working on new ID based join iterator

Author: hmottestad

core/sail/lmdb/src/main/java/org/eclipse/rdf4j/sail/lmdb/LmdbOverlayEvaluationDataset.java

@@ -292,8 +292,8 @@ public RecordIterator getOrderedRecordIterator(long[] binding, int subjIndex, in
 			return getRecordIteratorInternal(binding, subjIndex, predIndex, objIndex, ctxIndex, patternIds, keyBuffers,
 					bindingReuse, quadReuse);
 		}
-		return getOrderedRecordIterator(binding, subjIndex, predIndex, objIndex, ctxIndex, patternIds, order,
-				bindingReuse, quadReuse);
+		return LmdbEvaluationDataset.super.getOrderedRecordIterator(binding, subjIndex, predIndex, objIndex, ctxIndex,
+				patternIds, order, keyBuffers, bindingReuse, quadReuse);
 	}
 
 	@Override

core/sail/lmdb/src/main/java/org/eclipse/rdf4j/sail/lmdb/LmdbSailStore.java

@@ -1582,7 +1582,6 @@ public void close() {
 				if (base != null) {
 					base.close();
 					base = null;
-					lmdbBase = null;
 				}
 			}
 		}

core/sail/lmdb/src/main/java/org/eclipse/rdf4j/sail/lmdb/join/LmdbIdJoinIterator.java

@@ -38,7 +38,7 @@ public class LmdbIdJoinIterator extends LookAheadIteration<BindingSet> {
 
 	@FunctionalInterface
 	interface RecordIteratorFactory {
-		RecordIterator apply(long[] leftRecord) throws QueryEvaluationException;
+		RecordIterator apply(long[] leftRecord, RecordIterator reuse) throws QueryEvaluationException;
 	}
 
 	private static final RecordIterator EMPTY_RECORD_ITERATOR = new RecordIterator() {
@@ -228,6 +228,7 @@ private Value resolveValue(long id, int position, ValueStore valueStore) throws
 	private final BindingSet initialBindings;
 	private final ValueStore valueStore;
 
+	private RecordIterator reusableRightIterator;
 	private RecordIterator currentRightIterator;
 	private long[] currentLeftRecord;
 	private BindingSet currentLeftBinding;
@@ -263,21 +264,38 @@ protected BindingSet getNextElement() throws QueryEvaluationException {
 					}
 					return result;
 				}
-				currentRightIterator.close();
+				RecordIterator completed = currentRightIterator;
 				currentRightIterator = null;
+				if (completed != EMPTY_RECORD_ITERATOR) {
+					reusableRightIterator = completed;
+				} else {
+					reusableRightIterator = null;
+				}
+				completed.close();
 			}
 
 			long[] leftRecord = nextRecord(leftIterator);
 			if (leftRecord == null) {
+				reusableRightIterator = null;
 				return null;
 			}
 
 			currentLeftRecord = leftRecord;
 			currentLeftBinding = null;
 
-			currentRightIterator = rightFactory.apply(leftRecord);
+			RecordIterator reuseCandidate = reusableRightIterator;
+			if (reuseCandidate == EMPTY_RECORD_ITERATOR) {
+				reuseCandidate = null;
+			}
+
+			currentRightIterator = rightFactory.apply(leftRecord, reuseCandidate);
 			if (currentRightIterator == null) {
 				currentRightIterator = emptyRecordIterator();
+				reusableRightIterator = null;
+			} else if (currentRightIterator == EMPTY_RECORD_ITERATOR) {
+				reusableRightIterator = null;
+			} else {
+				reusableRightIterator = currentRightIterator;
 			}
 		}
 	}

core/sail/lmdb/src/main/java/org/eclipse/rdf4j/sail/lmdb/join/LmdbIdJoinQueryEvaluationStep.java

@@ -188,7 +188,6 @@ public CloseableIteration<BindingSet> evaluate(BindingSet bindings) {
 			}
 
 			final RecordIterator[] leftReuseHolder = new RecordIterator[1];
-			final RecordIterator[] rightReuseHolder = new RecordIterator[1];
 
 			if (!"false".equalsIgnoreCase(System.getProperty("rdf4j.lmdb.experimentalTwoPatternArrayJoin", "true"))) {
 				ValueStore valueStore = dataset.getValueStore();
@@ -216,7 +215,7 @@ public CloseableIteration<BindingSet> evaluate(BindingSet bindings) {
 				long[] bindingSnapshot = new long[initialBinding.length];
 				long[] rightScratch = new long[initialBinding.length];
 				long[] rightQuadScratch = new long[4];
-				LmdbIdJoinIterator.RecordIteratorFactory rightFactory = leftRecord -> {
+				LmdbIdJoinIterator.RecordIteratorFactory rightFactory = (leftRecord, reuse) -> {
 					System.arraycopy(initialBinding, 0, bindingSnapshot, 0, initialBinding.length);
 					for (String name : leftInfo.getVariableNames()) {
 						int pos = bindingInfo.getIndex(name);
@@ -228,13 +227,7 @@ public CloseableIteration<BindingSet> evaluate(BindingSet bindings) {
 						}
 					}
 					RecordIterator iter = dataset.getRecordIterator(bindingSnapshot, subjIdx, predIdx, objIdx, ctxIdx,
-							patternIds, keyBuffersFor(rightPattern), rightScratch, rightQuadScratch,
-							rightReuseHolder[0]);
-					if (iter != null && iter != LmdbIdJoinIterator.emptyRecordIterator()) {
-						rightReuseHolder[0] = iter;
-					} else {
-						rightReuseHolder[0] = null;
-					}
+							patternIds, keyBuffersFor(rightPattern), rightScratch, rightQuadScratch, reuse);
 					return iter;
 				};
 
@@ -252,19 +245,14 @@ patternIds, keyBuffersFor(rightPattern), rightScratch, rightQuadScratch,
 				leftReuseHolder[0] = null;
 			}
 
-			LmdbIdJoinIterator.RecordIteratorFactory rightFactory = leftRecord -> {
+			LmdbIdJoinIterator.RecordIteratorFactory rightFactory = (leftRecord, reuse) -> {
 				MutableBindingSet bs = context.createBindingSet();
 				bindings.forEach(binding -> bs.addBinding(binding.getName(), binding.getValue()));
 				if (!leftInfo.applyRecord(leftRecord, bs, valueStore)) {
 					return LmdbIdJoinIterator.emptyRecordIterator();
 				}
 				RecordIterator rightIter = dataset.getRecordIterator(rightPattern, bs, keyBuffersFor(rightPattern),
-						rightReuseHolder[0]);
-				if (rightIter != null && rightIter != LmdbIdJoinIterator.emptyRecordIterator()) {
-					rightReuseHolder[0] = rightIter;
-				} else {
-					rightReuseHolder[0] = null;
-				}
+						reuse);
 				return rightIter;
 			};