Merge pull request #5647 from vespa-engine/toregge/use-getattributereadguard-method-in-attribute-context

Use getAttributeReadGuard in AttributeContext

29 files changed, 182 insertions, 135 deletions

diff --git a/searchlib/src/tests/attribute/guard/attributeguard.cpp b/searchlib/src/tests/attribute/guard/attributeguard.cpp
index 314c5f336e0..b042806eb35 100644
--- a/searchlib/src/tests/attribute/guard/attributeguard.cpp
+++ b/searchlib/src/tests/attribute/guard/attributeguard.cpp
@@ -20,7 +20,7 @@ AttributeGuardTest::Main()
 
 
     AttributeVector::SP ssattr(new SingleStringExtAttribute("ss1"));
-    AttributeEnumGuard guard(ssattr);
+    AttributeGuard guard(ssattr);
     EXPECT_TRUE(guard.valid());
 
     TEST_DONE();
diff --git a/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp b/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp
index 53ad20c3b03..e8e16ffcc98 100644
--- a/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp
+++ b/searchlib/src/tests/attribute/imported_search_context/imported_search_context_test.cpp
@@ -20,7 +20,7 @@ struct Fixture : ImportedAttributeFixture {
     Fixture(bool useSearchCache = false) : ImportedAttributeFixture(useSearchCache) {}
 
     std::unique_ptr<ImportedSearchContext> create_context(std::unique_ptr<QueryTermSimple> term) {
-        return std::make_unique<ImportedSearchContext>(std::move(term), SearchContextParams(), *imported_attr);
+        return std::make_unique<ImportedSearchContext>(std::move(term), SearchContextParams(), *imported_attr, *target_attr);
     }
 
     std::unique_ptr<SearchIterator> create_iterator(
diff --git a/searchlib/src/tests/attribute/searchable/attribute_searchable_adapter_test.cpp b/searchlib/src/tests/attribute/searchable/attribute_searchable_adapter_test.cpp
index 1306a0aaaac..e5af6931977 100644
--- a/searchlib/src/tests/attribute/searchable/attribute_searchable_adapter_test.cpp
+++ b/searchlib/src/tests/attribute/searchable/attribute_searchable_adapter_test.cpp
@@ -7,6 +7,7 @@
 #include <vespa/searchlib/attribute/attributecontext.h>
 #include <vespa/searchlib/attribute/attributeguard.h>
 #include <vespa/searchlib/attribute/attributevector.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/extendableattributes.h>
 #include <vespa/searchlib/attribute/iattributemanager.h>
 #include <vespa/searchlib/attribute/predicate_attribute.h>
@@ -27,7 +28,6 @@
 #include <vespa/searchlib/queryeval/wand/parallel_weak_and_search.h>
 #include <memory>
 
-using search::AttributeEnumGuard;
 using search::AttributeFactory;
 using search::AttributeGuard;
 using search::AttributeVector;
@@ -100,13 +100,13 @@ public:
         }
     }
 
-    AttributeGuard::UP getAttributeStableEnum(const string &name) const override {
-        if (name == field) {
-            return AttributeGuard::UP(new AttributeEnumGuard(_attribute_vector));
-        } else if (name == other) {
-            return AttributeGuard::UP(new AttributeEnumGuard(_other));
+    std::unique_ptr<attribute::AttributeReadGuard> getAttributeReadGuard(const string &name, bool stableEnumGuard) const override {
+        if (name == field && _attribute_vector) {
+            return _attribute_vector->makeReadGuard(stableEnumGuard);
+        } else if (name == other && _other) {
+            return _other->makeReadGuard(stableEnumGuard);
         } else {
-            return AttributeGuard::UP(nullptr);
+            return std::unique_ptr<attribute::AttributeReadGuard>();
         }
     }
 
diff --git a/searchlib/src/tests/attribute/searchable/attribute_weighted_set_blueprint_test.cpp b/searchlib/src/tests/attribute/searchable/attribute_weighted_set_blueprint_test.cpp
index c22807f8bf5..39bbb8fb5ad 100644
--- a/searchlib/src/tests/attribute/searchable/attribute_weighted_set_blueprint_test.cpp
+++ b/searchlib/src/tests/attribute/searchable/attribute_weighted_set_blueprint_test.cpp
@@ -5,6 +5,7 @@
 #include <vespa/searchlib/attribute/attribute_weighted_set_blueprint.h>
 #include <vespa/searchlib/attribute/attributecontext.h>
 #include <vespa/searchlib/attribute/attributevector.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/extendableattributes.h>
 #include <vespa/searchlib/attribute/singlestringattribute.h>
 #include <vespa/searchlib/attribute/attributefactory.h>
@@ -50,8 +51,13 @@ public:
         return AttributeGuard::UP(new AttributeGuard(lookup(name)));
     }
 
