2 * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.controller.cluster.databroker.actors.dds;
10 import akka.actor.ActorRef;
11 import com.google.common.base.MoreObjects;
12 import com.google.common.base.Optional;
13 import com.google.common.base.Preconditions;
14 import com.google.common.base.Throwables;
15 import com.google.common.base.Verify;
16 import com.google.common.collect.Iterables;
17 import com.google.common.util.concurrent.CheckedFuture;
18 import com.google.common.util.concurrent.ListenableFuture;
19 import com.google.common.util.concurrent.SettableFuture;
20 import java.util.ArrayDeque;
21 import java.util.Deque;
22 import java.util.Iterator;
23 import java.util.concurrent.CountDownLatch;
24 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
25 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
26 import java.util.function.Consumer;
27 import javax.annotation.Nonnull;
28 import javax.annotation.Nullable;
29 import javax.annotation.concurrent.GuardedBy;
30 import javax.annotation.concurrent.NotThreadSafe;
31 import org.opendaylight.controller.cluster.access.client.ConnectionEntry;
32 import org.opendaylight.controller.cluster.access.commands.AbstractLocalTransactionRequest;
33 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
34 import org.opendaylight.controller.cluster.access.commands.TransactionAbortRequest;
35 import org.opendaylight.controller.cluster.access.commands.TransactionAbortSuccess;
36 import org.opendaylight.controller.cluster.access.commands.TransactionCanCommitSuccess;
37 import org.opendaylight.controller.cluster.access.commands.TransactionCommitSuccess;
38 import org.opendaylight.controller.cluster.access.commands.TransactionDoCommitRequest;
39 import org.opendaylight.controller.cluster.access.commands.TransactionPreCommitRequest;
40 import org.opendaylight.controller.cluster.access.commands.TransactionPreCommitSuccess;
41 import org.opendaylight.controller.cluster.access.commands.TransactionPurgeRequest;
42 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
43 import org.opendaylight.controller.cluster.access.concepts.Request;
44 import org.opendaylight.controller.cluster.access.concepts.RequestFailure;
45 import org.opendaylight.controller.cluster.access.concepts.Response;
46 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
47 import org.opendaylight.mdsal.common.api.ReadFailedException;
48 import org.opendaylight.yangtools.concepts.Identifiable;
49 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
50 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
51 import org.slf4j.Logger;
52 import org.slf4j.LoggerFactory;
55 * Class translating transaction operations towards a particular backend shard.
58 * This class is not safe to access from multiple application threads, as is usual for transactions. Internal state
59 * transitions coming from interactions with backend are expected to be thread-safe.
62 * This class interacts with the queueing mechanism in ClientActorBehavior, hence once we arrive at a decision
63 * to use either a local or remote implementation, we are stuck with it. We can re-evaluate on the next transaction.
65 * @author Robert Varga
67 abstract class AbstractProxyTransaction implements Identifiable<TransactionIdentifier> {
69 * Marker object used instead of read-type of requests, which are satisfied only once. This has a lower footprint
70 * and allows compressing multiple requests into a single entry.
73 private static final class IncrementSequence {
74 private final long sequence;
75 private long delta = 0;
77 IncrementSequence(final long sequence) {
78 this.sequence = sequence;
89 void incrementDelta() {
95 * Base class for representing logical state of this proxy. See individual instantiations and {@link SuccessorState}
98 private static class State {
99 private final String string;
101 State(final String string) {
102 this.string = Preconditions.checkNotNull(string);
106 public final String toString() {
112 * State class used when a successor has interfered. Contains coordinator latch, the successor and previous state.
113 * This is a temporary state introduced during reconnection process and is necessary for correct state hand-off
114 * between the old connection (potentially being accessed by the user) and the new connection (being cleaned up
118 * When a user operation encounters this state, it synchronizes on the it and wait until reconnection completes,
119 * at which point the request is routed to the successor transaction. This is a relatively heavy-weight solution
120 * to the problem of state transfer, but the user will observe it only if the race condition is hit.
