org.apache.jackrabbit.oak.plugins.commit.JcrLastModifiedConflictHandler 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.oak.plugins.commit;
import static org.apache.jackrabbit.JcrConstants.JCR_LASTMODIFIED;
import static org.apache.jackrabbit.JcrConstants.JCR_CREATED;
import static org.apache.jackrabbit.util.ISO8601.parse;
import java.util.Calendar;
import org.apache.jackrabbit.oak.api.PropertyState;
import org.apache.jackrabbit.oak.api.Type;
import org.apache.jackrabbit.oak.spi.state.NodeBuilder;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
/**
* Conflict Handler that merges concurrent updates to
* {@code org.apache.jackrabbit.JcrConstants.JCR_LASTMODIFIED} by picking the
* older of the 2 conflicting dates and
* {@code org.apache.jackrabbit.JcrConstants.JCR_CREATED} by picking the newer
* of the 2 conflicting dates.
*/
public class JcrLastModifiedConflictHandler extends DefaultThreeWayConflictHandler {
public JcrLastModifiedConflictHandler() {
super(Resolution.IGNORED);
}
@NotNull
@Override
public Resolution addExistingProperty(@NotNull NodeBuilder parent, @NotNull PropertyState ours, @NotNull PropertyState theirs) {
if (isModifiedOrCreated(ours.getName()) && merge(parent, ours, theirs)) {
return Resolution.MERGED;
} else {
return Resolution.IGNORED;
}
}
@NotNull
@Override
public Resolution changeChangedProperty(@NotNull NodeBuilder parent, @NotNull PropertyState ours, @NotNull PropertyState theirs,
@NotNull PropertyState base) {
if (isModifiedOrCreated(ours.getName()) && merge(parent, ours, theirs)) {
return Resolution.MERGED;
} else {
return Resolution.IGNORED;
}
}
/**
* Tries to merge two properties. The respective property of the parent is
* set if merging is successful. The the earlier value is used if
* jcr:created is true; the later is used if it is not jcr:created.
*
* @param parent the parent node
* @param ours our value
* @param theirs their value
* @return if merging is successful
*/
private static boolean merge(@NotNull NodeBuilder parent, @NotNull PropertyState ours, @NotNull PropertyState theirs) {
Calendar o = parse(ours.getValue(Type.DATE));
Calendar t = parse(theirs.getValue(Type.DATE));
Calendar value = pick(o, t, JCR_CREATED.equals(ours.getName()));
if (value != null) {
parent.setProperty(ours.getName(), value);
return true;
} else {
return false;
}
}
/**
* Pick "a" or "b", depending on which one is earlier (if jcrCreated = true) or later (if jcrCreated = false).
*
* @param ours the property state from our change set to have a conflict resolved.
* @param theirs the property state from their change set to have a conflict resolved.
* @param jcrCreated if true and 'ours' is before 'theirs', 'ours' is returned, otherwise 'theirs'
* @return the calendar; either "ours" or "theirs". It will return {@code null} if both are {@code null}
*/
@Nullable
private static Calendar pick(@Nullable Calendar ours, @Nullable Calendar theirs, boolean jcrCreated) {
if (ours == null) {
return theirs;
}
if (theirs == null) {
return ours;
}
if (ours.before(theirs)) {
return jcrCreated ? ours : theirs;
} else {
return jcrCreated ? theirs : ours;
}
}
private static boolean isModifiedOrCreated(@NotNull String name) {
return JCR_LASTMODIFIED.equals(name) || JCR_CREATED.equals(name);
}
}