make new bitvector when growing

18 files changed, 187 insertions, 151 deletions

diff --git a/searchlib/src/tests/common/bitvector/bitvector_test.cpp b/searchlib/src/tests/common/bitvector/bitvector_test.cpp
index a9850756ac6..79af28d20be 100644
--- a/searchlib/src/tests/common/bitvector/bitvector_test.cpp
+++ b/searchlib/src/tests/common/bitvector/bitvector_test.cpp
@@ -604,55 +604,55 @@ TEST("requireThatGrowWorks")
 {
     vespalib::GenerationHolder g;
     GrowableBitVector v(200, 200, g);
-    EXPECT_EQUAL(0u, v.countTrueBits());
+    EXPECT_EQUAL(0u, v.writer().countTrueBits());
     
-    v.setBitAndMaintainCount(7);
-    v.setBitAndMaintainCount(39);
-    v.setBitAndMaintainCount(71);
-    v.setBitAndMaintainCount(103);
-    EXPECT_EQUAL(4u, v.countTrueBits());
-
-    EXPECT_EQUAL(200u, v.size());
-    EXPECT_EQUAL(1023u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71,103]", v));
-    EXPECT_EQUAL(4u, v.countTrueBits());
+    v.writer().setBitAndMaintainCount(7);
+    v.writer().setBitAndMaintainCount(39);
+    v.writer().setBitAndMaintainCount(71);
+    v.writer().setBitAndMaintainCount(103);
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
+
+    EXPECT_EQUAL(200u, v.reader().size());
+    EXPECT_EQUAL(1023u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71,103]", v.reader()));
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
     EXPECT_TRUE(v.reserve(1024));
-    EXPECT_EQUAL(200u, v.size()); 
-    EXPECT_EQUAL(2047u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71,103]", v));
-    EXPECT_EQUAL(4u, v.countTrueBits());
+    EXPECT_EQUAL(200u, v.reader().size()); 
+    EXPECT_EQUAL(2047u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71,103]", v.reader()));
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
     EXPECT_FALSE(v.extend(202));
-    EXPECT_EQUAL(202u, v.size()); 
-    EXPECT_EQUAL(2047u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71,103]", v));
-    EXPECT_EQUAL(4u, v.countTrueBits());
+    EXPECT_EQUAL(202u, v.reader().size()); 
+    EXPECT_EQUAL(2047u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71,103]", v.reader()));
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
     EXPECT_FALSE(v.shrink(200));
-    EXPECT_EQUAL(200u, v.size()); 
-    EXPECT_EQUAL(2047u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71,103]", v));
-    EXPECT_EQUAL(4u, v.countTrueBits());
+    EXPECT_EQUAL(200u, v.reader().size()); 
+    EXPECT_EQUAL(2047u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71,103]", v.reader()));
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
     EXPECT_FALSE(v.reserve(2047));
-    EXPECT_EQUAL(200u, v.size()); 
-    EXPECT_EQUAL(2047u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71,103]", v));
-    EXPECT_EQUAL(4u, v.countTrueBits());
+    EXPECT_EQUAL(200u, v.reader().size()); 
+    EXPECT_EQUAL(2047u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71,103]", v.reader()));
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
     EXPECT_FALSE(v.shrink(202));
-    EXPECT_EQUAL(202u, v.size()); 
-    EXPECT_EQUAL(2047u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71,103]", v));
-    EXPECT_EQUAL(4u, v.countTrueBits());
+    EXPECT_EQUAL(202u, v.reader().size()); 
+    EXPECT_EQUAL(2047u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71,103]", v.reader()));
+    EXPECT_EQUAL(4u, v.writer().countTrueBits());
 
     EXPECT_FALSE(v.shrink(100));
-    EXPECT_EQUAL(100u, v.size()); 
-    EXPECT_EQUAL(2047u, v.capacity()); 
-    EXPECT_TRUE(assertBV("[7,39,71]", v));
-    EXPECT_EQUAL(3u, v.countTrueBits());
+    EXPECT_EQUAL(100u, v.reader().size()); 
+    EXPECT_EQUAL(2047u, v.writer().capacity()); 
+    EXPECT_TRUE(assertBV("[7,39,71]", v.reader()));
+    EXPECT_EQUAL(3u, v.writer().countTrueBits());
 
-    v.invalidateCachedCount();
+    v.writer().invalidateCachedCount();
     EXPECT_TRUE(v.reserve(3100));
-    EXPECT_EQUAL(100u, v.size());
-    EXPECT_EQUAL(4095u, v.capacity());
-    EXPECT_EQUAL(3u, v.countTrueBits());
+    EXPECT_EQUAL(100u, v.reader().size());
+    EXPECT_EQUAL(4095u, v.writer().capacity());
+    EXPECT_EQUAL(3u, v.writer().countTrueBits());
 
