Github user afs commented on a diff in the pull request:
https://github.com/apache/jena/pull/47#discussion_r29499213
--- Diff:
jena-core/src/main/java/com/hp/hpl/jena/reasoner/rulesys/impl/LPBRuleEngine.java
---
@@ -252,19 +272,31 @@ public synchronized void tablePredicate(Node
predicate) {
/**
* Return a generator for the given goal (assumes that the caller
knows that
* the goal should be tabled).
+ *
+ * Note: If an earlier Generator for the same <code>goal</code> exists
in the
+ * cache, it will be returned without considering the provided
<code>clauses</code>.
+ *
* @param goal the goal whose results are to be generated
* @param clauses the precomputed set of code blocks used to implement
the goal
*/
- public synchronized Generator generatorFor(TriplePattern goal,
List<RuleClauseCode> clauses) {
- Generator generator = tabledGoals.get(goal);
- if (generator == null) {
- LPInterpreter interpreter = new LPInterpreter(this, goal,
clauses, false);
- activeInterpreters.add(interpreter);
- generator = new Generator(interpreter, goal);
- schedule(generator);
- tabledGoals.put(goal, generator);
- }
- return generator;
+ public synchronized Generator generatorFor(final TriplePattern goal,
final List<RuleClauseCode> clauses) {
+ return getCachedTabledGoal(goal, new Callable<Generator>() {
+ @Override
+ public Generator call() {
+ /** FIXME: Unify with
#generatorFor(TriplePattern) - but investigate what about
+ * the edge case that this method might have
been called with the of goal == null
+ * or goal.size()==0 -- which gives different
behaviour in
+ * LPInterpreter constructor than through the
route of
+ * generatorFor(TriplePattern) which calls a
different LPInterpreter constructor
+ * which would fill in from RuleStore.
+ */
--- End diff --
I don't know enough about the rules engine to comment. We need another
reviewer here.
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