-    virtual AttributeGuard::UP getAttributeStableEnum(const vespalib::string &name) const override {
-        return AttributeGuard::UP(new AttributeEnumGuard(lookup(name)));
+    virtual std::unique_ptr<attribute::AttributeReadGuard> getAttributeReadGuard(const string &name, bool stableEnumGuard) const override {
+        auto vector = lookup(name);
+        if (vector) {
+            return vector->makeReadGuard(stableEnumGuard);
+        } else {
+            return std::unique_ptr<attribute::AttributeReadGuard>();
+        }
     }
 
     virtual void getAttributeList(std::vector<AttributeGuard> &list) const override {
diff --git a/searchlib/src/tests/attribute/searchable/attributeblueprint_test.cpp b/searchlib/src/tests/attribute/searchable/attributeblueprint_test.cpp
index 6753153c224..dc7cf53d188 100644
--- a/searchlib/src/tests/attribute/searchable/attributeblueprint_test.cpp
+++ b/searchlib/src/tests/attribute/searchable/attributeblueprint_test.cpp
@@ -4,6 +4,7 @@
 #include <vespa/searchlib/attribute/attribute_blueprint_factory.h>
 #include <vespa/searchlib/attribute/attributecontext.h>
 #include <vespa/searchlib/attribute/attributevector.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/extendableattributes.h>
 #include <vespa/searchlib/attribute/singlenumericattribute.h>
 #include <vespa/searchlib/attribute/singlenumericattribute.hpp>
@@ -17,7 +18,6 @@
 #include <vespa/log/log.h>
 LOG_SETUP("attributeblueprint_test");
 
-using search::AttributeEnumGuard;
 using search::AttributeGuard;
 using search::AttributeVector;
 using search::IAttributeManager;
@@ -64,10 +64,13 @@ public:
         return AttributeGuard::UP(new AttributeGuard(_attribute_vector));
     }
 
-    AttributeGuard::UP getAttributeStableEnum(const string &) const override {
-        return AttributeGuard::UP(new AttributeEnumGuard(_attribute_vector));
+    virtual std::unique_ptr<attribute::AttributeReadGuard> getAttributeReadGuard(const string &, bool stableEnumGuard) const override {
+        if (_attribute_vector) {
+            return _attribute_vector->makeReadGuard(stableEnumGuard);
+        } else {
+            return std::unique_ptr<attribute::AttributeReadGuard>();
+        }
     }
-
     void getAttributeList(vector<AttributeGuard> &) const override {
         assert(!"Not implemented");
     }
diff --git a/searchlib/src/vespa/searchlib/attribute/attributecontext.cpp b/searchlib/src/vespa/searchlib/attribute/attributecontext.cpp
index 0a3fe963aae..df8e7858f5f 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributecontext.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/attributecontext.cpp
@@ -2,6 +2,7 @@
 
 #include "attributecontext.h"
 #include "attributevector.h"
+#include "attribute_read_guard.h"
 #include <vespa/vespalib/stllike/hash_map.hpp>
 
 using namespace search;
@@ -14,20 +15,19 @@ AttributeContext::getAttribute(AttributeMap & map, const string & name, bool sta
 {
     AttributeMap::const_iterator itr = map.find(name);
     if (itr != map.end()) {
-        return itr->second->get();
-    } else {
-        AttributeGuard::UP ret;
-        if (stableEnum) {
-            ret = _manager.getAttributeStableEnum(name);
+        if (itr->second) {
+            return itr->second->attribute();
         } else {
-            ret = _manager.getAttribute(name);
+            return nullptr;
         }
-        if (ret) {
-            const AttributeGuard & guard = *ret;
-            map[name] = std::move(ret);
-            return guard.get();
+    } else {
+        auto readGuard = _manager.getAttributeReadGuard(name, stableEnum);
+        const IAttributeVector *attribute = nullptr;
+        if (readGuard) {
+            attribute = readGuard->attribute();
         }
-        return nullptr;
+        map[name] = std::move(readGuard);
+        return attribute;
     }
 }
 
diff --git a/searchlib/src/vespa/searchlib/attribute/attributecontext.h b/searchlib/src/vespa/searchlib/attribute/attributecontext.h
index 80abe84f8ef..6a158a26229 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributecontext.h
+++ b/searchlib/src/vespa/searchlib/attribute/attributecontext.h
@@ -16,7 +16,7 @@ namespace search {
 class AttributeContext : public attribute::IAttributeContext
 {
 private:
-    typedef vespalib::hash_map<string, AttributeGuard::UP> AttributeMap;
+    typedef vespalib::hash_map<string, std::unique_ptr<attribute::AttributeReadGuard>> AttributeMap;
 
     const search::IAttributeManager & _manager;
     mutable AttributeMap              _attributes;
diff --git a/searchlib/src/vespa/searchlib/attribute/attributeguard.cpp b/searchlib/src/vespa/searchlib/attribute/attributeguard.cpp
index 3b41ca9364b..02f1eb39853 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributeguard.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/attributeguard.cpp
@@ -16,31 +16,6 @@ AttributeGuard::AttributeGuard(const AttributeVector::SP & attr) :
 {
 }
 
-AttributeEnumGuard::AttributeEnumGuard(const AttributeVector::SP & attr) :
-    AttributeGuard(attr),
-    _lock()
-{
-    takeLock();
-}
-
-AttributeEnumGuard::AttributeEnumGuard(const AttributeGuard & attr) :
-    AttributeGuard(attr),
-    _lock()
-{
-    takeLock();
-}
-
-AttributeEnumGuard::~AttributeEnumGuard() { }
-
-void AttributeEnumGuard::takeLock() {
-    if (valid()) {
-        std::shared_lock<std::shared_timed_mutex> take(get()->getEnumLock(),
-                                                       std::defer_lock);
-        _lock = std::move(take);
-        _lock.lock();
-    }
-}
-
 template class ComponentGuard<AttributeVector>;
 
 }
diff --git a/searchlib/src/vespa/searchlib/attribute/attributeguard.h b/searchlib/src/vespa/searchlib/attribute/attributeguard.h
index ea389f8dda7..09538b75334 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributeguard.h
+++ b/searchlib/src/vespa/searchlib/attribute/attributeguard.h
@@ -23,21 +23,5 @@ public:
     AttributeGuard(const AttributeVectorSP & attribute);
 };
 
