Package org.jgroups.protocols.pbcast

Class STATE_TRANSFER

  • All Implemented Interfaces:
    ProcessingQueue.Handler<Address>
    public class STATE_TRANSFER
extends Protocol
implements ProcessingQueue.Handler<Address>
    STATE_TRANSFER protocol based on byte array transfer. A state request is sent to a chosen member (coordinator if null). That member makes a copy D of its current digest and asks the application for a copy of its current state S. Then the member returns both S and D to the requester. The requester first sets its digest to D and then returns the state to the application.
    Author:
    Bela Ban
    See Also:
    STATE, STATE_SOCK

    • Field Detail

      • start

        protected long start

      • stop

        protected long stop

      • num_state_reqs

        protected final java.util.concurrent.atomic.LongAdder num_state_reqs

      • num_bytes_sent

        protected final java.util.concurrent.atomic.LongAdder num_bytes_sent

      • avg_state_size

        protected double avg_state_size

      • local_addr

        protected Address local_addr

      • view

        protected volatile View view

      • members

        protected final java.util.List<Address> members

      • state_requesters

        protected final ProcessingQueue<Address> state_requesters
        List of members requesting state

      • waiting_for_state_response

        protected volatile boolean waiting_for_state_response
        set to true while waiting for a STATE_RSP

      • flushProtocolInStack

        protected boolean flushProtocolInStack

    • Constructor Detail

      • STATE_TRANSFER

        public STATE_TRANSFER()

    • Method Detail

      • getNumberOfStateRequests

        public long getNumberOfStateRequests()

      • getNumberOfStateBytesSent

        public long getNumberOfStateBytesSent()

      • getAverageStateSize

        public double getAverageStateSize()

      • requiredDownServices

        public java.util.List<java.lang.Integer> requiredDownServices()
        Description copied from class: Protocol
        List of events that are required to be answered by some layer below
        Overrides:
        requiredDownServices in class Protocol

      • 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

      • start

        public void start()
           throws java.lang.Exception
        Description copied from class: Protocol
        This method is called on a JChannel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.
        Overrides:
        start in class Protocol
        Throws:
        java.lang.Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so JChannel.connect(String) 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

      • closeBarrierAndSuspendStable

        public void closeBarrierAndSuspendStable()

      • openBarrierAndResumeStable

        public void openBarrierAndResumeStable()

      • openBarrier

        public void openBarrier()

      • resumeStable

        public void resumeStable()

      • 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

      • 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

      • isDigestNeeded

        protected boolean isDigestNeeded()
        When FLUSH is used we do not need to pass digests between members see JGroups/doc/design/PartialStateTransfer.txt see JGroups/doc/design/FLUSH.txt
        Returns:
        true if use of digests is required, false otherwise

      • punchHoleFor

        protected void punchHoleFor​(Address member)

      • closeHoleFor

        protected void closeHoleFor​(Address member)

      • determineCoordinator

        protected Address determineCoordinator()
        Return the first element of members which is not me. Otherwise return null.

      • handleViewChange

        protected void handleViewChange​(View v)

      • handleException

        protected void handleException​(java.lang.Throwable exception)

      • handleStateReq

        protected void handleStateReq​(Address requester)

      • getStateFromApplication

        protected void getStateFromApplication​(Address requester,
                                       Digest digest)

      • sendException

        protected void sendException​(Address requester,
                             java.lang.Throwable exception)

      • handleStateRsp

        protected void handleStateRsp​(Digest digest,
                              Address sender,
                              byte[] state)
        Set the digest and the send the state up to the application