122 private static class SuccessorState extends State {
123 private final CountDownLatch latch = new CountDownLatch(1);
124 private AbstractProxyTransaction successor;
125 private State prevState;
128 private boolean done;
134 // Synchronize with succession process and return the successor
135 AbstractProxyTransaction await() {
138 } catch (InterruptedException e) {
139 LOG.warn("Interrupted while waiting for latch of {}", successor);
140 throw Throwables.propagate(e);
149 State getPrevState() {
153 void setPrevState(final State prevState) {
154 Verify.verify(this.prevState == null, "Attempted to set previous state to %s when we already have %s",
155 prevState, this.prevState);
156 this.prevState = Preconditions.checkNotNull(prevState);
159 // To be called from safe contexts, where successor is known to be completed
160 AbstractProxyTransaction getSuccessor() {
161 return Verify.verifyNotNull(successor);
164 void setSuccessor(final AbstractProxyTransaction successor) {
165 Verify.verify(this.successor == null, "Attempted to set successor to %s when we already have %s",
166 successor, this.successor);
167 this.successor = Preconditions.checkNotNull(successor);
179 private static final Logger LOG = LoggerFactory.getLogger(AbstractProxyTransaction.class);
180 private static final AtomicIntegerFieldUpdater<AbstractProxyTransaction> SEALED_UPDATER =
181 AtomicIntegerFieldUpdater.newUpdater(AbstractProxyTransaction.class, "sealed");
182 private static final AtomicReferenceFieldUpdater<AbstractProxyTransaction, State> STATE_UPDATER =
183 AtomicReferenceFieldUpdater.newUpdater(AbstractProxyTransaction.class, State.class, "state");
186 * Transaction has been open and is being actively worked on.
188 private static final State OPEN = new State("OPEN");
191 * Transaction has been sealed by the user, but it has not completed flushing to the backed, yet. This is
192 * a transition state, as we are waiting for the user to initiate commit procedures.
195 * Since the reconnect mechanics relies on state replay for transactions, this state needs to be flushed into the
196 * queue to re-create state in successor transaction (which may be based on different messages as locality may have
197 * changed). Hence the transition to {@link #FLUSHED} state needs to be handled in a thread-safe manner.
199 private static final State SEALED = new State("SEALED");
202 * Transaction state has been flushed into the queue, i.e. it is visible by the successor and potentially
203 * the backend. At this point the transaction does not hold any state besides successful requests, all other state
204 * is held either in the connection's queue or the successor object.
207 * Transition to this state indicates we have all input from the user we need to initiate the correct commit
210 private static final State FLUSHED = new State("FLUSHED");
213 * Transaction state has been completely resolved, we have received confirmation of the transaction fate from
214 * the backend. The only remaining task left to do is finishing up the state cleanup, which is done via purge
215 * request. We need to hang on to the transaction until that is done, as we have to make sure backend completes
216 * purging its state -- otherwise we could have a leak on the backend.
218 private static final State DONE = new State("DONE");
220 // Touched from client actor thread only
221 private final Deque<Object> successfulRequests = new ArrayDeque<>();
222 private final ProxyHistory parent;
224 // Accessed from user thread only, which may not access this object concurrently
225 private long sequence;
228 * Atomic state-keeping is required to synchronize the process of propagating completed transaction state towards
229 * the backend -- which may include a successor.
231 * Successor, unlike {@link AbstractProxyTransaction#seal()} is triggered from the client actor thread, which means
232 * the successor placement needs to be atomic with regard to the application thread.
234 * In the common case, the application thread performs performs the seal operations and then "immediately" sends
235 * the corresponding message. The uncommon case is when the seal and send operations race with a connect completion
236 * or timeout, when a successor is injected.
238 * This leaves the problem of needing to completely transferring state just after all queued messages are replayed
239 * after a successor was injected, so that it can be properly sealed if we are racing. Further complication comes
240 * from lock ordering, where the successor injection works with a locked queue and locks proxy objects -- leading
241 * to a potential AB-BA deadlock in case of a naive implementation.
243 * For tracking user-visible state we use a single volatile int, which is flipped atomically from 0 to 1 exactly
244 * once in {@link AbstractProxyTransaction#seal()}. That keeps common operations fast, as they need to perform
245 * only a single volatile read to assert state correctness.
247 * For synchronizing client actor (successor-injecting) and user (commit-driving) thread, we keep a separate state
248 * variable. It uses pre-allocated objects for fast paths (i.e. no successor present) and a per-transition object
249 * for slow paths (when successor is injected/present).
