BUG-3516: make PingPongTransactionChain.close() asynchronous

[controller.git] / opendaylight / md-sal / sal-dom-broker / src / main / java / org / opendaylight / controller / md / sal / dom / broker / impl / PingPongTransactionChain.java

diff --git a/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/broker/impl/PingPongTransactionChain.java b/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/broker/impl/PingPongTransactionChain.java
index c3a56ed454024b3cb316c1e5bec9d7184c897edc..26b5685094f42e2fc484867a8ac44c8ecab9f5d7 100644 (file)
--- a/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/broker/impl/PingPongTransactionChain.java
+++ b/opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/broker/impl/PingPongTransactionChain.java
@@ -57,6 +57,8 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
 
     @GuardedBy("this")
     private boolean failed;
+    @GuardedBy("this")
+    private PingPongTransaction shutdownTx;
 
     /**
      * This updater is used to manipulate the "ready" transaction. We perform only atomic
@@ -124,6 +126,8 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
     }
 
     private synchronized PingPongTransaction slowAllocateTransaction() {
+        Preconditions.checkState(shutdownTx == null, "Transaction chain %s has been shut down", this);
+
         final DOMDataReadWriteTransaction delegateTx = delegate.newReadWriteTransaction();
         final PingPongTransaction newTx = new PingPongTransaction(delegateTx);
 
@@ -158,13 +162,16 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
 
     /*
      * This forces allocateTransaction() on a slow path, which has to happen after
-     * this method has completed executing.
+     * this method has completed executing. Also inflightTx may be updated outside
+     * the lock, hence we need to re-check.
      */
     @GuardedBy("this")
     private void processIfReady() {
-        final PingPongTransaction tx = READY_UPDATER.getAndSet(this, null);
-        if (tx != null) {
-            processTransaction(tx);
+        if (inflightTx == null) {
+            final PingPongTransaction tx = READY_UPDATER.getAndSet(this, null);
+            if (tx != null) {
+                processTransaction(tx);
+            }
         }
     }
 
@@ -175,7 +182,7 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
      * @param tx Transaction which needs processing.
      */
     @GuardedBy("this")
-    private void processTransaction(final @Nonnull PingPongTransaction tx) {
+    private void processTransaction(@Nonnull final PingPongTransaction tx) {
         if (failed) {
             LOG.debug("Cancelling transaction {}", tx);
             tx.getTransaction().cancel();
@@ -200,30 +207,37 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
         });
     }
 
-    private void transactionSuccessful(final PingPongTransaction tx, final Void result) {
-        LOG.debug("Transaction {} completed successfully", tx);
-
+    private void processNextTransaction(final PingPongTransaction tx) {
         final boolean success = INFLIGHT_UPDATER.compareAndSet(this, tx, null);
-        Preconditions.checkState(success, "Successful transaction %s while %s was submitted", tx, inflightTx);
+        Preconditions.checkState(success, "Completed transaction %s while %s was submitted", tx, inflightTx);
 
         synchronized (this) {
-            processIfReady();
+            final PingPongTransaction nextTx = READY_UPDATER.getAndSet(this, null);
+            if (nextTx != null) {
+                processTransaction(nextTx);
+            } else if (shutdownTx != null) {
+                processTransaction(shutdownTx);
+                delegate.close();
+                shutdownTx = null;
+            }
         }
+    }
+
+    private void transactionSuccessful(final PingPongTransaction tx, final Void result) {
+        LOG.debug("Transaction {} completed successfully", tx);
 
-        // Can run unsynchronized
         tx.onSuccess(result);
+        processNextTransaction(tx);
     }
 
     private void transactionFailed(final PingPongTransaction tx, final Throwable t) {
         LOG.debug("Transaction {} failed", tx, t);
 
-        final boolean success = INFLIGHT_UPDATER.compareAndSet(this, tx, null);
-        Preconditions.checkState(success, "Failed transaction %s while %s was submitted", tx, inflightTx);
-
         tx.onFailure(t);
+        processNextTransaction(tx);
     }
 
-    private void readyTransaction(final @Nonnull PingPongTransaction tx) {
+    private void readyTransaction(@Nonnull final PingPongTransaction tx) {
         // First mark the transaction as not locked.
         final boolean lockedMatch = LOCKED_UPDATER.compareAndSet(this, tx, null);
         Preconditions.checkState(lockedMatch, "Attempted to submit transaction %s while we have %s", tx, lockedTx);
@@ -235,7 +249,7 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
          */
         final boolean success = READY_UPDATER.compareAndSet(this, null, tx);
         Preconditions.checkState(success, "Transaction %s collided on ready state", tx, readyTx);
-        LOG.debug("Transaction {} readied");
+        LOG.debug("Transaction {} readied", tx);
 
         /*
          * We do not see a transaction being in-flight, so we need to take care of dispatching
@@ -251,12 +265,31 @@ public final class PingPongTransactionChain implements DOMTransactionChain {
     }
 
     @Override
-    public void close() {
+    public synchronized void close() {
         final PingPongTransaction notLocked = lockedTx;
         Preconditions.checkState(notLocked == null, "Attempted to close chain with outstanding transaction %s", notLocked);
 
-        synchronized (this) {
-            processIfReady();
+        // This is not reliable, but if we observe it to be null and the process has already completed,
+        // the backend transaction chain will throw the appropriate error.
+        Preconditions.checkState(shutdownTx == null, "Attempted to close an already-closed chain");
+
+        // Force allocations on slow path, picking up a potentially-outstanding transaction
+        final PingPongTransaction tx = READY_UPDATER.getAndSet(this, null);
+
+        if (tx != null) {
+            // We have one more transaction, which needs to be processed somewhere. If we do not
+            // a transaction in-flight, we need to push it down ourselves.
+            // If there is an in-flight transaction we will schedule this last one into a dedicated
+            // slot. Allocation slow path will check its presence and fail, the in-flight path will
+            // pick it up, submit and immediately close the chain.
+            if (inflightTx == null) {
+                processTransaction(tx);
+                delegate.close();
+            } else {
+                shutdownTx = tx;
+            }
+        } else {
+            // Nothing outstanding, we can safely shutdown
             delegate.close();
         }
     }