| /** |
| * 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.rya.streams.client.util; |
| |
| import static java.util.Objects.requireNonNull; |
| |
| import java.io.OutputStream; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| import org.apache.rya.api.model.VisibilityBindingSet; |
| import org.apache.rya.api.model.VisibilityStatement; |
| import org.apache.rya.streams.api.entity.QueryResultStream; |
| import org.apache.rya.streams.api.exception.RyaStreamsException; |
| import org.openrdf.query.TupleQueryResultHandlerException; |
| import org.openrdf.query.algebra.TupleExpr; |
| import org.openrdf.query.resultio.sparqljson.SPARQLResultsJSONWriter; |
| import org.openrdf.rio.RDFFormat; |
| import org.openrdf.rio.RDFHandlerException; |
| import org.openrdf.rio.RDFWriter; |
| import org.openrdf.rio.Rio; |
| import org.openrdf.rio.WriterConfig; |
| import org.openrdf.rio.helpers.BasicWriterSettings; |
| |
| import com.google.common.collect.Lists; |
| |
| import edu.umd.cs.findbugs.annotations.DefaultAnnotation; |
| import edu.umd.cs.findbugs.annotations.NonNull; |
| |
| /** |
| * A utility that writes {@link QueryResultStream} results to an {@link OutputStream}. |
| */ |
| @DefaultAnnotation(NonNull.class) |
| public class QueryResultsOutputUtil { |
| |
| /** |
| * Private constructor to prevent instantiation. |
| */ |
| private QueryResultsOutputUtil() { } |
| |
| /** |
| * Writes the results of a {@link QueryResultStream} to the output stream as NTriples until the |
| * shutdown signal is set. |
| * |
| * @param out - The stream the NTriples data will be written to. (not null) |
| * @param resultsStream - The results stream that will be polled for results to |
| * write to {@code out}. (not null) |
| * @param shutdownSignal - Setting this signal will cause the thread that |
| * is processing this function to finish and leave. (not null) |
| * @throws RDFHandlerException A problem was encountered while |
| * writing the NTriples to the output stream. |
| * @throws IllegalStateException The {@code resultsStream} is closed. |
| * @throws RyaStreamsException Could not fetch the next set of results. |
| */ |
| public static void toNtriplesFile( |
| final OutputStream out, |
| final QueryResultStream<VisibilityStatement> resultsStream, |
| final AtomicBoolean shutdownSignal) throws RDFHandlerException, IllegalStateException, RyaStreamsException { |
| requireNonNull(out); |
| requireNonNull(resultsStream); |
| requireNonNull(shutdownSignal); |
| |
| final RDFWriter writer = Rio.createWriter(RDFFormat.NTRIPLES, out); |
| writer.startRDF(); |
| |
| while(!shutdownSignal.get()) { |
| final Iterable<VisibilityStatement> it = resultsStream.poll(1000); |
| for(final VisibilityStatement result : it) { |
| writer.handleStatement(result); |
| } |
| } |
| |
| writer.endRDF(); |
| } |
| |
| /** |
| * Writes the results of a {@link QueryResultStream} to the output stream as JSON until the |
| * shutdown signal is set. |
| * |
| * @param out - The stream the JSON will be written to. (not null) |
| * @param query - The parsed SPARQL Query whose results are being output. This |
| * object is used to figure out which bindings may appear. (not null) |
| * @param resultsStream - The results stream that will be polled for results to |
| * write to {@code out}. (not null) |
| * @param shutdownSignal - Setting this signal will cause the thread that |
| * is processing this function to finish and leave. (not null) |
| * @throws TupleQueryResultHandlerException A problem was encountered while |
| * writing the JSON to the output stream. |
| * @throws IllegalStateException The {@code resultsStream} is closed. |
| * @throws RyaStreamsException Could not fetch the next set of results. |
| */ |
| public static void toBindingSetJSONFile( |
| final OutputStream out, |
| final TupleExpr query, |
| final QueryResultStream<VisibilityBindingSet> resultsStream, |
| final AtomicBoolean shutdownSignal) throws TupleQueryResultHandlerException, IllegalStateException, RyaStreamsException { |
| requireNonNull(out); |
| requireNonNull(query); |
| requireNonNull(resultsStream); |
| requireNonNull(shutdownSignal); |
| |
| // Create a writer that does not pretty print. |
| final SPARQLResultsJSONWriter writer = new SPARQLResultsJSONWriter(out); |
| final WriterConfig config = writer.getWriterConfig(); |
| config.set(BasicWriterSettings.PRETTY_PRINT, false); |
| |
| // Start the JSON and enumerate the possible binding names. |
| writer.startQueryResult( Lists.newArrayList(query.getBindingNames()) ); |
| |
| while(!shutdownSignal.get()) { |
| for(final VisibilityBindingSet result : resultsStream.poll(1000)) { |
| writer.handleSolution(result); |
| } |
| } |
| |
| writer.endQueryResult(); |
| } |
| } |