     g.transferHoldLists(1);
     g.trimHoldLists(2);
@@ -666,7 +666,7 @@ TEST("require that growable bit vectors keeps memory allocator")
     vespalib::GenerationHolder g;
     GrowableBitVector v(200, 200, g, &init_alloc);
     EXPECT_EQUAL(AllocStats(1, 0), stats);
-    v.resize(1);
+    v.writer().resize(1); // DO NOT TRY THIS AT HOME
     EXPECT_EQUAL(AllocStats(2, 1), stats);
     v.reserve(2000);
     EXPECT_EQUAL(AllocStats(3, 1), stats);
@@ -674,7 +674,7 @@ TEST("require that growable bit vectors keeps memory allocator")
     EXPECT_EQUAL(AllocStats(4, 1), stats);
     v.shrink(200);
     EXPECT_EQUAL(AllocStats(4, 1), stats);
-    v.resize(1);
+    v.writer().resize(1); // DO NOT TRY THIS AT HOME
     EXPECT_EQUAL(AllocStats(5, 2), stats);
     g.transferHoldLists(1);
     g.trimHoldLists(2);
diff --git a/searchlib/src/vespa/searchlib/attribute/flagattribute.cpp b/searchlib/src/vespa/searchlib/attribute/flagattribute.cpp
index d6aa136e15f..6e19d35a966 100644
--- a/searchlib/src/vespa/searchlib/attribute/flagattribute.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/flagattribute.cpp
@@ -62,7 +62,7 @@ void FlagAttributeT<B>::clearOldValues(DocId doc)
 {
     const typename B::WType * values(nullptr);
     for (uint32_t i(0), m(this->get(doc, values)); i < m; i++) {
-        BitVector * bv = _bitVectors[getOffset(multivalue::get_value(values[i]))];
+        BitVector * bv = _bitVectors[getOffset(multivalue::get_value(values[i]))].load_relaxed();
         if (bv != nullptr) {
             bv->clearBitAndMaintainCount(doc);
         }
@@ -103,7 +103,7 @@ bool FlagAttributeT<B>::onLoad(vespalib::Executor * executor)
 {
     for (size_t i(0), m(_bitVectors.size()); i < m; i++) {
         _bitVectorStore[i].reset();
-        _bitVectors[i] = nullptr;
+        _bitVectors[i].store_relaxed(nullptr);
     }
     _bitVectorSize = 0;
     return B::onLoad(executor);
@@ -119,12 +119,12 @@ void FlagAttributeT<B>::setNewValues(DocId doc, const std::vector<typename B::WT
     for (uint32_t i(0), m(values.size()); i < m; i++) {
         typename B::WType value = values[i];
         uint32_t offset = getOffset(value);
-        BitVector * bv = _bitVectors[offset];
+        BitVector * bv = _bitVectors[offset].load_relaxed();
         if (bv == nullptr) {
             assert(_bitVectorSize >= this->getNumDocs());
             _bitVectorStore[offset] = std::make_shared<GrowableBitVector>(_bitVectorSize, _bitVectorSize, _bitVectorHolder);
-            _bitVectors[offset] = _bitVectorStore[offset].get();
-            bv = _bitVectors[offset];
+            _bitVectors[offset].store_release(&_bitVectorStore[offset]->writer());
+            bv = _bitVectors[offset].load_relaxed();
             ensureGuardBit(*bv);
         }
         bv->setBitAndMaintainCount(doc);
@@ -136,12 +136,12 @@ void
 FlagAttributeT<B>::setNewBVValue(DocId doc, multivalue::ValueType_t<typename B::WType> value)
 {
     uint32_t offset = getOffset(value);
-    BitVector * bv = _bitVectors[offset];
+    BitVector * bv = _bitVectors[offset].load_relaxed();
     if (bv == nullptr) {
         assert(_bitVectorSize >= this->getNumDocs());
         _bitVectorStore[offset] = std::make_shared<GrowableBitVector>(_bitVectorSize, _bitVectorSize, _bitVectorHolder);
-        _bitVectors[offset] = _bitVectorStore[offset].get();
-        bv = _bitVectors[offset];
+        _bitVectors[offset].store_release(&_bitVectorStore[offset]->writer());
+        bv = _bitVectors[offset].load_relaxed();
         ensureGuardBit(*bv);
     }
     bv->setBitAndMaintainCount(doc);
@@ -186,7 +186,8 @@ template <typename B>
 void
 FlagAttributeT<B>::ensureGuardBit()
 {
-    for (BitVector * bv : _bitVectors) {
+    for (const auto &wrapper: _bitVectors) {
+        BitVector *bv = wrapper.load_relaxed();
         if (bv != nullptr) {
             ensureGuardBit(*bv);
         }
@@ -197,7 +198,8 @@ template <typename B>
 void
 FlagAttributeT<B>::clearGuardBit(DocId doc)
 {
-    for (BitVector * bv : _bitVectors) {
+    for (const auto &wrapper: _bitVectors) {
+        BitVector *bv = wrapper.load_relaxed();
         if (bv != nullptr) {
             bv->clearBit(doc); // clear guard bit and start using this doc id
         }
@@ -211,9 +213,12 @@ FlagAttributeT<B>::resizeBitVectors(uint32_t neededSize)
     const GrowStrategy & gs = this->getConfig().getGrowStrategy();
     uint32_t newSize = neededSize + (neededSize * gs.getDocsGrowFactor()) + gs.getDocsGrowDelta();
     for (size_t i(0), m(_bitVectors.size()); i < m; i++) {
-        BitVector *bv = _bitVectors[i];
+        BitVector *bv = _bitVectors[i].load_relaxed();
         if (bv != nullptr) {
-            _bitVectorStore[i]->extend(newSize);
+            if (_bitVectorStore[i]->extend(newSize)) {
+                _bitVectors[i].store_release(&_bitVectorStore[i]->writer());
+                bv = _bitVectors[i].load_relaxed();
+            }
             ensureGuardBit(*bv);
         }
     }
diff --git a/searchlib/src/vespa/searchlib/attribute/flagattribute.h b/searchlib/src/vespa/searchlib/attribute/flagattribute.h
index c4f4980e372..796c1493cc9 100644
--- a/searchlib/src/vespa/searchlib/attribute/flagattribute.h
+++ b/searchlib/src/vespa/searchlib/attribute/flagattribute.h
@@ -4,6 +4,7 @@
 #include "multinumericattribute.h"
 #include "multi_numeric_search_context.h"
 #include <vespa/searchlib/common/growablebitvector.h>
+#include <vespa/vespalib/datastore/atomic_value_wrapper.h>
 
 namespace search {
 
@@ -35,9 +36,10 @@ private:
     void removeOldGenerations(vespalib::GenerationHandler::generation_t firstUsed) override;
     uint32_t getOffset(int8_t value) const { return value + 128; }
 
