+++ /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.controller.md.sal.dom.store.impl.tree;
-
-import java.lang.ref.Reference;
-import java.lang.ref.WeakReference;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantReadWriteLock;
-
-import javax.annotation.concurrent.GuardedBy;
-
-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.DataChangeListenerRegistration;
-import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
-import org.opendaylight.yangtools.concepts.Identifiable;
-import org.opendaylight.yangtools.yang.data.api.InstanceIdentifier;
-import org.opendaylight.yangtools.yang.data.api.InstanceIdentifier.PathArgument;
-import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
-
-/**
- * A set of listeners organized as a tree by node to which they listen. This class
- * allows for efficient lookup of listeners when we walk the DataTreeCandidate.
- */
-public final class ListenerTree {
- private static final Logger LOG = LoggerFactory.getLogger(ListenerTree.class);
- private final ReadWriteLock rwLock = new ReentrantReadWriteLock(true);
- private final Node rootNode = new Node(null, null);
-
- private ListenerTree() {
- // Private to disallow direct instantiation
- }
-
- /**
- * Create a new empty instance of the listener tree.
- *
- * @return An empty instance.
- */
- public static ListenerTree create() {
- return new ListenerTree();
- }
-
- /**
- * Registers listener on this node.
- *
- * @param path Full path on which listener is registered.
- * @param listener Listener
- * @param scope Scope of triggering event.
- * @return Listener registration
- */
- public <L extends AsyncDataChangeListener<InstanceIdentifier, NormalizedNode<?, ?>>> DataChangeListenerRegistration<L> registerDataChangeListener(final InstanceIdentifier path,
- final L listener, final DataChangeScope scope) {
-
- // Take the write lock
- rwLock.writeLock().lock();
-
- try {
- Node walkNode = rootNode;
- for (final PathArgument arg : path.getPath()) {
- walkNode = walkNode.ensureChild(arg);
- }
-
- final Node node = walkNode;
- DataChangeListenerRegistration<L> reg = new DataChangeListenerRegistrationImpl<L>(listener) {
- @Override
- public DataChangeScope getScope() {
- return scope;
- }
-
- @Override
- public InstanceIdentifier getPath() {
- return path;
- }
-
- @Override
- protected void removeRegistration() {
- /*
- * TODO: Here's an interesting problem. The way the datastore works, it
- * enqueues requests towards the listener, so the listener will be
- * notified at some point in the future. Now if the registration is
- * closed, we will prevent any new events from being delivered, but
- * we have no way to purge that queue.
- *
- * While this does not directly violate the ListenerRegistration
- * contract, it is probably not going to be liked by the users.
- */
-
- // Take the write lock
- ListenerTree.this.rwLock.writeLock().lock();
- try {
- node.removeListener(this);
- } finally {
- // Always release the lock
- ListenerTree.this.rwLock.writeLock().unlock();
- }
- }
- };
-
- node.addListener(reg);
- return reg;
- } finally {
- // Always release the lock
- rwLock.writeLock().unlock();
- }
- }
-
- /**
- * Obtain a tree walking context. This context ensures a consistent view of
- * the listener registrations. The context should be closed as soon as it
- * is not required, because each unclosed instance blocks modification of
- * the listener tree.
- *
- * @return A walker instance.
- */
- public Walker getWalker() {
- /*
- * TODO: The only current user of this method is local to the datastore.
- * Since this class represents a read-lock, losing a reference to
- * it is a _major_ problem, as the registration process will get
- * wedged, eventually grinding the system to a halt. Should an
- * external user exist, make the Walker a phantom reference, which
- * will cleanup the lock if not told to do so.
- */
- final Walker ret = new Walker(rwLock.readLock(), rootNode);
- rwLock.readLock().lock();
- return ret;
- }
-
- /**
- * A walking context, pretty much equivalent to an iterator, but it
- * exposes the undelying tree structure.
- */
- public static final class Walker implements AutoCloseable {
- private final Lock lock;
- private final Node node;
-
- @GuardedBy("this")
- private boolean valid = true;
-
- private Walker(final Lock lock, final Node node) {
- this.lock = Preconditions.checkNotNull(lock);
- this.node = Preconditions.checkNotNull(node);
- }
-
- public Node getRootNode() {
- return node;
- }
-
- @Override
- public synchronized void close() {
- if (valid) {
- lock.unlock();
- valid = false;
- }
- }
- }
-
- /**
- * This is a single node within the listener 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 Walker} instance through which it is reached remains
- * unclosed.
- */
- public static final class Node implements StoreTreeNode<Node>, Identifiable<PathArgument> {
- private final Collection<DataChangeListenerRegistration<?>> listeners = new ArrayList<>();
- private final Map<PathArgument, Node> children = new HashMap<>();
- private final PathArgument identifier;
- private final Reference<Node> parent;
-
- private Node(final Node parent, final PathArgument identifier) {
- this.parent = new WeakReference<>(parent);
- this.identifier = identifier;
- }
-
- @Override
- public PathArgument getIdentifier() {
- return identifier;
- }
-
- @Override
- public Optional<Node> getChild(final PathArgument child) {
- return Optional.fromNullable(children.get(child));
- }
-
- /**
- * Return the list of current listeners. This collection is guaranteed
- * to be immutable only while the walker, through which this node is
- * reachable remains unclosed.
- *
- * @return the list of current listeners
- */
- public Collection<DataChangeListenerRegistration<?>> getListeners() {
- return listeners;
- }
-
- private Node ensureChild(final PathArgument child) {
- Node potential = children.get(child);
- if (potential == null) {
- potential = new Node(this, child);
- children.put(child, potential);
- }
- return potential;
- }
-
- private void addListener(final DataChangeListenerRegistration<?> listener) {
- listeners.add(listener);
- LOG.debug("Listener {} registered", listener);
- }
-
- private void removeListener(final DataChangeListenerRegistrationImpl<?> listener) {
- listeners.remove(listener);
- LOG.debug("Listener {} unregistered", listener);
-
- // We have been called with the write-lock held, so we can perform some cleanup.
- removeThisIfUnused();
- }
-
- private void removeThisIfUnused() {
- final Node p = parent.get();
- if (p != null && listeners.isEmpty() && children.isEmpty()) {
- p.removeChild(identifier);
- }
- }
-
- private void removeChild(final PathArgument arg) {
- children.remove(arg);
- removeThisIfUnused();
- }
-
- @Override
- public String toString() {
- return "Node [identifier=" + identifier + ", listeners=" + listeners.size() + ", children=" + children.size() + "]";
- }
-
-
- }
-
- private abstract static class DataChangeListenerRegistrationImpl<T extends AsyncDataChangeListener<InstanceIdentifier, NormalizedNode<?, ?>>> extends AbstractListenerRegistration<T> //
- implements DataChangeListenerRegistration<T> {
- public DataChangeListenerRegistrationImpl(final T listener) {
- super(listener);
- }
- }
-}
Code Review / controller.git / blobdiff