allow queries with filters to use fast-lane reducers

CHANGELOG.md

@@ -7,13 +7,18 @@ Changelog
 
 * `OSMEntitySnapshot` now also returns the `lastContributionTimestamp` for each snapshot ([#495])
 
+### performance improvements
+
+* Significantly improve performance of queries which use filters and don't use `flatMap` ([#511])
+
 ### other changes
 
 * `CellIterator` is now decoupled from implementation of the "Grid" ([#495])
 * Enhance geometry builder with methods to generate geometries from entities when their members are already pre-resolved for a specific timestamp ([#501])
 
 [#495]: https://github.com/GIScience/oshdb/pull/495
 [#501]: https://github.com/GIScience/oshdb/pull/501
+[#511]: https://github.com/GIScience/oshdb/pull/511
 
 
 ## 1.1.2

oshdb-api-ignite/src/main/java/org/heigit/ohsome/oshdb/api/mapreducer/backend/MapReducerIgniteAffinityCall.java

@@ -292,7 +292,7 @@ cacheName, cellIdRangeToCellIds(), cellIdRanges, cellProcessor, cellIterator
 
   @Override
   protected <R, S> S mapReduceCellsOSMContribution(
-      SerializableFunction<OSMContribution, R> mapper,
+      SerializableFunction<OSMContribution, Optional<R>> mapper,
       SerializableSupplier<S> identitySupplier,
       SerializableBiFunction<S, R, S> accumulator,
       SerializableBinaryOperator<S> combiner
@@ -331,7 +331,7 @@ protected <R, S> S flatMapReduceCellsOSMContributionGroupedById(
 
   @Override
   protected <R, S> S mapReduceCellsOSMEntitySnapshot(
-      SerializableFunction<OSMEntitySnapshot, R> mapper,
+      SerializableFunction<OSMEntitySnapshot, Optional<R>> mapper,
       SerializableSupplier<S> identitySupplier,
       SerializableBiFunction<S, R, S> accumulator,
       SerializableBinaryOperator<S> combiner
@@ -371,7 +371,7 @@ protected <R, S> S flatMapReduceCellsOSMEntitySnapshotGroupedById(
 
   @Override
   protected Stream<X> mapStreamCellsOSMContribution(
-      SerializableFunction<OSMContribution, X> mapper) throws Exception {
+      SerializableFunction<OSMContribution, Optional<X>> mapper) throws Exception {
     return stream(Kernels.getOSMContributionCellStreamer(mapper, this));
   }
 
@@ -383,7 +383,7 @@ protected Stream<X> flatMapStreamCellsOSMContributionGroupedById(
 
   @Override
   protected Stream<X> mapStreamCellsOSMEntitySnapshot(
-      SerializableFunction<OSMEntitySnapshot, X> mapper) throws Exception {
+      SerializableFunction<OSMEntitySnapshot, Optional<X>> mapper) throws Exception {
     return stream(Kernels.getOSMEntitySnapshotCellStreamer(mapper, this));
   }
 

oshdb-api-ignite/src/main/java/org/heigit/ohsome/oshdb/api/mapreducer/backend/MapReducerIgniteLocalPeek.java

@@ -78,7 +78,7 @@ protected MapReducer<X> copy() {
 
   @Override
   protected Stream<X> mapStreamCellsOSMContribution(
-      SerializableFunction<OSMContribution, X> mapper
+      SerializableFunction<OSMContribution, Optional<X>> mapper
   ) throws Exception {
     throw new UnsupportedOperationException("Stream function not yet implemented");
   }
@@ -92,7 +92,7 @@ protected Stream<X> flatMapStreamCellsOSMContributionGroupedById(
 
   @Override
   protected Stream<X> mapStreamCellsOSMEntitySnapshot(
-      SerializableFunction<OSMEntitySnapshot, X> mapper
+      SerializableFunction<OSMEntitySnapshot, Optional<X>> mapper
   ) throws Exception {
     throw new UnsupportedOperationException("Stream function not yet implemented");
   }
@@ -115,7 +115,8 @@ public boolean isCancelable() {
   }
 