251 private volatile int sealed;
252 private volatile State state;
254 AbstractProxyTransaction(final ProxyHistory parent, final boolean isDone) {
255 this.parent = Preconditions.checkNotNull(parent);
258 // DONE implies previous seal operation completed
265 final void executeInActor(final Runnable command) {
266 parent.context().executeInActor(behavior -> {
272 final ActorRef localActor() {
273 return parent.localActor();
276 final void incrementSequence(final long delta) {
278 LOG.debug("Transaction {} incremented sequence to {}", this, sequence);
281 final long nextSequence() {
282 final long ret = sequence++;
283 LOG.debug("Transaction {} allocated sequence {}", this, ret);
287 final void delete(final YangInstanceIdentifier path) {
293 final void merge(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
299 final void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
305 final CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
307 return doExists(path);
310 final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
315 final void enqueueRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
316 final long enqueuedTicks) {
317 LOG.debug("Transaction proxy {} enqueing request {} callback {}", this, request, callback);
318 parent.enqueueRequest(request, callback, enqueuedTicks);
321 final void sendRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback) {
322 LOG.debug("Transaction proxy {} sending request {} callback {}", this, request, callback);
323 parent.sendRequest(request, callback);
327 * Seal this transaction before it is either committed or aborted.
330 // Transition user-visible state first
331 final boolean success = SEALED_UPDATER.compareAndSet(this, 0, 1);
332 Preconditions.checkState(success, "Proxy %s was already sealed", getIdentifier());
336 final void ensureSealed() {
337 if (SEALED_UPDATER.compareAndSet(this, 0, 1)) {
342 private void internalSeal() {
344 parent.onTransactionSealed(this);
346 // Now deal with state transfer, which can occur via successor or a follow-up canCommit() or directCommit().
347 if (!STATE_UPDATER.compareAndSet(this, OPEN, SEALED)) {
348 // Slow path: wait for the successor to complete
349 final AbstractProxyTransaction successor = awaitSuccessor();
351 // At this point the successor has completed transition and is possibly visible by the user thread, which is
352 // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
353 // Propagate state and seal the successor.
354 flushState(successor);
355 successor.ensureSealed();
359 private void checkNotSealed() {
360 Preconditions.checkState(sealed == 0, "Transaction %s has already been sealed", getIdentifier());
363 private void checkSealed() {
364 Preconditions.checkState(sealed != 0, "Transaction %s has not been sealed yet", getIdentifier());
367 private SuccessorState getSuccessorState() {
368 final State local = state;
369 Verify.verify(local instanceof SuccessorState, "State %s has unexpected class", local);
370 return (SuccessorState) local;
373 private void checkReadWrite() {
374 if (isSnapshotOnly()) {
375 throw new UnsupportedOperationException("Transaction " + getIdentifier() + " is a read-only snapshot");
379 final void recordSuccessfulRequest(final @Nonnull TransactionRequest<?> req) {
380 successfulRequests.add(Verify.verifyNotNull(req));
383 final void recordFinishedRequest(final Response<?, ?> response) {
384 final Object last = successfulRequests.peekLast();
385 if (last instanceof IncrementSequence) {
386 ((IncrementSequence) last).incrementDelta();
388 successfulRequests.addLast(new IncrementSequence(response.getSequence()));
393 * Abort this transaction. This is invoked only for read-only transactions and will result in an explicit message
394 * being sent to the backend.
398 parent.abortTransaction(this);
400 sendRequest(abortRequest(), resp -> {
401 LOG.debug("Transaction {} abort completed with {}", getIdentifier(), resp);
406 final void abort(final VotingFuture<Void> ret) {
410 if (t instanceof TransactionAbortSuccess) {
412 } else if (t instanceof RequestFailure) {
413 ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
415 ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
418 // This is a terminal request, hence we do not need to record it
419 LOG.debug("Transaction {} abort completed", this);
424 final void enqueueAbort(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
426 parent.abortTransaction(this);
428 enqueueRequest(abortRequest(), resp -> {
429 LOG.debug("Transaction {} abort completed with {}", getIdentifier(), resp);
430 // Purge will be sent by the predecessor's callback
431 if (callback != null) {
432 callback.accept(resp);
437 final void enqueueDoAbort(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
438 enqueueRequest(new TransactionAbortRequest(getIdentifier(), nextSequence(), localActor()), callback,
442 final void sendDoAbort(final Consumer<Response<?, ?>> callback) {
443 sendRequest(new TransactionAbortRequest(getIdentifier(), nextSequence(), localActor()), callback);
447 * Commit this transaction, possibly in a coordinated fashion.
