org.javagroups.protocols
Class FD_PROB

java.lang.Object
  |
  +--org.javagroups.stack.Protocol
        |
        +--org.javagroups.protocols.FD_PROB
All Implemented Interfaces:
java.lang.Runnable

public class FD_PROB
extends Protocol
implements java.lang.Runnable

Probabilistic failure detection protocol based on "A Gossip-Style Failure Detection Service" by Renesse, Minsky and Hayden.

Each member maintains a list of all other members: for each member P, 2 data are maintained, a heartbeat counter and the time of the last increment of the counter. Each member periodically sends its own heartbeat counter list to a randomly chosen member Q. Q updates its own heartbeat counter list and the associated time (if counter was incremented). Each member periodically increments its own counter. If, when sending its heartbeat counter list, a member P detects that another member Q's heartbeat counter was not incremented for timeout seconds, Q will be suspected.

This protocol can be used both with a PBCAST *and* regular stacks.

Version:
$Revision: 1.7 $
Author:
Bela Ban 1999

Inner Class Summary
static class FD_PROB.FdHeader
           
 
Fields inherited from class org.javagroups.stack.Protocol
down_handler, down_prot, down_queue, down_thread, observer, props, stack, up_handler, up_prot, up_queue, up_thread
 
Constructor Summary
FD_PROB()
           
 
Method Summary
 void down(Event evt)
          An event is to be sent down the stack.
 java.lang.String getName()
           
 void run()
          Loop while more than 1 member available.
 boolean setProperties(java.util.Properties props)
          Configures the protocol initially.
 void up(Event evt)
          An event was received from the layer below.
 
Methods inherited from class org.javagroups.stack.Protocol
getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, init, passDown, passUp, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredDownServices, requiredUpServices, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setUpProtocol, startDownHandler, startUpHandler, stopInternal
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FD_PROB

public FD_PROB()
Method Detail

getName

public java.lang.String getName()
Overrides:
getName in class Protocol

setProperties

public boolean setProperties(java.util.Properties props)
Description copied from class: Protocol
Configures the protocol initially. A configuration string consists of name=value items, separated by a ';' (semicolon), e.g.:
 "loopback=false;unicast_inport=4444"
 
Overrides:
setProperties 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()
Loop while more than 1 member available. Choose a member randomly (not myself !) and send a heartbeat. Wait for ack. If ack not received withing timeout, mcast SUSPECT message.
Specified by:
run in interface java.lang.Runnable


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