--- /dev/null
+/*
+ * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.yangtools.yang.data.impl.schema.tree;
+
+import com.google.common.base.Preconditions;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.TreeNode;
+import org.opendaylight.yangtools.yang.model.api.SchemaContext;
+
+/**
+ * Instances of this class hold the current state of a DataTree instance.
+ * The need for encapsulation stems from atomic updates, which potentially change
+ * multiple fields in one go.
+ */
+final class DataTreeState {
+ private final LatestOperationHolder holder;
+ private final SchemaContext schemaContext;
+ private final TreeNode root;
+
+ private DataTreeState(final TreeNode root) {
+ this.root = Preconditions.checkNotNull(root);
+ holder = new LatestOperationHolder();
+ schemaContext = null;
+ }
+
+ private DataTreeState(final TreeNode root, final LatestOperationHolder holder, final SchemaContext schemaContext) {
+ // It should be impossible to instantiate a new root without a SchemaContext
+ this.schemaContext = Preconditions.checkNotNull(schemaContext);
+ this.holder = Preconditions.checkNotNull(holder);
+ this.root = Preconditions.checkNotNull(root);
+ }
+
+ static DataTreeState createInitial(final TreeNode root) {
+ return new DataTreeState(root);
+ }
+
+ TreeNode getRoot() {
+ return root;
+ }
+
+ InMemoryDataTreeSnapshot newSnapshot() {
+ return new InMemoryDataTreeSnapshot(schemaContext, root, holder.newSnapshot());
+ }
+
+ DataTreeState withSchemaContext(final SchemaContext newSchemaContext, final SchemaAwareApplyOperation operation) {
+ holder.setCurrent(operation);
+ return new DataTreeState(root, holder, newSchemaContext);
+ }
+
+ DataTreeState withRoot(final TreeNode newRoot) {
+ return new DataTreeState(newRoot, holder, schemaContext);
+ }
+}
\ No newline at end of file
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
-import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.Collections;
+import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
* Read-only snapshot of the data tree.
*/
final class InMemoryDataTree implements DataTree {
+ private static final YangInstanceIdentifier PUBLIC_ROOT_PATH = YangInstanceIdentifier.create(Collections.<PathArgument>emptyList());
+ private static final AtomicReferenceFieldUpdater<InMemoryDataTree, DataTreeState> STATE_UPDATER =
+ AtomicReferenceFieldUpdater.newUpdater(InMemoryDataTree.class, DataTreeState.class, "state");
private static final Logger LOG = LoggerFactory.getLogger(InMemoryDataTree.class);
- private static final YangInstanceIdentifier PUBLIC_ROOT_PATH = YangInstanceIdentifier.builder().build();
- private final ReadWriteLock rwLock = new ReentrantReadWriteLock(true);
- private final LatestOperationHolder operationHolder = new LatestOperationHolder();
- private SchemaContext currentSchemaContext;
- private TreeNode rootNode;
+ /**
+ * Current data store state generation.
+ */
+ private volatile DataTreeState state;
public InMemoryDataTree(final TreeNode rootNode, final SchemaContext schemaContext) {
- this.rootNode = Preconditions.checkNotNull(rootNode);
-
+ state = DataTreeState.createInitial(rootNode);
if (schemaContext != null) {
- // Also sets applyOper
setSchemaContext(schemaContext);
}
}
+ /*
+ * This method is synchronized to guard against user attempting to install
+ * multiple contexts. Otherwise it runs in a lock-free manner.
+ */
@Override
- public void setSchemaContext(final SchemaContext newSchemaContext) {
+ public synchronized void setSchemaContext(final SchemaContext newSchemaContext) {
Preconditions.checkNotNull(newSchemaContext);
LOG.info("Attempting to install schema contexts");
- LOG.debug("Following schema contexts will be attempted {}",newSchemaContext);
-
- /*
- * FIXME: we should walk the schema contexts, both current and new and see
- * whether they are compatible here. Reject incompatible changes.
