X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?p=controller.git;a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fcds-access-client%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Faccess%2Fclient%2FAbstractClientConnection.java;h=f190e14b61e01d4f2a48c78e1a6761fd84028e78;hp=0e9382dbba8a644c9317c8518ae05ed8c179b02f;hb=HEAD;hpb=32b322afd58f120a78208c939a01422aa224d0cf diff --git a/opendaylight/md-sal/cds-access-client/src/main/java/org/opendaylight/controller/cluster/access/client/AbstractClientConnection.java b/opendaylight/md-sal/cds-access-client/src/main/java/org/opendaylight/controller/cluster/access/client/AbstractClientConnection.java index 0e9382dbba..f34760ec03 100644 --- a/opendaylight/md-sal/cds-access-client/src/main/java/org/opendaylight/controller/cluster/access/client/AbstractClientConnection.java +++ b/opendaylight/md-sal/cds-access-client/src/main/java/org/opendaylight/controller/cluster/access/client/AbstractClientConnection.java @@ -7,23 +7,30 @@ */ package org.opendaylight.controller.cluster.access.client; +import static java.util.Objects.requireNonNull; + import akka.actor.ActorRef; import com.google.common.annotations.VisibleForTesting; -import com.google.common.base.Preconditions; -import com.google.common.base.Verify; +import com.google.common.base.MoreObjects; +import com.google.common.base.MoreObjects.ToStringHelper; import edu.umd.cs.findbugs.annotations.SuppressFBWarnings; -import java.util.ArrayDeque; +import java.util.Collection; +import java.util.List; import java.util.Optional; -import java.util.Queue; +import java.util.OptionalLong; 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.checkerframework.checker.lock.qual.GuardedBy; +import org.checkerframework.checker.lock.qual.Holding; +import org.eclipse.jdt.annotation.NonNull; import org.opendaylight.controller.cluster.access.concepts.Request; 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; @@ -31,119 +38,249 @@ import scala.concurrent.duration.FiniteDuration; /** * Base class for a connection to the backend. Responsible to queueing and dispatch of requests toward the backend. * Can be in three conceptual states: Connecting, Connected and Reconnecting, which are represented by public final - * classes exposed from this package. + * classes exposed from this package. This class NOT thread-safe, not are its subclasses expected to be thread-safe. * * @author Robert Varga */ -@NotThreadSafe public abstract class AbstractClientConnection { private static final Logger LOG = LoggerFactory.getLogger(AbstractClientConnection.class); - // Keep these constants in nanoseconds, as that prevents unnecessary conversions in the fast path - @VisibleForTesting - static final long NO_PROGRESS_TIMEOUT_NANOS = TimeUnit.MINUTES.toNanos(15); - @VisibleForTesting - static final long REQUEST_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30); + /* + * 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 attempt to reconnect + * it. + */ + 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. + */ + 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. + */ + 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 Queue pending; - private final ClientActorContext context; - private final Long cookie; + private final Lock lock = new ReentrantLock(); + private final @NonNull ClientActorContext context; + private final @NonNull Long cookie; + private final String backendName; + @GuardedBy("lock") + private final TransmitQueue queue; + + @GuardedBy("lock") + private boolean haveTimer; + + /** + * Time reference when we saw any activity from the backend. + */ + private long lastReceivedTicks; - private volatile ReconnectForwarder successor; private volatile RequestException poisoned; - private long lastProgress; - private AbstractClientConnection(final ClientActorContext context, final Long cookie, - final Queue pending) { - this.context = Preconditions.checkNotNull(context); - this.cookie = Preconditions.checkNotNull(cookie); - this.pending = Preconditions.checkNotNull(pending); - this.lastProgress = readTime(); + // Private constructor to avoid code duplication. + private AbstractClientConnection(final AbstractClientConnection oldConn, final TransmitQueue newQueue, + final String backendName) { + context = oldConn.context; + cookie = oldConn.cookie; + this.backendName = requireNonNull(backendName); + queue = requireNonNull(newQueue); + // Will be updated in finishReplay if needed. + 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 String backendName, + final int queueDepth) { + this.context = requireNonNull(context); + this.cookie = requireNonNull(cookie); + this.backendName = requireNonNull(backendName); + queue = new TransmitQueue.Halted(queueDepth); + lastReceivedTicks = currentTime(); } + // This constructor is only to be called (indirectly) by ReconnectingClientConnection constructor. // Do not allow subclassing outside of this package - AbstractClientConnection(final ClientActorContext context, final Long cookie) { - this(context, cookie, new ArrayDeque<>(1)); + AbstractClientConnection(final AbstractClientConnection oldConn) { + this(oldConn, new