()
void	init()           Called after instance has been created (null constructor) and before protocol is started.
boolean	isShun()
java.lang.String	printSuspectHistory()
void	resetStats()
void	setMaxTries(int max_tries)
boolean	setProperties(java.util.Properties props)           Configures the protocol initially.
void	setShun(boolean flag)
void	setTimeout(long timeout)
(package private)  void	shunInvalidHeartbeatSender(org.jgroups.Address hb_sender)           If sender is not a member, send a NOT_MEMBER to sender (after n pings received)
private  void	startMonitor()
void	stop()           This method is called on a Channel.disconnect()>Channel.disconnect() 55 .
private  void	stopMonitor()
(package private)  void	unsuspect(org.jgroups.Address mbr)
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, isTrace, isWarn, passDown, passUp, printStats, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredDownServices, requiredUpServices, 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

ping_dest

org.jgroups.Address ping_dest

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local_addr

org.jgroups.Address local_addr

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timeout

long timeout

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last_ack

long last_ack

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num_tries

int num_tries

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max_tries

int max_tries

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members

final java.util.Vector members

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invalid_pingers

final java.util.Hashtable invalid_pingers

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pingable_mbrs

final java.util.Vector pingable_mbrs

Members from which we select ping_dest. may be subset of members 55

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shun

boolean shun

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timer

org.jgroups.util.TimeScheduler timer

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monitor

FD.Monitor monitor

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monitor_mutex

private final java.lang.Object monitor_mutex

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num_heartbeats

private int num_heartbeats

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num_suspect_events

private int num_suspect_events

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bcast_task

final FD.Broadcaster bcast_task

Transmits SUSPECT message until view change or UNSUSPECT is received

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name

static final java.lang.String name

See Also:

Constant Field Values

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suspect_history

org.jgroups.util.BoundedList suspect_history

Constructor Detail

FD

public FD()

Method Detail

getName

public java.lang.String getName()

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getLocalAddress

public java.lang.String getLocalAddress()

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getMembers

public java.lang.String getMembers()

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getPingableMembers

public java.lang.String getPingableMembers()

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getPingDest

public java.lang.String getPingDest()

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getNumberOfHeartbeatsSent

public int getNumberOfHeartbeatsSent()

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getNumSuspectEventsGenerated

public int getNumSuspectEventsGenerated()

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getTimeout

public long getTimeout()

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setTimeout

public void setTimeout(long timeout)

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getMaxTries

public int getMaxTries()

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setMaxTries

public void setMaxTries(int max_tries)

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getCurrentNumTries

public int getCurrentNumTries()

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isShun

public boolean isShun()

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setShun

public void setShun(boolean flag)

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printSuspectHistory

public java.lang.String printSuspectHistory()

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setProperties

public boolean setProperties(java.util.Properties props)

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

Configures the protocol initially. A configuration string consists of name=value items, separated by a ';' (semicolon), e.g.:

 "loopback=false;unicast_inport=4444"
 

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resetStats

public void resetStats()

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init

public void init()
          throws java.lang.Exception

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

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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

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getPingDest

java.lang.Object getPingDest(java.util.Vector mbrs)

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startMonitor

private void startMonitor()

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stopMonitor

private void stopMonitor()

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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().

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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().

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unsuspect

void unsuspect(org.jgroups.Address mbr)

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shunInvalidHeartbeatSender

void shunInvalidHeartbeatSender(org.jgroups.Address hb_sender)

If sender is not a member, send a NOT_MEMBER to sender (after n pings received)

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

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