opendaylight/md-sal/cds-access-client/src/main/java/org/opendaylight/controller/cluster/access/client/AbstractClientConnection.java

   1 /*
   2  * Copyright (c) 2016 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.access.client;
   9
  10 import akka.actor.ActorRef;
  11 import com.google.common.annotations.VisibleForTesting;
  12 import com.google.common.base.Preconditions;
  13 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  14 import java.util.Optional;
  15 import java.util.concurrent.TimeUnit;
  16 import java.util.concurrent.locks.Lock;
  17 import java.util.concurrent.locks.ReentrantLock;
  18 import java.util.function.Consumer;
  19 import javax.annotation.Nonnull;
  20 import javax.annotation.concurrent.GuardedBy;
  21 import javax.annotation.concurrent.NotThreadSafe;
  22 import org.opendaylight.controller.cluster.access.concepts.Request;
  23 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  24 import org.opendaylight.controller.cluster.access.concepts.Response;
  25 import org.opendaylight.controller.cluster.access.concepts.ResponseEnvelope;
  26 import org.slf4j.Logger;
  27 import org.slf4j.LoggerFactory;
  28 import scala.concurrent.duration.FiniteDuration;
  29
  30 /**
  31  * Base class for a connection to the backend. Responsible to queueing and dispatch of requests toward the backend.
  32  * Can be in three conceptual states: Connecting, Connected and Reconnecting, which are represented by public final
  33  * classes exposed from this package.
  34  *
  35  * @author Robert Varga
  36  */
  37 @NotThreadSafe
  38 public abstract class AbstractClientConnection<T extends BackendInfo> {
  39     private static final Logger LOG = LoggerFactory.getLogger(AbstractClientConnection.class);
  40
  41     // Keep these constants in nanoseconds, as that prevents unnecessary conversions in the fast path
  42     @VisibleForTesting
  43     static final long NO_PROGRESS_TIMEOUT_NANOS = TimeUnit.MINUTES.toNanos(15);
  44     @VisibleForTesting
  45     static final long REQUEST_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(30);
  46
  47     private final Lock lock = new ReentrantLock();
  48     private final ClientActorContext context;
  49     @GuardedBy("lock")
  50     private final TransmitQueue queue;
  51     private final Long cookie;
  52
  53     // Updated from actor thread only
  54     private long lastProgress;
  55
  56     private volatile RequestException poisoned;
  57
  58     // Do not allow subclassing outside of this package
  59     AbstractClientConnection(final ClientActorContext context, final Long cookie,
  60             final TransmitQueue queue) {
  61         this.context = Preconditions.checkNotNull(context);
  62         this.cookie = Preconditions.checkNotNull(cookie);
  63         this.queue = Preconditions.checkNotNull(queue);
  64         this.lastProgress = readTime();
  65     }
  66
  67     // Do not allow subclassing outside of this package
  68     AbstractClientConnection(final AbstractClientConnection<T> oldConnection) {
  69         this.context = oldConnection.context;
  70         this.cookie = oldConnection.cookie;
  71         this.lastProgress = oldConnection.lastProgress;
  72         this.queue = new TransmitQueue.Halted();
  73     }
  74
  75     public final ClientActorContext context() {
  76         return context;
  77     }
  78
  79     public final @Nonnull Long cookie() {
  80         return cookie;
  81     }
  82
  83     public final ActorRef localActor() {
  84         return context.self();
  85     }
  86
  87     /**
  88      * Send a request to the backend and invoke a specified callback when it finishes. This method is safe to invoke
  89      * from any thread.
  90      *
  91      * @param request Request to send
  92      * @param callback Callback to invoke
  93      */
  94     public final void sendRequest(final Request<?, ?> request, final Consumer<Response<?, ?>> callback) {
  95         final RequestException maybePoison = poisoned;
  96         if (maybePoison != null) {
  97             throw new IllegalStateException("Connection " + this + " has been poisoned", maybePoison);
  98         }
  99
 100         final ConnectionEntry entry = new ConnectionEntry(request, callback, readTime());
 101
 102         lock.lock();
 103         try {
 104             queue.enqueue(entry, entry.getEnqueuedTicks());
 105         } finally {
 106             lock.unlock();
 107         }
 108     }
 109
 110     public abstract Optional<T> getBackendInfo();
 111
 112     final Iterable<ConnectionEntry> startReplay() {
 113         lock.lock();
 114         return queue.asIterable();
 115     }
 116
 117     @GuardedBy("lock")
 118     final void finishReplay(final ReconnectForwarder forwarder) {
 119         queue.setForwarder(forwarder, readTime());
 120         lock.unlock();
 121     }
 122
 123     @GuardedBy("lock")
 124     final void setForwarder(final ReconnectForwarder forwarder) {
 125         queue.setForwarder(forwarder, readTime());
 126     }
 127
 128     @GuardedBy("lock")
 129     abstract ClientActorBehavior<T> reconnectConnection(ClientActorBehavior<T> current);
 130
 131     private long readTime() {
 132         return context.ticker().read();
 133     }
 134
 135     final void enqueueEntry(final ConnectionEntry entry, final long now) {
 136         lock.lock();
 137         try {
 138             queue.enqueue(entry, now);
 139         } finally {
 140             lock.unlock();
 141         }
 142     }
 143
 144     /**
 145      * Schedule a timer to fire on the actor thread after a delay.
