org.apache.jackrabbit.mk.htree.HashDirectory Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.jackrabbit.mk.htree;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import org.apache.jackrabbit.mk.model.ChildNodeEntries;
import org.apache.jackrabbit.mk.model.ChildNodeEntry;
import org.apache.jackrabbit.mk.model.Id;
import org.apache.jackrabbit.mk.store.Binding;
import org.apache.jackrabbit.mk.store.RevisionProvider;
import org.apache.jackrabbit.mk.store.RevisionStore;
import org.apache.jackrabbit.mk.store.RevisionStore.PutToken;
/**
* Directory structure in an HTree.
*/
class HashDirectory implements ChildNodeEntries {
private static final List EMPTY = Collections.emptyList();
private static final int MAX_CHILDREN = 256;
private static final int BIT_SIZE = 8;
private static final int MAX_DEPTH = 3;
private final RevisionProvider provider;
private final int depth;
private int count;
private IndexEntry[] index = new IndexEntry[MAX_CHILDREN];
public HashDirectory(RevisionProvider provider, int depth) {
this.provider = provider;
this.depth = depth;
}
public HashDirectory(HashDirectory other) {
provider = other.provider;
depth = other.depth;
count = other.count;
index = other.index.clone();
}
@Override
public Object clone() {
HashDirectory clone = null;
try {
clone = (HashDirectory) super.clone();
} catch (CloneNotSupportedException e) {
// can't possibly get here
}
// shallow clone of array of immutable IndexEntry objects
clone.index = index.clone();
return clone;
}
public int getCount() {
return count;
}
public ChildNodeEntry get(String name) {
int hash = hashCode(name);
IndexEntry ie = index[hash];
if (ie == null) {
return null;
}
if (ie instanceof ChildNodeEntry) {
ChildNodeEntry cne = (ChildNodeEntry) ie;
return cne.getName().equals(name) ? cne : null;
}
ChildNodeEntries container = ((ContainerEntry) ie).getContainer();
if (container != null) {
return container.get(name);
}
return null;
}
public Iterator getEntries(int offset, int count) {
if (offset < 0 || count < -1) {
throw new IllegalArgumentException();
}
if (offset >= this.count || count == 0) {
return EMPTY.iterator();
}
int skipped = 0;
if (count == -1 || (offset + count) > this.count) {
count = this.count - offset;
}
ArrayList list = new ArrayList(count);
for (IndexEntry ie : index) {
if (ie == null) {
continue;
}
if (skipped + ie.getSize() <= offset) {
skipped += ie.getSize();
continue;
}
if (ie instanceof ChildNodeEntry) {
list.add((ChildNodeEntry) ie);
} else {
ChildNodeEntries container = ((ContainerEntry) ie).getContainer();
if (container != null) {
for (Iterator it = container.getEntries(offset - skipped, count - list.size());
it.hasNext(); ) {
list.add(it.next());
}
skipped = offset;
}
if (list.size() == count) {
break;
}
}
}
return list.iterator();
}
public ChildNodeEntry add(ChildNodeEntry entry) {
int hash = hashCode(entry.getName());
IndexEntry ie = index[hash];
if (ie == null) {
index[hash] = new NodeEntry(entry.getName(), entry.getId());
count++;
return null;
}
if (ie instanceof ChildNodeEntry) {
ChildNodeEntry existing = (ChildNodeEntry) ie;
if (existing.getName().equals(entry.getName())) {
index[hash] = new NodeEntry(entry.getName(), entry.getId());
return existing;
} else {
ContainerEntry ce = createContainerEntry();
ce.getContainer().add(existing);
ce.getContainer().add(entry);
index[hash] = ce;
count++;
return null;
}
}
ContainerEntry ce = (ContainerEntry) ie;
ChildNodeEntries container = ce.getContainer();
