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
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 |
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 |
FD_PROB
public FD_PROB()
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
Copyright © 2001,2002 www.javagroups.com . All Rights Reserved.