/*
* ModeShape (http://www.modeshape.org)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.modeshape.jcr;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.jcr.InvalidItemStateException;
import javax.jcr.ItemNotFoundException;
import javax.jcr.NodeIterator;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import org.modeshape.jcr.cache.CachedNode;
import org.modeshape.jcr.cache.NodeKey;
import org.modeshape.jcr.cache.SessionCache;
import org.modeshape.jcr.value.Path;
/**
* A class that manages for a single {@link JcrSession} the various sets of shared nodes for each of the shareable nodes. Some
* terminology:
* <ul>
* <li><i>shareable node</i> - A node that has the <code>mix:shareable</code> mixin, and which is capable of being shared.</li>
* <li><i>shared node</i> - The result of sharing a shareable node. Each shared node has its own name and location.</li>
* </ul>
* <p>
* The set of Node instances that represent the shared nodes for a given shareable node could be stored in the AbstractJcrNode
* instance that is the shareable node. However, since the "mix:shareable" can be added or removed at any time, we can't create a
* subclass of AbstractJcrNode to store this information, and we also don't want to store a null reference in <i>every</i>
* AbstractJcrNode instance.
* </p>
* <p>
* Therefore, this class is created lazily within the {@link JcrSession} and is used to maintain the Node instances for each of
* the shared nodes for each shareable node. This cache is required so that clients always get the same Node instance.
* </p>
*/
final class JcrSharedNodeCache {
private final ConcurrentMap<NodeKey, SharedSet> sharedSets = new ConcurrentHashMap<NodeKey, SharedSet>();
protected final JcrSession session;
JcrSharedNodeCache( JcrSession session ) {
this.session = session;
}
public JcrSession session() {
return session;
}
/**
* Get the {@link SharedSet} for the given shareable node.
*
* @param shareableNode the shareable node
* @return the SharedSet; never null
*/
public SharedSet getSharedSet( AbstractJcrNode shareableNode ) {
NodeKey shareableNodeKey = shareableNode.key();
SharedSet sharedSet = sharedSets.get(shareableNodeKey);
if (sharedSet == null) {
SharedSet newSharedSet = new SharedSet(shareableNode);
sharedSet = sharedSets.putIfAbsent(shareableNodeKey, newSharedSet);
if (sharedSet == null) sharedSet = newSharedSet;
}
return sharedSet;
}
/**
* Signal that the supplied shareable node was destroyed. This method will remove the corresponding {@link SharedSet}.
*
* @param shareableNodeKey the key shareable node that was destroyed
*/
public void destroyed( NodeKey shareableNodeKey ) {
sharedSets.remove(shareableNodeKey);
}
/**
* Signal that the supplied node was removed from it's parent. This method will adjust the corresponding {@link SharedSet}
* even if the removed node was the original shareable node.
*
* @param shareableNode the shareable node that was removed from its shared set
* @throws RepositoryException if there is a problem
*/
public void removed( AbstractJcrNode shareableNode ) throws RepositoryException {
NodeKey shareableNodeKey = shareableNode.key();
SharedSet sharedSet = getSharedSet(shareableNode);
if (sharedSet.shareableNode == shareableNode) {
// We're removing the original shareable node, so we need to recreate the SharedSet after
// we figure out the new parent ...
session().releaseCachedNode(shareableNode);
AbstractJcrNode newShared = session().node(shareableNodeKey, null);
SharedSet newSharedSet = new SharedSet(newShared);
sharedSets.put(shareableNodeKey, newSharedSet);
} else {
assert shareableNode instanceof JcrSharedNode;
sharedSet.remove((JcrSharedNode)shareableNode);
}
}
/**
* The set of shared nodes for a single shareable node.
*/
final class SharedSet {
/** The sharable node */
protected final AbstractJcrNode shareableNode;
/** The cache of Node instances that represent the shared nodes for a single shareable node. */
private final ConcurrentMap<NodeKey, JcrSharedNode> sharedNodesByParentKey = new ConcurrentHashMap<NodeKey, JcrSharedNode>();
protected SharedSet( AbstractJcrNode shareableNode ) {
this.shareableNode = shareableNode;
assert this.shareableNode != null;
}
/**
* Get the NodeKey for the shareable node.