+    using AtomicBitVectorPtr = vespalib::datastore::AtomicValueWrapper<BitVector *>;
     vespalib::GenerationHolder                       _bitVectorHolder;
     std::vector<std::shared_ptr<GrowableBitVector> > _bitVectorStore;
-    std::vector<BitVector *>                         _bitVectors;
+    std::vector<AtomicBitVectorPtr>                  _bitVectors;
     uint32_t                                         _bitVectorSize;
 };
 
diff --git a/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.cpp b/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.cpp
index 6a0be483a55..045d80bc6c4 100644
--- a/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.cpp
@@ -13,7 +13,7 @@ namespace search::attribute {
 using queryeval::SearchIterator;
 
 template <typename T, typename M>
-MultiNumericFlagSearchContext<T, M>::MultiNumericFlagSearchContext(std::unique_ptr<QueryTermSimple> qTerm, const AttributeVector& toBeSearched, MultiValueMappingReadView<M> mv_mapping_read_view, vespalib::ConstArrayRef<BitVector *> bit_vectors)
+MultiNumericFlagSearchContext<T, M>::MultiNumericFlagSearchContext(std::unique_ptr<QueryTermSimple> qTerm, const AttributeVector& toBeSearched, MultiValueMappingReadView<M> mv_mapping_read_view, AtomicBitVectorsRef bit_vectors)
     : MultiNumericSearchContext<T, M>(std::move(qTerm), toBeSearched, mv_mapping_read_view),
       _bit_vectors(bit_vectors),
       _zeroHits(false)
diff --git a/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.h b/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.h
index 00f7077b2d0..dd88ee4202c 100644
--- a/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.h
+++ b/searchlib/src/vespa/searchlib/attribute/multi_numeric_flag_search_context.h
@@ -3,6 +3,7 @@
 #pragma once
 
 #include "multi_numeric_search_context.h"
+#include <vespa/vespalib/datastore/atomic_value_wrapper.h>
 
 namespace search {
 class BitVector;
@@ -20,16 +21,19 @@ template <typename T, typename M>
 class MultiNumericFlagSearchContext : public MultiNumericSearchContext<T, M>
 {
 public:
-    MultiNumericFlagSearchContext(std::unique_ptr<QueryTermSimple> qTerm, const AttributeVector& toBeSearched, MultiValueMappingReadView<M> mv_mapping_read_view, vespalib::ConstArrayRef<BitVector *> bit_vectors);
+    using AtomicBitVectorsRef = vespalib::ConstArrayRef<vespalib::datastore::AtomicValueWrapper<BitVector *>>;
+
+    MultiNumericFlagSearchContext(std::unique_ptr<QueryTermSimple> qTerm, const AttributeVector& toBeSearched, MultiValueMappingReadView<M> mv_mapping_read_view,
+                                  AtomicBitVectorsRef bit_vectors);
 
     std::unique_ptr<queryeval::SearchIterator>
     createIterator(fef::TermFieldMatchData * matchData, bool strict) override;
 private:
-    vespalib::ConstArrayRef<BitVector *> _bit_vectors;
+    AtomicBitVectorsRef _bit_vectors;
     bool _zeroHits;
     const BitVector* get_bit_vector(T value) const {
         static_assert(std::is_same_v<T, int8_t>, "Flag attribute search context is only supported for int8_t data type");
-        return _bit_vectors[value + 128];
+        return _bit_vectors[value + 128].load_acquire();
     }
 
     template <class SC> friend class ::search::FlagAttributeIteratorT;
diff --git a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.cpp b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.cpp
index 8accb1123af..c17627a5026 100644
--- a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.cpp
@@ -33,7 +33,7 @@ PostingListSearchContext(const IEnumStoreDictionary& dictionary,
       _FSTC(0.0),
       _PLSTC(0.0),
       _minBvDocFreq(minBvDocFreq),
-      _gbv(nullptr),
+      _bv(nullptr),
       _baseSearchCtx(baseSearchCtx)
 {
 }
diff --git a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h
index 9ee56a27a85..5cc7c13c6bd 100644
--- a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h
+++ b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.h
@@ -45,7 +45,7 @@ protected:
     float _FSTC;  // Filtering Search Time Constant
     float _PLSTC; // Posting List Search Time Constant
     uint32_t                _minBvDocFreq;
-    const GrowableBitVector *_gbv; // bitvector if _useBitVector has been set
+    const BitVector *_bv; // bitvector if _useBitVector has been set
     const ISearchContext    &_baseSearchCtx;
 