 146      *
 147      * @param delay Delay, in nanoseconds
 148      */
 149     private void scheduleTimer(final FiniteDuration delay) {
 150         LOG.debug("{}: scheduling timeout in {}", context.persistenceId(), delay);
 151         context.executeInActor(this::runTimer, delay);
 152     }
 153
 154     /**
 155      * Check this queue for timeout and initiate reconnection if that happened. If the queue has not made progress
 156      * in {@link #NO_PROGRESS_TIMEOUT_NANOS} nanoseconds, it will be aborted.
 157      *
 158      * @param current Current behavior
 159      * @return Next behavior to use
 160      */
 161     @VisibleForTesting
 162     final ClientActorBehavior<T> runTimer(final ClientActorBehavior<T> current) {
 163         final Optional<FiniteDuration> delay;
 164
 165         lock.lock();
 166         try {
 167             final long now = readTime();
 168             if (!queue.isEmpty()) {
 169                 final long ticksSinceProgress = now - lastProgress;
 170                 if (ticksSinceProgress >= NO_PROGRESS_TIMEOUT_NANOS) {
 171                     LOG.error("Queue {} has not seen progress in {} seconds, failing all requests", this,
 172                         TimeUnit.NANOSECONDS.toSeconds(ticksSinceProgress));
 173
 174                     lockedPoison(new NoProgressException(ticksSinceProgress));
 175                     current.removeConnection(this);
 176                     return current;
 177                 }
 178             }
 179
 180             // Requests are always scheduled in sequence, hence checking for timeout is relatively straightforward.
 181             // Note we use also inquire about the delay, so we can re-schedule if needed, hence the unusual tri-state
 182             // return convention.
 183             delay = lockedCheckTimeout(now);
 184             if (delay == null) {
 185                 // We have timed out. There is no point in scheduling a timer
 186                 return reconnectConnection(current);
 187             }
 188         } finally {
 189             lock.unlock();
 190         }
 191
 192         if (delay.isPresent()) {
 193             // If there is new delay, schedule a timer
 194             scheduleTimer(delay.get());
 195         }
 196
 197         return current;
 198     }
 199
 200     @VisibleForTesting
 201     final Optional<FiniteDuration> checkTimeout(final long now) {
 202         lock.lock();
 203         try {
 204             return lockedCheckTimeout(now);
 205         } finally {
 206             lock.unlock();
 207         }
 208     }
 209
 210     /*
 211      * We are using tri-state return here to indicate one of three conditions:
 212      * - if there is no timeout to schedule, return Optional.empty()
 213      * - if there is a timeout to schedule, return a non-empty optional
 214      * - if this connections has timed out, return null
 215      */
 216     @SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
 217             justification = "Returning null Optional is documented in the API contract.")
 218     @GuardedBy("lock")
 219     private Optional<FiniteDuration> lockedCheckTimeout(final long now) {
 220         final ConnectionEntry head = queue.peek();
 221         if (head == null) {
 222             return Optional.empty();
 223         }
 224
 225         final long delay = head.getEnqueuedTicks() - now + REQUEST_TIMEOUT_NANOS;
 226         if (delay <= 0) {
 227             LOG.debug("Connection {} timed out", this);
 228             return null;
 229         }
 230
 231         return Optional.of(FiniteDuration.apply(delay, TimeUnit.NANOSECONDS));
 232     }
 233
 234     final void poison(final RequestException cause) {
 235         lock.lock();
 236         try {
 237             lockedPoison(cause);
 238         } finally {
 239             lock.unlock();
 240         }
 241     }
 242
 243     @GuardedBy("lock")
 244     private void lockedPoison(final RequestException cause) {
 245         poisoned = cause;
 246         queue.poison(cause);
 247     }
 248
 249     @VisibleForTesting
 250     final RequestException poisoned() {
 251         return poisoned;
 252     }
 253
 254     final void receiveResponse(final ResponseEnvelope<?> envelope) {
 255         final long now = readTime();
 256
 257         final Optional<TransmittedConnectionEntry> maybeEntry;
 258         lock.lock();
 259         try {
 260             maybeEntry = queue.complete(envelope, now);
 261         } finally {
 262             lock.unlock();
 263         }
 264
 265         if (maybeEntry.isPresent()) {
 266             final TransmittedConnectionEntry entry = maybeEntry.get();
 267             LOG.debug("Completing {} with {}", entry, envelope);
 268             entry.complete(envelope.getMessage());
 269         }
 270
 271         lastProgress = readTime();
 272     }
 273 }