BUG-509: make sure datastore commits are visible
[controller.git] / opendaylight / md-sal / sal-dom-broker / src / main / java / org / opendaylight / controller / md / sal / dom / store / impl / InMemoryDOMDataStore.java
index 39299ab1bdaefa1cea0626c60b7c7a697c46d9fd..2091913f24949106aae128e07083a4354b992b70 100644 (file)
@@ -11,15 +11,18 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 import static org.opendaylight.controller.md.sal.dom.store.impl.StoreUtils.increase;
 
+import java.util.Collections;
 import java.util.concurrent.Callable;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataBroker.DataChangeScope;
 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeListener;
 import org.opendaylight.controller.md.sal.dom.store.impl.tree.ListenerRegistrationNode;
+import org.opendaylight.controller.md.sal.dom.store.impl.tree.ListenerRegistrationNode.DataChangeListenerRegistration;
+import org.opendaylight.controller.md.sal.dom.store.impl.tree.ModificationType;
 import org.opendaylight.controller.md.sal.dom.store.impl.tree.NodeModification;
 import org.opendaylight.controller.md.sal.dom.store.impl.tree.StoreMetadataNode;
-import org.opendaylight.controller.md.sal.dom.store.impl.tree.TreeNodeUtils;
 import org.opendaylight.controller.sal.core.spi.data.DOMStore;
 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
@@ -37,6 +40,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import com.google.common.base.Optional;
+import com.google.common.base.Preconditions;
 import com.google.common.primitives.UnsignedLong;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
@@ -51,41 +55,39 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
     private final ListeningExecutorService executor;
     private final String name;
     private final AtomicLong txCounter = new AtomicLong(0);
-
-    private DataAndMetadataSnapshot snapshot;
-    private ModificationApplyOperation operationTree;
     private final ListenerRegistrationNode listenerTree;
+    private final AtomicReference<DataAndMetadataSnapshot> snapshot;
 
-
+    private ModificationApplyOperation operationTree;
 
     private SchemaContext schemaContext;
 
     public InMemoryDOMDataStore(final String name, final ListeningExecutorService executor) {
-        this.executor = executor;
-        this.name = name;
-        this.operationTree = new AllwaysFailOperation();
-        this.snapshot = DataAndMetadataSnapshot.createEmpty();
+        this.name = Preconditions.checkNotNull(name);
+        this.executor = Preconditions.checkNotNull(executor);
         this.listenerTree = ListenerRegistrationNode.createRoot();
+        this.snapshot = new AtomicReference<DataAndMetadataSnapshot>(DataAndMetadataSnapshot.createEmpty());
+        this.operationTree = new AlwaysFailOperation();
     }
 
     @Override
-    public String getIdentifier() {
+    public final String getIdentifier() {
         return name;
     }
 
     @Override
     public DOMStoreReadTransaction newReadOnlyTransaction() {
-        return new SnapshotBackedReadTransaction(nextIdentifier(), snapshot);
+        return new SnapshotBackedReadTransaction(nextIdentifier(), snapshot.get());
     }
 
     @Override
     public DOMStoreReadWriteTransaction newReadWriteTransaction() {
-        return new SnapshotBackedReadWriteTransaction(nextIdentifier(), snapshot, this, operationTree);
+        return new SnapshotBackedReadWriteTransaction(nextIdentifier(), snapshot.get(), this, operationTree);
     }
 
     @Override
     public DOMStoreWriteTransaction newWriteOnlyTransaction() {
-        return new SnaphostBackedWriteTransaction(nextIdentifier(), snapshot, this, operationTree);
+        return new SnaphostBackedWriteTransaction(nextIdentifier(), snapshot.get(), this, operationTree);
     }
 
     @Override
@@ -97,55 +99,72 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
     @Override
     public <L extends AsyncDataChangeListener<InstanceIdentifier, NormalizedNode<?, ?>>> ListenerRegistration<L> registerChangeListener(
             final InstanceIdentifier path, final L listener, final DataChangeScope scope) {
-
-        Optional<ListenerRegistrationNode> listenerNode = TreeNodeUtils.findNode(listenerTree, path);
-        checkState(listenerNode.isPresent());
-        synchronized (listener) {
-            notifyInitialState(path, listener);
+        LOG.debug("{}: Registering data change listener {} for {}",name,listener,path);
+        ListenerRegistrationNode listenerNode = listenerTree;
+        for(PathArgument arg : path.getPath()) {
+            listenerNode = listenerNode.ensureChild(arg);
         }
-        return listenerNode.get().registerDataChangeListener(listener, scope);
-    }
 
-    private void notifyInitialState(final InstanceIdentifier path,
-            final AsyncDataChangeListener<InstanceIdentifier, NormalizedNode<?, ?>> listener) {
-        Optional<StoreMetadataNode> currentState = snapshot.read(path);
-        try {
+        /*
+         * Make sure commit is not occurring right now. Listener has to be registered and its
+         * state capture enqueued at a consistent point.
+         *
+         * FIXME: improve this to read-write lock, such that multiple listener registrations
+         *        can occur simultaneously
+         */
+        final DataChangeListenerRegistration<L> reg;
+        synchronized (this) {
+            reg = listenerNode.registerDataChangeListener(path, listener, scope);
+
+            Optional<StoreMetadataNode> currentState = snapshot.get().read(path);
             if (currentState.isPresent()) {
-                NormalizedNode<?, ?> data = currentState.get().getData();
-                listener.onDataChanged(DOMImmutableDataChangeEvent.builder() //
+                final NormalizedNode<?, ?> data = currentState.get().getData();
+
+                final DOMImmutableDataChangeEvent event = DOMImmutableDataChangeEvent.builder() //
                         .setAfter(data) //
                         .addCreated(path, data) //
-                        .build() //
-                );
+                        .build();
+                executor.submit(new ChangeListenerNotifyTask(Collections.singletonList(reg), event));
             }
-        } catch (Exception e) {
-            LOG.error("Unhandled exception encountered when invoking listener {}", listener, e);
         }
 
