import akka.actor.ActorRef;
import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.MoreObjects;
+import com.google.common.base.MoreObjects.ToStringHelper;
import com.google.common.base.Preconditions;
-import com.google.common.base.Verify;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
-import java.util.ArrayDeque;
-import java.util.Iterator;
-import java.util.Map.Entry;
import java.util.Optional;
-import java.util.Queue;
import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Consumer;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.GuardedBy;
import javax.annotation.concurrent.NotThreadSafe;
import org.opendaylight.controller.cluster.access.concepts.Request;
-import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
import org.opendaylight.controller.cluster.access.concepts.RequestException;
import org.opendaylight.controller.cluster.access.concepts.Response;
import org.opendaylight.controller.cluster.access.concepts.ResponseEnvelope;
@VisibleForTesting
static final long REQUEST_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30);
- private final Queue<TransmittedConnectionEntry> inflight;
- private final Queue<ConnectionEntry> pending;
+ private static final FiniteDuration REQUEST_TIMEOUT_DURATION = FiniteDuration.apply(REQUEST_TIMEOUT_NANOS,
+ TimeUnit.NANOSECONDS);
+ private final Lock lock = new ReentrantLock();
private final ClientActorContext context;
+ @GuardedBy("lock")
+ private final TransmitQueue queue;
private final Long cookie;
- private volatile ReconnectForwarder successor;
+ @GuardedBy("lock")
+ private boolean haveTimer;
+
private volatile RequestException poisoned;
- private long lastProgress;
- private AbstractClientConnection(final ClientActorContext context, final Long cookie,
- final Queue<TransmittedConnectionEntry> inflight, final Queue<ConnectionEntry> pending) {
+ // Do not allow subclassing outside of this package
+ AbstractClientConnection(final ClientActorContext context, final Long cookie,
+ final TransmitQueue queue) {
this.context = Preconditions.checkNotNull(context);
this.cookie = Preconditions.checkNotNull(cookie);
- this.inflight = Preconditions.checkNotNull(inflight);
- this.pending = Preconditions.checkNotNull(pending);
- this.lastProgress = readTime();
- }
-
- // Do not allow subclassing outside of this package
- AbstractClientConnection(final ClientActorContext context, final Long cookie) {
- this(context, cookie, new ArrayDeque<>(), new ArrayDeque<>(1));
+ this.queue = Preconditions.checkNotNull(queue);
}
// Do not allow subclassing outside of this package
- AbstractClientConnection(final AbstractClientConnection<T> oldConnection) {
- this(oldConnection.context, oldConnection.cookie, oldConnection.inflight, oldConnection.pending);
+ AbstractClientConnection(final AbstractClientConnection<T> oldConnection, final int targetQueueSize) {
+ this.context = oldConnection.context;
+ this.cookie = oldConnection.cookie;
+ this.queue = new TransmitQueue.Halted(targetQueueSize);
}
public final ClientActorContext context() {
* Send a request to the backend and invoke a specified callback when it finishes. This method is safe to invoke
* from any thread.
*
+ * <p>This method may put the caller thread to sleep in order to throttle the request rate.
+ * The callback may be called before the sleep finishes.