   @Override
-  protected <R, S> S mapReduceCellsOSMContribution(SerializableFunction<OSMContribution, R> mapper,
+  protected <R, S> S mapReduceCellsOSMContribution(
+      SerializableFunction<OSMContribution, Optional<R>> mapper,
       SerializableSupplier<S> identitySupplier, SerializableBiFunction<S, R, S> accumulator,
       SerializableBinaryOperator<S> combiner) throws Exception {
     return mapReduceOnIgniteCache((OSHDBIgnite) this.oshdb, identitySupplier, combiner,
@@ -140,7 +141,8 @@ protected <R, S> S flatMapReduceCellsOSMContributionGroupedById(
 
   @Override
   protected <R, S> S mapReduceCellsOSMEntitySnapshot(
-      SerializableFunction<OSMEntitySnapshot, R> mapper, SerializableSupplier<S> identitySupplier,
+      SerializableFunction<OSMEntitySnapshot, Optional<R>> mapper,
+      SerializableSupplier<S> identitySupplier,
       SerializableBiFunction<S, R, S> accumulator, SerializableBinaryOperator<S> combiner)
       throws Exception {
     return mapReduceOnIgniteCache((OSHDBIgnite) this.oshdb, identitySupplier, combiner,
@@ -290,12 +292,13 @@ S execute(Ignite node, CellProcessor<S> cellProcessor) {
 
   private static class MapReduceCellsOSMContributionOnIgniteCacheComputeJob
       <R, S, P extends Geometry & Polygonal>
-      extends MapReduceCellsOnIgniteCacheComputeJob<OSMContribution, R, R, S, P> {
+      extends MapReduceCellsOnIgniteCacheComputeJob<OSMContribution, R, Optional<R>, S, P> {
     MapReduceCellsOSMContributionOnIgniteCacheComputeJob(TagInterpreter tagInterpreter,
         List<String> cacheNames, Iterable<CellIdRange> cellIdRanges,
         SortedSet<OSHDBTimestamp> tstamps, OSHDBBoundingBox bbox, P poly,
         OSHEntityFilter preFilter, OSMEntityFilter filter,
-        SerializableFunction<OSMContribution, R> mapper, SerializableSupplier<S> identitySupplier,
+        SerializableFunction<OSMContribution, Optional<R>> mapper,
+        SerializableSupplier<S> identitySupplier,
         SerializableBiFunction<S, R, S> accumulator, SerializableBinaryOperator<S> combiner) {
       super(tagInterpreter, cacheNames, cellIdRanges, tstamps, bbox, poly, preFilter, filter,
           mapper, identitySupplier, accumulator, combiner);
@@ -339,12 +342,13 @@ public S execute(Ignite node) {
 
   private static class MapReduceCellsOSMEntitySnapshotOnIgniteCacheComputeJob
       <R, S, P extends Geometry & Polygonal>
-      extends MapReduceCellsOnIgniteCacheComputeJob<OSMEntitySnapshot, R, R, S, P> {
+      extends MapReduceCellsOnIgniteCacheComputeJob<OSMEntitySnapshot, R, Optional<R>, S, P> {
     MapReduceCellsOSMEntitySnapshotOnIgniteCacheComputeJob(TagInterpreter tagInterpreter,
         List<String> cacheNames, Iterable<CellIdRange> cellIdRanges,
         SortedSet<OSHDBTimestamp> tstamps, OSHDBBoundingBox bbox, P poly,
         OSHEntityFilter preFilter, OSMEntityFilter filter,
-        SerializableFunction<OSMEntitySnapshot, R> mapper, SerializableSupplier<S> identitySupplier,
+        SerializableFunction<OSMEntitySnapshot, Optional<R>> mapper,
+        SerializableSupplier<S> identitySupplier,
         SerializableBiFunction<S, R, S> accumulator, SerializableBinaryOperator<S> combiner) {
       super(tagInterpreter, cacheNames, cellIdRanges, tstamps, bbox, poly, preFilter, filter,
           mapper, identitySupplier, accumulator, combiner);
@@ -408,7 +412,7 @@ private static <V, R, M, S, P extends Geometry & Polygonal> S mapReduceOnIgniteC
         null
     );
 
