Add ReadableAttributeVector interface used to create a short-lived read guard over an attribute vector.

Let AttributeVector and ImportedAttributeVector implement this interface.

19 files changed, 139 insertions, 29 deletions

diff --git a/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.cpp b/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.cpp
index 7a9d877621c..8e4714d6fa2 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.cpp
+++ b/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.cpp
@@ -2,6 +2,7 @@
 
 #include "imported_attributes_context.h"
 #include "imported_attributes_repo.h"
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/attributeguard.h>
 #include <vespa/searchlib/attribute/imported_attribute_vector.h>
 #include <vespa/vespalib/stllike/hash_map.hpp>
@@ -20,12 +21,12 @@ ImportedAttributesContext::getOrCacheAttribute(const vespalib::string &name,
 {
     auto itr = attributes.find(name);
     if (itr != attributes.end()) {
-        return itr->second.get();
+        return itr->second->attribute();
     }
     ImportedAttributeVector::SP result = _repo.get(name);
     if (result.get() != nullptr) {
         auto insRes = attributes.emplace(name, result->makeReadGuard(stableEnumGuard));
-        return insRes.first->second.get();
+        return insRes.first->second->attribute();
     } else {
         return nullptr;
     }
diff --git a/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.h b/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.h
index a0d785d8cc7..90f95ce6447 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.h
+++ b/searchcore/src/vespa/searchcore/proton/attribute/imported_attributes_context.h
@@ -10,6 +10,7 @@
 namespace search {
 class AttributeGuard;
 namespace attribute {
+class AttributeReadGuard;
 class IAttributeVector;
 class ImportedAttributeVector;
 }}
@@ -26,10 +27,11 @@ class ImportedAttributesRepo;
 class ImportedAttributesContext : public search::attribute::IAttributeContext {
 private:
     using AttributeGuard = search::AttributeGuard;
+    using AttributeReadGuard = search::attribute::AttributeReadGuard;
     using IAttributeVector = search::attribute::IAttributeVector;
     using ImportedAttributeVector = search::attribute::ImportedAttributeVector;
 
-    using AttributeCache = std::unordered_map<vespalib::string, std::unique_ptr<IAttributeVector>, vespalib::hash<vespalib::string>>;
+    using AttributeCache = std::unordered_map<vespalib::string, std::unique_ptr<AttributeReadGuard>, vespalib::hash<vespalib::string>>;
     using LockGuard = std::lock_guard<std::mutex>;
 
     const ImportedAttributesRepo &_repo;
diff --git a/searchlib/src/tests/attribute/imported_attribute_vector/imported_attribute_vector_test.cpp b/searchlib/src/tests/attribute/imported_attribute_vector/imported_attribute_vector_test.cpp
index 285c49c9133..90b63138fde 100644
--- a/searchlib/src/tests/attribute/imported_attribute_vector/imported_attribute_vector_test.cpp
+++ b/searchlib/src/tests/attribute/imported_attribute_vector/imported_attribute_vector_test.cpp
@@ -33,7 +33,7 @@ TEST_F("Accessors return expected attributes", Fixture) {
 TEST_F("getName() is equal to name given during construction", Fixture) {
     auto attr = f.create_attribute_vector_from_members("coolvector");
     EXPECT_EQUAL("coolvector", attr->getName());
-    EXPECT_EQUAL("coolvector", attr->makeReadGuard(false)->getName());
+    EXPECT_EQUAL("coolvector", attr->makeReadGuard(false)->attribute()->getName());
 }
 
