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.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;
@VisibleForTesting
static final long REQUEST_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30);
- 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<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.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<>(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.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() {
return context.self();
}
- final long readTime() {
+ public final long currentTime() {
return context.ticker().read();
}
- final Queue<ConnectionEntry> pending() {
- return pending;
+ /**
+ * 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) {
+ final long now = currentTime();
+ final long delay = enqueueEntry(new ConnectionEntry(request, callback, now), now);
+ try {
+ TimeUnit.NANOSECONDS.sleep(delay);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ LOG.debug("Interrupted after sleeping {}ns", e, currentTime() - now);
+ }
}
/**
* 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 sendRequest(final Request<?, ?> request, final Consumer<Response<?, ?>> callback) {
- Preconditions.checkState(poisoned == null, "Connection %s has been poisoned", this);
+ public final void enqueueRequest(final Request<?, ?> request, final Consumer<Response<?, ?>> callback,
+ final long enqueuedTicks) {
+ enqueueEntry(new ConnectionEntry(request, callback, enqueuedTicks), currentTime());
+ }
- 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;
- }
+ public abstract Optional<T> getBackendInfo();
- enqueueEntry(entry);
+ final Iterable<ConnectionEntry> startReplay() {
+ lock.lock();
+ return queue.asIterable();
+ }
- final ReconnectForwarder afterQueue = successor;
- if (afterQueue != null) {
- synchronized (this) {
- spliceToSuccessor(afterQueue);
- }
- }
+ @GuardedBy("lock")
+ final void finishReplay(final ReconnectForwarder forwarder) {
+ setForwarder(forwarder);
+ 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);
+ @GuardedBy("lock")
+ final void setForwarder(final ReconnectForwarder forwarder) {
+ queue.setForwarder(forwarder, currentTime());
}
- public abstract Optional<T> getBackendInfo();
+ @GuardedBy("lock")
+ abstract ClientActorBehavior<T> lockedReconnect(ClientActorBehavior<T> current);
- @GuardedBy("this")
- void spliceToSuccessor(final ReconnectForwarder successor) {
- ConnectionEntry entry = pending.poll();
- while (entry != null) {
- successor.forwardEntry(entry);
- entry = pending.poll();
- }
- }
+ 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 ConnectionEntry dequeEntry() {
- lastProgress = readTime();
- return pending.poll();
+ if (queue.isEmpty()) {
+ // The queue is becoming non-empty, schedule a timer
+ scheduleTimer(REQUEST_TIMEOUT_DURATION);
+ }
+ return queue.enqueue(entry, now);
+ } finally {
+ lock.unlock();
+ }
}
- void enqueueEntry(final ConnectionEntry entry) {
- 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;
}
/**
- * Check queue timeouts and return true if a timeout has occurred.
+ * Check this queue for timeout and initiate reconnection if that happened. If the queue has not made progress
+ * in {@link #NO_PROGRESS_TIMEOUT_NANOS} nanoseconds, it will be aborted.
*
- * @return True if a timeout occurred
- * @throws NoProgressException if the queue failed to make progress for an extended
- * time.
+ * @param current Current behavior
+ * @return Next behavior to use
*/
@VisibleForTesting
final ClientActorBehavior<T> runTimer(final ClientActorBehavior<T> current) {
- final long now = readTime();
-
- if (!isEmpty()) {
- final long ticksSinceProgress = now - lastProgress;
+ final Optional<FiniteDuration> delay;
+
+ lock.lock();
+ try {
+ haveTimer = false;
+ final long now = currentTime();
+ // 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;
}
- boolean isEmpty() {
- return pending.isEmpty();
+ @VisibleForTesting
+ final Optional<FiniteDuration> checkTimeout(final long now) {
+ lock.lock();
+ try {
+ return lockedCheckTimeout(now);
+ } finally {
+ lock.unlock();
+ }
}
/*
*/
@SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
justification = "Returning null Optional is documented in the API contract.")
- final 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));
- }
-
- /*
- * 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.")
- Optional<FiniteDuration> checkTimeout(final long now) {
- return checkTimeout(pending.peek(), now);
+ return Optional.of(FiniteDuration.apply(REQUEST_TIMEOUT_NANOS - beenOpen, TimeUnit.NANOSECONDS));
}
- 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));
+ final void poison(final RequestException cause) {
+ lock.lock();
+ try {
+ lockedPoison(cause);
+ } finally {
+ lock.unlock();
}
- queue.clear();
}
- void poison(final RequestException cause) {
+ @GuardedBy("lock")
+ private void lockedPoison(final RequestException cause) {
poisoned = cause;
- poisonQueue(pending, cause);
+ queue.poison(cause);
}
@VisibleForTesting
return poisoned;
}
- abstract ClientActorBehavior<T> reconnectConnection(ClientActorBehavior<T> current);
+ final void receiveResponse(final ResponseEnvelope<?> envelope) {
+ final long now = currentTime();
- abstract void receiveResponse(final ResponseEnvelope<?> envelope);
+ final Optional<TransmittedConnectionEntry> maybeEntry;
+ lock.lock();
+ try {
+ maybeEntry = queue.complete(envelope, now);
+ } finally {
+ lock.unlock();
+ }
+
+ if (maybeEntry.isPresent()) {
+ final TransmittedConnectionEntry entry = maybeEntry.get();
+ LOG.debug("Completing {} with {}", entry, envelope);
+ entry.complete(envelope.getMessage());
+ }
+ }
+
+ @Override
+ public final String toString() {
+ return addToStringAttributes(MoreObjects.toStringHelper(this).omitNullValues()).toString();
+ }
+
+ ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
+ return toStringHelper.add("client", context.getIdentifier()).add("cookie", cookie).add("poisoned", poisoned);
+ }
}
Code Review / controller.git / blobdiff