-    if (!oshdb.timeoutInMilliseconds().isPresent()) {
+    if (oshdb.timeoutInMilliseconds().isEmpty()) {
       return asyncResult.get();
     } else {
       try {

oshdb-api-ignite/src/main/java/org/heigit/ohsome/oshdb/api/mapreducer/backend/MapReducerIgniteScanQuery.java

@@ -9,6 +9,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Optional;
 import java.util.SortedSet;
 import java.util.TreeMap;
 import java.util.UUID;
@@ -110,7 +111,8 @@ public boolean isCancelable() {
   // === map-reduce operations ===
 
   @Override
-  protected <R, S> S mapReduceCellsOSMContribution(SerializableFunction<OSMContribution, R> mapper,
+  protected <R, S> S mapReduceCellsOSMContribution(
+      SerializableFunction<OSMContribution, Optional<R>> mapper,
       SerializableSupplier<S> identitySupplier, SerializableBiFunction<S, R, S> accumulator,
       SerializableBinaryOperator<S> combiner) throws Exception {
     // load tag interpreter helper which is later used for geometry building
@@ -147,7 +149,8 @@ protected <R, S> S flatMapReduceCellsOSMContributionGroupedById(
 
   @Override
   protected <R, S> S mapReduceCellsOSMEntitySnapshot(
-      SerializableFunction<OSMEntitySnapshot, R> mapper, SerializableSupplier<S> identitySupplier,
+      SerializableFunction<OSMEntitySnapshot, Optional<R>> mapper,
+      SerializableSupplier<S> identitySupplier,
       SerializableBiFunction<S, R, S> accumulator, SerializableBinaryOperator<S> combiner)
       throws Exception {
     // load tag interpreter helper which is later used for geometry building
@@ -185,7 +188,7 @@ protected <R, S> S flatMapReduceCellsOSMEntitySnapshotGroupedById(
 
   @Override
   protected Stream<X> mapStreamCellsOSMContribution(
-      SerializableFunction<OSMContribution, X> mapper) throws Exception {
+      SerializableFunction<OSMContribution, Optional<X>> mapper) throws Exception {
     // load tag interpreter helper which is later used for geometry building
     TagInterpreter tagInterpreter = this.getTagInterpreter();
 
@@ -219,7 +222,7 @@ protected Stream<X> flatMapStreamCellsOSMContributionGroupedById(
 
   @Override
   protected Stream<X> mapStreamCellsOSMEntitySnapshot(
-      SerializableFunction<OSMEntitySnapshot, X> mapper) throws Exception {
+      SerializableFunction<OSMEntitySnapshot, Optional<X>> mapper) throws Exception {
     // load tag interpreter helper which is later used for geometry building
     TagInterpreter tagInterpreter = this.getTagInterpreter();
 
@@ -367,12 +370,12 @@ S execute(Ignite node, CellProcessor<S> cellProcessor) {
 
   private static class MapReduceCellsOSMContributionOnIgniteCacheComputeJob
       <R, S, P extends Geometry & Polygonal>
-      extends MapReduceCellsOnIgniteCacheComputeJob<OSMContribution, R, R, S, P> {
+      extends MapReduceCellsOnIgniteCacheComputeJob<OSMContribution, R, Optional<R>, S, P> {
     MapReduceCellsOSMContributionOnIgniteCacheComputeJob(TagInterpreter tagInterpreter,
         String cacheName, Map<Integer, TreeMap<Long, CellIdRange>> cellIdRangesByLevel,
         SortedSet<OSHDBTimestamp> tstamps, OSHDBBoundingBox bbox, P poly,
         OSHEntityFilter preFilter, OSMEntityFilter filter,
-        SerializableFunction<OSMContribution, R> mapper,
+        SerializableFunction<OSMContribution, Optional<R>> mapper,
         SerializableSupplier<S> identitySupplier, SerializableBiFunction<S, R, S> accumulator,
         SerializableBinaryOperator<S> combiner) {
       super(tagInterpreter, cacheName, cellIdRangesByLevel, tstamps, bbox, poly, preFilter, filter,
@@ -417,12 +420,12 @@ public S execute(Ignite node) {
 
