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/*
* 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.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import org.apache.solr.client.solrj.io.Tuple;
import org.apache.solr.client.solrj.io.comp.StreamComparator;
import org.apache.solr.client.solrj.io.eq.FieldEqualitor;
import org.apache.solr.client.solrj.io.eq.StreamEqualitor;
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;
/** Defines a JoinStream which can hold N streams, all joined with the same equalitor */
public abstract class JoinStream extends TupleStream implements Expressible {
private static final long serialVersionUID = 1;
private List streams;
protected StreamEqualitor eq;
public JoinStream(StreamEqualitor eq, TupleStream first, TupleStream second, TupleStream... others) {
this.streams = new ArrayList();
this.eq = eq;
this.streams.add(new PushBackStream(first));
this.streams.add(new PushBackStream(second));
for (TupleStream other : others) {
this.streams.add(new PushBackStream(other));
}
}
protected abstract void validateTupleOrder() throws IOException;
public JoinStream(StreamExpression expression, StreamFactory factory) throws IOException {
// grab all parameters out
List streamExpressions = factory.getExpressionOperandsRepresentingTypes(expression,
Expressible.class, TupleStream.class);
StreamExpressionNamedParameter onExpression = factory.getNamedOperand(expression, "on");
// validate expression contains only what we want.
if (expression.getParameters().size() != streamExpressions.size() + 1) {
throw new IOException(String.format(Locale.ROOT, "Invalid expression %s - unknown operands found", expression));
}
if (streamExpressions.size() < 2) {
throw new IOException(String.format(Locale.ROOT,
"Invalid expression %s - expecting at least two streams but found %d (must be PushBackStream types)",
expression, streamExpressions.size()));
}
this.streams = new ArrayList();
for (StreamExpression streamExpression : streamExpressions) {
this.streams.add(new PushBackStream(factory.constructStream(streamExpression)));
}
if (null == onExpression || !(onExpression.getParameter() instanceof StreamExpressionValue)) {
throw new IOException(String.format(Locale.ROOT,
"Invalid expression %s - expecting single 'on' parameter listing fields to join on but didn't find one",
expression));
}
this.eq = factory.constructEqualitor(((StreamExpressionValue) onExpression.getParameter()).getValue(),
FieldEqualitor.class);
}
@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()));
// streams
for (PushBackStream stream : streams) {
if(includeStreams){
expression.addParameter(stream.toExpression(factory));
}
else{
expression.addParameter("");
}
}
// on
if (eq instanceof Expressible) {
expression.addParameter(new StreamExpressionNamedParameter("on", ((Expressible) eq).toExpression(factory)));
} else {
throw new IOException(
"This JoinStream contains a non-expressible equalitor - it cannot be converted to an expression");
}
return expression;
}
@Override
public Explanation toExplanation(StreamFactory factory) throws IOException {
StreamExplanation explanation = new StreamExplanation(getStreamNodeId().toString());
explanation.setFunctionName(factory.getFunctionName(this.getClass()));
explanation.setImplementingClass(this.getClass().getName());
explanation.setExpressionType(ExpressionType.STREAM_DECORATOR);
explanation.setExpression(toExpression(factory, false).toString());
explanation.addHelper(eq.toExplanation(factory));
for(TupleStream stream : streams){
explanation.addChild(stream.toExplanation(factory));
}
return explanation;
}
public void setStreamContext(StreamContext context) {
for (PushBackStream stream : streams) {
stream.setStreamContext(context);
}
}
public void open() throws IOException {
for (PushBackStream stream : streams) {
stream.open();
}
}
public void close() throws IOException {
for (PushBackStream stream : streams) {
stream.close();
}
}
public List children() {
List list = new ArrayList();
for (TupleStream stream : streams) {
list.add(stream);
}
return list;
}
public PushBackStream getStream(int idx) {
if (streams.size() > idx) {
return streams.get(idx);
}
throw new IllegalArgumentException(String.format(Locale.ROOT,"Stream idx=%d doesn't exist. Number of streams is %d", idx,
streams.size()));
}
protected boolean isValidTupleOrder() {
// Validate that the equalitor is derivable from the comparator in each stream. If it is, then we know all stream
// comparators are
// derivable with each other stream
for (TupleStream stream : streams) {
if (!eq.isDerivedFrom(stream.getStreamSort())) {
return false;
}
}
return true;
}
/**
* Given the stream, start from beginning and load group with all tuples that are equal to the first in stream
* (including the first one in the stream). All matched tuples are removed from the stream. Result is at least one
* tuple will be read from the stream and 0 or more tuples will exist in the group. If the first tuple is EOF then the
* group will have 0 items. Else it will have at least one item. The first group member is returned.
*
* @param group
* - should be empty
*/
protected Tuple loadEqualTupleGroup(PushBackStream stream, LinkedList group, StreamComparator groupComparator)
throws IOException {
// Find next set of same tuples from the stream
Tuple firstMember = stream.read();
if (!firstMember.EOF) {
// first in group, implicitly a member
group.add(firstMember);
BREAKPOINT: while (true) {
Tuple nMember = stream.read();
if (!nMember.EOF && 0 == groupComparator.compare(firstMember, nMember)) {
// they are in same group
group.add(nMember);
} else {
stream.pushBack(nMember);
break BREAKPOINT;
}
}
}
return firstMember;
}
public int getCost() {
return 0;
}
}
