*/
/**
* 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
+ * we have an outstanding request. If when this time expires, we tear down this connection and attempt to reconnect
* it.
*/
- @VisibleForTesting
- static final long BACKEND_ALIVE_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30);
+ public static final long DEFAULT_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.MINUTES.toNanos(2);
+ public static final long DEFAULT_REQUEST_TIMEOUT_NANOS = TimeUnit.MINUTES.toNanos(2);
/**
* 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);
+ public static final long DEFAULT_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;
private volatile RequestException poisoned;
+ // Private constructor to avoid code duplication.
+ private AbstractClientConnection(final AbstractClientConnection<T> oldConn, final TransmitQueue newQueue) {
+ this.context = Preconditions.checkNotNull(oldConn.context);
+ this.cookie = Preconditions.checkNotNull(oldConn.cookie);
+ this.queue = Preconditions.checkNotNull(newQueue);
+ // Will be updated in finishReplay if needed.
+ this.lastReceivedTicks = oldConn.lastReceivedTicks;
+ }
+
+ // This constructor is only to be called by ConnectingClientConnection constructor.
// Do not allow subclassing outside of this package
- AbstractClientConnection(final ClientActorContext context, final Long cookie,
- final TransmitQueue queue) {
+ AbstractClientConnection(final ClientActorContext context, final Long cookie, final int queueDepth) {
this.context = Preconditions.checkNotNull(context);
this.cookie = Preconditions.checkNotNull(cookie);
- this.queue = Preconditions.checkNotNull(queue);
+ this.queue = new TransmitQueue.Halted(queueDepth);
this.lastReceivedTicks = currentTime();
}
+ // This constructor is only to be called (indirectly) by ReconnectingClientConnection constructor.
// Do not allow subclassing outside of this package
- 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;
+ AbstractClientConnection(final AbstractClientConnection<T> oldConn) {
+ this(oldConn, new TransmitQueue.Halted(oldConn.queue, oldConn.currentTime()));
+ }
+
+ // This constructor is only to be called (indirectly) by ConnectedClientConnection constructor.
+ // Do not allow subclassing outside of this package
+ AbstractClientConnection(final AbstractClientConnection<T> oldConn, final T newBackend, final int queueDepth) {
+ this(oldConn, new TransmitQueue.Transmitting(oldConn.queue, queueDepth, newBackend, oldConn.currentTime(),
+ Preconditions.checkNotNull(oldConn.context).messageSlicer()));
}
public final ClientActorContext context() {
*/
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);
- }
+ sendEntry(new ConnectionEntry(request, callback, now), now);
}
/**
enqueueEntry(new ConnectionEntry(request, callback, enqueuedTicks), currentTime());
}
+ private long enqueueOrForward(final ConnectionEntry entry, final long now) {
+ lock.lock();
+ try {
+ commonEnqueue(entry, now);
+ return queue.enqueueOrForward(entry, now);
+ } finally {
+ lock.unlock();
+ }
+ }
+
+ /**
+ * Enqueue an entry, possibly also transmitting it.
+ */
+ public final void enqueueEntry(final ConnectionEntry entry, final long now) {
+ lock.lock();
+ try {
+ commonEnqueue(entry, now);
+ queue.enqueueOrReplay(entry, now);
+ } finally {
+ lock.unlock();
+ }
+ }
+
+ @GuardedBy("lock")
+ private void commonEnqueue(final ConnectionEntry entry, final long now) {
+ final RequestException maybePoison = poisoned;
+ if (maybePoison != null) {
+ throw new IllegalStateException("Connection " + this + " has been poisoned", maybePoison);
+ }
+
+ if (queue.isEmpty()) {
+ // The queue is becoming non-empty, schedule a timer.
+ scheduleTimer(entry.getEnqueuedTicks() + context.config().getRequestTimeout() - now);
+ }
+ }
+
+ // To be called from ClientActorBehavior on ConnectedClientConnection after entries are replayed.
