- Use asBitVectorIterator instead of isBitVector + casting to present a BitVectorIterator interface.

- Allow Filter wrapper to expose underlying BitVector.
   - This ensures that the bitvectors are handled first during termwise evaluation,
     as they have a constant cost and will reduce the cost for the ones coming later on.

4 files changed, 15 insertions, 10 deletions

diff --git a/searchlib/src/vespa/searchlib/common/bitvectoriterator.h b/searchlib/src/vespa/searchlib/common/bitvectoriterator.h
index 08d2e76f9ee..4c68168c34e 100644
--- a/searchlib/src/vespa/searchlib/common/bitvectoriterator.h
+++ b/searchlib/src/vespa/searchlib/common/bitvectoriterator.h
@@ -23,7 +23,7 @@ private:
     void doUnpack(uint32_t docId) override final {
         _tfmd.resetOnlyDocId(docId);
     }
-    bool isBitVector() const override { return true; }
+    BitVectorIterator * asBitVector() noexcept override { return this; }
     fef::TermFieldMatchData  &_tfmd;
 public:
     virtual bool isInverted() const = 0;
diff --git a/searchlib/src/vespa/searchlib/queryeval/filter_wrapper.h b/searchlib/src/vespa/searchlib/queryeval/filter_wrapper.h
index f3992c995f2..b3024694fb9 100644
--- a/searchlib/src/vespa/searchlib/queryeval/filter_wrapper.h
+++ b/searchlib/src/vespa/searchlib/queryeval/filter_wrapper.h
@@ -55,6 +55,9 @@ public:
     BitVector::UP get_hits(uint32_t begin_id) override {
         return _wrapped_search->get_hits(begin_id);
     }
+    BitVectorIterator * asBitVector() noexcept override {
+        return _wrapped_search->asBitVector();
+    }
     Trinary is_strict() const override {
         return _wrapped_search->is_strict();
     }
diff --git a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
index 4eb57eda911..84a13a8623f 100644
--- a/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
+++ b/searchlib/src/vespa/searchlib/queryeval/multibitvectoriterator.cpp
@@ -119,7 +119,7 @@ public:
           _mbv(getChildren().size() + 1)
     {
         for (const auto & child : getChildren()) {
-            const auto * bv = static_cast<const BitVectorIterator *>(child.get());
+            const auto * bv = child->asBitVector();
             _mbv.addBitVector(Meta(bv->getBitValues(), bv->isInverted()), bv->getDocIdLimit());
         }
     }
@@ -168,9 +168,9 @@ SearchIterator::UP
 MultiBitVectorIterator<Update>::andWith(UP filter, uint32_t estimate)
 {
     (void) estimate;
-    if (filter->isBitVector() && acceptExtraFilter()) {
-        const auto & bv = static_cast<const BitVectorIterator &>(*filter);
-        _mbv.addBitVector(Meta(bv.getBitValues(), bv.isInverted()), bv.getDocIdLimit());
+    const BitVectorIterator * bv = filter->asBitVector();
+    if (bv && acceptExtraFilter()) {
+        _mbv.addBitVector(Meta(bv->getBitValues(), bv->isInverted()), bv->getDocIdLimit());
         insert(getChildren().size(), std::move(filter));
         _mbv.reset();
     }
@@ -225,9 +225,7 @@ MultiBitVectorIteratorBase::doUnpack(uint32_t docid)
         MultiSearch::doUnpack(docid);
     } else {
         auto &children = getChildren();
-        _unpackInfo.each([&children,docid](size_t i) {
-                static_cast<BitVectorIterator *>(children[i].get())->unpack(docid);
-            }, children.size());
+        _unpackInfo.each([&children,docid](size_t i) { children[i]->unpack(docid); }, children.size());
     }
 }
 
diff --git a/searchlib/src/vespa/searchlib/queryeval/searchiterator.h b/searchlib/src/vespa/searchlib/queryeval/searchiterator.h
index 4ab066727af..7c01ad44789 100644
--- a/searchlib/src/vespa/searchlib/queryeval/searchiterator.h
+++ b/searchlib/src/vespa/searchlib/queryeval/searchiterator.h
@@ -15,7 +15,10 @@ namespace vespalib::slime {
     struct Inserter;
 }
 
-namespace search { class BitVector; }
+namespace search {
+    class BitVector;
+    class BitVectorIterator;
+}
 namespace search::attribute { class ISearchContext; }
 
 namespace search::queryeval {
@@ -331,7 +334,8 @@ public:
     /**
      * @return true if it is a bitvector
      */
-    virtual bool isBitVector() const { return false; }
+    bool isBitVector() noexcept { return asBitVector() != nullptr; }
+    virtual BitVectorIterator * asBitVector() noexcept { return nullptr; }
     /**
      * @return true if it is a source blender
      */