+ *
* @param request Request to send
* @param callback Callback to invoke
*/
public final void sendRequest(final Request<?, ?> request, final Consumer<Response<?, ?>> callback) {
- Preconditions.checkState(poisoned == null, "Connection %s has been poisoned", this);
-
- final ReconnectForwarder beforeQueue = successor;
- final ConnectionEntry entry = new ConnectionEntry(request, callback, readTime());
- if (beforeQueue != null) {
- LOG.trace("Forwarding entry {} from {} to {}", entry, this, beforeQueue);
- beforeQueue.forwardEntry(entry);
- return;
- }
-
- enqueueEntry(entry);
-
- final ReconnectForwarder afterQueue = successor;
- if (afterQueue != null) {
- synchronized (this) {
- spliceToSuccessor(afterQueue);
- }
+ final RequestException maybePoison = poisoned;
+ if (maybePoison != null) {
+ throw new IllegalStateException("Connection " + this + " has been poisoned", maybePoison);
}
- }
- public final synchronized void setForwarder(final ReconnectForwarder forwarder) {
- Verify.verify(successor == null, "Successor {} already set on connection {}", successor, this);
- successor = Preconditions.checkNotNull(forwarder);
- LOG.debug("Connection {} superseded by {}, splicing queue", this, successor);
- spliceToSuccessor(forwarder);
+ final ConnectionEntry entry = new ConnectionEntry(request, callback, readTime());
+ enqueueAndWait(entry, entry.getEnqueuedTicks());
}
public abstract Optional<T> getBackendInfo();
- abstract ClientActorBehavior<T> reconnectConnection(ClientActorBehavior<T> current);
-
- abstract int remoteMaxMessages();
-
- abstract Entry<ActorRef, RequestEnvelope> prepareForTransmit(Request<?, ?> req);
+ final Iterable<ConnectionEntry> startReplay() {
+ lock.lock();
+ return queue.asIterable();
+ }
- @GuardedBy("this")
- final void spliceToSuccessor(final ReconnectForwarder successor) {
- ConnectionEntry entry = inflight.poll();
- while (entry != null) {
- successor.forwardEntry(entry);
- entry = inflight.poll();
- }
+ @GuardedBy("lock")
+ final void finishReplay(final ReconnectForwarder forwarder) {
+ setForwarder(forwarder);
+ lock.unlock();
+ }
- entry = pending.poll();
- while (entry != null) {
- successor.forwardEntry(entry);
- entry = pending.poll();
- }
+ @GuardedBy("lock")
+ final void setForwarder(final ReconnectForwarder forwarder) {
+ queue.setForwarder(forwarder, readTime());
}
+ @GuardedBy("lock")
+ abstract ClientActorBehavior<T> lockedReconnect(ClientActorBehavior<T> current);
+
private long readTime() {
return context.ticker().read();
}
- private void transmit(final ConnectionEntry entry) {
- final Entry<ActorRef, RequestEnvelope> tuple = prepareForTransmit(entry.getRequest());
- final RequestEnvelope req = tuple.getValue();
-
- // We need to enqueue the request before we send it to the actor, as we may be executing on a different thread
- // than the client actor thread, in which case the round-trip could be made faster than we can enqueue --
- // in which case the receive routine would not find the entry.
- final TransmittedConnectionEntry txEntry = new TransmittedConnectionEntry(entry, req.getSessionId(),
- req.getTxSequence(), readTime());
- inflight.add(txEntry);
+ final long enqueueEntry(final ConnectionEntry entry, final long now) {
+ lock.lock();
+ try {
+ if (queue.isEmpty()) {
+ // The queue is becoming non-empty, schedule a timer
+ scheduleTimer(REQUEST_TIMEOUT_DURATION);
+ }
+ return queue.enqueue(entry, now);
+ } finally {
+ lock.unlock();
+ }
+ }
- final ActorRef actor = tuple.getKey();
- LOG.trace("Transmitting request {} as {} to {}", entry.getRequest(), req, actor);
- actor.tell(req, ActorRef.noSender());
+ final void enqueueAndWait(final ConnectionEntry entry, final long now) {
+ final long delay = enqueueEntry(entry, now);
+ try {
+ TimeUnit.NANOSECONDS.sleep(delay);
+ } catch (InterruptedException e) {
+ LOG.debug("Interrupted while sleeping", e);
+ }
}
- final void enqueueEntry(final ConnectionEntry entry) {
- if (inflight.size() < remoteMaxMessages()) {
- transmit(entry);
- LOG.debug("Enqueued request {} to queue {}", entry.getRequest(), this);
- } else {
- LOG.debug("Queue is at capacity, delayed sending of request {}", entry.getRequest());
- pending.add(entry);
+ final ClientActorBehavior<T> reconnect(final ClientActorBehavior<T> current) {
+ lock.lock();
+ try {
+ return lockedReconnect(current);
+ } finally {
+ lock.unlock();
}
}
*
* @param delay Delay, in nanoseconds
*/
+ @GuardedBy("lock")
private void scheduleTimer(final FiniteDuration delay) {
+ if (haveTimer) {
+ LOG.debug("{}: timer already scheduled", context.persistenceId());
+ return;
+ }
+ if (queue.hasSuccessor()) {
+ LOG.debug("{}: connection has successor, not scheduling timer", context.persistenceId());
+ return;
+ }
LOG.debug("{}: scheduling timeout in {}", context.persistenceId(), delay);
context.executeInActor(this::runTimer, delay);
+ haveTimer = true;
}
/**
*/
@VisibleForTesting
final ClientActorBehavior<T> runTimer(final ClientActorBehavior<T> current) {
- final long now = readTime();
-
- if (!inflight.isEmpty() || !pending.isEmpty()) {
- final long ticksSinceProgress = now - lastProgress;
+ final Optional<FiniteDuration> delay;
+
+ lock.lock();
+ try {
+ haveTimer = false;
+ final long now = readTime();
+ // The following line is only reliable when queue is not forwarding, but such state should not last long.