TransmitQueue.Halted(oldConn.queue, oldConn.currentTime()), oldConn.backendName); } + // This constructor is only to be called (indirectly) by ConnectedClientConnection constructor. // Do not allow subclassing outside of this package - AbstractClientConnection(final AbstractClientConnection oldConnection) { - this(oldConnection.context, oldConnection.cookie, oldConnection.pending); + AbstractClientConnection(final AbstractClientConnection oldConn, final T newBackend, + final int queueDepth) { + this(oldConn, new TransmitQueue.Transmitting(oldConn.queue, queueDepth, newBackend, oldConn.currentTime(), + requireNonNull(oldConn.context).messageSlicer()), newBackend.getName()); } - public final ClientActorContext context() { + public final @NonNull ClientActorContext context() { return context; } - public final @Nonnull Long cookie() { + public final @NonNull Long cookie() { return cookie; } - public final ActorRef localActor() { + public final @NonNull ActorRef localActor() { return context.self(); } - final long readTime() { + public final long currentTime() { return context.ticker().read(); } - final Queue 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. + * + *

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> callback) { + final long now = currentTime(); + sendEntry(new ConnectionEntry(request, callback, now), now); } /** * Send a request to the backend and invoke a specified callback when it finishes. This method is safe to invoke * from any thread. * + *

+ * Note that unlike {@link #sendRequest(Request, Consumer)}, this method does not exert backpressure, hence it + * should never be called from an application thread and serves mostly for moving requests between queues. + * * @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> callback) { - Preconditions.checkState(poisoned == null, "Connection %s has been poisoned", this); + public final void enqueueRequest(final Request request, final Consumer> 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; + 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(); } + } - enqueueEntry(entry); + @Holding("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); + } - 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() + context.config().getRequestTimeout() - now); } } - 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); + // To be called from ClientActorBehavior on ConnectedClientConnection after entries are replayed. + final void cancelDebt() { + queue.cancelDebt(currentTime()); } public abstract Optional getBackendInfo(); - @GuardedBy("this") - void spliceToSuccessor(final ReconnectForwarder successor) { - ConnectionEntry entry = pending.poll(); - while (entry != null) { - successor.forwardEntry(entry); - entry = pending.poll(); - } + final Collection startReplay() { + lock.lock(); + return queue.drain(); + } + + @Holding("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(); } - final ConnectionEntry dequeEntry() { - lastProgress = readTime(); - return pending.poll(); + @Holding("lock") + final void setForwarder(final ReconnectForwarder forwarder) { + queue.setForwarder(forwarder, currentTime()); } - void enqueueEntry(final ConnectionEntry entry) { - pending.add(entry); + @Holding("lock") + abstract ClientActorBehavior lockedReconnect(ClientActorBehavior current, + RequestException runtimeRequestException); + + final void sendEntry(final ConnectionEntry entry, final long now) { + long delay = enqueueOrForward(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", currentTime() - now, e); + } + } + + final ClientActorBehavior reconnect(final ClientActorBehavior current, final RequestException cause) { + lock.lock(); + try { + return lockedReconnect(current, cause); + } finally { + lock.unlock(); + } } /** @@ -151,53 +288,96 @@ public abstract class AbstractClientConnection { * * @param delay Delay, in nanoseconds */ - private void scheduleTimer(final FiniteDuration delay) { - LOG.debug("{}: scheduling timeout in {}", context.persistenceId(), delay); - context.executeInActor(this::runTimer, delay); + @Holding("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, context.config().getBackendAlivenessTimerInterval()); + + final FiniteDuration dur = FiniteDuration.fromNanos(normalized); + 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 */ @VisibleForTesting final ClientActorBehavior runTimer(final ClientActorBehavior current) { - final long now = readTime(); + lock.lock(); + + final List poisonEntries; + final NoProgressException poisonCause; + 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 < context.config().getNoProgressTimeout()) { + // 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 OptionalLong 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.orElseThrow()); + } else { + LOG.debug("{}: not scheduling timeout on {}", context.persistenceId(), this); + } - if (!isEmpty()) { - final long ticksSinceProgress = now - lastProgress; - 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)); - 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 delay = checkTimeout(now); - if (delay == null) { - // We have timed out. There