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.Collection;
import java.util.Optional;
-import java.util.Queue;
import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+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;
+import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import scala.concurrent.duration.FiniteDuration;
public abstract class AbstractClientConnection<T extends BackendInfo> {
private static final Logger LOG = LoggerFactory.getLogger(AbstractClientConnection.class);
- // Keep these constants in nanoseconds, as that prevents unnecessary conversions in the fast path
+ /*
+ * Timers involved in communication with the backend. There are three tiers which are spaced out to allow for
+ * recovery at each tier. Keep these constants in nanoseconds, as that prevents unnecessary conversions in the fast
+ * path.
+ */
+ /**
+ * Backend aliveness timer. This is reset whenever we receive a response from the backend and kept armed whenever
+ * we have an outstanding request. If when this time expires, we tear down this connection and attept to reconnect
+ * it.
+ */
@VisibleForTesting
- static final long NO_PROGRESS_TIMEOUT_NANOS = TimeUnit.MINUTES.toNanos(15);
+ static final long BACKEND_ALIVE_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30);
+
+ /**
+ * Request timeout. If the request fails to complete within this time since it was originally enqueued, we time
+ * the request out.
+ */
@VisibleForTesting
- static final long REQUEST_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30);
+ static final long REQUEST_TIMEOUT_NANOS = TimeUnit.MINUTES.toNanos(2);
- private final Queue<TransmittedConnectionEntry> inflight;
- private final Queue<ConnectionEntry> pending;
+ /**
+ * No progress timeout. A client fails to make any forward progress in this time, it will terminate itself.
+ */
+ @VisibleForTesting
+ static final long NO_PROGRESS_TIMEOUT_NANOS = TimeUnit.MINUTES.toNanos(15);
+ // Emit a debug entry if we sleep for more that this amount
+ private static final long DEBUG_DELAY_NANOS = TimeUnit.MILLISECONDS.toNanos(100);
+
+ // Upper bound on the time a thread is forced to sleep to keep queue size under control
+ private static final long MAX_DELAY_SECONDS = 5;
+ private static final long MAX_DELAY_NANOS = TimeUnit.SECONDS.toNanos(MAX_DELAY_SECONDS);
+
+ 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;
+
+ /**
+ * Time reference when we saw any activity from the backend.
+ */
+ private long lastReceivedTicks;
+
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);
+ this.lastReceivedTicks = currentTime();
}
// 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);
+ this.lastReceivedTicks = oldConnection.lastReceivedTicks;
}
public final ClientActorContext context() {
return context.self();
}
+ public final long currentTime() {
+ return context.ticker().read();
+ }
+
/**
* 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 long now = currentTime();
+ sendEntry(new ConnectionEntry(request, callback, now), now);
+ }
- 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;
- }
+ /**
+ * Send a request to the backend and invoke a specified callback when it finishes. This method is safe to invoke
+ * from any thread.
+ *
+ * <p>
+ * Note that unlike {@link #sendRequest(Request, Consumer)}, this method does not exert backpressure, hence it
+ * should never be called from an application thread.
+ *
+ * @param request Request to send
+ * @param callback Callback to invoke
+ * @param enqueuedTicks Time (according to {@link #currentTime()} of request enqueue
+ */
+ public final void enqueueRequest(final Request<?, ?> request, final Consumer<Response<?, ?>> callback,
+ final long enqueuedTicks) {
+ enqueueEntry(new ConnectionEntry(request, callback, enqueuedTicks), currentTime());
+ }
- enqueueEntry(entry);
+ public final long enqueueEntry(final ConnectionEntry entry, final long now) {
+ lock.lock();
+ try {
+ final RequestException maybePoison = poisoned;
+ if (maybePoison != null) {
+ throw new IllegalStateException("Connection " + this + " has been poisoned", maybePoison);
+ }
- final ReconnectForwarder afterQueue = successor;
- if (afterQueue != null) {
- synchronized (this) {
- spliceToSuccessor(afterQueue);
+ if (queue.isEmpty()) {
+ // The queue is becoming non-empty, schedule a timer.