+ final void cancelDebt() {
+ queue.cancelDebt(currentTime());
+ }
+
public abstract Optional<T> getBackendInfo();
final Collection<ConnectionEntry> startReplay() {
@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();
}
abstract ClientActorBehavior<T> lockedReconnect(ClientActorBehavior<T> current,
RequestException runtimeRequestException);
- final long enqueueEntry(final ConnectionEntry entry, final long now) {
- lock.lock();
+ final void sendEntry(final ConnectionEntry entry, final long now) {
+ long delay = enqueueOrForward(entry, now);
try {
- final RequestException maybePoison = poisoned;
- if (maybePoison != null) {
- throw new IllegalStateException("Connection " + this + " has been poisoned", maybePoison);
- }
-
- if (queue.isEmpty()) {
- // The queue is becoming non-empty, schedule a timer.
- scheduleTimer(entry.getEnqueuedTicks() + REQUEST_TIMEOUT_NANOS - now);
+ 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);
+ }
}
- return queue.enqueue(entry, now);
- } finally {
- lock.unlock();
+ TimeUnit.NANOSECONDS.sleep(delay);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ LOG.debug("Interrupted after sleeping {}ns", e, currentTime() - now);
}
}
@GuardedBy("lock")
private void scheduleTimer(final long delay) {
if (haveTimer) {
- LOG.debug("{}: timer already scheduled", context.persistenceId());
+ LOG.debug("{}: timer already scheduled on {}", context.persistenceId(), this);
return;
}
if (queue.hasSuccessor()) {
- LOG.debug("{}: connection has successor, not scheduling timer", context.persistenceId());
+ 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 long normalized = delay <= 0 ? 0 : Math.min(delay, context.config().getBackendAlivenessTimerInterval());
final FiniteDuration dur = FiniteDuration.fromNanos(normalized);
- LOG.debug("{}: scheduling timeout in {}", context.persistenceId(), dur);
+ LOG.debug("{}: connection {} scheduling timeout in {}", context.persistenceId(), this, dur);
context.executeInActor(this::runTimer, dur);
haveTimer = true;
}
/**
* 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.
+ * in {@link #DEFAULT_NO_PROGRESS_TIMEOUT_NANOS} nanoseconds, it will be aborted.
*
* @param current Current behavior
* @return Next behavior to use
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) {
+ if (ticksSinceProgress >= context.config().getNoProgressTimeout()) {
LOG.error("Queue {} has not seen progress in {} seconds, failing all requests", this,
TimeUnit.NANOSECONDS.toSeconds(ticksSinceProgress));
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());
+ } else {
+ LOG.debug("{}: not scheduling timeout on {}", context.persistenceId(), this);
}
} finally {
lock.unlock();
@GuardedBy("lock")
private Optional<Long> lockedCheckTimeout(final long now) {
if (queue.isEmpty()) {
+ LOG.debug("{}: connection {} is empty", context.persistenceId(), this);
return Optional.empty();
}
final long backendSilentTicks = backendSilentTicks(now);
- if (backendSilentTicks >= BACKEND_ALIVE_TIMEOUT_NANOS) {
- LOG.debug("Connection {} has not seen activity from backend for {} nanoseconds, timing out", this,
- backendSilentTicks);
+ if (backendSilentTicks >= context.config().getBackendAlivenessTimerInterval()) {
+ LOG.debug("{}: Connection {} has not seen activity from backend for {} nanoseconds, timing out",
+ context.persistenceId(), this, backendSilentTicks);
return null;
}
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);
+ final long requestTimeout = context.config().getRequestTimeout();
+ if (beenOpen < requestTimeout) {
+ return Optional.of(requestTimeout - beenOpen);
}
tasksTimedOut++;
queue.remove(now);
- LOG.debug("Connection {} timed out entryt {}", this, head);
+ 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 " + beenOpen + "ns")));
+ new RequestTimeoutException("Timed out after " + time + "seconds")));
}
LOG.debug("Connection {} timed out {} tasks", this, tasksTimedOut);
return poisoned;
}
- final void receiveResponse(final ResponseEnvelope<?> envelope) {
+ void receiveResponse(final ResponseEnvelope<?> envelope) {
final long now = currentTime();
lastReceivedTicks = now;
Code Review / controller.git / blobdiff