Package org.jgroups.protocols

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.
    Author:
    Bela Ban

    • Field Detail

      • max_close_time

        protected long max_close_time

      • flush_timeout

        protected long flush_timeout

      • lock

        protected final java.util.concurrent.locks.Lock lock

      • barrier_closed

        protected final java.util.concurrent.atomic.AtomicBoolean barrier_closed

      • no_pending_threads

        protected java.util.concurrent.locks.Condition no_pending_threads
        signals to waiting threads that the barrier is open again

      • in_flight_threads

        protected java.util.Map<java.lang.Thread,​java.lang.Object> in_flight_threads

      • barrier_opener_future

        protected volatile java.util.concurrent.Future<?> barrier_opener_future

      • local_addr

        protected Address local_addr

      • holes

        protected final java.util.Set<Address> holes

      • mcast_queue

        protected final java.util.Map<Address,​Message> mcast_queue

      • ucast_queue

        protected final java.util.Map<Address,​Message> ucast_queue

      • transport

        protected TP transport

      • NULL

        protected static final java.lang.Object NULL

    • Constructor Detail

      • BARRIER

        public BARRIER()

    • Method Detail

      • isClosed

        public boolean isClosed()

      • getHoles

        public java.lang.String getHoles()

      • getNumberOfInFlightThreads

        public int getNumberOfInFlightThreads()

      • getInFlightThreadsCount

        public int getInFlightThreadsCount()

      • isOpenerScheduled

        public boolean isOpenerScheduled()

      • 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 JChannel.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 JChannel.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. A protocol 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 protocol may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down().
        Overrides:
        down in class Protocol

      • up

        public java.lang.Object up​(Event evt)
        Description copied from class: Protocol
        An event was received from the protocol below. Usually the current protocol 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

      • up

        public java.lang.Object up​(Message msg)
        Description copied from class: Protocol
        A single message was received. Protocols may examine the message and do something (e.g. add a header) with it before passing it up.
        Overrides:
        up in class Protocol

      • up

        public void up​(MessageBatch batch)
        Description copied from class: Protocol
        Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.

        The default processing below sends messages up the stack individually, based on a matching criteria (calling Protocol.accept(org.jgroups.Message)), and - if true - calls Protocol.up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.

        Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.getMatchingMessages(short,boolean)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.

        Overrides:
        up in class Protocol
        Parameters:
        batch - The message batch

      • unblock

        protected void unblock​(java.lang.Thread current_thread)

      • closeBarrier

        public void closeBarrier()
                  throws java.util.concurrent.TimeoutException
        Close the barrier. Temporarily remove all threads which are waiting or blocked, re-insert them after the call
        Throws:
        java.util.concurrent.TimeoutException

      • openBarrier

        public void openBarrier()

      • printInFlightThreads

        protected java.lang.String printInFlightThreads()

      • flushQueue

        protected void flushQueue​(java.util.Map<Address,​Message> queue)

      • scheduleBarrierOpener

        protected void scheduleBarrierOpener()

      • cancelBarrierOpener

        protected void cancelBarrierOpener()