Package 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
    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 Details

    • 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