ChildNodeEntry existing = container.add(entry);
if (entry.equals(existing)) {
// no-op
return existing;
}
ce.setDirty(container);
if (existing == null) {
// new entry
count++;
}
return existing;
}
public ChildNodeEntry remove(String name) {
int hash = hashCode(name);
IndexEntry ie = index[hash];
if (ie == null) {
return null;
}
if (ie instanceof ChildNodeEntry) {
ChildNodeEntry existing = (ChildNodeEntry) ie;
if (existing.getName().equals(name)) {
index[hash] = null;
count--;
return existing;
} else {
return null;
}
}
ContainerEntry ce = (ContainerEntry) ie;
ChildNodeEntries container = ce.getContainer();
ChildNodeEntry existing = container.remove(name);
if (existing == null) {
return null;
}
if (container.getCount() == 0) {
index[hash] = null;
} else if (container.getCount() == 1) {
// inline single remaining entry
ChildNodeEntry remaining = container.getEntries(0, 1).next();
index[hash] = new NodeEntry(remaining.getName(), remaining.getId());
} else {
ce.setDirty(container);
}
count--;
return existing;
}
public Iterator getAdded(ChildNodeEntries otherContainer) {
if (!(otherContainer instanceof HashDirectory)) {
// needs no implementation
return null;
}
HashDirectory other = (HashDirectory) otherContainer;
List added = new ArrayList();
for (int i = 0; i < index.length; i++) {
IndexEntry ie1 = index[i];
IndexEntry ie2 = other.index[i];
if (ie1 == null && ie2 == null || (ie1 != null && ie1.equals(ie2))) {
continue;
}
// index entries aren't equal
if (ie1 == null) {
// this index entry in null => other must be non-null, add all its entries
if (ie2 instanceof ChildNodeEntry) {
added.add((ChildNodeEntry) ie2);
} else {
ChildNodeEntries container = ((ContainerEntry) ie2).getContainer();
for (Iterator it = container.getEntries(0, -1); it.hasNext(); ) {
added.add(it.next());
}
}
continue;
}
// optimization for simple child node entries
if (ie1 instanceof ChildNodeEntry && ie2 instanceof ChildNodeEntry) {
ChildNodeEntry cne1 = (ChildNodeEntry) ie1;
ChildNodeEntry cne2 = (ChildNodeEntry) ie2;
if (cne2.getName().equals(cne1.getName())) {
added.add(cne2);
}
continue;
}
// all other cases
for (Iterator it = ie1.getAdded(ie2); it.hasNext(); ) {
added.add(it.next());
}
}
return added.iterator();
}
public Iterator getModified(ChildNodeEntries otherContainer) {
if (!(otherContainer instanceof HashDirectory)) {
// needs no implementation
return null;
}
HashDirectory other = (HashDirectory) otherContainer;
List modified = new ArrayList();
for (int i = 0; i < index.length; i++) {
IndexEntry ie1 = index[i];
IndexEntry ie2 = other.index[i];
if (ie1 == null || ie2 == null || ie1.equals(ie2)) {
continue;
}
// optimization for simple child node entries
if (ie1 instanceof ChildNodeEntry && ie2 instanceof ChildNodeEntry) {
ChildNodeEntry cne1 = (ChildNodeEntry) ie1;
ChildNodeEntry cne2 = (ChildNodeEntry) ie2;
if (cne1.getName().equals(cne2.getName()) && !cne1.getId().equals(cne2.getId())) {
modified.add(cne1);
continue;
}
}
// all other cases
for (Iterator it = ie1.getModified(ie2); it.hasNext();) {
modified.add(it.next());
}
}
return modified.iterator();
}
private ContainerEntry createContainerEntry() {
return depth < MAX_DEPTH - 1 ? new DirectoryEntry(depth + 1) : new BucketEntry();
}
private int hashCode(String name) {
int hashMask = hashMask();
int hash = name.hashCode();
hash = hash & hashMask;
hash = hash >>> ((MAX_DEPTH - depth) * BIT_SIZE);
hash = hash % MAX_CHILDREN;
return hash;
}
int hashMask() {
int bits = MAX_CHILDREN-1;