449 * @param coordinated True if this transaction should be coordinated across multiple participants.
450 * @return Future completion
452 final ListenableFuture<Boolean> directCommit() {
456 // Precludes startReconnect() from interfering with the fast path
457 synchronized (this) {
458 if (STATE_UPDATER.compareAndSet(this, SEALED, FLUSHED)) {
459 final SettableFuture<Boolean> ret = SettableFuture.create();
460 sendRequest(Verify.verifyNotNull(commitRequest(false)), t -> {
461 if (t instanceof TransactionCommitSuccess) {
462 ret.set(Boolean.TRUE);
463 } else if (t instanceof RequestFailure) {
464 ret.setException(((RequestFailure<?, ?>) t).getCause().unwrap());
466 ret.setException(new IllegalStateException("Unhandled response " + t.getClass()));
469 // This is a terminal request, hence we do not need to record it
470 LOG.debug("Transaction {} directCommit completed", this);
478 // We have had some interference with successor injection, wait for it to complete and defer to the successor.
479 return awaitSuccessor().directCommit();
482 final void canCommit(final VotingFuture<?> ret) {
486 // Precludes startReconnect() from interfering with the fast path
487 synchronized (this) {
488 if (STATE_UPDATER.compareAndSet(this, SEALED, FLUSHED)) {
489 final TransactionRequest<?> req = Verify.verifyNotNull(commitRequest(true));
491 sendRequest(req, t -> {
492 if (t instanceof TransactionCanCommitSuccess) {
494 } else if (t instanceof RequestFailure) {
495 ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
497 ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
500 recordSuccessfulRequest(req);
501 LOG.debug("Transaction {} canCommit completed", this);
508 // We have had some interference with successor injection, wait for it to complete and defer to the successor.
509 awaitSuccessor().canCommit(ret);
512 private AbstractProxyTransaction awaitSuccessor() {
513 return getSuccessorState().await();
516 final void preCommit(final VotingFuture<?> ret) {
520 final TransactionRequest<?> req = new TransactionPreCommitRequest(getIdentifier(), nextSequence(),
522 sendRequest(req, t -> {
523 if (t instanceof TransactionPreCommitSuccess) {
525 } else if (t instanceof RequestFailure) {
526 ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
528 ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
531 onPreCommitComplete(req);
535 private void onPreCommitComplete(final TransactionRequest<?> req) {
537 * The backend has agreed that the transaction has entered PRE_COMMIT phase, meaning it will be committed
538 * to storage after the timeout completes.
540 * All state has been replicated to the backend, hence we do not need to keep it around. Retain only
541 * the precommit request, so we know which request to use for resync.
543 LOG.debug("Transaction {} preCommit completed, clearing successfulRequests", this);
544 successfulRequests.clear();
546 // TODO: this works, but can contain some useless state (like batched operations). Create an empty
547 // equivalent of this request and store that.
548 recordSuccessfulRequest(req);
551 final void doCommit(final VotingFuture<?> ret) {
555 sendRequest(new TransactionDoCommitRequest(getIdentifier(), nextSequence(), localActor()), t -> {
556 if (t instanceof TransactionCommitSuccess) {
558 } else if (t instanceof RequestFailure) {
559 ret.voteNo(((RequestFailure<?, ?>) t).getCause().unwrap());
561 ret.voteNo(new IllegalStateException("Unhandled response " + t.getClass()));
564 LOG.debug("Transaction {} doCommit completed", this);
566 // Needed for ProxyHistory$Local data tree rebase points.
