/*
* 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.client.solrj.io.stream;
import java.io.IOException;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.PriorityQueue;
import org.apache.solr.client.solrj.io.Tuple;
import org.apache.solr.client.solrj.io.comp.FieldComparator;
import org.apache.solr.client.solrj.io.comp.StreamComparator;
import org.apache.solr.client.solrj.io.stream.expr.Explanation;
import org.apache.solr.client.solrj.io.stream.expr.Explanation.ExpressionType;
import org.apache.solr.client.solrj.io.stream.expr.Expressible;
import org.apache.solr.client.solrj.io.stream.expr.StreamExplanation;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionNamedParameter;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionValue;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;
import static org.apache.solr.common.params.CommonParams.SORT;
/**
* Iterates over a TupleStream and Ranks the topN tuples based on a Comparator.
**/
public class RankStream extends TupleStream implements Expressible {
private static final long serialVersionUID = 1;
private TupleStream stream;
private StreamComparator comp;
private int size;
private transient PriorityQueue<Tuple> top;
private transient boolean finished = false;
private transient LinkedList<Tuple> topList;
public RankStream(TupleStream tupleStream, int size, StreamComparator comp) throws IOException {
init(tupleStream,size,comp);
}
public RankStream(StreamExpression expression, StreamFactory factory) throws IOException {
// grab all parameters out
List<StreamExpression> streamExpressions = factory.getExpressionOperandsRepresentingTypes(expression, Expressible.class, TupleStream.class);
StreamExpressionNamedParameter nParam = factory.getNamedOperand(expression, "n");
StreamExpressionNamedParameter sortExpression = factory.getNamedOperand(expression, SORT);
// validate expression contains only what we want.
if(expression.getParameters().size() != streamExpressions.size() + 2){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - unknown operands found", expression));
}
if(null == nParam || null == nParam.getParameter() || !(nParam.getParameter() instanceof StreamExpressionValue)){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting a single 'n' parameter of type positive integer but didn't find one",expression));
}
String nStr = ((StreamExpressionValue)nParam.getParameter()).getValue();
int nInt = 0;
try{
nInt = Integer.parseInt(nStr);
if(nInt <= 0){
throw new IOException(String.format(Locale.ROOT,"invalid expression %s - topN '%s' must be greater than 0.",expression, nStr));
}
}
catch(NumberFormatException e){
throw new IOException(String.format(Locale.ROOT,"invalid expression %s - topN '%s' is not a valid integer.",expression, nStr));
}
if(1 != streamExpressions.size()){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting a single stream but found %d",expression, streamExpressions.size()));
}
if(null == sortExpression || !(sortExpression.getParameter() instanceof StreamExpressionValue)){
throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting single 'over' parameter listing fields to unique over but didn't find one",expression));
}
TupleStream stream = factory.constructStream(streamExpressions.get(0));
StreamComparator comp = factory.constructComparator(((StreamExpressionValue)sortExpression.getParameter()).getValue(), FieldComparator.class);
init(stream,nInt,comp);
}
private void init(TupleStream tupleStream, int size, StreamComparator comp) throws IOException{
this.stream = tupleStream;
this.comp = comp;
this.size = size;
// Rank stream does not demand that its order is derivable from the order of the incoming stream. No derivation check required
}
@Override
public StreamExpression toExpression(StreamFactory factory) throws IOException{
return toExpression(factory, true);
}
private StreamExpression toExpression(StreamFactory factory, boolean includeStreams) throws IOException {
// function name
StreamExpression expression = new StreamExpression(factory.getFunctionName(this.getClass()));
// n
expression.addParameter(new StreamExpressionNamedParameter("n", Integer.toString(size)));
if(includeStreams){
// stream
if(stream instanceof Expressible){
expression.addParameter(((Expressible)stream).toExpression(factory));
}
else{
throw new IOException("This RankStream contains a non-expressible TupleStream - it cannot be converted to an expression");
}
}
else{
expression.addParameter("<stream>");
}
// sort
expression.addParameter(new StreamExpressionNamedParameter(SORT, comp.toExpression(factory)));
return expression;
}
@Override
public Explanation toExplanation(StreamFactory factory) throws IOException {
return new StreamExplanation(getStreamNodeId().toString())
.withChildren(new Explanation[]{
stream.toExplanation(factory)
})
.withFunctionName(factory.getFunctionName(this.getClass()))
.withImplementingClass(this.getClass().getName())
.withExpressionType(ExpressionType.STREAM_DECORATOR)
.withExpression(toExpression(factory, false).toString())
.withHelper(comp.toExplanation(factory));
}
public void setStreamContext(StreamContext context) {
this.stream.setStreamContext(context);
}
public List<TupleStream> children() {
List<TupleStream> l = new ArrayList<TupleStream>();
l.add(stream);
return l;
}
public void open() throws IOException {
this.top = new PriorityQueue<Tuple>(size, new ReverseComp(comp));
this.topList = new LinkedList<Tuple>();
stream.open();
}
public void close() throws IOException {
stream.close();
}
public StreamComparator getComparator(){
return this.comp;
}
public Tuple read() throws IOException {
if(!finished) {
while(true) {
Tuple tuple = stream.read();
if(tuple.EOF) {
finished = true;
int s = top.size();
for(int i=0; i<s; i++) {
Tuple t = top.poll();
topList.addFirst(t);
}
topList.addLast(tuple);
break;
} else {
if(top.size() >= size) {
Tuple peek = top.peek();
if(comp.compare(tuple, peek) < 0) {
top.poll();
top.add(tuple);
}
} else {
top.add(tuple);
}
}
}
}
return topList.pollFirst();
}
/** Return the stream sort - ie, the order in which records are returned */
public StreamComparator getStreamSort(){
return comp;
}
public int getCost() {
return 0;
}
static class ReverseComp implements Comparator<Tuple>, Serializable {
private static final long serialVersionUID = 1L;
private StreamComparator comp;
public ReverseComp(StreamComparator comp) {
this.comp = comp;
}
public int compare(Tuple t1, Tuple t2) {
return comp.compare(t1, t2)*(-1);
}
}
}