*/
package org.opendaylight.mdsal.dom.spi;
+import static java.util.Objects.requireNonNull;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.MoreObjects;
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.StampedLock;
import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.opendaylight.yangtools.concepts.AbstractRegistration;
+import org.opendaylight.yangtools.concepts.Identifiable;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifier;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
+import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeWithValue;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
/**
* An abstract tree of registrations. Allows a read-only snapshot to be taken.
* @param <T> Type of registered object
*/
public abstract class AbstractRegistrationTree<T> {
- private final RegistrationTreeNode<T> rootNode = new RegistrationTreeNode<>(null, null);
- private final Lock writeLock;
- private final Lock readLock;
+ /**
+ * This is a single node within the registration tree. Note that the data returned from and instance of this class
+ * is guaranteed to have any relevance or consistency only as long as the {@link Snapshot} instance through which it
+ * is reached remains unclosed.
+ *
+ * @param <T> registration type
+ */
+ protected static final class Node<T> implements Identifiable<PathArgument> {
+ private static final Logger LOG = LoggerFactory.getLogger(Node.class);
+
+ private final Map<PathArgument, Node<T>> children = new HashMap<>();
+ private final List<T> registrations = new ArrayList<>(2);
+ private final List<T> publicRegistrations = Collections.unmodifiableList(registrations);
+ private final Reference<Node<T>> parent;
+ private final PathArgument identifier;
+
+ Node(final Node<T> parent, final PathArgument identifier) {
+ this.parent = new WeakReference<>(parent);
+ this.identifier = identifier;
+ }
+
+ @Override
+ public PathArgument getIdentifier() {
+ return identifier;
+ }
+
+ /**
+ * Return the child matching a {@link PathArgument} specification.
+ *
+ * @param arg Child identifier
+ * @return Child matching exactly, or {@code null}.
+ */
+ public @Nullable Node<T> getExactChild(final @NonNull PathArgument arg) {
+ return children.get(requireNonNull(arg));
+ }
+
+ /**
+ * Return a collection children which match a {@link PathArgument} specification inexactly.
+ * This explicitly excludes the child returned by {@link #getExactChild(PathArgument)}.
+ *
+ * @param arg Child identifier
+ * @return Collection of children, guaranteed to be non-null.
+ */
+ public @NonNull Collection<Node<T>> getInexactChildren(final @NonNull PathArgument arg) {
+ requireNonNull(arg);
+ if (arg instanceof NodeWithValue || arg instanceof NodeIdentifierWithPredicates) {
+ /*
+ * TODO: This just all-or-nothing wildcards, which we have historically supported. Given
+ * that the argument is supposed to have all the elements filled out, we could support
+ * partial wildcards by iterating over the registrations and matching the maps for
+ * partial matches.
+ */
+ final var child = children.get(new NodeIdentifier(arg.getNodeType()));
+ return child == null ? List.of() : Collections.singletonList(child);
+ }
+
+ return List.of();
+ }
+
+ public Collection<T> getRegistrations() {
+ return publicRegistrations;
+ }
+
+ @VisibleForTesting
+ @NonNull Node<T> ensureChild(final @NonNull PathArgument child) {
+ return children.computeIfAbsent(requireNonNull(child), key -> new Node<>(this, key));
+ }
+
+ @VisibleForTesting
+ void addRegistration(final @NonNull T registration) {
+ registrations.add(requireNonNull(registration));
+ LOG.debug("Registration {} added", registration);
+ }
+
+ @VisibleForTesting
+ void removeRegistration(final @NonNull T registration) {
+ if (registrations.remove(requireNonNull(registration))) {
+ LOG.debug("Registration {} removed", registration);
+
+ // We have been called with the write-lock held, so we can perform some cleanup.
+ removeThisIfUnused();
+ }
+ }
+
+ private void removeThisIfUnused() {
+ final var p = parent.get();
+ if (p != null && registrations.isEmpty() && children.isEmpty()) {
+ p.removeChild(identifier);
+ }
+ }
+
+ private void removeChild(final PathArgument arg) {
+ children.remove(arg);
+ removeThisIfUnused();
+ }
+
+ @Override
+ public String toString() {
+ return MoreObjects.toStringHelper(this)
+ .add("identifier", identifier)
+ .add("registrations", registrations.size())
+ .add("children", children.size())
+ .toString();
+ }
+ }
+
+ /**
+ * A stable read-only snapshot of a {@link AbstractRegistrationTree}.
+ */
+ @NonNullByDefault
+ protected static final class Snapshot<T> extends AbstractRegistration {
+ private final Node<T> node;
+ private final Lock lock;
+
+ Snapshot(final Lock lock, final Node<T> node) {
+ this.lock = requireNonNull(lock);
+ this.node = requireNonNull(node);
+ }
+
+ public Node<T> getRootNode() {
+ return node;
+ }
+
+ @Override
+ protected void removeRegistration() {
+ lock.unlock();
+ }
+ }
+
+ private final @NonNull Node<T> rootNode = new Node<>(null, null);
+ private final @NonNull Lock writeLock;
+ private final @NonNull Lock readLock;
protected AbstractRegistrationTree() {
- final StampedLock lock = new StampedLock();
+ final var lock = new StampedLock();
readLock = lock.asReadLock();
writeLock = lock.asWriteLock();
}
* @param path Path to find a node for
* @return A registration node for the specified path
*/
- protected final @NonNull
RegistrationTreeNode<T> findNodeFor(final @NonNull Iterable<PathArgument> path) {
- RegistrationTreeNode<T> walkNode = rootNode;
- for (final PathArgument arg : path) {
+ protected final @NonNull Node<T> findNodeFor(final @NonNull Iterable<PathArgument> path) {
+ var walkNode = rootNode;
+ for (var arg : path) {
walkNode = walkNode.ensureChild(arg);
}
-
return walkNode;
}
* @param node Tree node
* @param registration Registration instance
*/
- protected final void addRegistration(final @NonNull RegistrationTreeNode<T> node, final @NonNull T registration) {
+ protected final void addRegistration(final @NonNull Node<T> node, final @NonNull T registration) {
node.addRegistration(registration);
}
* @param node Tree node
* @param registration Registration instance
*/
- protected final void removeRegistration(final @NonNull RegistrationTreeNode<T> node,
+ protected final void removeRegistration(final @NonNull Node<T> node,
final @NonNull T registration) {
// Take the write lock
writeLock.lock();
}
/**
- * Obtain a tree snapshot. This snapshot ensures a consistent view of
- * registrations. The snapshot should be closed as soon as it is not required,
- * because each unclosed instance blocks modification of this tree.
+ * Obtain a tree snapshot. This snapshot ensures a consistent view of registrations. The snapshot should be closed
+ * as soon as it is not required, because each unclosed instance blocks modification of this tree.
*
* @return A snapshot instance.
*/
- public final @NonNull RegistrationTreeSnapshot<T> takeSnapshot() {
+ protected final @NonNull Snapshot<T> takeSnapshot() {
readLock.lock();
- return new RegistrationTreeSnapshot<>(readLock, rootNode);
+ return new Snapshot<>(readLock, rootNode);
}
}
Code Review / mdsal.git / blobdiff