import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.base.Verify;
+import com.google.common.collect.Iterables;
import com.google.common.util.concurrent.CheckedFuture;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import javax.annotation.concurrent.GuardedBy;
import javax.annotation.concurrent.NotThreadSafe;
import org.opendaylight.controller.cluster.access.client.ConnectionEntry;
+import org.opendaylight.controller.cluster.access.commands.AbstractLocalTransactionRequest;
+import org.opendaylight.controller.cluster.access.commands.ClosedTransactionException;
+import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
import org.opendaylight.controller.cluster.access.commands.TransactionAbortRequest;
import org.opendaylight.controller.cluster.access.commands.TransactionAbortSuccess;
import org.opendaylight.controller.cluster.access.commands.TransactionCanCommitSuccess;
*/
@NotThreadSafe
private static final class IncrementSequence {
- private long delta = 1;
+ private final long sequence;
+ private long delta = 0;
+
+ IncrementSequence(final long sequence) {
+ this.sequence = sequence;
+ }
long getDelta() {
return delta;
}
+ long getSequence() {
+ return sequence;
+ }
+
void incrementDelta() {
delta++;
}
}
- // Generic state base class. Direct instances are used for fast paths, sub-class is used for successor transitions
+ /**
+ * Base class for representing logical state of this proxy. See individual instantiations and {@link SuccessorState}
+ * for details.
+ */
private static class State {
private final String string;
}
}
- // State class used when a successor has interfered. Contains coordinator latch, the successor and previous state
- private static final class SuccessorState extends State {
+ /**
+ * State class used when a successor has interfered. Contains coordinator latch, the successor and previous state.
+ * This is a temporary state introduced during reconnection process and is necessary for correct state hand-off
+ * between the old connection (potentially being accessed by the user) and the new connection (being cleaned up
+ * by the actor.
+ *
+ * <p>
+ * When a user operation encounters this state, it synchronizes on the it and wait until reconnection completes,
+ * at which point the request is routed to the successor transaction. This is a relatively heavy-weight solution
+ * to the problem of state transfer, but the user will observe it only if the race condition is hit.
+ */
+ private static class SuccessorState extends State {
private final CountDownLatch latch = new CountDownLatch(1);
private AbstractProxyTransaction successor;
private State prevState;
+ // SUCCESSOR + DONE
+ private boolean done;
+
SuccessorState() {
- super("successor");
+ super("SUCCESSOR");
}
// Synchronize with succession process and return the successor
}
State getPrevState() {
- return prevState;
+ return Verify.verifyNotNull(prevState, "Attempted to access previous state, which was not set");
}
void setPrevState(final State prevState) {
- Verify.verify(this.prevState == null);
+ Verify.verify(this.prevState == null, "Attempted to set previous state to %s when we already have %s",
+ prevState, this.prevState);
this.prevState = Preconditions.checkNotNull(prevState);
+ // We cannot have duplicate successor states, so this check is sufficient
+ this.done = DONE.equals(prevState);
}
// To be called from safe contexts, where successor is known to be completed
}
void setSuccessor(final AbstractProxyTransaction successor) {
- Verify.verify(this.successor == null);
+ Verify.verify(this.successor == null, "Attempted to set successor to %s when we already have %s",
+ successor, this.successor);
this.successor = Preconditions.checkNotNull(successor);
}
+
+ boolean isDone() {
+ return done;
+ }
+
+ void setDone() {
+ done = true;
+ }
}
private static final Logger LOG = LoggerFactory.getLogger(AbstractProxyTransaction.class);
AtomicIntegerFieldUpdater.newUpdater(AbstractProxyTransaction.class, "sealed");
private static final AtomicReferenceFieldUpdater<AbstractProxyTransaction, State> STATE_UPDATER =
AtomicReferenceFieldUpdater.newUpdater(AbstractProxyTransaction.class, State.class, "state");
- private static final State OPEN = new State("open");
- private static final State SEALED = new State("sealed");
- private static final State FLUSHED = new State("flushed");
+
+ /**
+ * Transaction has been open and is being actively worked on.
+ */
+ private static final State OPEN = new State("OPEN");
+
+ /**
+ * Transaction has been sealed by the user, but it has not completed flushing to the backed, yet. This is
+ * a transition state, as we are waiting for the user to initiate commit procedures.
+ *
+ * <p>
+ * Since the reconnect mechanics relies on state replay for transactions, this state needs to be flushed into the
+ * queue to re-create state in successor transaction (which may be based on different messages as locality may have
+ * changed). Hence the transition to {@link #FLUSHED} state needs to be handled in a thread-safe manner.
