/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.search.query;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.FilterCollector;
import org.apache.lucene.search.FilterLeafCollector;
import org.apache.lucene.search.LeafCollector;
import org.elasticsearch.common.inject.Provider;
import org.elasticsearch.tasks.TaskCancelledException;
import java.io.IOException;
/**
* Collector that checks if the task it is executed under is cancelled.
*/
public class CancellableCollector extends FilterCollector {
private final Provider<Boolean> cancelled;
private final boolean leafLevel;
/**
* Constructor
* @param cancelled supplier of the cancellation flag, the supplier will be called for each segment if lowLevelCancellation is set
* to false and for each collected record if lowLevelCancellation is set to true. In other words this class assumes
* that the supplier is fast, with performance on the order of a volatile read.
* @param lowLevelCancellation true if collector should check for cancellation for each collected record, false if check should be
* performed only once per segment
* @param in wrapped collector
*/
public CancellableCollector(Provider<Boolean> cancelled, boolean lowLevelCancellation, Collector in) {
super(in);
this.cancelled = cancelled;
this.leafLevel = lowLevelCancellation;
}
@Override
public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException {
if (cancelled.get()) {
throw new TaskCancelledException("cancelled");
}
if (leafLevel) {
return new CancellableLeafCollector(super.getLeafCollector(context));
} else {
return super.getLeafCollector(context);
}
}
private class CancellableLeafCollector extends FilterLeafCollector {
private CancellableLeafCollector(LeafCollector in) {
super(in);
}
@Override
public void collect(int doc) throws IOException {
if (cancelled.get()) {
throw new TaskCancelledException("cancelled");
}
super.collect(doc);
}
}
}