+ final long ticksSinceProgress = queue.ticksStalling(now);
if (ticksSinceProgress >= NO_PROGRESS_TIMEOUT_NANOS) {
LOG.error("Queue {} has not seen progress in {} seconds, failing all requests", this,
TimeUnit.NANOSECONDS.toSeconds(ticksSinceProgress));
- poison(new NoProgressException(ticksSinceProgress));
+ lockedPoison(new NoProgressException(ticksSinceProgress));
current.removeConnection(this);
return current;
}
- }
- // Requests are always scheduled in sequence, hence checking for timeout is relatively straightforward.
- // Note we use also inquire about the delay, so we can re-schedule if needed, hence the unusual tri-state
- // return convention.
- final Optional<FiniteDuration> delay = checkTimeout(now);
- if (delay == null) {
- // We have timed out. There is no point in scheduling a timer
- return reconnectConnection(current);
- }
+ // Requests are always scheduled in sequence, hence checking for timeout is relatively straightforward.
+ // Note we use also inquire about the delay, so we can re-schedule if needed, hence the unusual tri-state
+ // return convention.
+ delay = lockedCheckTimeout(now);
+ if (delay == null) {
+ // We have timed out. There is no point in scheduling a timer
+ return lockedReconnect(current);
+ }
- if (delay.isPresent()) {
- // If there is new delay, schedule a timer
- scheduleTimer(delay.get());
+ if (delay.isPresent()) {
+ // If there is new delay, schedule a timer
+ scheduleTimer(delay.get());
+ }
+ } finally {
+ lock.unlock();
}
return current;
}
+ @VisibleForTesting
+ final Optional<FiniteDuration> checkTimeout(final long now) {
+ lock.lock();
+ try {
+ return lockedCheckTimeout(now);
+ } finally {
+ lock.unlock();
+ }
+ }
+
/*
* We are using tri-state return here to indicate one of three conditions:
* - if there is no timeout to schedule, return Optional.empty()
*/
@SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
justification = "Returning null Optional is documented in the API contract.")
- private Optional<FiniteDuration> checkTimeout(final ConnectionEntry head, final long now) {
+ @GuardedBy("lock")
+ private Optional<FiniteDuration> lockedCheckTimeout(final long now) {
+ final ConnectionEntry head = queue.peek();
if (head == null) {
return Optional.empty();
}
- final long delay = head.getEnqueuedTicks() - now + REQUEST_TIMEOUT_NANOS;
- if (delay <= 0) {
- LOG.debug("Connection {} timed out", this);
+ final long beenOpen = now - head.getEnqueuedTicks();
+ if (beenOpen >= REQUEST_TIMEOUT_NANOS) {
+ LOG.debug("Connection {} has a request not completed for {} nanoseconds, timing out", this, beenOpen);
return null;
}
- return Optional.of(FiniteDuration.apply(delay, TimeUnit.NANOSECONDS));
+ return Optional.of(FiniteDuration.apply(REQUEST_TIMEOUT_NANOS - beenOpen, TimeUnit.NANOSECONDS));
}
- /*
- * We are using tri-state return here to indicate one of three conditions:
- * - if there is no timeout to schedule, return Optional.empty()
- * - if there is a timeout to schedule, return a non-empty optional
- * - if this connections has timed out, return null
- */
- @SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
- justification = "Returning null Optional is documented in the API contract.")