*
* @return the key; never null and always the same
*/
public final NodeKey key() {
return shareableNode.key();
}
/**
* Get the {@link Session} to which this set belongs.
*
* @return the session instance; never null and always the same
*/
public final JcrSession session() {
return JcrSharedNodeCache.this.session();
}
/**
* Get the {@link JcrSharedNode shared Node instance} that is a child of the specified parent.
*
* @param cachedNode the cached node; may not be null
* @param parentKey the key of the parent node; may not b enull
* @return the shared node instance; never null
*/
public AbstractJcrNode getSharedNode( CachedNode cachedNode,
NodeKey parentKey ) {
assert parentKey != null;
try {
NodeKey actualParentKey = shareableNode.parentKey();
assert actualParentKey != null;
if (!actualParentKey.equals(parentKey)) {
// Obtain the set of keys for all parents ...
final SessionCache cache = session.cache();
Set<NodeKey> additionalParents = cachedNode.getAdditionalParentKeys(cache);
// And get the shared node for the parent key, first making sure the parent exists ...
if (additionalParents.contains(parentKey) && session.nodeExists(parentKey)) {
return getOrCreateSharedNode(parentKey);
}
}
return shareableNode;
} catch (RepositoryException e) {
throw new RuntimeException(e);
}
}
/**
* Determine and return the first of any nodes in the shared set exist at a location that is at or below the supplied
* path.
*
* @param path the path; may not be null
* @return the node in the shared set that exists at or below the supplied path; or null if none of the nodes in the
* shared set are at or below the supplied path
* @throws ItemNotFoundException
* @throws InvalidItemStateException
* @throws RepositoryException
*/
public AbstractJcrNode getSharedNodeAtOrBelow( Path path )
throws RepositoryException, ItemNotFoundException, InvalidItemStateException {
NodeIterator iter = getSharedNodes();
while (iter.hasNext()) {
AbstractJcrNode shared = (AbstractJcrNode)iter.nextNode();
if (shared.path().isAtOrBelow(path)) return shared;
}
return null;
}
protected void remove( JcrSharedNode sharedNode ) {
sharedNodesByParentKey.remove(sharedNode.parentKey());
}
private JcrSharedNode getOrCreateSharedNode( NodeKey parentKey ) {
assert parentKey != null;
JcrSharedNode sharedNode = sharedNodesByParentKey.get(parentKey);
if (sharedNode == null) {
JcrSharedNode newShared = new JcrSharedNode(this, parentKey);
sharedNode = sharedNodesByParentKey.putIfAbsent(parentKey, newShared);
if (sharedNode == null) sharedNode = newShared;
}
return sharedNode;
}
/**
* Get the number of shared nodes within this shared set.
*
* @return the number of shared nodes; always 1 or more
* @throws RepositoryException if there's a problem getting the size
*/
public int getSize() throws RepositoryException {
final SessionCache cache = session().cache();
Set<NodeKey> additionalParents = shareableNode.node().getAdditionalParentKeys(cache);
return additionalParents.size() + 1;
}
/**
* Find all of the {@link javax.jcr.Node}s that make up the shared set.
*
* @return the iterator over the nodes in the node set; never null, but possibly empty if this is not shareable, or of
* size 1 if the node is shareable but hasn't been shared
* @throws RepositoryException if there is a problem finding the nodes in the set
*/
public NodeIterator getSharedNodes() throws RepositoryException {
// Obtain the set of keys for all parents ...
final SessionCache cache = session().cache();
Set<NodeKey> additionalParents = shareableNode.node().getAdditionalParentKeys(cache);
// Obtain the Node objects for each of these ...
final NodeKey key = shareableNode.key();
final String workspaceKey = key.getWorkspaceKey();
Collection<AbstractJcrNode> sharedNodes = new ArrayList<AbstractJcrNode>(additionalParents.size() + 1);
sharedNodes.add(shareableNode); // add the shareable node
for (NodeKey parentKey : additionalParents) {
if (!workspaceKey.equals(parentKey.getWorkspaceKey())) {
// The parent node has to be in this workspace ...
continue;
}
if (session.nodeExists(parentKey)) {
sharedNodes.add(getOrCreateSharedNode(parentKey));
}
}
// Return an iterator ...
return new JcrNodeListIterator(sharedNodes.iterator(), sharedNodes.size());
}
}
}