org.apache.solr.handler.sql.LimitStream 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.solr.handler.sql;
import org.apache.solr.client.solrj.io.Tuple;
import org.apache.solr.client.solrj.io.comp.StreamComparator;
import org.apache.solr.client.solrj.io.stream.StreamContext;
import org.apache.solr.client.solrj.io.stream.TupleStream;
import org.apache.solr.client.solrj.io.stream.expr.Explanation;
import org.apache.solr.client.solrj.io.stream.expr.StreamExplanation;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
class LimitStream extends TupleStream {
private final TupleStream stream;
private final int limit;
private int count;
LimitStream(TupleStream stream, int limit) {
this.stream = stream;
this.limit = limit;
}
public void open() throws IOException {
this.stream.open();
}
public void close() throws IOException {
this.stream.close();
}
public List children() {
List children = new ArrayList<>();
children.add(stream);
return children;
}
public StreamComparator getStreamSort(){
return stream.getStreamSort();
}
public void setStreamContext(StreamContext context) {
stream.setStreamContext(context);
}
@Override
public Explanation toExplanation(StreamFactory factory) throws IOException {
return new StreamExplanation(getStreamNodeId().toString())
.withChildren(new Explanation[]{
stream.toExplanation(factory)
})
.withFunctionName("SQL LIMIT")
.withExpression("--non-expressible--")
.withImplementingClass(this.getClass().getName())
.withExpressionType(Explanation.ExpressionType.STREAM_DECORATOR);
}
public Tuple read() throws IOException {
++count;
if(count > limit) {
return Tuple.EOF();
}
return stream.read();
}
}