/*
* 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.cache.document;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.modeshape.common.annotation.ThreadSafe;
import org.modeshape.jcr.cache.ChildReference;
import org.modeshape.jcr.cache.NodeKey;
import org.modeshape.jcr.value.Name;
/**
*
*/
@ThreadSafe
public class MutableChildReferences extends AbstractChildReferences {
private final ReadWriteLock lock = new ReentrantReadWriteLock();
private final Map<Name, List<NodeKey>> childReferenceKeysByName;
private final Map<NodeKey, ChildReference> childReferencesByKey;
public MutableChildReferences() {
this.childReferenceKeysByName = new HashMap<>();
this.childReferencesByKey = new LinkedHashMap<>();
}
@Override
public long size() {
Lock lock = this.lock.readLock();
try {
lock.lock();
return childReferencesByKey.size();
} finally {
lock.unlock();
}
}
@Override
public int getChildCount( Name name ) {
Lock lock = this.lock.readLock();
try {
lock.lock();
List<NodeKey> nodeKeys = childReferenceKeysByName.get(name);
return nodeKeys != null ? nodeKeys.size() : 0;
} finally {
lock.unlock();
}
}
@Override
public ChildReference getChild( Name name,
int snsIndex,
Context context ) {
if (context == null) context = new SingleNameContext();
Lock lock = this.lock.readLock();
try {
lock.lock();
List<NodeKey> childrenKeysWithSameName = this.childReferenceKeysByName.get(name);
if (childrenKeysWithSameName == null || childrenKeysWithSameName.isEmpty()) {
// This segment contains no nodes with the supplied name ...
return null;
}
// there are no changes, so we can optimize this lookup
if (snsIndex > childrenKeysWithSameName.size()) {
return null;
} else {
NodeKey nodeKey = childrenKeysWithSameName.get(snsIndex - 1);
return this.childReferencesByKey.get(nodeKey).with(snsIndex);
}
} finally {
lock.unlock();
}
}
@Override
public ChildReference getChild( NodeKey key,
Context context ) {
if (context == null) context = new SingleNameContext();
Lock lock = this.lock.readLock();
try {
lock.lock();
ChildReference ref = childReferencesByKey.get(key);
if (ref != null) {
// It's in this list but there may be changes ...
List<NodeKey> childrenKeysWithSameName = this.childReferenceKeysByName.get(ref.getName());
assert childrenKeysWithSameName != null;
assert childrenKeysWithSameName.size() != 0;
int index = childrenKeysWithSameName.indexOf(key);
return ref.with(index + 1);
}
return null;
} finally {
lock.unlock();
}
}
@Override
public ChildReference getChild( NodeKey key ) {
return getChild(key, new BasicContext());
}
@Override
public boolean hasChild( NodeKey key ) {
Lock lock = this.lock.readLock();
try {
lock.lock();
return childReferencesByKey.containsKey(key);
} finally {
lock.unlock();
}
}
@Override
public Iterator<ChildReference> iterator() {
Lock lock = this.lock.readLock();
try {
lock.lock();
// we need to copy to be thread safe
return new ArrayList<>(childReferencesByKey.values()).iterator();
} finally {
lock.unlock();
}
}
@Override
public Iterator<ChildReference> iterator( Name name ) {
Lock lock = this.lock.readLock();
try {
lock.lock();
final List<NodeKey> nodeKeys = childReferenceKeysByName.get(name);
if (nodeKeys == null || nodeKeys.isEmpty()) {
return Collections.emptyIterator();
}
List<ChildReference> childReferences = new ArrayList<>(nodeKeys.size());
for (ChildReference childReference : childReferencesByKey.values()) {
if (name.equals(childReference.getName())) {
childReferences.add(childReference);
}
}
return childReferences.iterator();
} finally {
lock.unlock();
}
}
@Override
public Iterator<NodeKey> getAllKeys() {
Lock lock = this.lock.readLock();
try {
lock.lock();
//we need to copy to be thread safe
return new ArrayList<>(childReferencesByKey.keySet()).iterator();
} finally {
lock.unlock();
}
}
public void append( NodeKey key,
Name name ) {
ChildReference reference = new ChildReference(key, name, 1);
Lock lock = this.lock.writeLock();
try {
lock.lock();
ChildReference old = this.childReferencesByKey.put(key, reference);
if (old != null && old.getName().equals(name)) {
// We already have this key/name pair, so we don't need to add it again ...
return;
}
// We've not seen this node key yet, so it is okay. In fact, we should not see any
// node key more than once, since that is clearly an unexpected condition (as a child
// may not appear more than once in its parent's list of child nodes). See MODE-2120.
List<NodeKey> nodeKeysWithSameName = this.childReferenceKeysByName.get(name);
if (nodeKeysWithSameName == null) {
nodeKeysWithSameName = new ArrayList<>();
this.childReferenceKeysByName.put(name, nodeKeysWithSameName);
}
nodeKeysWithSameName.add(key);
} finally {
lock.unlock();
}
}
public void append( Iterable<ChildReference> references ) {
Iterator<ChildReference> childReferenceIterator = references.iterator();
if (!childReferenceIterator.hasNext()) {
return;
}
Lock lock = this.lock.writeLock();
try {
lock.lock();
while (childReferenceIterator.hasNext()) {
ChildReference reference = childReferenceIterator.next();
reference = reference.with(1);
ChildReference old = this.childReferencesByKey.put(reference.getKey(), reference);
if (old != null && old.getName().equals(reference.getName())) {
// We already have this key/name pair, so we don't need to add it again ...
continue;
}
// We've not seen this node key yet, so it is okay. In fact, we should not see any
// node key more than once, since that is clearly an unexpected condition (as a child
// may not appear more than once in its parent's list of child nodes). See MODE-2120.
Name name = reference.getName();
List<NodeKey> nodeKeysWithSameName = this.childReferenceKeysByName.get(name);
if (nodeKeysWithSameName == null) {
nodeKeysWithSameName = new ArrayList<>();
this.childReferenceKeysByName.put(name, nodeKeysWithSameName);
}
nodeKeysWithSameName.add(reference.getKey());
}
} finally {
lock.unlock();
}
}
public ChildReference remove( NodeKey key ) {
Lock lock = this.lock.writeLock();
try {
lock.lock();
ChildReference existing = this.childReferencesByKey.remove(key);
if (existing != null) {
List<NodeKey> nodeKeys = this.childReferenceKeysByName.get(existing.getName());
assert nodeKeys != null;
nodeKeys.remove(key);
}
return existing;
} finally {
lock.unlock();
}
}
@Override
public StringBuilder toString( StringBuilder sb ) {
sb.append("appended: ");
Lock lock = this.lock.readLock();
try {
lock.lock();
Iterator<ChildReference> iter = this.childReferencesByKey.values().iterator();
if (iter.hasNext()) {
sb.append(iter.next());
while (iter.hasNext()) {
sb.append(", ");
sb.append(iter.next());
}
}
} finally {
lock.unlock();
}
return sb;
}
@Override
public boolean allowsSNS() {
// we don't really have any way of knowing SNS information here, so assume true to cover all cases
return true;
}
}