/**
* 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.ambari.server.api.query;
import java.util.LinkedList;
import java.util.List;
import org.apache.ambari.server.controller.predicate.AlwaysPredicate;
import org.apache.ambari.server.controller.predicate.ArrayPredicate;
import org.apache.ambari.server.controller.predicate.CategoryPredicate;
import org.apache.ambari.server.controller.predicate.ComparisonPredicate;
import org.apache.ambari.server.controller.predicate.NotPredicate;
import org.apache.ambari.server.controller.predicate.PredicateVisitor;
import org.apache.ambari.server.controller.predicate.UnaryPredicate;
import org.apache.ambari.server.controller.spi.Predicate;
import org.apache.ambari.server.controller.utilities.PredicateHelper;
/**
* A predicate visitor used to extract the sub resource elements from a given predicate
* and produce a new predicate that can be evaluated with a sub resource of the
* given category. For example, given the category 'components' the predicate ...
*
* ServiceInfo/service_name = HBASE AND
* components/ServiceComponentInfo/category = SLAVE AND
* components/host_components/metrics/cpu/cpu_num >= 1
*
* ... will produce the new predicate ...
*
* ServiceComponentInfo/category = SLAVE AND
* host_components/metrics/cpu/cpu_num >= 1
*/
public class SubResourcePredicateVisitor implements PredicateVisitor {
/**
* The last visited predicate.
*/
private Predicate lastVisited = null;
/**
* The sub resource category (i.e components, host_components, etc).
*/
private final String category;
//----- Constructors -------------------------------------------------------
/**
* Constructor.
*/
public SubResourcePredicateVisitor(String category) {
this.category = category;
}
// ----- PredicateVisitor --------------------------------------------------
@Override
public void acceptComparisonPredicate(ComparisonPredicate predicate) {
String propertyId = predicate.getPropertyId();
int index = propertyId.indexOf("/");
String category = index == -1 ? propertyId : propertyId.substring(0, index);
if(index > -1 && category.equals(this.category)) {
// copy and strip off category
lastVisited = predicate.copy(propertyId.substring(index + 1));
} else {
lastVisited = AlwaysPredicate.INSTANCE;
}
}
@Override
public void acceptArrayPredicate(ArrayPredicate arrayPredicate) {
List<Predicate> predicateList = new LinkedList<>();
Predicate[] predicates = arrayPredicate.getPredicates();
if (predicates.length > 0) {
for (Predicate predicate : predicates) {
PredicateHelper.visit(predicate, this);
predicateList.add(lastVisited);
}
}
lastVisited = arrayPredicate.create(predicateList.toArray(new Predicate[predicateList.size()]));
}
@Override
public void acceptUnaryPredicate(UnaryPredicate predicate) {
//TODO implement subresource parsing not only for ComparisonPredicate
if (predicate.getPredicate() instanceof ComparisonPredicate) {
ComparisonPredicate innerPredicate = (ComparisonPredicate) predicate.getPredicate();
String propertyId = innerPredicate.getPropertyId();
int index = propertyId.indexOf("/");
String category = index == -1 ? propertyId : propertyId.substring(0, index);
if(index > -1 && category.equals(this.category)) {
// copy and strip off category
lastVisited = new NotPredicate(innerPredicate.copy(propertyId.substring(index + 1)));
} else {
lastVisited = AlwaysPredicate.INSTANCE;
}
} else {
lastVisited = predicate;
}
}
@Override
public void acceptAlwaysPredicate(AlwaysPredicate predicate) {
lastVisited = predicate;
}
@Override
public void acceptCategoryPredicate(CategoryPredicate predicate) {
lastVisited = predicate;
}
// ----- utility methods -------------------------------------------------
/**
* Obtain a predicate that can be evaluated with sub resources
* belonging to the associated category.
*
* @return a sub resource predicate
*/
public Predicate getSubResourcePredicate() {
return lastVisited;
}
}