+ scheduleTimer(entry.getEnqueuedTicks() + REQUEST_TIMEOUT_NANOS - now);
}
+ return queue.enqueue(entry, now);
+ } finally {
+ lock.unlock();
}
}
- 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);
- }
-
public abstract Optional<T> getBackendInfo();
- abstract ClientActorBehavior<T> reconnectConnection(ClientActorBehavior<T> current);
-
- abstract int remoteMaxMessages();
-
- abstract Entry<ActorRef, RequestEnvelope> prepareForTransmit(Request<?, ?> req);
-
- @GuardedBy("this")
- final void spliceToSuccessor(final ReconnectForwarder successor) {
- ConnectionEntry entry = inflight.poll();
- while (entry != null) {
- successor.forwardEntry(entry);
- entry = inflight.poll();
- }
-
- entry = pending.poll();
- while (entry != null) {
- successor.forwardEntry(entry);
- entry = pending.poll();
- }
+ final Collection<ConnectionEntry> startReplay() {
+ lock.lock();
+ return queue.drain();
}
- private long readTime() {
- return context.ticker().read();
+ @GuardedBy("lock")
+ final void finishReplay(final ReconnectForwarder forwarder) {
+ setForwarder(forwarder);
+
+ /*
+ * The process of replaying all messages may have taken a significant chunk of time, depending on type
+ * of messages, queue depth and available processing power. In extreme situations this may have already
+ * exceeded BACKEND_ALIVE_TIMEOUT_NANOS, in which case we are running the risk of not making reasonable forward
+ * progress before we start a reconnect cycle.
+ *
+ * Note that the timer is armed after we have sent the first message, hence we should be seeing a response
+ * from the backend before we see a timeout, simply due to how the mailbox operates.
+ *
+ * At any rate, reset the timestamp once we complete reconnection (which an atomic transition from the
+ * perspective of outside world), as that makes it a bit easier to reason about timing of events.
+ */
+ lastReceivedTicks = currentTime();
+ lock.unlock();
}
- 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);
+ @GuardedBy("lock")
+ final void setForwarder(final ReconnectForwarder forwarder) {
+ queue.setForwarder(forwarder, currentTime());
+ }
- final ActorRef actor = tuple.getKey();
- LOG.trace("Transmitting request {} as {} to {}", entry.getRequest(), req, actor);
- actor.tell(req, ActorRef.noSender());
+ @GuardedBy("lock")
+ abstract ClientActorBehavior<T> lockedReconnect(ClientActorBehavior<T> current,
+ RequestException runtimeRequestException);
+
+ final void sendEntry(final ConnectionEntry entry, final long now) {
+ long delay = enqueueEntry(entry, now);
+ try {
+ if (delay >= DEBUG_DELAY_NANOS) {
+ if (delay > MAX_DELAY_NANOS) {
+ LOG.info("Capping {} throttle delay from {} to {} seconds", this,
+ TimeUnit.NANOSECONDS.toSeconds(delay), MAX_DELAY_SECONDS, new Throwable());
+ delay = MAX_DELAY_NANOS;
+ }
+ if (LOG.isDebugEnabled()) {
+ LOG.debug("{}: Sleeping for {}ms on connection {}", context.persistenceId(),
+ TimeUnit.NANOSECONDS.toMillis(delay), this);
+ }
+ }
+ TimeUnit.NANOSECONDS.sleep(delay);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ LOG.debug("Interrupted after sleeping {}ns", e, currentTime() - now);
+ }
}
- 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, final RequestException cause) {
+ lock.lock();
+ try {
+ return lockedReconnect(current, cause);
+ } finally {
+ lock.unlock();
}
}
*
* @param delay Delay, in nanoseconds
*/
- private void scheduleTimer(final FiniteDuration delay) {
- LOG.debug("{}: scheduling timeout in {}", context.persistenceId(), delay);
- context.executeInActor(this::runTimer, delay);
+ @GuardedBy("lock")
+ private void scheduleTimer(final long delay) {
+ if (haveTimer) {
+ LOG.debug("{}: timer already scheduled on {}", context.persistenceId(), this);
+ return;
+ }
+ if (queue.hasSuccessor()) {
+ LOG.debug("{}: connection {} has a successor, not scheduling timer", context.persistenceId(), this);
+ return;
+ }
+
+ // If the delay is negative, we need to schedule an action immediately. While the caller could have checked
+ // for that condition and take appropriate action, but this is more convenient and less error-prone.
+ final long normalized = delay <= 0 ? 0 : Math.min(delay, BACKEND_ALIVE_TIMEOUT_NANOS);
+
+ final FiniteDuration dur = FiniteDuration.fromNanos(normalized);
+ LOG.debug("{}: connection {} scheduling timeout in {}", context.persistenceId(), this, dur);
+ context.executeInActor(this::runTimer, dur);
+ haveTimer = true;
}
/**
*/
@VisibleForTesting
final ClientActorBehavior<T> runTimer(final ClientActorBehavior<T> current) {
- final long now = readTime();
+ final Optional<Long> delay;
- if (!inflight.isEmpty() || !pending.isEmpty()) {
- final long ticksSinceProgress = now - lastProgress;
+ lock.lock();
+ try {
+ haveTimer = false;
+ final long now = currentTime();
+
+ LOG.debug("{}: running timer on {}", context.persistenceId(), this);
+
+ // The following line is only reliable when queue is not forwarding, but such state should not last long.
