Factor out fallback_to_approx_num_hits() member function in

posting list search contexts.

2 files changed, 16 insertions, 32 deletions

diff --git a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h
index 6f148d1d5ba..1baf75d1bdf 100644
--- a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h
+++ b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h
@@ -32,6 +32,10 @@ protected:
     using FrozenDictionary = Dictionary::FrozenView;
     using EnumIndex = IEnumStore::Index;
 
+    static constexpr long MIN_UNIQUE_VALUES_BEFORE_APPROXIMATION = 100;
+    static constexpr long MIN_UNIQUE_VALUES_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION = 20;
+    static constexpr long MIN_APPROXHITS_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION = 10;
+
     const IEnumStoreDictionary & _dictionary;
     const ISearchContext       &_baseSearchCtx;
     const BitVector            *_bv; // bitvector if _useBitVector has been set
@@ -89,6 +93,12 @@ protected:
         return (numHits > 1000) &&
             (calculateFilteringCost() < calculatePostingListCost(numHits));
     }
+    virtual bool fallback_to_approx_num_hits() const {
+        return ((_uniqueValues > MIN_UNIQUE_VALUES_BEFORE_APPROXIMATION) &&
+                ((_uniqueValues * MIN_UNIQUE_VALUES_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION > static_cast<int>(_docIdLimit)) ||
+                 (calculateApproxNumHits() * MIN_APPROXHITS_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION > _docIdLimit) ||
+                 (_uniqueValues > MIN_UNIQUE_VALUES_BEFORE_APPROXIMATION*10)));
+    }
 };
 
 
@@ -110,10 +120,6 @@ protected:
      */
     PostingListMerger<DataT> _merger;
 
-    static const long MIN_UNIQUE_VALUES_BEFORE_APPROXIMATION = 100;
-    static const long MIN_UNIQUE_VALUES_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION = 20;
-    static const long MIN_APPROXHITS_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION = 10;
-
     PostingListSearchContextT(const IEnumStoreDictionary& dictionary, uint32_t docIdLimit, uint64_t numValues,
                               bool hasWeight, const PostingList &postingList,
                               bool useBitVector, const ISearchContext &baseSearchCtx);
@@ -156,7 +162,7 @@ protected:
                                     bool hasWeight, const PostingList &postingList,
                                     bool useBitVector, const ISearchContext &baseSearchCtx);
 
-    unsigned int approximateHits() const override;
+    bool fallback_to_approx_num_hits() const override;
 };
 
 
diff --git a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp
index b466f8189f1..91054b02d1e 100644
--- a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp
+++ b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp
@@ -234,18 +234,9 @@ PostingListSearchContextT<DataT>::approximateHits() const
     } else {
         if (this->fallbackToFiltering()) {
             numHits = _docIdLimit;
-        } else if (_uniqueValues > MIN_UNIQUE_VALUES_BEFORE_APPROXIMATION) {
-            if ((_uniqueValues * MIN_UNIQUE_VALUES_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION > static_cast<int>(_docIdLimit)) ||
-                (this->calculateApproxNumHits() * MIN_APPROXHITS_TO_NUMDOCS_RATIO_BEFORE_APPROXIMATION > _docIdLimit) ||
-                (_uniqueValues > MIN_UNIQUE_VALUES_BEFORE_APPROXIMATION*10))
-            {
-                numHits = this->calculateApproxNumHits();
-            } else {
-                // XXX: Unsafe
-                numHits = countHits();
-            }
+        } else if (this->fallback_to_approx_num_hits()) {
+            numHits = this->calculateApproxNumHits();
         } else {
-            // XXX: Unsafe
             numHits = countHits();
         }
     }
@@ -286,24 +277,11 @@ PostingListFoldedSearchContextT(const IEnumStoreDictionary& dictionary, uint32_t
 {
 }
 
-
 template <typename DataT>
-unsigned int
-PostingListFoldedSearchContextT<DataT>::approximateHits() const
+bool
+PostingListFoldedSearchContextT<DataT>::fallback_to_approx_num_hits() const
 {
-    unsigned int numHits = 0;
-    if (_uniqueValues == 0u) {
-    } else if (_uniqueValues == 1u) {
-        numHits = singleHits();
-    } else {
-        if (this->fallbackToFiltering()) {
-            numHits = _docIdLimit;
-        } else {
-            // XXX: Unsafe
-            numHits = countHits();
-        }
-    }
-    return numHits;
+    return false;
 }
 
 }