 
diff --git a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp
index cd783ec2fe8..14e0cf041f2 100644
--- a/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp
+++ b/searchlib/src/vespa/searchlib/attribute/postinglistsearchcontext.hpp
@@ -46,7 +46,7 @@ PostingListSearchContextT<DataT>::lookupSingle()
             const BitVectorEntry *bve = _postingList.getBitVectorEntry(_pidx);
             const GrowableBitVector *bv = bve->_bv.get();
             if (_useBitVector) {
-                _gbv = bv;
+                _bv = &bv->reader();
             } else {
                 _pidx = bve->_tree;
                 if (_pidx.valid()) { 
@@ -56,7 +56,7 @@ PostingListSearchContextT<DataT>::lookupSingle()
                         _pidx = vespalib::datastore::EntryRef();
                     }
                 } else {
-                    _gbv = bv; 
+                    _bv = &bv->reader(); 
                 }
             }
         } else {
@@ -179,8 +179,8 @@ createPostingIterator(fef::TermFieldMatchData *matchData, bool strict)
         return search::BitVectorIterator::create(bv, bv->size(), *matchData, strict);
     }
     if (_uniqueValues == 1) {
-        if (_gbv != nullptr) {
-            return BitVectorIterator::create(_gbv, std::min(_gbv->size(), _docIdLimit), *matchData, strict);
+        if (_bv != nullptr) {
+            return BitVectorIterator::create(_bv, std::min(_bv->size(), _docIdLimit), *matchData, strict);
         }
         if (!_pidx.valid()) {
             return std::make_unique<EmptySearch>();
@@ -217,9 +217,9 @@ template <typename DataT>
 unsigned int
 PostingListSearchContextT<DataT>::singleHits() const
 {
-    if (_gbv) {
+    if (_bv) {
         // Some inaccuracy is expected, data changes underfeet
-        return _gbv->countTrueBits();
+        return _bv->countTrueBits();
     }
     if (!_pidx.valid()) {
         return 0u;
diff --git a/searchlib/src/vespa/searchlib/attribute/postingstore.cpp b/searchlib/src/vespa/searchlib/attribute/postingstore.cpp
index df016b050af..a942e70085a 100644
--- a/searchlib/src/vespa/searchlib/attribute/postingstore.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/postingstore.cpp
@@ -101,7 +101,7 @@ PostingStore<DataT>::removeSparseBitVectors()
         assert(isBitVector(typeId));
         BitVectorEntry *bve = getWBitVectorEntry(iRef);
         GrowableBitVector &bv = *bve->_bv.get();
-        uint32_t docFreq = bv.countTrueBits();
+        uint32_t docFreq = bv.writer().countTrueBits();
         if (bve->_tree.valid()) {
             RefType iRef2(bve->_tree);
             assert(isBTree(iRef2));
@@ -111,19 +111,19 @@ PostingStore<DataT>::removeSparseBitVectors()
         }
         if (docFreq < _minBvDocFreq)
             needscan = true;
-        unsigned int oldExtraSize = bv.extraByteSize();
-        if (bv.size() > _bvSize) {
+        unsigned int oldExtraSize = bv.writer().extraByteSize();
+        if (bv.writer().size() > _bvSize) {
             bv.shrink(_bvSize);
             res = true;
         }
-        if (bv.capacity() < _bvCapacity) {
+        if (bv.writer().capacity() < _bvCapacity) {
             bv.reserve(_bvCapacity);
             res = true;
         }
-        if (bv.size() < _bvSize) {
+        if (bv.writer().size() < _bvSize) {
             bv.extend(_bvSize);
         }
-        unsigned int newExtraSize = bv.extraByteSize();
+        unsigned int newExtraSize = bv.writer().extraByteSize();
         if (oldExtraSize != newExtraSize) {
             _bvExtraBytes = _bvExtraBytes + newExtraSize - oldExtraSize;
         }
@@ -149,7 +149,7 @@ PostingStore<DataT>::consider_remove_sparse_bitvector(std::vector<EntryRef>& ref
         assert(isBitVector(typeId));
         assert(_bvs.find(iRef.ref()) != _bvs.end());
         BitVectorEntry *bve = getWBitVectorEntry(iRef);
-        BitVector &bv = *bve->_bv.get();
+        BitVector &bv = bve->_bv->writer();
         uint32_t docFreq = bv.countTrueBits();
         if (bve->_tree.valid()) {
             RefType iRef2(bve->_tree);
@@ -226,12 +226,12 @@ PostingStore<DataT>::dropBitVector(EntryRef &ref)
     assert(isBitVector(typeId));
     (void) typeId;
     BitVectorEntry *bve = getWBitVectorEntry(iRef);
-    AllocatedBitVector *bv = bve->_bv.get();
+    GrowableBitVector *bv = bve->_bv.get();
     assert(bv);
-    uint32_t docFreq = bv->countTrueBits();
+    uint32_t docFreq = bv->writer().countTrueBits();
     EntryRef ref2(bve->_tree);
     if (!ref2.valid()) {
-        makeDegradedTree(ref2, *bv);
+        makeDegradedTree(ref2, bv->writer());
     }
     assert(ref2.valid());
     assert(isBTree(ref2));
@@ -242,7 +242,7 @@ PostingStore<DataT>::dropBitVector(EntryRef &ref)
     _bvs.erase(ref.ref());
     _store.holdElem(iRef, 1);
     _status.decBitVectors();
-    _bvExtraBytes -= bv->extraByteSize();
+    _bvExtraBytes -= bv->writer().extraByteSize();
     ref = ref2;
 }
 