+ */
+ private static final State SEALED = new State("SEALED");
+
+ /**
+ * Transaction state has been flushed into the queue, i.e. it is visible by the successor and potentially
+ * the backend. At this point the transaction does not hold any state besides successful requests, all other state
+ * is held either in the connection's queue or the successor object.
+ *
+ * <p>
+ * Transition to this state indicates we have all input from the user we need to initiate the correct commit
+ * protocol.
+ */
+ private static final State FLUSHED = new State("FLUSHED");
+
+ /**
+ * Transaction state has been completely resolved, we have received confirmation of the transaction fate from
+ * the backend. The only remaining task left to do is finishing up the state cleanup, which is done via purge
+ * request. We need to hang on to the transaction until that is done, as we have to make sure backend completes
+ * purging its state -- otherwise we could have a leak on the backend.
+ */
+ private static final State DONE = new State("DONE");
// Touched from client actor thread only
private final Deque<Object> successfulRequests = new ArrayDeque<>();
* variable. It uses pre-allocated objects for fast paths (i.e. no successor present) and a per-transition object
* for slow paths (when successor is injected/present).
*/
- private volatile int sealed = 0;
- private volatile State state = OPEN;
+ private volatile int sealed;
+ private volatile State state;
- AbstractProxyTransaction(final ProxyHistory parent) {
+ AbstractProxyTransaction(final ProxyHistory parent, final boolean isDone) {
this.parent = Preconditions.checkNotNull(parent);
+ if (isDone) {
+ state = DONE;
+ // DONE implies previous seal operation completed
+ sealed = 1;
+ } else {
+ state = OPEN;
+ }
+ }
+
+ final void executeInActor(final Runnable command) {
+ parent.context().executeInActor(behavior -> {
+ command.run();
+ return behavior;
+ });
}
final ActorRef localActor() {
return parent.localActor();
}
- private void incrementSequence(final long delta) {
+ final void incrementSequence(final long delta) {
sequence += delta;
LOG.debug("Transaction {} incremented sequence to {}", this, sequence);
}
return doRead(path);
}
+ final void enqueueRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+ final long enqueuedTicks) {
+ LOG.debug("Transaction proxy {} enqueing request {} callback {}", this, request, callback);
+ parent.enqueueRequest(request, callback, enqueuedTicks);
+ }
+
final void sendRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback) {
LOG.debug("Transaction proxy {} sending request {} callback {}", this, request, callback);
parent.sendRequest(request, callback);
}
/**
- * Seal this transaction before it is either committed or aborted.
+ * Seal this transaction before it is either committed or aborted. This method should only be invoked from
+ * application thread.
*/
final void seal() {
// Transition user-visible state first
- final boolean success = SEALED_UPDATER.compareAndSet(this, 0, 1);
+ final boolean success = markSealed();
Preconditions.checkState(success, "Proxy %s was already sealed", getIdentifier());
- internalSeal();
+
+ if (!sealAndSend(Optional.absent())) {
+ sealSuccessor();
+ }
}
- final void ensureSealed() {
- if (SEALED_UPDATER.compareAndSet(this, 0, 1)) {
- internalSeal();
+ /**
+ * Internal seal propagation method, invoked when we have raced with reconnection thread. Note that there may have
+ * been multiple reconnects, so we have to make sure the action is propagate through all intermediate instances.
+ */
+ private void sealSuccessor() {
+ // Slow path: wait for the successor to complete
+ final AbstractProxyTransaction successor = awaitSuccessor();
+
+ // At this point the successor has completed transition and is possibly visible by the user thread, which is
+ // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
+ // Propagate state and seal the successor.
+ flushState(successor);
+ successor.predecessorSealed();
+ }
+
+ private void predecessorSealed() {
+ if (markSealed() && !sealAndSend(Optional.absent())) {
+ sealSuccessor();
}
}
- private void internalSeal() {
- doSeal();
+ void sealOnly() {
parent.onTransactionSealed(this);
+ final boolean success = STATE_UPDATER.compareAndSet(this, OPEN, SEALED);
+ Verify.verify(success, "Attempted to replay seal on {}", this);
+ }
- // Now deal with state transfer, which can occur via successor or a follow-up canCommit() or directCommit().
- if (!STATE_UPDATER.compareAndSet(this, OPEN, SEALED)) {
- // Slow path: wait for the successor to complete
- final AbstractProxyTransaction successor = awaitSuccessor();
+ /**
+ * Seal this transaction and potentially send it out towards the backend. If this method reports false, the caller
+ * needs to deal with propagating the seal operation towards the successor.
