| org.jgroups.stack.RpcProtocol
 org.jgroups.protocols.STABLE
| STABLE | | public class STABLE extends RpcProtocol (Code) | | Computes the broadcast messages that are stable; i.e., that have been received
by all members. Sends STABLE events up the stack when this is the case.
Uses a probabilistic scheme to do so, as described in:
GSGC: An Efficient Gossip-Style Garbage Collection Scheme for Scalable
Reliable Multicast, K. Guo et al., 1997.
The only difference is that instead of using counters for an estimation of
messages received from each member, we retrieve this actual information
from the NAKACK layer (which must be present for the STABLE protocol to
work).
Note: the the Event.MSG call path path must be as lightweight as
possible. It should not request any lock for which there is a high
contention and/or long delay.
Changes(igeorg - 2.VI.2001):
i. Thread-safety (in RPC calls most notably on the lines of Gianluca
Collot's bugfix)
ii. All slow calls (RPCs, seqnos requests, etc.) placed outside locks
iii. Removed redundant initialization in adaptation to a higher round
iv. heard_from[this meber] is always set to true on every new round
(i.e. on every stability bcast).
v. Replaced gossip thread with TimeScheduler.Task
[[[ TODO(igeorg - 2.VI.2001)
i. Faster stability convergence by better selection of gossip subsets
(replace Util.pickSubset()).
ii. Special mutex on the Event.MSG call path. I.e. remove
synchronized(this)> with e.g. synchronized(msg_mutex).
]] TODO
|
| Method Summary | |
| public String | getName()
| | public void | gossip(ViewId view_id, long gossip_round, long[] gossip_seqnos, boolean[] heard, Object sender)
Contains the highest sequence numbers as seen by sender
Parameters:
view_id - The view ID in which the gossip was sent. | | public boolean | handleDownEvent(Event evt)
Callback. | | public boolean | handleUpEvent(Event evt)
Callback. | | public Vector | requiredUpServices()
| | public boolean | setProperties(Properties props)
Set the parameters for this layer. | | public void | stability(ViewId view_id, long gossip_round, long[] stability_vector, Object sender)
Contains the highest message sequence numbers (for each member) that
can safely be deleted (because they have been seen by all members). | | public void | start()
Start the layer:
i. | | public void | stop()
|
| gossip | | public void gossip(ViewId view_id, long gossip_round, long[] gossip_seqnos, boolean[] heard, Object sender)(Code) | | Contains the highest sequence numbers as seen by sender
Parameters:
view_id - The view ID in which the gossip was sent. Must be thesame as ours, otherwise it is discarded
Parameters:
gossip_round - The round in which the gossip was sent
Parameters:
gossip_seqnos - A vector with the highest sequence numbers asseen by sender
Parameters:
heard - The sender's heard_from array. This allowsus to minimize the gossip msgs for a given round as a member does nothave to receive gossip msgs from each member, but members pass gossipsthey've received from others on in their own gossips. E.g. when amember P (of group {P,Q,R}) receives a gossip from R, its own gossipto Q might be {R,P}. Q, who hasn't received a gossip from R, will notneed to receive it anymore as it is already sent by P. This simplescheme reduces the number of gossip messages needed.
Parameters:
sender - The sender of the gossip message (obviously :-)) |
| handleDownEvent | | public boolean handleDownEvent(Event evt)(Code) | | Callback. Called by superclass when event may be handled.
Do not use PassDown in this method as the event is
passed down by default by the superclass after this method returns !
boolean Defaults to true. If false, event will not be passeddown the stack. |
| handleUpEvent | | public boolean handleUpEvent(Event evt)(Code) | | Callback. Called by superclass when event may be handled.
Do not use PassUp in this method as the event is passed
up by default by the superclass after this method returns !
boolean Defaults to true. If false, event will not be passedup the stack. |
| requiredUpServices | | public Vector requiredUpServices()(Code) | | The events expected to be handled from some layer above:
-
GET_MSGS_RECEIVED: NAKACK layer
a list of events expected by to be handled from some layerabove |
| setProperties | | public boolean setProperties(Properties props)(Code) | | Set the parameters for this layer.
-
subset: the percentage of the group'size to which the
msgs_seen_so_far gossip is sent periodically.
-
max_msgs: the max number of msgs to wait for between two
consecutive gossipings.
-
max_wait_time: the max time to wait for between two consecutive
gossipings.
-
highest_seqno_timeout: time to wait to receive from NAKACK
the array of highest deliverable seqnos
Parameters:
props - the list of parameters |
| stability | | public void stability(ViewId view_id, long gossip_round, long[] stability_vector, Object sender)(Code) | | Contains the highest message sequence numbers (for each member) that
can safely be deleted (because they have been seen by all members).
|
| start | | public void start() throws Exception(Code) | | Start the layer:
i. Set the gossip task scheduler
ii. Reset the layer's state.
iii. Start the gossiping task
|
| stop | | public void stop()(Code) | | Stop scheduling the gossip task
|
| Methods inherited from org.jgroups.stack.RpcProtocol | public Object callRemoteMethod(Address dest, String method_name, int mode, long timeout) throws TimeoutException, SuspectedException(Code)(Java Doc)
public Object callRemoteMethod(Address dest, String method_name, Object[] args, Class[] types, int mode, long timeout) throws TimeoutException, SuspectedException(Code)(Java Doc)
public Object callRemoteMethod(Address dest, String method_name, Object[] args, String[] signature, int mode, long timeout) throws TimeoutException, SuspectedException(Code)(Java Doc)
public Object callRemoteMethod(Address dest, MethodCall method_call, int mode, long timeout) throws TimeoutException, SuspectedException(Code)(Java Doc)
public RspList callRemoteMethods(Vector dests, String method_name, Object[] args, Class[] types, int mode, long timeout)(Code)(Java Doc)
public RspList callRemoteMethods(Vector dests, String method_name, Object[] args, String[] signature, int mode, long timeout)(Code)(Java Doc)
public RspList callRemoteMethods(Vector dests, MethodCall method_call, int mode, long timeout)(Code)(Java Doc)
public String getName()(Code)(Java Doc)
public Object handle(Message req)(Code)(Java Doc)
public boolean handleDownEvent(Event evt)(Code)(Java Doc)
public boolean handleUpEvent(Event evt)(Code)(Java Doc)
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