- */
-
- // Instantiate new apply operation, this still may fail
- final ModificationApplyOperation newApplyOper = SchemaAwareApplyOperation.from(newSchemaContext);
-
- // Ready to change the context now, make sure no operations are running
- rwLock.writeLock().lock();
- try {
- this.operationHolder.setCurrent(newApplyOper);
- this.currentSchemaContext = newSchemaContext;
- } finally {
- rwLock.writeLock().unlock();
- }
+ LOG.debug("Following schema contexts will be attempted {}", newSchemaContext);
+
+ final SchemaAwareApplyOperation operation = SchemaAwareApplyOperation.from(newSchemaContext);
+
+ DataTreeState currentState, newState;
+ do {
+ currentState = state;
+ newState = currentState.withSchemaContext(newSchemaContext, operation);
+ } while (!STATE_UPDATER.compareAndSet(this, currentState, newState));
}
@Override
public InMemoryDataTreeSnapshot takeSnapshot() {
- rwLock.readLock().lock();
- try {
- return new InMemoryDataTreeSnapshot(currentSchemaContext, rootNode, operationHolder.newSnapshot());
- } finally {
- rwLock.readLock().unlock();
- }
+ return state.newSnapshot();
}
@Override
Preconditions.checkArgument(modification instanceof InMemoryDataTreeModification, "Invalid modification class %s", modification.getClass());
final InMemoryDataTreeModification m = (InMemoryDataTreeModification)modification;
- rwLock.readLock().lock();
- try {
- m.getStrategy().checkApplicable(PUBLIC_ROOT_PATH, m.getRootModification(), Optional.<TreeNode>of(rootNode));
- } finally {
- rwLock.readLock().unlock();
- }
+ m.getStrategy().checkApplicable(PUBLIC_ROOT_PATH, m.getRootModification(), Optional.<TreeNode>of(state.getRoot()));
}
@Override
return new NoopDataTreeCandidate(PUBLIC_ROOT_PATH, root);
}
- rwLock.writeLock().lock();
- try {
- final Optional<TreeNode> newRoot = m.getStrategy().apply(m.getRootModification(),
- Optional.<TreeNode>of(rootNode), m.getVersion());
- Preconditions.checkState(newRoot.isPresent(), "Apply strategy failed to produce root node");
- return new InMemoryDataTreeCandidate(PUBLIC_ROOT_PATH, root, rootNode, newRoot.get());
- } finally {
- rwLock.writeLock().unlock();
- }
+ final TreeNode currentRoot = state.getRoot();
+ final Optional<TreeNode> newRoot = m.getStrategy().apply(m.getRootModification(),
+ Optional.<TreeNode>of(currentRoot), m.getVersion());
+ Preconditions.checkState(newRoot.isPresent(), "Apply strategy failed to produce root node");
+ return new InMemoryDataTreeCandidate(PUBLIC_ROOT_PATH, root, currentRoot, newRoot.get());
}
@Override
Preconditions.checkArgument(candidate instanceof InMemoryDataTreeCandidate, "Invalid candidate class %s", candidate.getClass());
final InMemoryDataTreeCandidate c = (InMemoryDataTreeCandidate)candidate;
- LOG.debug("Updating datastore from {} to {}", rootNode, c.getAfterRoot());
-
if (LOG.isTraceEnabled()) {
LOG.trace("Data Tree is {}", StoreUtils.toStringTree(c.getAfterRoot().getData()));
}
- // Ready to change the context now, make sure no operations are running
- rwLock.writeLock().lock();
- try {
- Preconditions.checkState(c.getBeforeRoot() == rootNode,
- "Store tree %s and candidate base %s differ.", rootNode, c.getBeforeRoot());
- this.rootNode = c.getAfterRoot();
- } finally {
- rwLock.writeLock().unlock();
- }
+ final TreeNode newRoot = c.getAfterRoot();
+ DataTreeState currentState, newState;
+ do {
+ currentState = state;
+ final TreeNode currentRoot = currentState.getRoot();
+ LOG.debug("Updating datastore from {} to {}", currentRoot, newRoot);
+
+ final TreeNode oldRoot = c.getBeforeRoot();
+ Preconditions.checkState(oldRoot == currentRoot, "Store tree %s and candidate base %s differ.", currentRoot, oldRoot);
+
+ newState = currentState.withRoot(newRoot);
+ LOG.trace("Updated state from {} to {}", currentState, newState);
+ } while (!STATE_UPDATER.compareAndSet(this, currentState, newState));
}
}