+ // FIXME: BUG-8422: this may not be accurate w.r.t. replayed entries
+ 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
+ LOG.debug("{}: connection {} timed out", context.persistenceId(), this);
+ return lockedReconnect(current, new RuntimeRequestException("Backend connection timed out",
+ new TimeoutException()));
+ }
- 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());
+ } else {
+ LOG.debug("{}: not scheduling timeout on {}", context.persistenceId(), this);
+ }
+ } finally {
+ lock.unlock();
}
return current;
}
- /*
- * 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.")
- private Optional<FiniteDuration> checkTimeout(final ConnectionEntry head, final long now) {
- if (head == null) {
- return Optional.empty();
- }
-
- final long delay = head.getEnqueuedTicks() - now + REQUEST_TIMEOUT_NANOS;
- if (delay <= 0) {
- LOG.debug("Connection {} timed out", this);
- return null;
+ @VisibleForTesting
+ final Optional<Long> checkTimeout(final long now) {
+ lock.lock();
+ try {
+ return lockedCheckTimeout(now);
+ } finally {
+ lock.unlock();
}
+ }
- return Optional.of(FiniteDuration.apply(delay, TimeUnit.NANOSECONDS));
+ long backendSilentTicks(final long now) {
+ return now - lastReceivedTicks;
}
/*
*/
@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;
+ @GuardedBy("lock")
+ private Optional<Long> lockedCheckTimeout(final long now) {
+ if (queue.isEmpty()) {
+ LOG.debug("{}: connection {} is empty", context.persistenceId(), this);
+ return Optional.empty();
}
- final Optional<FiniteDuration> pend = checkTimeout(pending.peek(), now);
- if (pend == null) {
+
+ final long backendSilentTicks = backendSilentTicks(now);
+ if (backendSilentTicks >= BACKEND_ALIVE_TIMEOUT_NANOS) {
+ LOG.debug("{}: Connection {} has not seen activity from backend for {} nanoseconds, timing out",
+ context.persistenceId(), this, backendSilentTicks);
return null;
}
- if (!xmit.isPresent()) {
- return pend;
+
+ int tasksTimedOut = 0;
+ for (ConnectionEntry head = queue.peek(); head != null; head = queue.peek()) {
+ final long beenOpen = now - head.getEnqueuedTicks();
+ if (beenOpen < REQUEST_TIMEOUT_NANOS) {
+ return Optional.of(REQUEST_TIMEOUT_NANOS - beenOpen);
+ }
+
+ tasksTimedOut++;
+ queue.remove(now);
+ LOG.debug("{}: Connection {} timed out entry {}", context.persistenceId(), this, head);
+
+ final double time = (beenOpen * 1.0) / 1_000_000_000;
+ head.complete(head.getRequest().toRequestFailure(
+ new RequestTimeoutException("Timed out after " + time + "seconds")));
}
- if (!pend.isPresent()) {
- return xmit;
+
+ LOG.debug("Connection {} timed out {} tasks", this, tasksTimedOut);
+ if (tasksTimedOut != 0) {
+ queue.tryTransmit(now);
}
- return Optional.of(xmit.get().min(pend.get()));
+ return Optional.empty();
}
final void poison(final RequestException cause) {
- poisoned = cause;
+ lock.lock();
+ try {
+ lockedPoison(cause);
+ } finally {
+ lock.unlock();
+ }
+ }
+
+ @GuardedBy("lock")
+ private void lockedPoison(final RequestException cause) {
+ poisoned = enrichPoison(cause);
+ queue.poison(cause);
+ }
- poisonQueue(inflight, cause);
- poisonQueue(pending, cause);
+ RequestException enrichPoison(final RequestException ex) {
+ return ex;
}
@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 = currentTime();
+ lastReceivedTicks = now;
+
+ final Optional<TransmittedConnectionEntry> maybeEntry;
+ lock.lock();
+ try {
+ maybeEntry = queue.complete(envelope, now);
+ } finally {
+ lock.unlock();
}
- if (maybeEntry == null || !maybeEntry.isPresent()) {
- LOG.warn("No request matching {} found, ignoring response", envelope);
- return;
+ if (maybeEntry.isPresent()) {
+ final TransmittedConnectionEntry entry = maybeEntry.get();
+ LOG.debug("Completing {} with {}", entry, envelope);
+ entry.complete(envelope.getMessage());
}
-
- 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--;
- }
-
- 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);
}
}
Code Review / controller.git / blobdiff