   private static class MapReduceCellsOSMEntitySnapshotOnIgniteCacheComputeJob
       <R, S, P extends Geometry & Polygonal>
-      extends MapReduceCellsOnIgniteCacheComputeJob<OSMEntitySnapshot, R, R, S, P> {
+      extends MapReduceCellsOnIgniteCacheComputeJob<OSMEntitySnapshot, R, Optional<R>, S, P> {
     MapReduceCellsOSMEntitySnapshotOnIgniteCacheComputeJob(TagInterpreter tagInterpreter,
         String cacheName, Map<Integer, TreeMap<Long, CellIdRange>> cellIdRangesByLevel,
         SortedSet<OSHDBTimestamp> tstamps, OSHDBBoundingBox bbox, P poly,
         OSHEntityFilter preFilter, OSMEntityFilter filter,
-        SerializableFunction<OSMEntitySnapshot, R> mapper,
+        SerializableFunction<OSMEntitySnapshot, Optional<R>> mapper,
         SerializableSupplier<S> identitySupplier, SerializableBiFunction<S, R, S> accumulator,
         SerializableBinaryOperator<S> combiner) {
       super(tagInterpreter, cacheName, cellIdRangesByLevel, tstamps, bbox, poly, preFilter, filter,

oshdb-api-ignite/src/test/java/org/heigit/ohsome/oshdb/api/tests/MapReduceOSHDBIgniteAffinityCallTest.java

@@ -22,19 +22,4 @@ class MapReduceOSHDBIgniteAffinityCallTest extends MapReduceOSHDBIgniteTest {
   MapReduceOSHDBIgniteAffinityCallTest() throws Exception {
     super(oshdb -> oshdb.computeMode(AFFINITY_CALL));
   }
-
-  @Test
-  void testOSMEntitySnapshotViewStreamNullValues() throws Exception {
-    // simple stream query
-    Set<Integer> result = createMapReducerOSMEntitySnapshot()
-        .timestamps(
-            new OSHDBTimestamps("2010-01-01", "2015-01-01", OSHDBTimestamps.Interval.YEARLY))
-        .filter("id:617308093")
-        .map(snapshot -> snapshot.getEntity().getUserId())
-        .map(x -> (Integer) null)
-        .stream()
-        .collect(Collectors.toSet());
-
-    assertEquals(1, result.size());
-  }
 }

oshdb-api/src/main/java/org/heigit/ohsome/oshdb/api/mapreducer/FilterFunction.java

@@ -0,0 +1,28 @@
+package org.heigit.ohsome.oshdb.api.mapreducer;
+
+import java.util.Collections;
+import org.heigit.ohsome.oshdb.util.function.SerializablePredicate;
+
+/**
+ * A special map function that represents a filter.
+ *
+ * <p>Note that this class is using raw types on purpose because MapReducer's "map functions"
+ * are designed to input and output arbitrary data types. The necessary type checks are performed
+ * at at runtime in the respective setters.</p>
+ */
+@SuppressWarnings({"rawtypes", "unchecked"}) // see javadoc above
+class FilterFunction extends MapFunction {
+  private final SerializablePredicate filter;
+
+  FilterFunction(SerializablePredicate filter) {
+    super((x, ignored) -> filter.test(x)
+        ? Collections.singletonList(x)
+        : Collections.emptyList(),
+        true);
+    this.filter = filter;
+  }
+
+  public boolean test(Object root) {
+    return this.filter.test(root);
+  }
+}