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java.lang.Objectorg.jgroups.stack.Protocol
org.jgroups.protocols.pbcast.STABLE
Computes the broadcast messages that are stable; i.e., have been received by all members. Sends STABLE events up the stack when this is the case. This allows NAKACK to garbage collect messages that have been seen by all members.
Works as follows: periodically we mcast our highest seqnos (seen for each member) to the group. A stability vector, which maintains the highest seqno for each member and initially contains no data, is updated when such a message is received. The entry for a member P is computed set to min(entry[P], digest[P]). When messages from all members have been received, a stability message is mcast, which causes all members to send a STABLE event up the stack (triggering garbage collection in the NAKACK layer).
The stable task now terminates after max_num_gossips if no messages or view changes have been sent or received
in the meantime. It will resume when messages are received. This effectively suspends sending superfluous
STABLE messages in the face of no activity.
New: when max_bytes
is exceeded (unless disabled by setting it to 0),
a STABLE task will be started (unless it is already running).
Nested Class Summary | |
static class |
STABLE.StableHeader
|
Field Summary |
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 | |
STABLE()
|
Method Summary | |
void |
down(Event evt)
An event is to be sent down the stack. |
long |
getDesiredAverageGossip()
|
long |
getMaxBytes()
|
java.lang.String |
getName()
|
int |
getNumberOfGossipMessages()
|
java.util.Vector |
requiredDownServices()
List of events that are required to be answered by some layer below. |
void |
resetStats()
|
void |
runMessageGarbageCollection()
|
void |
setDesiredAverageGossip(long gossip_interval)
|
void |
setMaxBytes(long max_bytes)
|
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. |
Methods inherited from class org.jgroups.stack.Protocol |
destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, handleSpecialDownEvent, init, isTrace, isWarn, passDown, passUp, printStats, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredUpServices, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setTrace, setUpProtocol, setWarn, startDownHandler, startUpHandler, statsEnabled, stopInternal, upThreadEnabled |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public STABLE()
Method Detail |
public java.lang.String getName()
getName
in class Protocol
public long getDesiredAverageGossip()
public void setDesiredAverageGossip(long gossip_interval)
public long getMaxBytes()
public void setMaxBytes(long max_bytes)
public int getNumberOfGossipMessages()
public void resetStats()
resetStats
in class Protocol
public java.util.Vector requiredDownServices()
Protocol
requiredDownServices
in class Protocol
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 flushed
stop
in class Protocol
public void up(Event evt)
Protocol
passDown()
or c) the event (or another event) is sent up
the stack using passUp()
.
up
in class Protocol
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()
.
down
in class Protocol
public void runMessageGarbageCollection()
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