@@ -258,7 +258,7 @@ PostingStore<DataT>::makeBitVector(EntryRef &ref)
     (void) typeId;
     vespalib::GenerationHolder &genHolder = _store.getGenerationHolder();
     auto bvsp = std::make_shared<GrowableBitVector>(_bvSize, _bvCapacity, genHolder);
-    AllocatedBitVector &bv = *bvsp.get();
+    BitVector &bv = bvsp->writer();
     uint32_t docIdLimit = _bvSize;
     (void) docIdLimit;
     Iterator it = begin(ref);
@@ -283,7 +283,7 @@ PostingStore<DataT>::makeBitVector(EntryRef &ref)
     bve->_bv = bvsp;
     _bvs.insert(bPair.ref.ref());
     _status.incBitVectors();
-    _bvExtraBytes += bv.extraByteSize();
+    _bvExtraBytes += bvsp->writer().extraByteSize();
     // barrier ?
     ref = bPair.ref;
 }
@@ -299,7 +299,7 @@ PostingStore<DataT>::applyNewBitVector(EntryRef &ref,
     RefType iRef(ref);
     vespalib::GenerationHolder &genHolder = _store.getGenerationHolder();
     auto bvsp = std::make_shared<GrowableBitVector>(_bvSize, _bvCapacity, genHolder);
-    AllocatedBitVector &bv = *bvsp.get();
+    BitVector &bv = bvsp->writer();
     uint32_t docIdLimit = _bvSize;
     (void) docIdLimit;
     uint32_t expDocFreq = ae - aOrg;
@@ -319,7 +319,7 @@ PostingStore<DataT>::applyNewBitVector(EntryRef &ref,
     bve->_bv = bvsp;
     _bvs.insert(bPair.ref.ref());
     _status.incBitVectors();
-    _bvExtraBytes += bv.extraByteSize();
+    _bvExtraBytes += bvsp->writer().extraByteSize();
     // barrier ?
     ref = bPair.ref;
 }
@@ -390,7 +390,7 @@ PostingStore<DataT>::apply(EntryRef &ref,
             BTreeType *tree = getWTreeEntry(iRef2);
             applyTree(tree, a, ae, r, re, CompareT());
         }
-        BitVector *bv = bve->_bv.get();
+        BitVector *bv = &bve->_bv->writer();
         assert(bv);
         apply(*bv, a, ae, r, re);
         uint32_t docFreq = bv->countTrueBits();
@@ -433,7 +433,7 @@ PostingStore<DataT>::internalSize(uint32_t typeId, const RefType & iRef) const
             const BTreeType *tree = getTreeEntry(iRef2);
             return tree->size(_allocator);
         } else {
-            const BitVector *bv = bve->_bv.get();
+            const BitVector *bv = &bve->_bv->writer();
             return bv->countTrueBits();
         }
     } else {
@@ -456,7 +456,7 @@ PostingStore<DataT>::internalFrozenSize(uint32_t typeId, const RefType & iRef) c
             return tree->frozenSize(_allocator);
         } else {
             // Some inaccuracy is expected, data changes underfeet
-            return bve->_bv->countTrueBits();
+            return bve->_bv->reader().countTrueBits();
         }
     } else {
         const BTreeType *tree = getTreeEntry(iRef);
@@ -608,7 +608,7 @@ PostingStore<DataT>::clear(const EntryRef ref)
             }
             _bvs.erase(ref.ref());
             _status.decBitVectors();
-            _bvExtraBytes -= bve->_bv->extraByteSize();
+            _bvExtraBytes -= bve->_bv->writer().extraByteSize();
             _store.holdElem(ref, 1);
         } else {
             BTreeType *tree = getWTreeEntry(iRef);
diff --git a/searchlib/src/vespa/searchlib/attribute/postingstore.hpp b/searchlib/src/vespa/searchlib/attribute/postingstore.hpp
index 1993714e49d..7dab24e996f 100644
--- a/searchlib/src/vespa/searchlib/attribute/postingstore.hpp
+++ b/searchlib/src/vespa/searchlib/attribute/postingstore.hpp
@@ -25,7 +25,7 @@ PostingStore<DataT>::foreach_frozen_key(EntryRef ref, FunctionType func) const {
                 const BTreeType *tree = getTreeEntry(iRef2);
                 _allocator.getNodeStore().foreach_key(tree->getFrozenRoot(), func);
             } else {
-                const BitVector *bv = bve->_bv.get();
+                const BitVector *bv = &bve->_bv->reader();
                 uint32_t docIdLimit = bv->size();
                 uint32_t docId = bv->getFirstTrueBit(1);
                 while (docId < docIdLimit) {
@@ -67,7 +67,7 @@ PostingStore<DataT>::foreach_frozen(EntryRef ref, FunctionType func) const {
                 const BTreeType *tree = getTreeEntry(iRef2);
                 _allocator.getNodeStore().foreach(tree->getFrozenRoot(), func);
             } else {
-                const BitVector *bv = bve->_bv.get();
+                const BitVector *bv = &bve->_bv->reader();
                 uint32_t docIdLimit = bv->size();
                 uint32_t docId = bv->getFirstTrueBit(1);
                 while (docId < docIdLimit) {
diff --git a/searchlib/src/vespa/searchlib/attribute/singleboolattribute.cpp b/searchlib/src/vespa/searchlib/attribute/singleboolattribute.cpp
index 8db99c115a0..46fd47014d3 100644
--- a/searchlib/src/vespa/searchlib/attribute/singleboolattribute.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/singleboolattribute.cpp
@@ -32,7 +32,7 @@ SingleBoolAttribute::~SingleBoolAttribute()
 