-/**
- * This class makes sure that the attribute vector is not updated with enum changes while the guard is held.
- **/
-class AttributeEnumGuard : public AttributeGuard
-{
-public:
-    AttributeEnumGuard(const AttributeEnumGuard &) = delete;
-    AttributeEnumGuard & operator = (const AttributeEnumGuard &) = delete;
-    explicit AttributeEnumGuard(const AttributeVectorSP & attribute);
-    explicit AttributeEnumGuard(const AttributeGuard & attribute);
-    ~AttributeEnumGuard();
-private:
-    mutable std::shared_lock<std::shared_timed_mutex> _lock;
-    void takeLock();
-};
-
 }
 
diff --git a/searchlib/src/vespa/searchlib/attribute/attributemanager.cpp b/searchlib/src/vespa/searchlib/attribute/attributemanager.cpp
index f10f3491ac0..402824327ff 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributemanager.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/attributemanager.cpp
@@ -3,6 +3,7 @@
 #include "attributemanager.h"
 #include "attributecontext.h"
 #include "attributefactory.h"
+#include "attribute_read_guard.h"
 #include "attrvector.h"
 #include "attributefile.h"
 #include "interlock.h"
@@ -177,15 +178,15 @@ AttributeManager::getAttribute(const string & name) const
     return attrGuard;
 }
 
-AttributeGuard::UP
-AttributeManager::getAttributeStableEnum(const string & name) const
+std::unique_ptr<attribute::AttributeReadGuard>
+AttributeManager::getAttributeReadGuard(const string &name, bool stableEnumGuard) const
 {
-    AttributeGuard::UP attrGuard(new AttributeEnumGuard(VectorHolder()));
     const VectorHolder * vh = findAndLoadAttribute(name);
-    if ( vh != NULL ) {
-        attrGuard.reset(new AttributeEnumGuard(*vh));
+    if (vh != nullptr) {
+        return (*vh)->makeReadGuard(stableEnumGuard);
+    } else {
+        return std::unique_ptr<attribute::AttributeReadGuard>();
     }
-    return attrGuard;
 }
 
 bool
diff --git a/searchlib/src/vespa/searchlib/attribute/attributemanager.h b/searchlib/src/vespa/searchlib/attribute/attributemanager.h
index 3b23881e3bc..7f3937a7721 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributemanager.h
+++ b/searchlib/src/vespa/searchlib/attribute/attributemanager.h
@@ -37,7 +37,7 @@ public:
     const VectorHolder * getAttributeRef(const string & name) const;
 
     AttributeGuard::UP getAttribute(const string & name) const override;
-    AttributeGuard::UP getAttributeStableEnum(const string & name) const override;
+    std::unique_ptr<attribute::AttributeReadGuard> getAttributeReadGuard(const string &name, bool stableEnumGuard) const override;
     /**
      * This will load attributes in the most memory economical way by loading largest first.
      */
diff --git a/searchlib/src/vespa/searchlib/attribute/attributevector.cpp b/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
index e94eaa3f542..e92c7e38114 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
@@ -330,6 +330,28 @@ AttributeVector::getCollectionType() const {
 }
 
 bool
+AttributeVector::getIsFilter() const {
+    return _config.getIsFilter();
+}
+
+bool
+AttributeVector::getIsFastSearch() const {
+    return _config.fastSearch();
+}
+
+uint32_t
+AttributeVector::getCommittedDocIdLimitSlow() const
+{
+    return getCommittedDocIdLimit();
+}
+
+bool
+AttributeVector::isImported() const
+{
+    return false;
+}
+
+bool
 AttributeVector::headerTypeOK(const vespalib::GenericHeader &header) const
 {
     return header.hasTag(dataTypeTag) &&
@@ -886,12 +908,30 @@ AttributeVector::getEstimatedShrinkLidSpaceGain() const
     return canFree;
 }
 
+
+namespace {
+
+class ReadGuard : public attribute::AttributeReadGuard
+{
+    using GenerationHandler = vespalib::GenerationHandler;
+    GenerationHandler::Guard _generationGuard;
+    using EnumGuard = std::shared_lock<std::shared_timed_mutex>;
+    EnumGuard _enumGuard;
+public:
+    ReadGuard(const attribute::IAttributeVector *attr, GenerationHandler::Guard &&generationGuard, std::shared_timed_mutex *enumLock)
+        : attribute::AttributeReadGuard(attr),
+          _generationGuard(std::move(generationGuard)),
+          _enumGuard(enumLock != nullptr ? EnumGuard(*enumLock) : EnumGuard())
+    {
+    }
+};
+
+}
+
 std::unique_ptr<attribute::AttributeReadGuard>
 AttributeVector::makeReadGuard(bool stableEnumGuard) const
 {
-    (void) stableEnumGuard;
-    // TODO: implement
-    return std::unique_ptr<attribute::AttributeReadGuard>();
+    return std::make_unique<ReadGuard>(this, _genHandler.takeGuard(), stableEnumGuard ? &_enumLock : nullptr);
 }
 
