/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package lupos.engine.operators.singleinput.federated;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
import lupos.datastructures.bindings.Bindings;
import lupos.datastructures.items.Variable;
import lupos.datastructures.items.literal.LazyLiteral;
import lupos.datastructures.items.literal.Literal;
import lupos.datastructures.items.literal.URILiteral;
import lupos.datastructures.queryresult.QueryResult;
import lupos.endpoint.client.Client;
import lupos.misc.util.ImmutableIterator;
import lupos.sparql1_1.Node;
public class FederatedQueryFetchAsNeededWithCache extends FederatedQueryFetchAsNeeded {
public HashMap<Bindings, QueryResult> cache = new HashMap<Bindings, QueryResult>();
public FederatedQueryFetchAsNeededWithCache(final Node federatedQuery) {
super(federatedQuery);
}
@Override
public QueryResult process(final QueryResult bindings, final int operandID) {
return QueryResult.createInstance(new ImmutableIterator<Bindings>(){
private final Iterator<Bindings> bindingsIterator = bindings.iterator();
private Iterator<Bindings> currentIteratorQueryResult = this.nextIteratorQueryResult();
@Override
public boolean hasNext() {
if(this.currentIteratorQueryResult==null){
return false;
}
while(!this.currentIteratorQueryResult.hasNext()){
this.currentIteratorQueryResult = this.nextIteratorQueryResult();
if(this.currentIteratorQueryResult==null){
return false;
}
}
return true;
}
@Override
public Bindings next() {
if(this.hasNext()){
return this.currentIteratorQueryResult.next();
} else {
return null;
}
}
private Iterator<Bindings> nextIteratorQueryResult(){
try {
if(!this.bindingsIterator.hasNext()){
return null;
}
final Bindings bindingsTemp = this.bindingsIterator.next();
final Bindings bindingsKey = bindingsTemp.clone();
final Set<Variable> otherVars = bindingsKey.getVariableSet();
otherVars.removeAll(FederatedQueryFetchAsNeededWithCache.this.variablesInServiceCall);
otherVars.remove(FederatedQueryFetchAsNeededWithCache.this.endpoint);
for(final Variable var: otherVars){
bindingsKey.add(var, null);
}
final QueryResult cached = FederatedQueryFetchAsNeededWithCache.this.cache.get(bindingsKey);
if(cached!=null){
return cached.iterator();
}
final String fQuery = FederatedQueryFetchAsNeededWithCache.this.toStringQuery(bindingsTemp);
if (!FederatedQueryFetchAsNeededWithCache.this.endpoint.isVariable()) {
final QueryResult queryResult = QueryResult.createInstance(new IteratorQueryResultAndOneBindings(Client.submitQuery(((URILiteral)FederatedQueryFetchAsNeededWithCache.this.endpoint).getString(), fQuery, FederatedQueryFetchAsNeededWithCache.this.bindingsFactory), bindingsTemp));
queryResult.materialize();
FederatedQueryFetchAsNeededWithCache.this.cache.put(bindingsKey, queryResult);
return queryResult.iterator();
} else {
Literal endpointURI = bindingsTemp.get((Variable) FederatedQueryFetchAsNeededWithCache.this.endpoint);
if (endpointURI instanceof LazyLiteral) {
endpointURI = ((LazyLiteral) endpointURI).getLiteral();
}
if (endpointURI instanceof URILiteral) {
final QueryResult queryResult = QueryResult.createInstance(new IteratorQueryResultAndOneBindings(Client.submitQuery(((URILiteral) endpointURI).getString(), fQuery, FederatedQueryFetchAsNeededWithCache.this.bindingsFactory), bindingsTemp));
queryResult.materialize();
FederatedQueryFetchAsNeededWithCache.this.cache.put(bindingsKey, queryResult);
return queryResult.iterator();
} else {
// ignore or error message?
}
}
} catch(final IOException e){
System.err.println(e);
e.printStackTrace();
}
// in case of error try next one:
return this.nextIteratorQueryResult();
}
});
}
}