public class FD_PID extends Protocol
A cache of Addresses and PIDs is maintained in each member, which is adjusted upon reception of view changes.
The population of the addr:pid cache is as follows:
When a new member joins, it requests the PID cache from the coordinator. Then it broadcasts its own addr:pid
association, so all members can update their cache. When a member P is to be pinged by Q, and Q doesn't have
P'd PID, Q will broadcast a WHO_HAS_PID message, to which all members who have that entry will respond. The
latter case should actually never happen because all members should always have consistent caches. However,
it is left in the code as a second line of defense.
Note that 1. The SET_PID has to be sent down after connecting to a channel !
2. Note that if a process is shunned and subsequently reconnects, the SET_PID event has to be resent !
3. This protocol only works for groups whose members are on the same host . 'Host' actually means the same IP address (e.g. for multi-homed systems).
Modifier and Type | Class and Description |
---|---|
static class |
FD_PID.FdHeader |
down_handler, down_prot, down_queue, down_thread, down_thread_prio, log, observer, props, stack, stats, up_handler, up_prot, up_queue, up_thread, up_thread_prio
Constructor and Description |
---|
FD_PID() |
Modifier and Type | Method and Description |
---|---|
void |
down(Event evt)
An event is to be sent down the stack.
|
java.lang.String |
getName() |
boolean |
setProperties(java.util.Properties props)
Configures the protocol initially.
|
void |
start()
This method is called on a
Channel.connect(String) . |
void |
stop()
This method is called on a
Channel.disconnect() . |
void |
up(Event evt)
An event was received from the layer below.
|
destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, handleSpecialDownEvent, init, passDown, passUp, printStats, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setUpProtocol, startDownHandler, startUpHandler, statsEnabled, stopInternal, upThreadEnabled
public boolean setProperties(java.util.Properties props)
Protocol
"loopback=false;unicast_inport=4444"
setProperties
in class Protocol
public void start() throws java.lang.Exception
Protocol
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 class Protocol
java.lang.Exception
- Thrown if protocol cannot be started successfully. This will cause the ProtocolStack
to fail, so Channel.connect(String)
will throw an exceptionpublic void stop()
Protocol
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 flushedpublic void up(Event evt)
Protocol
passDown()
or c) the event (or another event) is sent up
the stack using passUp()
.public void down(Event evt)
Protocol
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()
.Copyright ? 1998-2006 Bela Ban. All Rights Reserved.