 MemoryUsage
diff --git a/searchlib/src/vespa/searchlib/attribute/attributevector.h b/searchlib/src/vespa/searchlib/attribute/attributevector.h
index 5917972b4fe..9d69bf587ed 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributevector.h
+++ b/searchlib/src/vespa/searchlib/attribute/attributevector.h
@@ -431,6 +431,10 @@ public:
     // Implements IAttributeVector
     virtual BasicType::Type getBasicType() const override;
     virtual CollectionType::Type getCollectionType() const override;
+    virtual bool getIsFilter() const override;
+    virtual bool getIsFastSearch() const override;
+    virtual uint32_t getCommittedDocIdLimitSlow() const override;
+    virtual bool isImported() const override;
 
     /**
      * Updates the base file name of this attribute vector and saves
@@ -590,7 +594,7 @@ private:
     BaseName               _baseFileName;
     Config                 _config;
     std::shared_ptr<attribute::Interlock> _interlock;
-    std::shared_timed_mutex _enumLock;
+    mutable std::shared_timed_mutex _enumLock;
     GenerationHandler      _genHandler;
     GenerationHolder       _genHolder;
     Status                 _status;
@@ -626,7 +630,6 @@ private:
     std::shared_timed_mutex & getEnumLock() { return _enumLock; }
 
     friend class ComponentGuard<AttributeVector>;
-    friend class AttributeEnumGuard;
     friend class AttributeValueGuard;
     friend class AttributeTest;
     friend class AttributeManagerTest;
diff --git a/searchlib/src/vespa/searchlib/attribute/iattributemanager.h b/searchlib/src/vespa/searchlib/attribute/iattributemanager.h
index 5dc692d56a8..079463dd290 100644
--- a/searchlib/src/vespa/searchlib/attribute/iattributemanager.h
+++ b/searchlib/src/vespa/searchlib/attribute/iattributemanager.h
@@ -8,6 +8,8 @@
 
 namespace search {
 
+namespace attribute { class AttributeReadGuard; }
+
 /**
  * This is an interface used to access all registered attribute vectors.
  **/
@@ -27,13 +29,13 @@ public:
     virtual AttributeGuard::UP getAttribute(const string & name) const = 0;
 
     /**
-     * Returns a view of the attribute vector with the given name.
-     * Makes sure that the underlying enum values are stable during the use of this attribute vector.
+     * Returns a read view of the attribute vector with the given name.
      *
      * @param name name of the attribute vector.
-     * @return view of the attribute vector or empty view if the attribute vector does not exists.
+     * @param stableEnumGuard flag to block enumeration changes during use of the attribute vector via the view.
+     * @return read view of the attribute vector if the attribute vector exists
      **/
-    virtual AttributeGuard::UP getAttributeStableEnum(const string & name) const = 0;
+    virtual std::unique_ptr<attribute::AttributeReadGuard> getAttributeReadGuard(const string &name, bool stableEnumGuard) const = 0;
 
     /**
      * Fill the given list with all attribute vectors registered in this manager.
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp
index 62244b2c3d6..37969bc1eed 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp
@@ -10,7 +10,7 @@ namespace search::attribute {
 ImportedAttributeVector::ImportedAttributeVector(
             vespalib::stringref name,
             std::shared_ptr<ReferenceAttribute> reference_attribute,
-            std::shared_ptr<AttributeVector> target_attribute,
+            std::shared_ptr<ReadableAttributeVector> target_attribute,
             std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
             bool use_search_cache)
     : _name(name),
@@ -24,7 +24,7 @@ ImportedAttributeVector::ImportedAttributeVector(
 
 ImportedAttributeVector::ImportedAttributeVector(vespalib::stringref name,
                                                  std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                                 std::shared_ptr<AttributeVector> target_attribute,
+                                                 std::shared_ptr<ReadableAttributeVector> target_attribute,
                                                  std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                                  std::shared_ptr<BitVectorSearchCache> search_cache)
     : _name(name),
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h
index fa5470d2449..6ad69fa88eb 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h
@@ -3,19 +3,18 @@
 #pragma once
 
 #include "readable_attribute_vector.h"
-#include "reference_attribute.h"
 #include <vespa/vespalib/stllike/string.h>
 #include <memory>
 
 namespace search {
 
-class AttributeGuard;
-class AttributeEnumGuard;
 class IDocumentMetaStoreContext;
 
 namespace attribute {
 
 class BitVectorSearchCache;
+class ReadableAttributeVector;
+class ReferenceAttribute;
 
 /**
  * Attribute vector which does not store values of its own, but rather serves as a
@@ -32,12 +31,12 @@ public:
     using SP = std::shared_ptr<ImportedAttributeVector>;
     ImportedAttributeVector(vespalib::stringref name,
                             std::shared_ptr<ReferenceAttribute> reference_attribute,
-                            std::shared_ptr<AttributeVector> target_attribute,
+                            std::shared_ptr<ReadableAttributeVector> target_attribute,
                             std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                             bool use_search_cache);
     ImportedAttributeVector(vespalib::stringref name,
                             std::shared_ptr<ReferenceAttribute> reference_attribute,
-                            std::shared_ptr<AttributeVector> target_attribute,
+                            std::shared_ptr<ReadableAttributeVector> target_attribute,
                             std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                             std::shared_ptr<BitVectorSearchCache> search_cache);
     virtual ~ImportedAttributeVector();
@@ -45,7 +44,7 @@ public:
     const std::shared_ptr<ReferenceAttribute>& getReferenceAttribute() const noexcept {
         return _reference_attribute;
     }
-    const std::shared_ptr<AttributeVector>& getTargetAttribute() const noexcept {
+    const std::shared_ptr<ReadableAttributeVector>& getTargetAttribute() const noexcept {
         return _target_attribute;
     }
     const std::shared_ptr<IDocumentMetaStoreContext> &getDocumentMetaStore() const {
@@ -64,7 +63,7 @@ public:
 protected:
     vespalib::string                           _name;
     std::shared_ptr<ReferenceAttribute>        _reference_attribute;
-    std::shared_ptr<AttributeVector>           _target_attribute;
+    std::shared_ptr<ReadableAttributeVector>   _target_attribute;
     std::shared_ptr<IDocumentMetaStoreContext> _document_meta_store;
     std::shared_ptr<BitVectorSearchCache>      _search_cache;
 };
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.cpp b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.cpp
index 8161abe61f4..ae0fdcf1b83 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.cpp
@@ -2,6 +2,8 @@
 
