org.apache.sling.discovery.commons.providers

Interface ViewStateManager

All Known Implementing Classes:

ViewStateManagerImpl

public interface ViewStateManager

The ViewStateManager is at the core of managing TopologyEventListeners, the 'view state' (changing vs changed) and sending out the appropriate and according TopologyEvents to the registered listeners - depending on the implementation it also supports the ClusterSyncService, which is invoked on handleNewView.

Method Summary

Modifier and Type	Method and Description
void	bind(TopologyEventListener eventListener) Binds the given eventListener, sending it an INIT event if applicable.
void	handleActivated() Handles activation - ie marks this manager as activated thus the TOPOLOGY_INIT event can be sent to already bound listeners and subsequent calls to handleChanging/handleNewView will result in according/appropriate TOPOLOGY_CHANGING/ TOPOLOGY_CHANGED events.
void	handleChanging() Handles the fact that some (possibly early) indicator of a change in a topology has been detected and that a new view is being agreed upon (whatever that means, be it voting or similar).
void	handleDeactivated() Must be called when the corresponding service (typically a DiscoveryService implementation) is deactivated.
void	handleNewView(BaseTopologyView newView) Handles the fact that a new view became true/established and sends out TOPOLOGY_INIT to uninitialized listeners and TOPOLOGY_CHANGED to already initialized listeners (in the latter case, also sends a TOPOLOGY_CHANGING if that has not yet been done)
void	installMinEventDelayHandler(DiscoveryService discoveryService, Scheduler scheduler, long minEventDelaySecs) Installs an optional 'min event delay handler' which, using the given scheduler, delays sending TOPOLOGY_CHANGED event after receiving a handleNewView - with the idea as to limit the number of toggling between view states.
boolean	unbind(TopologyEventListener eventListener) Unbinds the given eventListener, returning whether or not it was bound at all.
int	waitForAsyncEvents(long timeout) for testing only: wait for any potentially queued async events to be delivered before returning.

Method Detail

installMinEventDelayHandler

void installMinEventDelayHandler(DiscoveryService discoveryService,
                                 Scheduler scheduler,
                                 long minEventDelaySecs)

Installs an optional 'min event delay handler' which, using the given scheduler, delays sending TOPOLOGY_CHANGED event after receiving a handleNewView - with the idea as to limit the number of toggling between view states.

bind

void bind(TopologyEventListener eventListener)

Binds the given eventListener, sending it an INIT event if applicable.

Parameters:

eventListener - the eventListener that is to bind

unbind

boolean unbind(TopologyEventListener eventListener)

Unbinds the given eventListener, returning whether or not it was bound at all.

Parameters:

eventListener - the eventListner that is to unbind

Returns:

whether or not the listener was added in the first place

handleActivated

void handleActivated()

Handles activation - ie marks this manager as activated thus the TOPOLOGY_INIT event can be sent to already bound listeners and subsequent calls to handleChanging/handleNewView will result in according/appropriate TOPOLOGY_CHANGING/ TOPOLOGY_CHANGED events.

handleDeactivated

void handleDeactivated()

Must be called when the corresponding service (typically a DiscoveryService implementation) is deactivated.

Will mark this manager as deactivated and flags the last available view as not current.

handleChanging

void handleChanging()

Handles the fact that some (possibly early) indicator of a change in a topology has been detected and that a new view is being agreed upon (whatever that means, be it voting or similar).

Will send out TOPOLOGY_CHANGING to all initialized listeners.

handleNewView

void handleNewView(BaseTopologyView newView)

Handles the fact that a new view became true/established and sends out TOPOLOGY_INIT to uninitialized listeners and TOPOLOGY_CHANGED to already initialized listeners (in the latter case, also sends a TOPOLOGY_CHANGING if that has not yet been done)

Parameters:

newView - the new, established view true if we were either in changing mode or the newView was different from the previous one.

waitForAsyncEvents

int waitForAsyncEvents(long timeout)

for testing only: wait for any potentially queued async events to be delivered before returning.

Parameters:

timeout - time in millis to wait for at max - 0 to not wait at all - -1 to wait indefinitely

Returns:

0 if no more async events exist, or the number of queued or in-flight (being sent) events if the timeout hit early