567 parent.completeTransaction(this);
573 private void enqueuePurge() {
577 final void enqueuePurge(final Consumer<Response<?, ?>> callback) {
578 // Purge request are dispatched internally, hence should not wait
579 enqueuePurge(callback, parent.currentTime());
582 final void enqueuePurge(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
583 LOG.debug("{}: initiating purge", this);
585 final State prev = state;
586 if (prev instanceof SuccessorState) {
587 ((SuccessorState) prev).setDone();
589 final boolean success = STATE_UPDATER.compareAndSet(this, prev, DONE);
591 LOG.warn("{}: moved from state {} while we were purging it", this, prev);
595 successfulRequests.clear();
597 enqueueRequest(new TransactionPurgeRequest(getIdentifier(), nextSequence(), localActor()), resp -> {
598 LOG.debug("{}: purge completed", this);
599 parent.purgeTransaction(this);
601 if (callback != null) {
602 callback.accept(resp);
607 // Called with the connection unlocked
608 final synchronized void startReconnect() {
609 // At this point canCommit/directCommit are blocked, we assert a new successor state, retrieving the previous
610 // state. This method is called with the queue still unlocked.
611 final SuccessorState nextState = new SuccessorState();
612 final State prevState = STATE_UPDATER.getAndSet(this, nextState);
614 LOG.debug("Start reconnect of proxy {} previous state {}", this, prevState);
615 Verify.verify(!(prevState instanceof SuccessorState), "Proxy %s duplicate reconnect attempt after %s", this,
618 // We have asserted a slow-path state, seal(), canCommit(), directCommit() are forced to slow paths, which will
619 // wait until we unblock nextState's latch before accessing state. Now we record prevState for later use and we
621 nextState.setPrevState(prevState);
624 // Called with the connection locked
625 final void replayMessages(final ProxyHistory successorHistory, final Iterable<ConnectionEntry> enqueuedEntries) {
626 final SuccessorState local = getSuccessorState();
627 final State prevState = local.getPrevState();
629 final boolean isDone = DONE.equals(state)
630 || state instanceof SuccessorState && ((SuccessorState) state).isDone();
631 final AbstractProxyTransaction successor = successorHistory.createTransactionProxy(getIdentifier(),
632 isSnapshotOnly(), isDone);
633 LOG.debug("{} created successor {}", this, successor);
634 local.setSuccessor(successor);
636 // Replay successful requests first
637 if (!successfulRequests.isEmpty()) {
638 // We need to find a good timestamp to use for successful requests, as we do not want to time them out
639 // nor create timing inconsistencies in the queue -- requests are expected to be ordered by their enqueue
640 // time. We will pick the time of the first entry available. If there is none, we will just use current
641 // time, as all other requests will get enqueued afterwards.
642 final ConnectionEntry firstInQueue = Iterables.getFirst(enqueuedEntries, null);
643 final long now = firstInQueue != null ? firstInQueue.getEnqueuedTicks() : parent.currentTime();
645 for (Object obj : successfulRequests) {
646 if (obj instanceof TransactionRequest) {
647 LOG.debug("Forwarding successful request {} to successor {}", obj, successor);
648 successor.replayRequest((TransactionRequest<?>) obj, resp -> { }, now);
650 Verify.verify(obj instanceof IncrementSequence);
651 final IncrementSequence increment = (IncrementSequence) obj;
652 successor.replayRequest(new IncrementTransactionSequenceRequest(getIdentifier(),
653 increment.getSequence(), localActor(), isSnapshotOnly(), increment.getDelta()), resp -> { },
655 LOG.debug("Incrementing sequence {} to successor {}", obj, successor);
658 LOG.debug("{} replayed {} successful requests", getIdentifier(), successfulRequests.size());
659 successfulRequests.clear();
662 // Now replay whatever is in the connection
663 final Iterator<ConnectionEntry> it = enqueuedEntries.iterator();
664 while (it.hasNext()) {
665 final ConnectionEntry e = it.next();
666 final Request<?, ?> req = e.getRequest();
668 if (getIdentifier().equals(req.getTarget())) {
669 Verify.verify(req instanceof TransactionRequest, "Unhandled request %s", req);
670 LOG.debug("Replaying queued request {} to successor {}", req, successor);
671 successor.replayRequest((TransactionRequest<?>) req, e.getCallback(), e.getEnqueuedTicks());
677 * Check the state at which we have started the reconnect attempt. State transitions triggered while we were
678 * reconnecting have been forced to slow paths, which will be unlocked once we unblock the state latch
679 * at the end of this method.
