Class BARRIER


  • public class BARRIER
    extends Protocol
    All messages up the stack have to go through a barrier (read lock, RL). By default, the barrier is open. When a CLOSE_BARRIER event is received, we close the barrier by acquiring a write lock (WL). This succeeds when all previous messages have completed (by releasing their RLs). Thus, when we have acquired the WL, we know that there are no pending messages processed.
    When an OPEN_BARRIER event is received, we simply open the barrier again and let all messages pass in the up direction. This is done by releasing the WL.
    Version:
    $Id: BARRIER.java,v 1.6.4.4 2008/05/22 13:23:06 belaban Exp $
    Author:
    Bela Ban
    • Constructor Detail

      • BARRIER

        public BARRIER()
    • Method Detail

      • getName

        public java.lang.String getName()
        Specified by:
        getName in class Protocol
      • setProperties

        public boolean setProperties​(java.util.Properties props)
        Description copied from class: Protocol
        Configures the protocol initially. A configuration string consists of name=value items, separated by a ';' (semicolon), e.g.:
         "loopback=false;unicast_inport=4444"
         
        Overrides:
        setProperties in class Protocol
      • isClosed

        public boolean isClosed()
      • isOpenerScheduled

        public boolean isOpenerScheduled()
      • getMaxCloseTime

        public long getMaxCloseTime()
      • getNumberOfInFlightThreads

        public int getNumberOfInFlightThreads()
      • init

        public void init()
                  throws java.lang.Exception
        Description copied from class: Protocol
        Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.
        Overrides:
        init in class Protocol
        Throws:
        java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception
      • stop

        public void stop()
        Description copied from class: Protocol
        This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed
        Overrides:
        stop in class Protocol
      • destroy

        public void destroy()
        Description copied from class: Protocol
        This method is called on a Channel.close(). Does some cleanup; after the call the VM will terminate
        Overrides:
        destroy in class Protocol
      • down

        public java.lang.Object down​(Event evt)
        Description copied from class: Protocol
        An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().
        Overrides:
        down in class Protocol
      • up

        public java.lang.Object up​(Event evt)
        Description copied from class: Protocol
        An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().
        Overrides:
        up in class Protocol