+ *
+ * @param enqueuedTicks Enqueue ticks when this is invoked from replay path.
+ * @return True if seal operation was successful, false if this proxy has a successor.
+ */
+ boolean sealAndSend(final Optional<Long> enqueuedTicks) {
+ parent.onTransactionSealed(this);
- // At this point the successor has completed transition and is possibly visible by the user thread, which is
- // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
- // Propagate state and seal the successor.
- flushState(successor);
- successor.ensureSealed();
- }
+ // Transition internal state to sealed and detect presence of a successor
+ return STATE_UPDATER.compareAndSet(this, OPEN, SEALED);
+ }
+
+ /**
+ * Mark this proxy as having been sealed.
+ *
+ * @return True if this call has transitioned to sealed state.
+ */
+ final boolean markSealed() {
+ return SEALED_UPDATER.compareAndSet(this, 0, 1);
}
private void checkNotSealed() {
successfulRequests.add(Verify.verifyNotNull(req));
}
- final void recordFinishedRequest() {
+ final void recordFinishedRequest(final Response<?, ?> response) {
final Object last = successfulRequests.peekLast();
if (last instanceof IncrementSequence) {
((IncrementSequence) last).incrementDelta();
} else {
- successfulRequests.addLast(new IncrementSequence());
+ successfulRequests.addLast(new IncrementSequence(response.getSequence()));
}
}
*/
final void abort() {
checkNotSealed();
- doAbort();
parent.abortTransaction(this);
+
+ sendRequest(abortRequest(), resp -> {
+ LOG.debug("Transaction {} abort completed with {}", getIdentifier(), resp);
+ enqueuePurge();
+ });
}
final void abort(final VotingFuture<Void> ret) {
checkSealed();
- sendAbort(t -> {
+ sendDoAbort(t -> {
if (t instanceof TransactionAbortSuccess) {
ret.voteYes();
} else if (t instanceof RequestFailure) {
// This is a terminal request, hence we do not need to record it
LOG.debug("Transaction {} abort completed", this);
- purge();
+ enqueuePurge();
});
}
- final void sendAbort(final Consumer<Response<?, ?>> callback) {
+ final void enqueueAbort(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
+ checkNotSealed();
+ parent.abortTransaction(this);
+
+ enqueueRequest(abortRequest(), resp -> {
+ LOG.debug("Transaction {} abort completed with {}", getIdentifier(), resp);
+ // Purge will be sent by the predecessor's callback
+ if (callback != null) {
+ callback.accept(resp);
+ }
+ }, enqueuedTicks);
+ }
+
+ final void enqueueDoAbort(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
+ enqueueRequest(new TransactionAbortRequest(getIdentifier(), nextSequence(), localActor()), callback,
+ enqueuedTicks);
+ }
+
+ final void sendDoAbort(final Consumer<Response<?, ?>> callback) {
sendRequest(new TransactionAbortRequest(getIdentifier(), nextSequence(), localActor()), callback);
}
if (t instanceof TransactionCommitSuccess) {
ret.set(Boolean.TRUE);
} else if (t instanceof RequestFailure) {
- ret.setException(((RequestFailure<?, ?>) t).getCause().unwrap());
+ final Throwable cause = ((RequestFailure<?, ?>) t).getCause().unwrap();
+ if (cause instanceof ClosedTransactionException) {
+ // This is okay, as it indicates the transaction has been completed. It can happen
+ // when we lose connectivity with the backend after it has received the request.
+ ret.set(Boolean.TRUE);
+ } else {
+ ret.setException(cause);
+ }
} else {
ret.setException(new IllegalStateException("Unhandled response " + t.getClass()));
}
// This is a terminal request, hence we do not need to record it
LOG.debug("Transaction {} directCommit completed", this);
- purge();
+ enqueuePurge();
});
return ret;
}
LOG.debug("Transaction {} doCommit completed", this);
- purge();
+
+ // Needed for ProxyHistory$Local data tree rebase points.