 void
 SingleBoolAttribute::ensureRoom(DocId docIdLimit) {
-    if (_bv.capacity() < docIdLimit) {
+    if (_bv.writer().capacity() < docIdLimit) {
         const GrowStrategy & gs = this->getConfig().getGrowStrategy();
         uint32_t newSize = docIdLimit + (docIdLimit * gs.getDocsGrowFactor()) + gs.getDocsGrowDelta();
         bool incGen = _bv.reserve(newSize);
@@ -72,7 +72,7 @@ SingleBoolAttribute::onCommit() {
                 setBit(change._doc, val != 0);
             } else if (change._type == ChangeBase::CLEARDOC) {
                 std::atomic_thread_fence(std::memory_order_release);
-                _bv.clearBitAndMaintainCount(change._doc);
+                _bv.writer().clearBitAndMaintainCount(change._doc);
             }
         }
     }
@@ -91,11 +91,11 @@ SingleBoolAttribute::onAddDocs(DocId docIdLimit) {
 void
 SingleBoolAttribute::onUpdateStat() {
     vespalib::MemoryUsage usage;
-    usage.setAllocatedBytes(_bv.extraByteSize());
-    usage.setUsedBytes(_bv.sizeBytes());
+    usage.setAllocatedBytes(_bv.writer().extraByteSize());
+    usage.setUsedBytes(_bv.writer().sizeBytes());
     usage.mergeGenerationHeldBytes(getGenerationHolder().getHeldBytes());
     usage.merge(this->getChangeVectorMemoryUsage());
-    this->updateStatistics(_bv.size(), _bv.size(), usage.allocatedBytes(), usage.usedBytes(),
+    this->updateStatistics(_bv.writer().size(), _bv.writer().size(), usage.allocatedBytes(), usage.usedBytes(),
                            usage.deadBytes(), usage.allocatedBytesOnHold());
 }
 
@@ -188,13 +188,13 @@ SingleBoolAttribute::onLoad(vespalib::Executor *)
     if (ok) {
         setCreateSerialNum(attrReader.getCreateSerialNum());
         getGenerationHolder().clearHoldLists();
-        _bv.clear();
+        _bv.writer().clear();
         uint32_t numDocs = attrReader.getNextData();
         _bv.extend(numDocs);
-        ssize_t bytesRead = attrReader.getReader().read(_bv.getStart(), _bv.sizeBytes());
-        _bv.invalidateCachedCount();
-        _bv.countTrueBits();
-        assert(bytesRead == _bv.sizeBytes());
+        ssize_t bytesRead = attrReader.getReader().read(_bv.writer().getStart(), _bv.writer().sizeBytes());
+        _bv.writer().invalidateCachedCount();
+        _bv.writer().countTrueBits();
+        assert(bytesRead == _bv.writer().sizeBytes());
         setNumDocs(numDocs);
         setCommittedDocIdLimit(numDocs);
     }
@@ -207,7 +207,7 @@ SingleBoolAttribute::onSave(IAttributeSaveTarget &saveTarget)
 {
     assert(!saveTarget.getEnumerated());
     const size_t numDocs(getCommittedDocIdLimit());
-    const size_t sz(sizeof(uint32_t) + _bv.sizeBytes());
+    const size_t sz(sizeof(uint32_t) + _bv.writer().sizeBytes());
     IAttributeSaveTarget::Buffer buf(saveTarget.datWriter().allocBuf(sz));
 
     char *p = buf->getFree();
@@ -215,8 +215,8 @@ SingleBoolAttribute::onSave(IAttributeSaveTarget &saveTarget)
     uint32_t numDocs2 = numDocs;
     memcpy(p, &numDocs2, sizeof(uint32_t));
     p += sizeof(uint32_t);
-    memcpy(p, _bv.getStart(), _bv.sizeBytes());
-    p += _bv.sizeBytes();
+    memcpy(p, _bv.writer().getStart(), _bv.writer().sizeBytes());
+    p += _bv.writer().sizeBytes();
     assert(p == e);
     (void) e;
     buf->moveFreeToData(sz);
@@ -249,7 +249,7 @@ uint64_t
 SingleBoolAttribute::getEstimatedSaveByteSize() const
 {
     constexpr uint64_t headerSize = FileSettings::DIRECTIO_ALIGNMENT + sizeof(uint32_t);
-    return headerSize + _bv.sizeBytes();
+    return headerSize + _bv.reader().sizeBytes();
 }
 
 void
diff --git a/searchlib/src/vespa/searchlib/attribute/singleboolattribute.h b/searchlib/src/vespa/searchlib/attribute/singleboolattribute.h
index 77c8b7e318f..3465269de8a 100644
--- a/searchlib/src/vespa/searchlib/attribute/singleboolattribute.h
+++ b/searchlib/src/vespa/searchlib/attribute/singleboolattribute.h
@@ -34,7 +34,7 @@ public:
     getSearch(std::unique_ptr<QueryTermSimple> term, const attribute::SearchContextParams & params) const override;
 
     uint32_t getValueCount(DocId doc) const override {
-        return (doc >= _bv.size()) ? 0 : 1;
+        return (doc >= _bv.reader().size()) ? 0 : 1;
     }
     largeint_t getInt(DocId doc) const override {
         return static_cast<largeint_t>(getFast(doc));
@@ -81,12 +81,12 @@ public:
     int8_t get(DocId doc) const override {
         return getFast(doc);
     }
-    const BitVector & getBitVector() const { return _bv; }
+    const BitVector & getBitVector() const { return _bv.reader(); }
     void setBit(DocId doc, bool value) {
         if (value) {
-            _bv.setBitAndMaintainCount(doc);
+            _bv.writer().setBitAndMaintainCount(doc);
         } else {
-            _bv.clearBitAndMaintainCount(doc);
+            _bv.writer().clearBitAndMaintainCount(doc);
         }
     }
 protected:
@@ -99,7 +99,7 @@ private:
         return 0;
     }
     int8_t getFast(DocId doc) const {
-        return _bv.testBit(doc) ? 1 : 0;
+        return _bv.reader().testBit(doc) ? 1 : 0;
     }
     vespalib::alloc::Alloc _init_alloc;
     GrowableBitVector _bv;
diff --git a/searchlib/src/vespa/searchlib/common/bitvector.cpp b/searchlib/src/vespa/searchlib/common/bitvector.cpp
index 36ebc6597fa..2d7fda32037 100644
--- a/searchlib/src/vespa/searchlib/common/bitvector.cpp
+++ b/searchlib/src/vespa/searchlib/common/bitvector.cpp
@@ -41,9 +41,6 @@ constexpr size_t MMAP_LIMIT = 256_Mi;
 namespace search {
 
 using vespalib::nbostream;
-using vespalib::GenerationHeldBase;
-using vespalib::GenerationHeldAlloc;
-using vespalib::GenerationHolder;
 
