X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-distributed-datastore%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fdatabroker%2Factors%2Fdds%2FAbstractProxyTransaction.java;h=549cab269fb7682b4575c141243dda12b028d23f;hb=4ddfbaf460366ef4194e15c19649039a7d616399;hp=bf56376fcee3d538d483a063d652ae6d3d5a5654;hpb=7933189a19f5c0f58b91baea300a2f512aac154f;p=controller.git

diff --git a/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/AbstractProxyTransaction.java b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/AbstractProxyTransaction.java
index bf56376fce..549cab269f 100644
--- a/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/AbstractProxyTransaction.java
+++ b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/AbstractProxyTransaction.java
@@ -91,7 +91,10 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         }
     }
 
-    // Generic state base class. Direct instances are used for fast paths, sub-class is used for successor transitions
+    /**
+     * Base class for representing logical state of this proxy. See individual instantiations and {@link SuccessorState}
+     * for details.
+     */
     private static class State {
         private final String string;
 
@@ -105,14 +108,24 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         }
     }
 
-    // State class used when a successor has interfered. Contains coordinator latch, the successor and previous state
+    /**
+     * State class used when a successor has interfered. Contains coordinator latch, the successor and previous state.
+     * This is a temporary state introduced during reconnection process and is necessary for correct state hand-off
+     * between the old connection (potentially being accessed by the user) and the new connection (being cleaned up
+     * by the actor.
+     *
+     * <p>
+     * When a user operation encounters this state, it synchronizes on the it and wait until reconnection completes,
+     * at which point the request is routed to the successor transaction. This is a relatively heavy-weight solution
+     * to the problem of state transfer, but the user will observe it only if the race condition is hit.
+     */
     private static final class SuccessorState extends State {
         private final CountDownLatch latch = new CountDownLatch(1);
         private AbstractProxyTransaction successor;
         private State prevState;
 
         SuccessorState() {
-            super("successor");
+            super("SUCCESSOR");
         }
 
         // Synchronize with succession process and return the successor
@@ -135,7 +148,8 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         }
 
         void setPrevState(final State prevState) {
-            Verify.verify(this.prevState == null);
+            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);
         }
 
@@ -145,7 +159,8 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
         }
 
         void setSuccessor(final AbstractProxyTransaction successor) {
-            Verify.verify(this.successor == null);
+            Verify.verify(this.successor == null, "Attempted to set successor to %s when we already have %s",
+                    successor, this.successor);
             this.successor = Preconditions.checkNotNull(successor);
         }
     }
@@ -155,9 +170,41 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
             AtomicIntegerFieldUpdater.newUpdater(AbstractProxyTransaction.class, "sealed");
     private static final AtomicReferenceFieldUpdater<AbstractProxyTransaction, State> STATE_UPDATER =
             AtomicReferenceFieldUpdater.newUpdater(AbstractProxyTransaction.class, State.class, "state");
-    private static final State OPEN = new State("open");
-    private static final State SEALED = new State("sealed");
-    private static final State FLUSHED = new State("flushed");
+
+    /**
+     * Transaction has been open and is being actively worked on.
+     */
+    private static final State OPEN = new State("OPEN");
+
+    /**
+     * Transaction has been sealed by the user, but it has not completed flushing to the backed, yet. This is
+     * a transition state, as we are waiting for the user to initiate commit procedures.
+     *
+     * <p>
+     * Since the reconnect mechanics relies on state replay for transactions, this state needs to be flushed into the
+     * queue to re-create state in successor transaction (which may be based on different messages as locality may have
+     * changed). Hence the transition to {@link #FLUSHED} state needs to be handled in a thread-safe manner.
+     */
+    private static final State SEALED = new State("SEALED");
+
+    /**
+     * Transaction state has been flushed into the queue, i.e. it is visible by the successor and potentially
+     * the backend. At this point the transaction does not hold any state besides successful requests, all other state
+     * is held either in the connection's queue or the successor object.
+     *
+     * <p>
+     * Transition to this state indicates we have all input from the user we need to initiate the correct commit
+     * protocol.
+     */
+    private static final State FLUSHED = new State("FLUSHED");
+
+    /**
+     * Transaction state has been completely resolved, we have received confirmation of the transaction fate from
+     * the backend. The only remaining task left to do is finishing up the state cleanup, which is done via purge
+     * request. We need to hang on to the transaction until that is done, as we have to make sure backend completes
+     * purging its state -- otherwise we could have a leak on the backend.
+     */
+    private static final State DONE = new State("DONE");
 
     // Touched from client actor thread only
     private final Deque<Object> successfulRequests = new ArrayDeque<>();
@@ -543,9 +590,13 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
     }
 
     // Called with the connection locked
-    final void replayMessages(final AbstractProxyTransaction successor,
-            final Iterable<ConnectionEntry> enqueuedEntries) {
+    final void replayMessages(final ProxyHistory successorHistory, final Iterable<ConnectionEntry> enqueuedEntries) {
         final SuccessorState local = getSuccessorState();
+        final State prevState = local.getPrevState();
+
+        final AbstractProxyTransaction successor = successorHistory.createTransactionProxy(getIdentifier(),
+            isSnapshotOnly());
+        LOG.debug("{} created successor transaction proxy {}", this, successor);
         local.setSuccessor(successor);
 
         // Replay successful requests first
@@ -593,7 +644,6 @@ abstract class AbstractProxyTransaction implements Identifiable<TransactionIdent
          * reconnecting have been forced to slow paths, which will be unlocked once we unblock the state latch
          * at the end of this method.
          */
-        final State prevState = local.getPrevState();
         if (SEALED.equals(prevState)) {
             LOG.debug("Proxy {} reconnected while being sealed, propagating state to successor {}", this, successor);
             flushState(successor);