- @VisibleForTesting
- final Optional<FiniteDuration> checkTimeout(final long now) {
- final Optional<FiniteDuration> xmit = checkTimeout(inflight.peek(), now);
- if (xmit == null) {
- return null;
- }
- final Optional<FiniteDuration> pend = checkTimeout(pending.peek(), now);
- if (pend == null) {
- return null;
- }
- if (!xmit.isPresent()) {
- return pend;
- }
- if (!pend.isPresent()) {
- return xmit;
+ final void poison(final RequestException cause) {
+ lock.lock();
+ try {
+ lockedPoison(cause);
+ } finally {
+ lock.unlock();
}
-
- return Optional.of(xmit.get().min(pend.get()));
}
- final void poison(final RequestException cause) {
+ @GuardedBy("lock")
+ private void lockedPoison(final RequestException cause) {
poisoned = cause;
-
- poisonQueue(inflight, cause);
- poisonQueue(pending, cause);
+ queue.poison(cause);
}
@VisibleForTesting
}
final void receiveResponse(final ResponseEnvelope<?> envelope) {
- Optional<TransmittedConnectionEntry> maybeEntry = findMatchingEntry(inflight, envelope);
- if (maybeEntry == null) {
- LOG.debug("Request for {} not found in inflight queue, checking pending queue", envelope);
- maybeEntry = findMatchingEntry(pending, envelope);
- }
+ final long now = readTime();
- if (maybeEntry == null || !maybeEntry.isPresent()) {
- LOG.warn("No request matching {} found, ignoring response", envelope);
- return;
+ final Optional<TransmittedConnectionEntry> maybeEntry;
+ lock.lock();
+ try {
+ maybeEntry = queue.complete(envelope, now);
+ } finally {
+ lock.unlock();
}
- final TransmittedConnectionEntry entry = maybeEntry.get();
- LOG.debug("Completing {} with {}", entry, envelope);
- entry.complete(envelope.getMessage());
-
- // We have freed up a slot, try to transmit something
- int toSend = remoteMaxMessages() - inflight.size();
- while (toSend > 0) {
- final ConnectionEntry e = pending.poll();
- if (e == null) {
- break;
- }
-
- LOG.debug("Transmitting entry {}", e);
- transmit(e);
- toSend--;
+ if (maybeEntry.isPresent()) {
+ final TransmittedConnectionEntry entry = maybeEntry.get();
+ LOG.debug("Completing {} with {}", entry, envelope);
+ entry.complete(envelope.getMessage());
}
-
- lastProgress = readTime();
}
- private static void poisonQueue(final Queue<? extends ConnectionEntry> queue, final RequestException cause) {
- for (ConnectionEntry e : queue) {
- final Request<?, ?> request = e.getRequest();
- LOG.trace("Poisoning request {}", request, cause);
- e.complete(request.toRequestFailure(cause));
- }
- queue.clear();
+ @Override
+ public final String toString() {
+ return addToStringAttributes(MoreObjects.toStringHelper(this).omitNullValues()).toString();
}
- /*
- * We are using tri-state return here to indicate one of three conditions:
- * - if a matching entry is found, return an Optional containing it
- * - if a matching entry is not found, but it makes sense to keep looking at other queues, return null
- * - if a conflicting entry is encountered, indicating we should ignore this request, return an empty Optional
- */
- @SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
- justification = "Returning null Optional is documented in the API contract.")
- private static Optional<TransmittedConnectionEntry> findMatchingEntry(final Queue<? extends ConnectionEntry> queue,
- final ResponseEnvelope<?> envelope) {
- // Try to find the request in a queue. Responses may legally come back in a different order, hence we need
- // to use an iterator
- final Iterator<? extends ConnectionEntry> it = queue.iterator();
- while (it.hasNext()) {
- final ConnectionEntry e = it.next();
- final Request<?, ?> request = e.getRequest();
- final Response<?, ?> response = envelope.getMessage();
-
- // First check for matching target, or move to next entry
- if (!request.getTarget().equals(response.getTarget())) {
- continue;
- }
-
- // Sanity-check logical sequence, ignore any out-of-order messages
- if (request.getSequence() != response.getSequence()) {
- LOG.debug("Expecting sequence {}, ignoring response {}", request.getSequence(), envelope);
- return Optional.empty();
- }
-
- // Check if the entry has (ever) been transmitted
- if (!(e instanceof TransmittedConnectionEntry)) {
- return Optional.empty();
- }
-
- final TransmittedConnectionEntry te = (TransmittedConnectionEntry) e;
-
- // Now check session match
- if (envelope.getSessionId() != te.getSessionId()) {
- LOG.debug("Expecting session {}, ignoring response {}", te.getSessionId(), envelope);
- return Optional.empty();
- }
- if (envelope.getTxSequence() != te.getTxSequence()) {
- LOG.warn("Expecting txSequence {}, ignoring response {}", te.getTxSequence(), envelope);
- return Optional.empty();
- }
-
- LOG.debug("Completing request {} with {}", request, envelope);
- it.remove();
- return Optional.of(te);
- }
-
- return null;
+ ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
+ return toStringHelper.add("client", context.getIdentifier()).add("cookie", cookie).add("poisoned", poisoned);
}
}