Lightweight FLUSH for state transfer ------------------------------------ Key: JGRP-587 URL: https://issues.jboss.org/browse/JGRP-587 Project: JGroups Issue Type: Feature Request Reporter: Vladimir Blagojevic Assignee: Vladimir Blagojevic Fix For: Future We should investigate introduction of lightweight FLUSH in Multiplexer. Lightweight FLUSH would introduce stop-the-world model to only specific mux application leaving other mux applications unaffected. For example, if there are three mux applications A,B, and C and we need to FLUSH only application C, lightweight FLUSH would block all message sending for C only while applications A and B are unaffected. For Multiplexer, JOIN's will still need to block everyone, because we're actually creating the underlying JChannel. For state transfer on the Multiplexer, the example should be: - Members {A,B,C}. A and B have services X and Y, C has only service Y - Service B.X requests a state transfer (MuxChannel.getState()) - The FLUSH needs to be qualified with the service-id: FLUSH(X) - A, B and C receive a START-FLUSH(X) message, which invokes A.X.block(), B.X.block(). - For C, since there is no X service, Multiplexer.block() simply returns - When A has received all FLUSH-OK messages from A, B and C, we transfer the state from A.X to B.X - Then we terminate the FLUSH by sending a STOP-FLUSH(x) to {A,B,C} - This again calls A.X.unblock(), B.X.unblock() and is a no-op for C This allows other services, e.g. Y, to be unaffected (ie., non-blocked) by the flushing of A.X