Package org.jgroups.protocols.pbcast

Class FLUSH

  • All Implemented Interfaces:
    Lifecycle
    public class FLUSH
extends Protocol
    Flush, as it name implies, forces group members to flush their pending messages while blocking them to send any additional messages. The process of flushing acquiesces the group so that state transfer or a join can be done. It is also called stop-the-world model as nobody will be able to send messages while a flush is in process.

    Flush is needed for:

    (1) State transfer. When a member requests state transfer, the coordinator tells everyone to stop sending messages and waits for everyone's ack. Then it asks the application for its state and ships it back to the requester. After the requester has received and set the state successfully, the coordinator tells everyone to resume sending messages.

    (2) View changes (e.g.a join). Before installing a new view V2, flushing would ensure that all messages *sent* in the current view V1 are indeed *delivered* in V1, rather than in V2 (in all non-faulty members). This is essentially Virtual Synchrony.

    Since:
    2.4

    • Field Detail

      • timeout

        protected long timeout

      • start_flush_timeout

        protected long start_flush_timeout

      • end_flush_timeout

        protected long end_flush_timeout

      • retry_timeout

        protected long retry_timeout

      • enable_reconciliation

        protected boolean enable_reconciliation

      • bypass

        protected boolean bypass

      • startFlushTime

        private long startFlushTime

      • totalTimeInFlush

        private long totalTimeInFlush

      • numberOfFlushes

        private int numberOfFlushes

      • averageFlushDuration

        private double averageFlushDuration

      • currentView

        private View currentView

      • flushCoordinator

        private Address flushCoordinator
        Group member that requested FLUSH. For view installations flush coordinator is the group coordinator For state transfer flush coordinator is the state requesting member

      • flushMembers

        private final java.util.List<Address> flushMembers

      • viewCounter

        private final java.util.concurrent.atomic.AtomicInteger viewCounter

      • flushCompletedMap

        private final java.util.Map<Address,​Digest> flushCompletedMap

      • flushNotCompletedMap

        private final java.util.List<Address> flushNotCompletedMap

      • suspected

        private final java.util.Set<Address> suspected

      • reconcileOks

        private final java.util.List<Address> reconcileOks

      • sharedLock

        private final java.lang.Object sharedLock

      • blockMutex

        private final java.util.concurrent.locks.ReentrantLock blockMutex

      • notBlockedDown

        private final java.util.concurrent.locks.Condition notBlockedDown

      • isBlockingFlushDown

        private volatile boolean isBlockingFlushDown
        Indicates if FLUSH.down() is currently blocking threads Condition predicate associated with blockMutex

      • flushCompleted

        private boolean flushCompleted

      • flush_unblock_promise

        private final Promise<java.lang.Boolean> flush_unblock_promise

      • flushInProgress

        private final java.util.concurrent.atomic.AtomicBoolean flushInProgress

      • sentBlock

        private final java.util.concurrent.atomic.AtomicBoolean sentBlock

      • sentUnblock

        private final java.util.concurrent.atomic.AtomicBoolean sentUnblock

    • Constructor Detail

      • FLUSH

        public FLUSH()

    • Method Detail

      • getStartFlushTimeout

        public long getStartFlushTimeout()

      • setStartFlushTimeout

        public FLUSH setStartFlushTimeout​(long start_flush_timeout)

      • getRetryTimeout

        public long getRetryTimeout()

      • setRetryTimeout

        public FLUSH setRetryTimeout​(long retry_timeout)

      • 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 ready to receive events. Will be called from bottom to top.
        Specified by:
        start in interface Lifecycle
        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

      • getAverageFlushDuration

        public double getAverageFlushDuration()

      • getTotalTimeInFlush

        public long getTotalTimeInFlush()

      • getNumberOfFlushes

        public int getNumberOfFlushes()

      • setBypass

        public boolean setBypass​(boolean flag)

      • startFlush

        public void startFlush()

      • startFlush

        private void startFlush​(Event evt)

      • startFlush

        private void startFlush​(java.util.List<Address> flushParticipants)

      • stopFlush

        public void stopFlush()

      • 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

      • down

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

      • handleConnect

        private java.lang.Object handleConnect​(Event evt,
                                       boolean waitForUnblock)

      • blockMessageDuringFlush

        private void blockMessageDuringFlush()

      • 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(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

      • waitForUnblock

        private void waitForUnblock()

      • onFlushReconcileOK

        private void onFlushReconcileOK​(Message msg)

      • handleFlushReconcile

        private void handleFlushReconcile​(Message msg)

      • rejectFlush

        private void rejectFlush​(java.util.Collection<? extends Address> participants,
                         long viewId)

      • providedDownServices

        public java.util.List<java.lang.Integer> providedDownServices()
        Description copied from class: Protocol
        List of events that are provided to layers below (they will be handled when sent from down below)
        Overrides:
        providedDownServices in class Protocol

      • sendBlockUpToChannel

        private void sendBlockUpToChannel()

      • sendUnBlockUpToChannel

        private void sendUnBlockUpToChannel()

      • isCurrentFlushMessage

        private boolean isCurrentFlushMessage​(FLUSH.FlushHeader fh)

      • currentViewId

        private long currentViewId()

      • onViewChange

        private boolean onViewChange​(View view)

      • onStopFlush

        private void onStopFlush()

      • resetForNextFlush

        private void resetForNextFlush()

      • onSuspend

        private void onSuspend​(java.util.List<Address> members)
        Starts the flush protocol
        Parameters:
        members - List of participants in the flush protocol. Guaranteed to be non-null

      • onResume

        private void onResume​(Event evt)

      • hasVirtualSynchronyGaps

        private boolean hasVirtualSynchronyGaps()

      • same

        protected static boolean same​(java.util.List<Digest> digests)

      • findHighestSequences

        private Digest findHighestSequences​(View view)

      • maxSeqnos

        protected static Digest maxSeqnos​(View view,
                                  java.util.List<Digest> digests)
        Returns a digest which contains, for all members of view, the highest delivered and received seqno of all digests

      • onSuspect

        private void onSuspect​(java.util.Collection<Address> addresses)

      • marshal

        protected static ByteArray marshal​(java.util.Collection<? extends Address> participants,
                                   Digest digest)

      • readParticipantsAndDigest

        protected Tuple<java.util.Collection<? extends Address>,​Digest> readParticipantsAndDigest​(byte[] buffer,
                                                                                                int offset,
                                                                                                int length)