 #include "imported_attribute_vector_factory.h"
 #include "imported_attribute_vector.h"
+#include "attribute_read_guard.h"
+#include <vespa/searchcommon/attribute/iattributevector.h>
 #include <vespa/searchlib/tensor/imported_tensor_attribute_vector.h>
 
 namespace search::attribute {
@@ -10,9 +12,14 @@ using search::tensor::ImportedTensorAttributeVector;
 
 namespace {
 
-BasicType::Type getBasicType(const std::shared_ptr<AttributeVector> &attr)
+BasicType::Type getBasicType(const std::shared_ptr<attribute::ReadableAttributeVector> &attr)
 {
-    return attr ? attr->getBasicType() : BasicType::Type::NONE;
+    if (attr) {
+        auto readGuard = attr->makeReadGuard(false);
+        return readGuard->attribute()->getBasicType();
+    } else {
+        return BasicType::Type::NONE;
+    }
 }
 
 }
@@ -20,7 +27,7 @@ BasicType::Type getBasicType(const std::shared_ptr<AttributeVector> &attr)
 std::shared_ptr<ImportedAttributeVector>
 ImportedAttributeVectorFactory::create(vespalib::stringref name,
                                        std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                       std::shared_ptr<AttributeVector> target_attribute,
+                                       std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
                                        std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                        bool use_search_cache)
 {
@@ -36,7 +43,7 @@ ImportedAttributeVectorFactory::create(vespalib::stringref name,
 std::shared_ptr<ImportedAttributeVector>
 ImportedAttributeVectorFactory::create(vespalib::stringref name,
                                        std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                       std::shared_ptr<AttributeVector> target_attribute,
+                                       std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
                                        std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                        std::shared_ptr<BitVectorSearchCache> search_cache)
 {
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.h b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.h
index 363fb9f29bc..9c3b5a8bb47 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.h
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_factory.h
@@ -7,13 +7,13 @@
 
 namespace search {
 
-class AttributeVector;
 class IDocumentMetaStoreContext;
 
 namespace attribute {
 
 class BitVectorSearchCache;
 class ImportedAttributeVector;
+class ReadableAttributeVector;
 class ReferenceAttribute;
 
 /*
@@ -25,14 +25,14 @@ public:
     static std::shared_ptr<ImportedAttributeVector>
     create(vespalib::stringref name,
            std::shared_ptr<ReferenceAttribute> reference_attribute,
-           std::shared_ptr<AttributeVector> target_attribute,
+           std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
            std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
            bool use_search_cache);
 
     static std::shared_ptr<ImportedAttributeVector>
     create(vespalib::stringref name,
            std::shared_ptr<ReferenceAttribute> reference_attribute,
-           std::shared_ptr<AttributeVector> target_attribute,
+           std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
            std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
            std::shared_ptr<BitVectorSearchCache> search_cache);
 };
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.cpp b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.cpp
index 0a752980a19..a27c73e112e 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.cpp
@@ -1,7 +1,9 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #include "imported_attribute_vector_read_guard.h"
+#include "imported_attribute_vector.h"
 #include "imported_search_context.h"
+#include "reference_attribute.h"
 #include <vespa/searchlib/common/i_gid_to_lid_mapper.h>
 #include <vespa/searchlib/common/i_gid_to_lid_mapper_factory.h>
 #include <vespa/searchlib/query/queryterm.h>
@@ -16,10 +18,9 @@ ImportedAttributeVectorReadGuard::ImportedAttributeVectorReadGuard(
       _imported_attribute(imported_attribute),
       _referencedLids(),
       _reference_attribute_guard(imported_attribute.getReferenceAttribute()),
-      _target_attribute_guard(stableEnumGuard ? std::shared_ptr<AttributeVector>() : imported_attribute.getTargetAttribute()),
-      _target_attribute_enum_guard(stableEnumGuard ? imported_attribute.getTargetAttribute(): std::shared_ptr<AttributeVector>()),
+      _target_attribute_guard(imported_attribute.getTargetAttribute()->makeReadGuard(stableEnumGuard)),
       _reference_attribute(*imported_attribute.getReferenceAttribute()),
-      _target_attribute(*imported_attribute.getTargetAttribute()),
+      _target_attribute(*_target_attribute_guard->attribute()),
       _mapper(_reference_attribute.getGidToLidMapperFactory()->getMapper())
 {
     _referencedLids = _reference_attribute.getReferencedLids();
@@ -106,7 +107,7 @@ const char * ImportedAttributeVectorReadGuard::getStringFromEnum(EnumHandle e) c
 
 std::unique_ptr<ISearchContext> ImportedAttributeVectorReadGuard::createSearchContext(std::unique_ptr<QueryTermSimple> term,
                                                                              const SearchContextParams &params) const {
-    return std::make_unique<ImportedSearchContext>(std::move(term), params, _imported_attribute);
+    return std::make_unique<ImportedSearchContext>(std::move(term), params, _imported_attribute, _target_attribute);
 }
 
 const IDocumentWeightAttribute *ImportedAttributeVectorReadGuard::asDocumentWeightAttribute() const {
@@ -133,6 +134,23 @@ bool ImportedAttributeVectorReadGuard::hasEnum() const {
     return _target_attribute.hasEnum();
 }
 