 Alloc
 BitVector::allocatePaddedAndAligned(Index start, Index end, Index capacity, const Alloc* init_alloc)
diff --git a/searchlib/src/vespa/searchlib/common/bitvector.h b/searchlib/src/vespa/searchlib/common/bitvector.h
index 7fea95661d7..dfc3d0b280a 100644
--- a/searchlib/src/vespa/searchlib/common/bitvector.h
+++ b/searchlib/src/vespa/searchlib/common/bitvector.h
@@ -6,7 +6,6 @@
 #include <memory>
 #include <vespa/vespalib/util/alloc.h>
 #include <vespa/vespalib/util/atomic.h>
-#include <vespa/vespalib/util/generationholder.h>
 #include <vespa/fastos/types.h>
 
 namespace vespalib {
@@ -24,8 +23,6 @@ class BitVector : protected BitWord
 {
 public:
     using Index = BitWord::Index;
-    using GenerationHolder = vespalib::GenerationHolder;
-    using GenerationHeldBase = vespalib::GenerationHeldBase;
     using UP = std::unique_ptr<BitVector>;
     class Range {
     public:
@@ -50,12 +47,11 @@ public:
     bool testBit(Index idx) const {
         return ((load_word(wordNum(idx)) & mask(idx)) != 0);
     }
-    Index getSizeSafe() const {
+    Index getSizeAcquire() const {
         return vespalib::atomic::load_ref_acquire(_sz);
     }
-    bool testBitSafe(Index idx) const {
-        auto my_words = vespalib::atomic::load_ref_acquire(_words);
-        auto my_word = vespalib::atomic::load_ref_acquire(my_words[wordNum(idx)]);
+    bool testBitAcquire(Index idx) const {
+        auto my_word = vespalib::atomic::load_ref_acquire(_words[wordNum(idx)]);
         return (my_word & mask(idx)) != 0;
     }
     bool hasTrueBits() const {
diff --git a/searchlib/src/vespa/searchlib/common/growablebitvector.cpp b/searchlib/src/vespa/searchlib/common/growablebitvector.cpp
index 7a548b3e7ac..e3334be3fd9 100644
--- a/searchlib/src/vespa/searchlib/common/growablebitvector.cpp
+++ b/searchlib/src/vespa/searchlib/common/growablebitvector.cpp
@@ -7,52 +7,65 @@
 namespace search {
 
 using vespalib::GenerationHeldBase;
-using vespalib::GenerationHeldAlloc;
 using vespalib::GenerationHolder;
 
+namespace {
+
+struct GenerationHeldAllocatedBitVector : public vespalib::GenerationHeldBase {
+    std::unique_ptr<AllocatedBitVector> vector;
+    GenerationHeldAllocatedBitVector(std::unique_ptr<AllocatedBitVector> vector_in)
+      : GenerationHeldBase(sizeof(AllocatedBitVector) + vector_in->extraByteSize()),
+        vector(std::move(vector_in)) {}
+};
+
+}
+
 GenerationHeldBase::UP
-GrowableBitVector::grow(Index newSize, Index newCapacity)
+GrowableBitVector::grow(BitWord::Index newSize, BitWord::Index newCapacity)
 {
+    AllocatedBitVector &self = *_stored;
     assert(newCapacity >= newSize);
-    GenerationHeldBase::UP ret;
-    if (newCapacity != capacity()) {
-        AllocatedBitVector tbv(newSize, newCapacity, _alloc.get(), size(), &_alloc);
-        if (newSize > size()) {
-            tbv.clearBitAndMaintainCount(size());  // Clear old guard bit.
+    if (newCapacity != self.capacity()) {
+        auto tbv = std::make_unique<AllocatedBitVector>(newSize, newCapacity, self._alloc.get(), self.size(), &self._alloc);
+        if (newSize > self.size()) {
+            tbv->clearBitAndMaintainCount(self.size());  // Clear old guard bit.
         }
-        ret = std::make_unique<GenerationHeldAlloc<Alloc>>(_alloc);
-        swap(tbv);
+        auto to_hold = std::make_unique<GenerationHeldAllocatedBitVector>(std::move(_stored));
+        _self.store(tbv.get(), std::memory_order_release);
+        _stored = std::move(tbv);
+        return to_hold;
     } else {
-        if (newSize > size()) {
-            Range clearRange(size(), newSize);
-            setSize(newSize);
-            clearIntervalNoInvalidation(clearRange);
+        if (newSize > self.size()) {
+            BitVector::Range clearRange(self.size(), newSize);
+            self.setSize(newSize);
+            self.clearIntervalNoInvalidation(clearRange);
         } else {
-            clearIntervalNoInvalidation(Range(newSize, size()));
-            setSize(newSize);
-            updateCount();
+            self.clearIntervalNoInvalidation(BitVector::Range(newSize, self.size()));
+            self.setSize(newSize);
+            self.updateCount();
         }
     }
-    return ret;
+    return {};
 }
 