+ parent.completeTransaction(this);
+
+ enqueuePurge();
});
}
- void purge() {
+ private void enqueuePurge() {
+ enqueuePurge(null);
+ }
+
+ final void enqueuePurge(final Consumer<Response<?, ?>> callback) {
+ // Purge request are dispatched internally, hence should not wait
+ enqueuePurge(callback, parent.currentTime());
+ }
+
+ final void enqueuePurge(final Consumer<Response<?, ?>> callback, final long enqueuedTicks) {
+ LOG.debug("{}: initiating purge", this);
+
+ final State prev = state;
+ if (prev instanceof SuccessorState) {
+ ((SuccessorState) prev).setDone();
+ } else {
+ final boolean success = STATE_UPDATER.compareAndSet(this, prev, DONE);
+ if (!success) {
+ LOG.warn("{}: moved from state {} while we were purging it", this, prev);
+ }
+ }
+
successfulRequests.clear();
- final TransactionRequest<?> req = new TransactionPurgeRequest(getIdentifier(), nextSequence(), localActor());
- sendRequest(req, t -> {
- LOG.debug("Transaction {} purge completed", this);
- parent.completeTransaction(this);
- });
+ enqueueRequest(new TransactionPurgeRequest(getIdentifier(), nextSequence(), localActor()), resp -> {
+ LOG.debug("{}: purge completed", this);
+ parent.purgeTransaction(this);
+
+ if (callback != null) {
+ callback.accept(resp);
+ }
+ }, enqueuedTicks);
}
// Called with the connection unlocked
}
// Called with the connection locked
- final void replayMessages(final AbstractProxyTransaction successor,
- final Iterable<ConnectionEntry> enqueuedEntries) {
+ final void replayMessages(final ProxyHistory successorHistory, final Iterable<ConnectionEntry> enqueuedEntries) {
final SuccessorState local = getSuccessorState();
+ final State prevState = local.getPrevState();
+
+ final AbstractProxyTransaction successor = successorHistory.createTransactionProxy(getIdentifier(),
+ isSnapshotOnly(), local.isDone());
+ LOG.debug("{} created successor {}", this, successor);
local.setSuccessor(successor);
// Replay successful requests first
- for (Object obj : successfulRequests) {
- if (obj instanceof TransactionRequest) {
- LOG.debug("Forwarding successful request {} to successor {}", obj, successor);
- successor.handleForwardedRemoteRequest((TransactionRequest<?>) obj, response -> { });
- } else {
- Verify.verify(obj instanceof IncrementSequence);
- successor.incrementSequence(((IncrementSequence) obj).getDelta());
+ if (!successfulRequests.isEmpty()) {
+ // We need to find a good timestamp to use for successful requests, as we do not want to time them out
+ // nor create timing inconsistencies in the queue -- requests are expected to be ordered by their enqueue
+ // time. We will pick the time of the first entry available. If there is none, we will just use current
+ // time, as all other requests will get enqueued afterwards.
+ final ConnectionEntry firstInQueue = Iterables.getFirst(enqueuedEntries, null);
+ final long now = firstInQueue != null ? firstInQueue.getEnqueuedTicks() : parent.currentTime();
+
+ for (Object obj : successfulRequests) {
+ if (obj instanceof TransactionRequest) {
+ LOG.debug("Forwarding successful request {} to successor {}", obj, successor);
+ successor.doReplayRequest((TransactionRequest<?>) obj, resp -> { }, now);
+ } else {
+ Verify.verify(obj instanceof IncrementSequence);
+ final IncrementSequence increment = (IncrementSequence) obj;
+ successor.doReplayRequest(new IncrementTransactionSequenceRequest(getIdentifier(),
+ increment.getSequence(), localActor(), isSnapshotOnly(), increment.getDelta()), resp -> { },
+ now);
+ LOG.debug("Incrementing sequence {} to successor {}", obj, successor);
+ }
}
+ LOG.debug("{} replayed {} successful requests", getIdentifier(), successfulRequests.size());
+ successfulRequests.clear();
}
- LOG.debug("{} replayed {} successful requests", getIdentifier(), successfulRequests.size());
- successfulRequests.clear();
// Now replay whatever is in the connection
final Iterator<ConnectionEntry> it = enqueuedEntries.iterator();
if (getIdentifier().equals(req.getTarget())) {
Verify.verify(req instanceof TransactionRequest, "Unhandled request %s", req);
- LOG.debug("Forwarding queued request{} to successor {}", req, successor);
- successor.handleForwardedRemoteRequest((TransactionRequest<?>) req, e.getCallback());
+ LOG.debug("Replaying queued request {} to successor {}", req, successor);
+ successor.doReplayRequest((TransactionRequest<?>) req, e.getCallback(), e.getEnqueuedTicks());
it.remove();
}
}
* reconnecting have been forced to slow paths, which will be unlocked once we unblock the state latch
* at the end of this method.