+bool ImportedAttributeVectorReadGuard::getIsFilter() const {
+    return _target_attribute.getIsFilter();
+}
+
+bool ImportedAttributeVectorReadGuard::getIsFastSearch() const {
+    return _target_attribute.getIsFastSearch();
+}
+
+uint32_t ImportedAttributeVectorReadGuard::getCommittedDocIdLimitSlow() const {
+    return _reference_attribute.getCommittedDocIdLimit();
+}
+
+bool ImportedAttributeVectorReadGuard::isImported() const
+{
+    return true;
+}
+
 long ImportedAttributeVectorReadGuard::onSerializeForAscendingSort(DocId doc,
                                                                    void *serTo,
                                                                    long available,
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.h b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.h
index 92d4af518f2..6c8dca11d31 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.h
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector_read_guard.h
@@ -4,7 +4,7 @@
 
 #include "attribute_read_guard.h"
 #include "attributeguard.h"
-#include "imported_attribute_vector.h"
+#include <vespa/vespalib/util/arrayref.h>
 #include <vespa/searchcommon/attribute/iattributevector.h>
 
 namespace search { class IGidToLidMapper; }
@@ -12,6 +12,8 @@ namespace search { class IGidToLidMapper; }
 namespace search::attribute {
 
 class BitVectorSearchCache;
+class ImportedAttributeVector;
+class ReferenceAttribute;
 
 /*
  * Short lived attribute vector that does not store values on its own.
@@ -27,10 +29,11 @@ private:
     const ImportedAttributeVector   &_imported_attribute;
     ReferencedLids                   _referencedLids;
     AttributeGuard                   _reference_attribute_guard;
-    AttributeGuard                   _target_attribute_guard;
-    AttributeEnumGuard               _target_attribute_enum_guard;
+    std::unique_ptr<attribute::AttributeReadGuard> _target_attribute_guard;
     const ReferenceAttribute        &_reference_attribute;
-    const AttributeVector           &_target_attribute;
+protected:
+    const IAttributeVector          &_target_attribute;
+private:
     std::unique_ptr<IGidToLidMapper> _mapper;
 
 protected:
@@ -70,6 +73,10 @@ public:
     virtual size_t getFixedWidth() const override;
     virtual CollectionType::Type getCollectionType() const override;
     virtual bool hasEnum() const override;
+    virtual bool getIsFilter() const override;
+    virtual bool getIsFastSearch() const override;
+    virtual uint32_t getCommittedDocIdLimitSlow() const override;
+    virtual bool isImported() const override;
 
 protected:
     virtual long onSerializeForAscendingSort(DocId doc, void * serTo, long available,
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_search_context.cpp b/searchlib/src/vespa/searchlib/attribute/imported_search_context.cpp
index cfac9f66062..3c4029627df 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_search_context.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/imported_search_context.cpp
@@ -3,6 +3,7 @@
 #include "bitvector_search_cache.h"
 #include "imported_search_context.h"
 #include "imported_attribute_vector.h"
+#include "reference_attribute.h"
 #include <vespa/searchlib/common/bitvectoriterator.h>
 #include <vespa/searchlib/queryeval/emptysearch.h>
 #include "attributeiterators.hpp"
@@ -23,7 +24,8 @@ namespace search::attribute {
 ImportedSearchContext::ImportedSearchContext(
         std::unique_ptr<QueryTermSimple> term,
         const SearchContextParams& params,
-        const ImportedAttributeVector& imported_attribute)
+        const ImportedAttributeVector& imported_attribute,
+        const IAttributeVector &target_attribute)
     : _imported_attribute(imported_attribute),
       _queryTerm(term->getTerm()),
       _useSearchCache(_imported_attribute.getSearchCache().get() != nullptr),
@@ -32,7 +34,7 @@ ImportedSearchContext::ImportedSearchContext(
       _dmsReadGuard((_useSearchCache && !_searchCacheLookup) ? imported_attribute.getDocumentMetaStore()->getReadGuard() :
                     std::unique_ptr<IDocumentMetaStoreContext::IReadGuard>()),
       _reference_attribute(*_imported_attribute.getReferenceAttribute()),
-      _target_attribute(*_imported_attribute.getTargetAttribute()),
+      _target_attribute(target_attribute),
       _target_search_context(_target_attribute.createSearchContext(std::move(term), params)),
       _referencedLids(_reference_attribute.getReferencedLids()),
       _merger(_reference_attribute.getCommittedDocIdLimit()),
@@ -193,7 +195,7 @@ public:
 
