BUG-8704: rework seal mechanics to not wait during replay
[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / main / java / org / opendaylight / controller / cluster / databroker / actors / dds / AbstractProxyTransaction.java
index ac91f2d0413ad8aca71391ba86921c92dc1b008b..07b89e09230949da6c4849b3fb5dc03d4c3c36d8 100644 (file)
@@ -30,6 +30,7 @@ import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.NotThreadSafe;
 import org.opendaylight.controller.cluster.access.client.ConnectionEntry;
 import org.opendaylight.controller.cluster.access.commands.AbstractLocalTransactionRequest;
+import org.opendaylight.controller.cluster.access.commands.ClosedTransactionException;
 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
 import org.opendaylight.controller.cluster.access.commands.TransactionAbortRequest;
 import org.opendaylight.controller.cluster.access.commands.TransactionAbortSuccess;
@@ -147,13 +148,15 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         }
 
         State getPrevState() {
-            return prevState;
+            return Verify.verifyNotNull(prevState, "Attempted to access previous state, which was not set");
         }
 
         void setPrevState(final State prevState) {
             Verify.verify(this.prevState == null, "Attempted to set previous state to %s when we already have %s",
                     prevState, this.prevState);
             this.prevState = Preconditions.checkNotNull(prevState);
+            // We cannot have duplicate successor states, so this check is sufficient
+            this.done = DONE.equals(prevState);
         }
 
         // To be called from safe contexts, where successor is known to be completed
@@ -248,11 +251,18 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
      * variable. It uses pre-allocated objects for fast paths (i.e. no successor present) and a per-transition object
      * for slow paths (when successor is injected/present).
      */
-    private volatile int sealed = 0;
-    private volatile State state = OPEN;
+    private volatile int sealed;
+    private volatile State state;
 
-    AbstractProxyTransaction(final ProxyHistory parent) {
+    AbstractProxyTransaction(final ProxyHistory parent, final boolean isDone) {
         this.parent = Preconditions.checkNotNull(parent);
+        if (isDone) {
+            state = DONE;
+            // DONE implies previous seal operation completed
+            sealed = 1;
+        } else {
+            state = OPEN;
+        }
     }
 
     final void executeInActor(final Runnable command) {
@@ -317,36 +327,67 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
     }
 
     /**
-     * Seal this transaction before it is either committed or aborted.
+     * Seal this transaction before it is either committed or aborted. This method should only be invoked from
+     * application thread.
      */
     final void seal() {
         // Transition user-visible state first
-        final boolean success = SEALED_UPDATER.compareAndSet(this, 0, 1);
+        final boolean success = markSealed();
         Preconditions.checkState(success, "Proxy %s was already sealed", getIdentifier());
-        internalSeal();
+
+        if (!sealAndSend(Optional.absent())) {
+            sealSuccessor();
+        }
     }
 
-    final void ensureSealed() {
-        if (SEALED_UPDATER.compareAndSet(this, 0, 1)) {
-            internalSeal();
+    /**
+     * Internal seal propagation method, invoked when we have raced with reconnection thread. Note that there may have
+     * been multiple reconnects, so we have to make sure the action is propagate through all intermediate instances.
+     */
+    private void sealSuccessor() {
+        // Slow path: wait for the successor to complete
+        final AbstractProxyTransaction successor = awaitSuccessor();
+
+        // At this point the successor has completed transition and is possibly visible by the user thread, which is
+        // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
+        // Propagate state and seal the successor.
+        flushState(successor);
+        successor.predecessorSealed();
+    }
+
+    private void predecessorSealed() {
+        if (markSealed() && !sealAndSend(Optional.absent())) {
+            sealSuccessor();
         }
     }
 
-    private void internalSeal() {
-        doSeal();
+    void sealOnly() {
+        parent.onTransactionSealed(this);
+        final boolean success = STATE_UPDATER.compareAndSet(this, OPEN, SEALED);
+        Verify.verify(success, "Attempted to replay seal on {}", this);
+    }
+
+    /**
+     * Seal this transaction and potentially send it out towards the backend. If this method reports false, the caller
+     * needs to deal with propagating the seal operation towards the successor.
+     *
+     * @param enqueuedTicks Enqueue ticks when this is invoked from replay path.
+     * @return True if seal operation was successful, false if this proxy has a successor.
+     */
+    boolean sealAndSend(final Optional<Long> enqueuedTicks) {
         parent.onTransactionSealed(this);
 
-        // Now deal with state transfer, which can occur via successor or a follow-up canCommit() or directCommit().
-        if (!STATE_UPDATER.compareAndSet(this, OPEN, SEALED)) {
-            // Slow path: wait for the successor to complete
-            final AbstractProxyTransaction successor = awaitSuccessor();
+        // Transition internal state to sealed and detect presence of a successor
+        return STATE_UPDATER.compareAndSet(this, OPEN, SEALED);
+    }
 