681 if (SEALED.equals(prevState)) {
682 LOG.debug("Proxy {} reconnected while being sealed, propagating state to successor {}", this, successor);
683 flushState(successor);
684 successor.ensureSealed();
689 * Invoked from {@link #replayMessages(AbstractProxyTransaction, Iterable)} to have successor adopt an in-flight
693 * Note: this method is invoked by the predecessor on the successor.
695 * @param request Request which needs to be forwarded
696 * @param callback Callback to be invoked once the request completes
697 * @param enqueuedTicks ticker-based time stamp when the request was enqueued
699 private void replayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
700 final long enqueuedTicks) {
701 if (request instanceof AbstractLocalTransactionRequest) {
702 handleReplayedLocalRequest((AbstractLocalTransactionRequest<?>) request, callback, enqueuedTicks);
704 handleReplayedRemoteRequest(request, callback, enqueuedTicks);
708 // Called with the connection locked
709 final void finishReconnect() {
710 final SuccessorState local = getSuccessorState();
711 LOG.debug("Finishing reconnect of proxy {}", this);
713 // All done, release the latch, unblocking seal() and canCommit() slow paths
718 * Invoked from a retired connection for requests which have been in-flight and need to be re-adjusted
719 * and forwarded to the successor connection.
721 * @param request Request to be forwarded
722 * @param callback Original callback
724 final void forwardRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback) {
725 forwardToSuccessor(getSuccessorState().getSuccessor(), request, callback);
728 final void forwardToSuccessor(final AbstractProxyTransaction successor, final TransactionRequest<?> request,
729 final Consumer<Response<?, ?>> callback) {
730 if (successor instanceof LocalProxyTransaction) {
731 forwardToLocal((LocalProxyTransaction)successor, request, callback);
732 } else if (successor instanceof RemoteProxyTransaction) {
733 forwardToRemote((RemoteProxyTransaction)successor, request, callback);
735 throw new IllegalStateException("Unhandled successor " + successor);
739 abstract boolean isSnapshotOnly();
741 abstract void doDelete(YangInstanceIdentifier path);
743 abstract void doMerge(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
745 abstract void doWrite(YangInstanceIdentifier path, NormalizedNode<?, ?> data);
747 abstract CheckedFuture<Boolean, ReadFailedException> doExists(YangInstanceIdentifier path);
749 abstract CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> doRead(YangInstanceIdentifier path);
751 abstract void doSeal();
754 abstract void flushState(AbstractProxyTransaction successor);
756 abstract TransactionRequest<?> abortRequest();
758 abstract TransactionRequest<?> commitRequest(boolean coordinated);
761 * Replay a request originating in this proxy to a successor remote proxy.
763 abstract void forwardToRemote(RemoteProxyTransaction successor, TransactionRequest<?> request,
764 Consumer<Response<?, ?>> callback);
767 * Replay a request originating in this proxy to a successor local proxy.
769 abstract void forwardToLocal(LocalProxyTransaction successor, TransactionRequest<?> request,
770 Consumer<Response<?, ?>> callback);
773 * Invoked from {@link LocalProxyTransaction} when it replays its successful requests to its successor.
776 * Note: this method is invoked by the predecessor on the successor.
778 * @param request Request which needs to be forwarded
779 * @param callback Callback to be invoked once the request completes
780 * @param enqueuedTicks Time stamp to use for enqueue time
782 abstract void handleReplayedLocalRequest(AbstractLocalTransactionRequest<?> request,
783 @Nullable Consumer<Response<?, ?>> callback, long enqueuedTicks);
786 * Invoked from {@link RemoteProxyTransaction} when it replays its successful requests to its successor.
789 * Note: this method is invoked by the predecessor on the successor.
791 * @param request Request which needs to be forwarded
792 * @param callback Callback to be invoked once the request completes
793 * @param enqueuedTicks Time stamp to use for enqueue time
795 abstract void handleReplayedRemoteRequest(TransactionRequest<?> request,
796 @Nullable Consumer<Response<?, ?>> callback, long enqueuedTicks);
799 public final String toString() {
800 return MoreObjects.toStringHelper(this).add("identifier", getIdentifier()).add("state", state).toString();