int hashMask = bits << ((MAX_DEPTH - depth) * BIT_SIZE);
return hashMask;
}
public void deserialize(Binding binding) throws Exception {
count = binding.readIntValue(":count");
Binding.StringEntryIterator iter = binding.readStringMap(":index");
int pos = -1;
while (iter.hasNext()) {
Binding.StringEntry entry = iter.next();
++pos;
// deserialize index array entry
assert(pos == Integer.parseInt(entry.getKey()));
if (entry.getValue().length() == 0) {
// ""
index[pos] = null;
} else {
switch (entry.getValue().charAt(0)) {
case 'n':
String value = entry.getValue().substring(1);
int i = value.indexOf(':');
String id = value.substring(0, i);
String name = value.substring(i + 1);
index[pos] = new NodeEntry(name, Id.fromString(id));
break;
case 'b':
value = entry.getValue().substring(1);
i = value.indexOf(':');
id = value.substring(0, i);
int count = Integer.parseInt(value.substring(i + 1));
index[pos] = new BucketEntry(provider, Id.fromString(id), count);
break;
case 'd':
value = entry.getValue().substring(1);
i = value.indexOf(':');
id = value.substring(0, i);
count = Integer.parseInt(value.substring(i + 1));
index[pos] = new DirectoryEntry(provider, Id.fromString(id), count, depth + 1);
break;
}
}
}
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof HashDirectory) {
HashDirectory other = (HashDirectory) obj;
return Arrays.equals(index, other.index);
}
return false;
}
public void prePersist(RevisionStore store, PutToken token)
throws Exception {
for (int i = 0; i < index.length; i++) {
if (index[i] instanceof ContainerEntry) {
ContainerEntry ce = (ContainerEntry) index[i];
if (ce.isDirty()) {
ce.store(store, token);
}
}
}
}
public void serialize(Binding binding) throws Exception {
final IndexEntry[] index = this.index;
binding.write(":count", count);
binding.writeMap(":index", index.length, new Binding.StringEntryIterator() {
int pos = -1;
@Override
public boolean hasNext() {
return pos < index.length - 1;
}
@Override
public Binding.StringEntry next() {
pos++;
if (pos >= index.length) {
throw new NoSuchElementException();
}
// serialize index array entry
IndexEntry entry = index[pos];
if (entry == null) {
// null entry: ""
return new Binding.StringEntry(Integer.toString(pos), "");
} else {
return new Binding.StringEntry(Integer.toString(pos), entry.toString());
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
});
}
/**
* Entry inside this directory's index.
*/
static interface IndexEntry {
public int getSize();
public Iterator getAdded(IndexEntry other);
public Iterator getModified(IndexEntry other);
}
/**
* Direct entry inside this directory's index, pointing to a child node.
*/
static class NodeEntry extends ChildNodeEntry implements IndexEntry {
public NodeEntry(String name, Id id) {
super(name, id);
}
public int getSize() {
return 1;
}
public Iterator getAdded(IndexEntry other) {
if (other == null) {
return null;
}
ChildNodeEntries container = ((ContainerEntry) other).createCompatibleContainer();
container.add(this);
return container.getAdded(((ContainerEntry) other).getContainer());
}
public Iterator getModified(IndexEntry other) {
if (other == null) {
return null;
}
ChildNodeEntries container = ((ContainerEntry) other).createCompatibleContainer();
container.add(this);
return container.getModified(((ContainerEntry) other).getContainer());
}
@Override
public String toString() {
return "n" + getId() + ":" + getName();
}
}
/**
* Container entry inside this directory's index, pointing to either a
* directory or a bucket.