*/
- final State prevState = local.getPrevState();
if (SEALED.equals(prevState)) {
LOG.debug("Proxy {} reconnected while being sealed, propagating state to successor {}", this, successor);
flushState(successor);
- successor.ensureSealed();
+ if (successor.markSealed()) {
+ successor.sealAndSend(Optional.of(parent.currentTime()));
+ }
+ }
+ }
+
+ /**
+ * Invoked from {@link #replayMessages(AbstractProxyTransaction, Iterable)} to have successor adopt an in-flight
+ * request.
+ *
+ * <p>
+ * Note: this method is invoked by the predecessor on the successor.
+ *
+ * @param request Request which needs to be forwarded
+ * @param callback Callback to be invoked once the request completes
+ * @param enqueuedTicks ticker-based time stamp when the request was enqueued
+ */
+ private void doReplayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+ final long enqueuedTicks) {
+ if (request instanceof AbstractLocalTransactionRequest) {
+ handleReplayedLocalRequest((AbstractLocalTransactionRequest<?>) request, callback, enqueuedTicks);
+ } else {
+ handleReplayedRemoteRequest(request, callback, enqueuedTicks);
}
}
* @param callback Original callback
*/
final void forwardRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback) {
- final AbstractProxyTransaction successor = getSuccessorState().getSuccessor();
+ forwardToSuccessor(getSuccessorState().getSuccessor(), request, callback);
+ }
+ final void forwardToSuccessor(final AbstractProxyTransaction successor, final TransactionRequest<?> request,
+ final Consumer<Response<?, ?>> callback) {
if (successor instanceof LocalProxyTransaction) {
forwardToLocal((LocalProxyTransaction)successor, request, callback);
} else if (successor instanceof RemoteProxyTransaction) {
}
}
+ final void replayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+ final long enqueuedTicks) {
+ getSuccessorState().getSuccessor().doReplayRequest(request, callback, enqueuedTicks);
+ }
+
abstract boolean isSnapshotOnly();
abstract void doDelete(YangInstanceIdentifier path);
abstract CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> doRead(YangInstanceIdentifier path);
- abstract void doSeal();
-
- abstract void doAbort();
-
@GuardedBy("this")
abstract void flushState(AbstractProxyTransaction successor);
- abstract TransactionRequest<?> commitRequest(boolean coordinated);
+ abstract TransactionRequest<?> abortRequest();
- /**
- * Invoked from {@link RemoteProxyTransaction} when it replays its successful requests to its successor. There is
- * no equivalent of this call from {@link LocalProxyTransaction} because it does not send a request until all
- * operations are packaged in the message.
- *
- * <p>
- * Note: this method is invoked by the predecessor on the successor.
- *
- * @param request Request which needs to be forwarded
- * @param callback Callback to be invoked once the request completes
- */
- abstract void handleForwardedRemoteRequest(TransactionRequest<?> request,
- @Nullable Consumer<Response<?, ?>> callback);
+ abstract TransactionRequest<?> commitRequest(boolean coordinated);
/**
* Replay a request originating in this proxy to a successor remote proxy.
abstract void forwardToLocal(LocalProxyTransaction successor, TransactionRequest<?> request,
Consumer<Response<?, ?>> callback);
+ /**
+ * Invoked from {@link LocalProxyTransaction} when it replays its successful requests to its successor.
+ *
+ * <p>
+ * Note: this method is invoked by the predecessor on the successor.
+ *
+ * @param request Request which needs to be forwarded
+ * @param callback Callback to be invoked once the request completes
+ * @param enqueuedTicks Time stamp to use for enqueue time
+ */
+ abstract void handleReplayedLocalRequest(AbstractLocalTransactionRequest<?> request,
+ @Nullable Consumer<Response<?, ?>> callback, long enqueuedTicks);
+
+ /**
+ * Invoked from {@link RemoteProxyTransaction} when it replays its successful requests to its successor.
+ *
+ * <p>
+ * Note: this method is invoked by the predecessor on the successor.
+ *
+ * @param request Request which needs to be forwarded
+ * @param callback Callback to be invoked once the request completes
+ * @param enqueuedTicks Time stamp to use for enqueue time
+ */
+ abstract void handleReplayedRemoteRequest(TransactionRequest<?> request,
+ @Nullable Consumer<Response<?, ?>> callback, long enqueuedTicks);
+
@Override
public final String toString() {
return MoreObjects.toStringHelper(this).add("identifier", getIdentifier()).add("state", state).toString();
Code Review / controller.git / blobdiff