Github user ajs6f commented on a diff in the pull request:
https://github.com/apache/jena/pull/94#discussion_r44025441
--- Diff:
jena-arq/src/main/java/org/apache/jena/sparql/core/assembler/InMemDatasetAssembler.java
---
@@ -0,0 +1,67 @@
+package org.apache.jena.sparql.core.assembler;
+
+import static org.apache.jena.assembler.JA.MemoryDataset;
+import static org.apache.jena.assembler.JA.data;
+import static org.apache.jena.query.DatasetFactory.createTxnMem;
+import static org.apache.jena.riot.RDFDataMgr.loadModel;
+import static org.apache.jena.riot.RDFDataMgr.read;
+import static
org.apache.jena.sparql.core.assembler.AssemblerUtils.setContext;
+import static
org.apache.jena.sparql.core.assembler.DatasetAssemblerVocab.*;
+import static org.apache.jena.sparql.util.FmtUtils.stringForRDFNode;
+import static org.apache.jena.sparql.util.graph.GraphUtils.*;
+
+import java.util.function.Predicate;
+
+import org.apache.jena.assembler.Assembler;
+import org.apache.jena.assembler.Mode;
+import org.apache.jena.assembler.assemblers.AssemblerBase;
+import org.apache.jena.query.Dataset;
+import org.apache.jena.rdf.model.Model;
+import org.apache.jena.rdf.model.RDFNode;
+import org.apache.jena.rdf.model.Resource;
+
+/**
+ * An {@link Assembler} that creates in-memory {@link Dataset}s.
+ *
+ */
+public class InMemDatasetAssembler extends AssemblerBase {
+
+ @Override
+ public Dataset open(final Assembler assembler, final Resource root,
final Mode mode) {
+ checkType(root, MemoryDataset);
+ final Dataset dataset = createTxnMem();
+ setContext(root, dataset.getContext());
+ // Default graph can be defined with ja:graph or ja:defaultGraph
+ final Resource defaultGraphDef =
root.hasProperty(pDefaultGraph) ? getResourceValue(root,
+ pDefaultGraph) : root.hasProperty(pGraph) ?
getResourceValue(root, pGraph) : null;
+ if (defaultGraphDef != null)
dataset.setDefaultModel(retrieve(defaultGraphDef, assembler, mode));
+ // or with ja:data
+ final Predicate<RDFNode> isResource = n -> {
+ if (n.isResource()) return true;
+ throw new DatasetAssemblerException(root, "Not a
resource: " + stringForRDFNode(n));
+ };
+ multiValue(root, data).parallelStream().filter(isResource)
+ .forEach(defaultGraphNode -> read(dataset,
defaultGraphNode.asResource().getURI()));
+
--- End diff --
The hope from using `parallelStream` was indeed to queue on the lock, but
get _reading_ going in parallel. IOW, reading could require network access or
filesystem access that could very well be parallelized. But I take your point
about the order of error messages. That could be really terribly confusing.
I'll pull out the parallelization.
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