-            // At this point the successor has completed transition and is possibly visible by the user thread, which is
-            // still stuck here. The successor has not seen final part of our state, nor the fact it is sealed.
-            // Propagate state and seal the successor.
-            flushState(successor);
-            successor.ensureSealed();
-        }
+    /**
+     * Mark this proxy as having been sealed.
+     *
+     * @return True if this call has transitioned to sealed state.
+     */
+    final boolean markSealed() {
+        return SEALED_UPDATER.compareAndSet(this, 0, 1);
     }
 
     private void checkNotSealed() {
@@ -454,7 +495,14 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
                     if (t instanceof TransactionCommitSuccess) {
                         ret.set(Boolean.TRUE);
                     } else if (t instanceof RequestFailure) {
-                        ret.setException(((RequestFailure<?, ?>) t).getCause().unwrap());
+                        final Throwable cause = ((RequestFailure<?, ?>) t).getCause().unwrap();
+                        if (cause instanceof ClosedTransactionException) {
+                            // This is okay, as it indicates the transaction has been completed. It can happen
+                            // when we lose connectivity with the backend after it has received the request.
+                            ret.set(Boolean.TRUE);
+                        } else {
+                            ret.setException(cause);
+                        }
                     } else {
                         ret.setException(new IllegalStateException("Unhandled response " + t.getClass()));
                     }
@@ -620,8 +668,8 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         final State prevState = local.getPrevState();
 
         final AbstractProxyTransaction successor = successorHistory.createTransactionProxy(getIdentifier(),
-            isSnapshotOnly());
-        LOG.debug("{} created successor transaction proxy {}", this, successor);
+            isSnapshotOnly(), local.isDone());
+        LOG.debug("{} created successor {}", this, successor);
         local.setSuccessor(successor);
 
         // Replay successful requests first
@@ -636,11 +684,11 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
             for (Object obj : successfulRequests) {
                 if (obj instanceof TransactionRequest) {
                     LOG.debug("Forwarding successful request {} to successor {}", obj, successor);
-                    successor.replayRequest((TransactionRequest<?>) obj, resp -> { }, now);
+                    successor.doReplayRequest((TransactionRequest<?>) obj, resp -> { }, now);
                 } else {
                     Verify.verify(obj instanceof IncrementSequence);
                     final IncrementSequence increment = (IncrementSequence) obj;
-                    successor.replayRequest(new IncrementTransactionSequenceRequest(getIdentifier(),
+                    successor.doReplayRequest(new IncrementTransactionSequenceRequest(getIdentifier(),
                         increment.getSequence(), localActor(), isSnapshotOnly(), increment.getDelta()), resp -> { },
                         now);
                     LOG.debug("Incrementing sequence {} to successor {}", obj, successor);
@@ -659,7 +707,7 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
             if (getIdentifier().equals(req.getTarget())) {
                 Verify.verify(req instanceof TransactionRequest, "Unhandled request %s", req);
                 LOG.debug("Replaying queued request {} to successor {}", req, successor);
-                successor.replayRequest((TransactionRequest<?>) req, e.getCallback(), e.getEnqueuedTicks());
+                successor.doReplayRequest((TransactionRequest<?>) req, e.getCallback(), e.getEnqueuedTicks());
                 it.remove();
             }
         }
@@ -672,7 +720,9 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         if (SEALED.equals(prevState)) {
             LOG.debug("Proxy {} reconnected while being sealed, propagating state to successor {}", this, successor);
             flushState(successor);
-            successor.ensureSealed();
+            if (successor.markSealed()) {
+                successor.sealAndSend(Optional.of(parent.currentTime()));
+            }
         }
     }
 
@@ -687,7 +737,7 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
      * @param callback Callback to be invoked once the request completes
      * @param enqueuedTicks ticker-based time stamp when the request was enqueued
      */
-    private void replayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+    private void doReplayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
             final long enqueuedTicks) {
         if (request instanceof AbstractLocalTransactionRequest) {
             handleReplayedLocalRequest((AbstractLocalTransactionRequest<?>) request, callback, enqueuedTicks);
@@ -727,6 +777,11 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         }
     }
 
+    final void replayRequest(final TransactionRequest<?> request, final Consumer<Response<?, ?>> callback,
+            final long enqueuedTicks) {
+        getSuccessorState().getSuccessor().doReplayRequest(request, callback, enqueuedTicks);
+    }
+
     abstract boolean isSnapshotOnly();
 
     abstract void doDelete(YangInstanceIdentifier path);
@@ -739,8 +794,6 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
 
     abstract CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> doRead(YangInstanceIdentifier path);
 
-    abstract void doSeal();
-
     @GuardedBy("this")
     abstract void flushState(AbstractProxyTransaction successor);