 void ImportedSearchContext::makeMergedPostings(bool isFilter)
 {
-    uint32_t committedTargetDocIdLimit = _target_attribute.getCommittedDocIdLimit();
+    uint32_t committedTargetDocIdLimit = _target_attribute.getCommittedDocIdLimitSlow();
     std::atomic_thread_fence(std::memory_order_acquire);
     const auto &reverseMapping = _reference_attribute.getReverseMapping();
     if (isFilter) {
@@ -229,8 +231,8 @@ void ImportedSearchContext::fetchPostings(bool strict) {
     _fetchPostingsDone = true;
     if (!_searchCacheLookup) {
         _target_search_context->fetchPostings(strict);
-        if (strict || _target_attribute.getConfig().fastSearch()) {
-            makeMergedPostings(_target_attribute.getConfig().getIsFilter());
+        if (strict || _target_attribute.getIsFastSearch()) {
+            makeMergedPostings(_target_attribute.getIsFilter());
             considerAddSearchCacheEntry();
         }
     }
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_search_context.h b/searchlib/src/vespa/searchlib/attribute/imported_search_context.h
index 32bca66cc1b..e7f4c89fc46 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_search_context.h
+++ b/searchlib/src/vespa/searchlib/attribute/imported_search_context.h
@@ -33,7 +33,7 @@ class ImportedSearchContext : public ISearchContext {
     BitVectorSearchCache::Entry::SP                 _searchCacheLookup;
     IDocumentMetaStoreContext::IReadGuard::UP       _dmsReadGuard;
     const ReferenceAttribute&                       _reference_attribute;
-    const AttributeVector&                          _target_attribute;
+    const IAttributeVector                         &_target_attribute;
     std::unique_ptr<ISearchContext>                 _target_search_context;
     ReferencedLids                                  _referencedLids;
     PostingListMerger<int32_t>                      _merger;
@@ -48,7 +48,8 @@ class ImportedSearchContext : public ISearchContext {
 public:
     ImportedSearchContext(std::unique_ptr<QueryTermSimple> term,
                           const SearchContextParams& params,
-                          const ImportedAttributeVector& imported_attribute);
+                          const ImportedAttributeVector& imported_attribute,
+                          const attribute::IAttributeVector &target_attribute);
     ~ImportedSearchContext();
 
 
diff --git a/searchlib/src/vespa/searchlib/features/dotproductfeature.cpp b/searchlib/src/vespa/searchlib/features/dotproductfeature.cpp
index be909d7a7e6..3688e00d47d 100644
--- a/searchlib/src/vespa/searchlib/features/dotproductfeature.cpp
+++ b/searchlib/src/vespa/searchlib/features/dotproductfeature.cpp
@@ -355,10 +355,6 @@ template class ArrayParam<double>;
 
 namespace {
 
-bool isImportedAttribute(const IAttributeVector& attribute) noexcept {
-    return dynamic_cast<const ImportedAttributeVectorReadGuard*>(&attribute) != nullptr;
-}
-
 using dotproduct::ArrayParam;
 
 template <typename A>
@@ -373,7 +369,7 @@ bool supportsGetRawValues(const A & attr) noexcept {
     }
 }
 
-// Precondition: isImportedAttribute(*attribute) == false
+// Precondition: attribute->isImported() == false
 template <typename A>
 FeatureExecutor &
 createForDirectArrayImpl(const IAttributeVector * attribute,
@@ -471,7 +467,7 @@ FeatureExecutor &
 createFromObject(const IAttributeVector * attribute, const fef::Anything & object, vespalib::Stash &stash)
 {
     if (attribute->getCollectionType() == attribute::CollectionType::ARRAY) {
-        if (!isImportedAttribute(*attribute)) {
+        if (!attribute->isImported()) {
             switch (attribute->getBasicType()) {
                 case BasicType::INT32:
                     return createForDirectArray<IntegerAttributeTemplate<int32_t>>(attribute, dynamic_cast<const ArrayParam<int32_t> &>(object), stash);
@@ -507,7 +503,7 @@ createFromObject(const IAttributeVector * attribute, const fef::Anything & objec
 FeatureExecutor * createTypedArrayExecutor(const IAttributeVector * attribute,
                                            const Property & prop,
                                            vespalib::Stash & stash) {
-    if (!isImportedAttribute(*attribute)) {
+    if (!attribute->isImported()) {
         switch (attribute->getBasicType()) {
             case BasicType::INT32:
                 return &createForDirectArray<IntegerAttributeTemplate<int32_t>>(attribute, prop, stash);
@@ -586,7 +582,7 @@ createFromString(const IAttributeVector * attribute, const Property & prop, vesp
 }
 
 fef::Anything::UP attemptParseArrayQueryVector(const IAttributeVector & attribute, const Property & prop) {
-    if (!isImportedAttribute(attribute)) {
+    if (!attribute.isImported()) {
         switch (attribute.getBasicType()) {
             case BasicType::INT32:
                 return std::make_unique<ArrayParam<int32_t>>(prop);
diff --git a/searchlib/src/vespa/searchlib/features/internal_max_reduce_prod_join_feature.cpp b/searchlib/src/vespa/searchlib/features/internal_max_reduce_prod_join_feature.cpp
index b9a9d96ff66..90451c01294 100644
--- a/searchlib/src/vespa/searchlib/features/internal_max_reduce_prod_join_feature.cpp
+++ b/searchlib/src/vespa/searchlib/features/internal_max_reduce_prod_join_feature.cpp
@@ -143,10 +143,6 @@ InternalMaxReduceProdJoinBlueprint::setup(const IIndexEnvironment &env, const Pa
     return true;
 }
 