*/
static abstract class ContainerEntry implements IndexEntry {
protected RevisionProvider provider;
protected Id id;
protected int count;
protected ChildNodeEntries container;
public ContainerEntry(RevisionProvider provider, Id id, int count) {
this.provider = provider;
this.id = id;
this.count = count;
}
public ContainerEntry() {
}
public abstract ChildNodeEntries getContainer();
public abstract ChildNodeEntries createCompatibleContainer();
public boolean isDirty() {
return container != null;
}
public void setDirty(ChildNodeEntries container) {
this.container = container;
}
public Id getId() {
return id;
}
public int getSize() {
if (container != null) {
return container.getCount();
}
return count;
}
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other instanceof ContainerEntry) {
ContainerEntry ce = (ContainerEntry) other;
if (container != null && ce.container != null) {
return container.equals(ce.container);
}
if (container == null && ce.container == null) {
return (count == ce.count && id == null ? ce.id == null : id.equals(ce.id));
}
}
return false;
}
public Iterator getAdded(IndexEntry other) {
if (other == null) {
return null;
}
if (other instanceof ChildNodeEntry) {
ChildNodeEntries container = createCompatibleContainer();
container.add((ChildNodeEntry) other);
return getContainer().getAdded(container);
}
return getContainer().getAdded(((ContainerEntry) other).getContainer());
}
public Iterator getModified(IndexEntry other) {
if (other == null) {
return null;
}
if (other instanceof ChildNodeEntry) {
ChildNodeEntries container = createCompatibleContainer();
container.add((ChildNodeEntry) other);
return getContainer().getModified(container);
}
return getContainer().getModified(((ContainerEntry) other).getContainer());
}
public void store(RevisionStore store, PutToken token) throws Exception {
store.putCNEMap(token, container);
}
}
/**
* Directory entry inside this directory's index, pointing to a directory on the
* next level.
*/
static class DirectoryEntry extends ContainerEntry {
private final int depth;
public DirectoryEntry(RevisionProvider provider, Id id, int count, int depth) {
super(provider, id, count);
this.depth = depth;
}
public DirectoryEntry(int depth) {
this.depth = depth;
}
public ChildNodeEntries getContainer() {
if (container != null) {
return container;
}
try {
// TODO return provider.getCNEMap(id);
return new HashDirectory(provider, depth);
} catch (Exception e) {
// todo log error and gracefully handle exception
return null;
}
}
public ChildNodeEntries createCompatibleContainer() {
return new HashDirectory(provider, depth);
}
@Override
public String toString() {
return "d" + getId() + ":" + getSize();
}
public void store(RevisionStore store, PutToken token) throws Exception {
((HashDirectory) container).prePersist(store, token);
super.store(store, token);
}
}
/**
* Bucket entry inside this directory's index, pointing to a bucket or leaf node.
*/
static class BucketEntry extends ContainerEntry {
public BucketEntry(RevisionProvider provider, Id id, int count) {
super(provider, id, count);
}
public BucketEntry() {
}
public HashBucket getContainer() {
if (container != null) {
return (HashBucket) container;
}
try {
return new HashBucket(provider.getCNEMap(id));
} catch (Exception e) {
// todo log error and gracefully handle exception
return null;
}
}
public ChildNodeEntries createCompatibleContainer() {
return new HashBucket();
}
@Override
public String toString() {
return "b" + getId() + ":" + getSize();
}
}
// ------------------------------------------------------------------------------------------- unimplemented methods
@Override
public boolean inlined() {
throw new NoSuchMethodError();
}
@Override
public Iterator getNames(int offset, int count) {
throw new NoSuchMethodError();
}
@Override
public ChildNodeEntry rename(String oldName, String newName) {
throw new NoSuchMethodError();
}
@Override
public Iterator getRemoved(ChildNodeEntries other) {
throw new NoSuchMethodError();
}
@Override
public int getMemory() {
// assuming a fixed size of 1000 entries, each with 100 bytes, plus 100
// bytes overhead
int memory = 100 + 1000 * 100;
return memory;
}
}
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