org.jgroups.protocols
Class FD_PROB
- Runnable
public class FD_PROB
implements 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.
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 |
destroy , down , downThreadEnabled , dumpStats , enableStats , getDownProtocol , getDownQueue , getName , getProperties , getUpProtocol , getUpQueue , handleSpecialDownEvent , init , isTrace , isWarn , passDown , passUp , printStats , providedDownServices , providedUpServices , receiveDownEvent , receiveUpEvent , requiredDownServices , requiredUpServices , resetStats , setDownProtocol , setObserver , setProperties , setPropertiesInternal , setProtocolStack , setTrace , setUpProtocol , setWarn , start , startDownHandler , startUpHandler , statsEnabled , stop , stopInternal , up , upThreadEnabled |
down
public void down(Event evt)
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()
.
- down in interface 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.
setProperties
public boolean setProperties(Properties props)
Configures the protocol initially. A configuration string consists of name=value
items, separated by a ';' (semicolon), e.g.:
"loopback=false;unicast_inport=4444"
- setProperties in interface Protocol
start
public void start()
throws Exception
This method is called on a
Channel.connect(String)
. Starts work.
Protocols are connected and queues are ready to receive events.
Will be called
from bottom to top. This call will replace
the
START and
START_OK events.
- start in interface Protocol
stop
public void stop()
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
- stop in interface Protocol
up
public void up(Event evt)
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()
.
- up in interface Protocol
Copyright B) 1998-2005 Bela Ban. All Rights Reserved.