is no point in scheduling a timer - return reconnectConnection(current); - } - if (delay.isPresent()) { - // If there is new delay, schedule a timer - scheduleTimer(delay.get()); + LOG.error("Queue {} has not seen progress in {} seconds, failing all requests", this, + TimeUnit.NANOSECONDS.toSeconds(ticksSinceProgress)); + poisonCause = new NoProgressException(ticksSinceProgress); + poisonEntries = lockedPoison(poisonCause); + current.removeConnection(this); + } finally { + lock.unlock(); } + poison(poisonEntries, poisonCause); return current; } - boolean isEmpty() { - return pending.isEmpty(); + @VisibleForTesting + final OptionalLong checkTimeout(final long now) { + lock.lock(); + try { + return lockedCheckTimeout(now); + } finally { + lock.unlock(); + } + } + + long backendSilentTicks(final long now) { + return now - lastReceivedTicks; } /* @@ -208,44 +388,87 @@ public abstract class AbstractClientConnection { */ @SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL", justification = "Returning null Optional is documented in the API contract.") - final Optional checkTimeout(final ConnectionEntry head, final long now) { - if (head == null) { - return Optional.empty(); + @GuardedBy("lock") + private OptionalLong lockedCheckTimeout(final long now) { + if (queue.isEmpty()) { + LOG.debug("{}: connection {} is empty", context.persistenceId(), this); + return OptionalLong.empty(); } - final long delay = head.getEnqueuedTicks() - now + REQUEST_TIMEOUT_NANOS; - if (delay <= 0) { - LOG.debug("Connection {} timed out", this); + final long backendSilentTicks = backendSilentTicks(now); + if (backendSilentTicks >= context.config().getBackendAlivenessTimerInterval()) { + LOG.debug("{}: Connection {} has not seen activity from backend for {} nanoseconds, timing out", + context.persistenceId(), this, backendSilentTicks); return null; } - return Optional.of(FiniteDuration.apply(delay, TimeUnit.NANOSECONDS)); + int tasksTimedOut = 0; + for (ConnectionEntry head = queue.peek(); head != null; head = queue.peek()) { + final long beenOpen = now - head.getEnqueuedTicks(); + final long requestTimeout = context.config().getRequestTimeout(); + if (beenOpen < requestTimeout) { + return OptionalLong.of(requestTimeout - beenOpen); + } + + tasksTimedOut++; + queue.remove(now); + LOG.debug("{}: Connection {} timed out entry {}", context.persistenceId(), this, head); + + timeoutEntry(head, beenOpen); + } + + LOG.debug("Connection {} timed out {} tasks", this, tasksTimedOut); + if (tasksTimedOut != 0) { + queue.tryTransmit(now); + } + + return OptionalLong.empty(); } - /* - * 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 checkTimeout(final long now) { - return checkTimeout(pending.peek(), now); + private void timeoutEntry(final ConnectionEntry entry, final long beenOpen) { + // Timeouts needs to be re-scheduled on actor thread because we are holding the lock on the current queue, + // which may be the tail of a successor chain. This is a problem if the callback attempts to send a request + // because that will attempt to lock the chain from the start, potentially causing a deadlock if there is + // a concurrent attempt to transmit. + context.executeInActor(current -> { + final double time = beenOpen * 1.0 / 1_000_000_000; + entry.complete(entry.getRequest().toRequestFailure( + new RequestTimeoutException(entry.getRequest() + " timed out after " + time + + " seconds. The backend for " + backendName + " is not available."))); + return current; + }); } - static void poisonQueue(final Queue queue, final RequestException cause) { - for (ConnectionEntry e : queue) { + final void poison(final RequestException cause) { + final List entries; + + lock.lock(); + try { + entries = lockedPoison(cause); + } finally { + lock.unlock(); + } + + poison(entries, cause); + } + + // Do not hold any locks while calling this + private static void poison(final Collection entries, final RequestException cause) { + for (ConnectionEntry e : entries) { final Request request = e.getRequest(); LOG.trace("Poisoning request {}", request, cause); e.complete(request.toRequestFailure(cause)); } - queue.clear(); } - void poison(final RequestException cause) { - poisoned = cause; - poisonQueue(pending, cause); + @Holding("lock") + private List lockedPoison(final RequestException cause) { + poisoned = enrichPoison(cause); + return queue.poison(); + } + + RequestException enrichPoison(final RequestException ex) { + return ex; } @VisibleForTesting @@ -253,7 +476,31 @@ public abstract class AbstractClientConnection { return poisoned; } - abstract ClientActorBehavior reconnectConnection(ClientActorBehavior current); + void receiveResponse(final ResponseEnvelope envelope) { + final long now = currentTime(); + lastReceivedTicks = now; - abstract void receiveResponse(final ResponseEnvelope envelope); + final Optional maybeEntry; + lock.lock(); + try { + maybeEntry = queue.complete(envelope, now); + } finally { + lock.unlock(); + } + + if (maybeEntry.isPresent()) { + final TransmittedConnectionEntry entry = maybeEntry.orElseThrow(); + 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); + } }