-bool isImportedAttribute(const IAttributeVector &attribute) noexcept {
-    return dynamic_cast<const ImportedAttributeVectorReadGuard*>(&attribute) != nullptr;
-}
-
 template<typename A>
 bool supportsGetRawValues(const A &attr) noexcept {
     try {
@@ -163,7 +159,7 @@ template <typename BaseType>
 FeatureExecutor &
 selectTypedExecutor(const IAttributeVector *attribute, const IntegerVector &vector, vespalib::Stash &stash)
 {
-    if (!isImportedAttribute(*attribute)) {
+    if (!attribute->isImported()) {
         using A = IntegerAttributeTemplate<BaseType>;
         using VT = multivalue::Value<BaseType>;
         using ExactA = MultiValueNumericAttribute<A, VT>;
diff --git a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.cpp b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.cpp
index 71aca30ca5e..6b3f4adb6e4 100644
--- a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.cpp
+++ b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.cpp
@@ -10,7 +10,7 @@ using vespalib::tensor::Tensor;
 
 ImportedTensorAttributeVector::ImportedTensorAttributeVector(vespalib::stringref name,
                                                              std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                                             std::shared_ptr<AttributeVector> target_attribute,
+                                                             std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
                                                              std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                                              bool use_search_cache)
     : ImportedAttributeVector(name, std::move(reference_attribute),
@@ -22,7 +22,7 @@ ImportedTensorAttributeVector::ImportedTensorAttributeVector(vespalib::stringref
 
 ImportedTensorAttributeVector::ImportedTensorAttributeVector(vespalib::stringref name,
                                                              std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                                             std::shared_ptr<AttributeVector> target_attribute,
+                                                             std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
                                                              std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                                              std::shared_ptr<BitVectorSearchCache> search_cache)
     : ImportedAttributeVector(name, std::move(reference_attribute),
diff --git a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.h b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.h
index b9f643b179f..c7ccd9ec599 100644
--- a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.h
+++ b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.h
@@ -19,12 +19,12 @@ class ImportedTensorAttributeVector : public attribute::ImportedAttributeVector
 public:
     ImportedTensorAttributeVector(vespalib::stringref name,
                                   std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                  std::shared_ptr<AttributeVector> target_attribute,
+                                  std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
                                   std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                   bool use_search_cache);
     ImportedTensorAttributeVector(vespalib::stringref name,
                                   std::shared_ptr<ReferenceAttribute> reference_attribute,
-                                  std::shared_ptr<AttributeVector> target_attribute,
+                                  std::shared_ptr<attribute::ReadableAttributeVector> target_attribute,
                                   std::shared_ptr<IDocumentMetaStoreContext> document_meta_store,
                                   std::shared_ptr<BitVectorSearchCache> search_cache);
     ~ImportedTensorAttributeVector();
diff --git a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector_read_guard.cpp b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector_read_guard.cpp
index 4f355255db5..c6db5a76ed1 100644
--- a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector_read_guard.cpp
+++ b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector_read_guard.cpp
@@ -1,6 +1,7 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #include "imported_tensor_attribute_vector_read_guard.h"
+#include <vespa/searchlib/attribute/attributevector.h>
 #include <vespa/eval/tensor/tensor.h>
 
 namespace search::tensor {
@@ -23,7 +24,7 @@ ImportedTensorAttributeVectorReadGuard::ImportedTensorAttributeVectorReadGuard(c
                                                                                bool stableEnumGuard)
     : ImportedAttributeVectorReadGuard(imported_attribute,
                                        stableEnumGuard),
-      _target_tensor_attribute(getTensorAttribute(*imported_attribute.getTargetAttribute()))
+      _target_tensor_attribute(getTensorAttribute(_target_attribute))
 {
 }
 
diff --git a/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h b/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h
index 339060bbfc3..3eb20e1b646 100644
--- a/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h
+++ b/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h
@@ -13,6 +13,7 @@
 #include <vespa/searchlib/attribute/imported_attribute_vector_factory.h>
 #include <vespa/searchlib/attribute/integerbase.h>
 #include <vespa/searchlib/attribute/not_implemented_attribute.h>
+#include <vespa/searchlib/attribute/reference_attribute.h>
 #include <vespa/searchlib/attribute/stringbase.h>
 #include <vespa/searchlib/common/i_document_meta_store_context.h>
 #include <vespa/searchlib/query/queryterm.h>
diff --git a/searchlib/src/vespa/searchlib/test/mock_attribute_manager.h b/searchlib/src/vespa/searchlib/test/mock_attribute_manager.h
index 33bd11e8d6f..fa12089b3cf 100644
--- a/searchlib/src/vespa/searchlib/test/mock_attribute_manager.h
+++ b/searchlib/src/vespa/searchlib/test/mock_attribute_manager.h
@@ -4,6 +4,7 @@
 #include <vespa/searchlib/attribute/attributecontext.h>
 #include <vespa/searchlib/attribute/attributeguard.h>
 #include <vespa/searchlib/attribute/attributevector.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/iattributemanager.h>
 
 namespace search {
@@ -33,9 +34,13 @@ public:
         return AttributeGuard::UP(new AttributeGuard(attr));
     }
 
-    virtual AttributeGuard::UP getAttributeStableEnum(const vespalib::string &name) const override {
+    virtual std::unique_ptr<AttributeReadGuard> getAttributeReadGuard(const vespalib::string &name, bool stableEnumGuard) const override {
         AttributeVector::SP attr = findAttribute(name);
-        return AttributeGuard::UP(new AttributeEnumGuard(attr));
+        if (attr) {
+            return attr->makeReadGuard(stableEnumGuard);
+        } else {
+            return std::unique_ptr<AttributeReadGuard>();
+        }
     }
 
     virtual void getAttributeList(std::vector<AttributeGuard> &list) const override {