-GrowableBitVector::GrowableBitVector(Index newSize, Index newCapacity,
+GrowableBitVector::GrowableBitVector(BitWord::Index newSize, BitWord::Index newCapacity,
                                      GenerationHolder &generationHolder,
-                                     const Alloc* init_alloc)
-    : AllocatedBitVector(newSize, newCapacity, nullptr, 0, init_alloc),
-      _generationHolder(generationHolder)
+                                     const Alloc *init_alloc)
+  : _stored(std::make_unique<AllocatedBitVector>(newSize, newCapacity, nullptr, 0, init_alloc)),
+    _self(_stored.get()),
+    _generationHolder(generationHolder)
 {
     assert(newSize <= newCapacity);
 }
 
 bool
-GrowableBitVector::reserve(Index newCapacity)
+GrowableBitVector::reserve(BitWord::Index newCapacity)
 {
-    Index oldCapacity = capacity();
+    BitWord::Index oldCapacity = _stored->capacity();
     assert(newCapacity >= oldCapacity);
     if (newCapacity == oldCapacity)
         return false;
-    return hold(grow(size(), newCapacity));
+    return hold(grow(_stored->size(), newCapacity));
 }
 
 bool
@@ -66,18 +79,18 @@ GrowableBitVector::hold(GenerationHeldBase::UP v)
 }
 
 bool
-GrowableBitVector::shrink(Index newCapacity)
+GrowableBitVector::shrink(BitWord::Index newCapacity)
 {
-    Index oldCapacity = capacity();
+    BitWord::Index oldCapacity = _stored->capacity();
     assert(newCapacity <= oldCapacity);
     (void) oldCapacity;
-    return hold(grow(newCapacity, std::max(capacity(), newCapacity)));
+    return hold(grow(newCapacity, std::max(_stored->capacity(), newCapacity)));
 }
 
 bool
-GrowableBitVector::extend(Index newCapacity)
+GrowableBitVector::extend(BitWord::Index newCapacity)
 {
-    return hold(grow(newCapacity, std::max(capacity(), newCapacity)));
+    return hold(grow(newCapacity, std::max(_stored->capacity(), newCapacity)));
 }
 
 } // namespace search
diff --git a/searchlib/src/vespa/searchlib/common/growablebitvector.h b/searchlib/src/vespa/searchlib/common/growablebitvector.h
index 8773f1573d6..e9443512040 100644
--- a/searchlib/src/vespa/searchlib/common/growablebitvector.h
+++ b/searchlib/src/vespa/searchlib/common/growablebitvector.h
@@ -3,22 +3,39 @@
 #pragma once
 
 #include "allocatedbitvector.h"
+#include <vespa/vespalib/util/atomic.h>
+#include <vespa/vespalib/util/generationholder.h>
 
 namespace search {
 
-class GrowableBitVector : public AllocatedBitVector
+class GrowableBitVector
 {
 public:
-    GrowableBitVector(Index newSize, Index newCapacity, GenerationHolder &generationHolder, const Alloc* init_alloc = nullptr);
+    using Alloc = vespalib::alloc::Alloc;
+    using GenerationHolder = vespalib::GenerationHolder;
+    using GenerationHeldBase = vespalib::GenerationHeldBase;
+    GrowableBitVector(BitWord::Index newSize, BitWord::Index newCapacity,
+                      GenerationHolder &generationHolder, const Alloc *init_alloc = nullptr);
+
+    const BitVector &reader() const { return acquire_self(); }
+    AllocatedBitVector &writer() { return *_stored; }
+
+    BitWord::Index extraByteSize() const {
+        return sizeof(AllocatedBitVector) + acquire_self().extraByteSize();
+    }
 
     /** Will return true if a a buffer is held */
-    bool reserve(Index newCapacity);
-    bool shrink(Index newCapacity);
-    bool extend(Index newCapacity);
+    bool reserve(BitWord::Index newCapacity);
+    bool shrink(BitWord::Index newCapacity);
+    bool extend(BitWord::Index newCapacity);
 private:
-    GenerationHeldBase::UP grow(Index newLength, Index newCapacity);
+    GenerationHeldBase::UP grow(BitWord::Index newLength, BitWord::Index newCapacity);
+
+    AllocatedBitVector &acquire_self() const { return *(_self.load(std::memory_order_acquire)); }
 
     VESPA_DLL_LOCAL bool hold(GenerationHeldBase::UP v);
+    std::unique_ptr<AllocatedBitVector> _stored;
+    std::atomic<AllocatedBitVector *> _self;
     GenerationHolder &_generationHolder;
 };
 
diff --git a/searchlib/src/vespa/searchlib/diskindex/bitvectordictionary.h b/searchlib/src/vespa/searchlib/diskindex/bitvectordictionary.h
index 7f44728e1be..b1e5ca55a15 100644
--- a/searchlib/src/vespa/searchlib/diskindex/bitvectordictionary.h
+++ b/searchlib/src/vespa/searchlib/diskindex/bitvectordictionary.h
@@ -6,6 +6,7 @@
 #include <vespa/searchlib/index/bitvectorkeys.h>
 #include <vespa/searchlib/common/tunefileinfo.h>
 #include <vespa/vespalib/stllike/string.h>
+#include <vector>
 
 namespace search::diskindex {
 
diff --git a/searchlib/src/vespa/searchlib/diskindex/bitvectorfile.h b/searchlib/src/vespa/searchlib/diskindex/bitvectorfile.h
index 007368babdd..162ca512cec 100644
--- a/searchlib/src/vespa/searchlib/diskindex/bitvectorfile.h
+++ b/searchlib/src/vespa/searchlib/diskindex/bitvectorfile.h
@@ -7,6 +7,7 @@
 #include <vespa/searchlib/common/tunefileinfo.h>
 #include <vespa/vespalib/stllike/string.h>
 #include <vespa/vespalib/stllike/allocator.h>
+#include <vector>
 
 class Fast_BufferedFile;