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

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	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

Interface ViewStateManager

Method Summary

Method Detail

installMinEventDelayHandler

bind

unbind

handleActivated

handleDeactivated

handleChanging

handleNewView

waitForAsyncEvents