+        return reg;
     }
 
     private synchronized DOMStoreThreePhaseCommitCohort submit(
-            final SnaphostBackedWriteTransaction snaphostBackedWriteTransaction) {
-        return new ThreePhaseCommitImpl(snaphostBackedWriteTransaction);
+            final SnaphostBackedWriteTransaction writeTx) {
+        LOG.debug("Tx: {} is submitted. Modifications: {}",writeTx.getIdentifier(),writeTx.getMutatedView());
+        return new ThreePhaseCommitImpl(writeTx);
     }
 
     private Object nextIdentifier() {
         return name + "-" + txCounter.getAndIncrement();
     }
 
-    private synchronized void commit(final DataAndMetadataSnapshot currentSnapshot,
+    private void commit(final DataAndMetadataSnapshot currentSnapshot,
             final StoreMetadataNode newDataTree, final Iterable<ChangeListenerNotifyTask> listenerTasks) {
         LOG.debug("Updating Store snaphot version: {} with version:{}",currentSnapshot.getMetadataTree().getSubtreeVersion(),newDataTree.getSubtreeVersion());
-        checkState(snapshot == currentSnapshot, "Store snapshot and transaction snapshot differs");
-        snapshot = DataAndMetadataSnapshot.builder() //
+
+        if(LOG.isTraceEnabled()) {
+            LOG.trace("Data Tree is {}",StoreUtils.toStringTree(newDataTree));
+        }
+
+        final DataAndMetadataSnapshot newSnapshot = DataAndMetadataSnapshot.builder() //
                 .setMetadataTree(newDataTree) //
                 .setSchemaContext(schemaContext) //
                 .build();
 
-        for(ChangeListenerNotifyTask task : listenerTasks) {
-            executor.submit(task);
-        }
+        /*
+         * The commit has to occur atomically with regard to listener registrations.
+         */
+        synchronized (this) {
+            final boolean success = snapshot.compareAndSet(currentSnapshot, newSnapshot);
+            checkState(success, "Store snapshot and transaction snapshot differ. This should never happen.");
 
+            for (ChangeListenerNotifyTask task : listenerTasks) {
+                executor.submit(task);
+            }
+        }
     }
 
     private static class SnapshotBackedReadTransaction implements DOMStoreReadTransaction {
@@ -156,6 +175,8 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
         public SnapshotBackedReadTransaction(final Object identifier, final DataAndMetadataSnapshot snapshot) {
             this.identifier = identifier;
             this.stableSnapshot = snapshot;
+            LOG.debug("ReadOnly Tx: {} allocated with snapshot {}",identifier,snapshot.getMetadataTree().getSubtreeVersion());
+
         }
 
         @Override
@@ -195,6 +216,7 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
             this.identifier = identifier;
             mutableTree = MutableDataTree.from(snapshot, applyOper);
             this.store = store;
+            LOG.debug("Write Tx: {} allocated with snapshot {}",identifier,snapshot.getMetadataTree().getSubtreeVersion());
         }
 
         @Override
@@ -283,7 +305,7 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
 
         @Override
         public ListenableFuture<Boolean> canCommit() {
-            final DataAndMetadataSnapshot snapshotCapture = snapshot;
+            final DataAndMetadataSnapshot snapshotCapture = snapshot.get();
             final ModificationApplyOperation snapshotOperation = operationTree;
 
             return executor.submit(new Callable<Boolean>() {
@@ -300,7 +322,10 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
 
         @Override
         public ListenableFuture<Void> preCommit() {
-            storeSnapshot = snapshot;
+            storeSnapshot = snapshot.get();
+            if(modification.getModificationType() == ModificationType.UNMODIFIED) {
+                return Futures.immediateFuture(null);
+            }
             return executor.submit(new Callable<Void>() {
 
 
@@ -312,7 +337,6 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
                     proposedSubtree = operationTree.apply(modification, Optional.of(metadataTree),
                             increase(metadataTree.getSubtreeVersion()));
 
-
                     listenerTasks = DataChangeEventResolver.create() //
                             .setRootPath(PUBLIC_ROOT_PATH) //
                             .setBeforeRoot(Optional.of(metadataTree)) //
@@ -335,8 +359,12 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
 
         @Override
         public ListenableFuture<Void> commit() {
-            checkState(proposedSubtree != null);
-            checkState(storeSnapshot != null);
+            if(modification.getModificationType() == ModificationType.UNMODIFIED) {
+                return Futures.immediateFuture(null);
+            }
+
+            checkState(proposedSubtree != null,"Proposed subtree must be computed");
+            checkState(storeSnapshot != null,"Proposed subtree must be computed");
             // return ImmediateFuture<>;
             InMemoryDOMDataStore.this.commit(storeSnapshot, proposedSubtree.get(),listenerTasks);
             return Futures.<Void> immediateFuture(null);
@@ -344,7 +372,7 @@ public class InMemoryDOMDataStore implements DOMStore, Identifiable<String>, Sch
 
     }
 
-    private class AllwaysFailOperation implements ModificationApplyOperation {
+    private static final class AlwaysFailOperation implements ModificationApplyOperation {
 
         @Override
         public Optional<StoreMetadataNode> apply(final NodeModification modification,