 TEST_F("getNumDocs() returns number of documents in reference attribute vector", Fixture) {
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 2f302e50470..53ad20c3b03 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
@@ -1,6 +1,7 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #include <vespa/searchcommon/attribute/search_context_params.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/imported_search_context.h>
 #include <vespa/searchlib/fef/termfieldmatchdata.h>
 #include <vespa/searchlib/queryeval/simpleresult.h>
diff --git a/searchlib/src/tests/features/imported_dot_product/imported_dot_product_test.cpp b/searchlib/src/tests/features/imported_dot_product/imported_dot_product_test.cpp
index 13225836bd1..42ce9725f91 100644
--- a/searchlib/src/tests/features/imported_dot_product/imported_dot_product_test.cpp
+++ b/searchlib/src/tests/features/imported_dot_product/imported_dot_product_test.cpp
@@ -1,5 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/features/dotproductfeature.h>
 #include <vespa/searchlib/test/imported_attribute_fixture.h>
 #include <vespa/searchlib/fef/test/ftlib.h>
@@ -45,10 +46,11 @@ struct FixtureBase : ImportedAttributeFixture {
         if (pre_parsed) {
             feature.getQueryEnv().getObjectStore().add("dotProduct.vector.object", std::move(pre_parsed));
         }
-        std::shared_ptr<IAttributeVector> readable_imported_attr = imported_attr->makeReadGuard(false);
-        feature.getIndexEnv().getAttributeMap().add(readable_imported_attr);
+        auto readGuard = imported_attr->makeReadGuard(false);
+        const IAttributeVector *attr = readGuard->attribute();
+        feature.getIndexEnv().getAttributeMap().add(std::move(readGuard));
         schema::CollectionType collection_type(
-                (readable_imported_attr->getCollectionType() == attribute::CollectionType::ARRAY)
+                (attr->getCollectionType() == attribute::CollectionType::ARRAY)
                 ? schema::CollectionType::ARRAY : schema::CollectionType::WEIGHTEDSET);
         feature.getIndexEnv().getBuilder().addField(
                 FieldType::ATTRIBUTE, collection_type, imported_attr->getName());
diff --git a/searchlib/src/vespa/searchlib/attribute/CMakeLists.txt b/searchlib/src/vespa/searchlib/attribute/CMakeLists.txt
index cc6736e21c5..794e0b2bdf6 100644
--- a/searchlib/src/vespa/searchlib/attribute/CMakeLists.txt
+++ b/searchlib/src/vespa/searchlib/attribute/CMakeLists.txt
@@ -5,6 +5,7 @@ vespa_add_library(searchlib_attribute OBJECT
     attribute.cpp
     attribute_blueprint_factory.cpp
     attribute_header.cpp
+    attribute_read_guard.cpp
     attribute_weighted_set_blueprint.cpp
     attributecontext.cpp
     attributefactory.cpp
diff --git a/searchlib/src/vespa/searchlib/attribute/attribute_read_guard.cpp b/searchlib/src/vespa/searchlib/attribute/attribute_read_guard.cpp
new file mode 100644
index 00000000000..9f88d37aa6b
--- /dev/null
+++ b/searchlib/src/vespa/searchlib/attribute/attribute_read_guard.cpp
@@ -0,0 +1,16 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include "attribute_read_guard.h"
+
+namespace search::attribute {
+
+AttributeReadGuard::AttributeReadGuard(const IAttributeVector *attr)
+    : _attr(attr)
+{
+}
+
+AttributeReadGuard::~AttributeReadGuard()
+{
+}
+
+}
diff --git a/searchlib/src/vespa/searchlib/attribute/attribute_read_guard.h b/searchlib/src/vespa/searchlib/attribute/attribute_read_guard.h
new file mode 100644
index 00000000000..aeccb6c8828
--- /dev/null
+++ b/searchlib/src/vespa/searchlib/attribute/attribute_read_guard.h
@@ -0,0 +1,33 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+namespace search::attribute {
+
+class IAttributeVector;
+
+/**
+ * Short-lived guard for getting read access to an attribute vector.
+ *
+ * Sub-classes must ensure that the appropriate guard(s)
+ * are held during the lifetime of this object.
+ */
+class AttributeReadGuard {
+private:
+    const IAttributeVector *_attr;
+
+protected:
+    AttributeReadGuard(const IAttributeVector *attr);
+
+public:
+    AttributeReadGuard(const AttributeReadGuard &) = delete;
+    AttributeReadGuard &operator=(const AttributeReadGuard &) = delete;
+    AttributeReadGuard(AttributeReadGuard &&) = delete;
+    AttributeReadGuard &operator=(AttributeReadGuard &&) = delete;
+    virtual ~AttributeReadGuard();
+    const IAttributeVector *operator->() const { return _attr; }
+    const IAttributeVector &operator*()  const { return *_attr; }
+    const IAttributeVector *attribute() const { return _attr; }
+};
+
+}
diff --git a/searchlib/src/vespa/searchlib/attribute/attributevector.cpp b/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
index 8b3af9bddd3..b3a25207e00 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
@@ -1,5 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
+#include "attribute_read_guard.h"
 #include "attributefilesavetarget.h"
 #include "attributeiterators.hpp"
 #include "attributesaver.h"
@@ -884,6 +885,14 @@ AttributeVector::getEstimatedShrinkLidSpaceGain() const
     return canFree;
 }
 
+std::unique_ptr<attribute::AttributeReadGuard>
+AttributeVector::makeReadGuard(bool stableEnumGuard) const
+{
+    (void) stableEnumGuard;
+    // TODO: implement
+    return std::unique_ptr<attribute::AttributeReadGuard>();
+}
+
 MemoryUsage
 AttributeVector::getChangeVectorMemoryUsage() const
 {
diff --git a/searchlib/src/vespa/searchlib/attribute/attributevector.h b/searchlib/src/vespa/searchlib/attribute/attributevector.h
index bdb5e5c02db..efec7d4edb3 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributevector.h
+++ b/searchlib/src/vespa/searchlib/attribute/attributevector.h
@@ -4,6 +4,7 @@
 
 #include "address_space_usage.h"
 #include "changevector.h"
+#include "readable_attribute_vector.h"
 #include <vespa/fastlib/text/normwordfolder.h>
 #include <vespa/searchcommon/attribute/config.h>
 #include <vespa/searchcommon/attribute/i_search_context.h>
@@ -110,7 +111,8 @@ public:
 
 class AttributeVector : public vespalib::Identifiable,
                         public attribute::IAttributeVector,
-                        public common::ICompactableLidSpace
+                        public common::ICompactableLidSpace,
+                        public attribute::ReadableAttributeVector
 {
 protected:
     using Config = search::attribute::Config;
@@ -664,6 +666,8 @@ public:
     virtual void onShrinkLidSpace();
     virtual size_t getEstimatedShrinkLidSpaceGain() const override;
 
+    virtual std::unique_ptr<attribute::AttributeReadGuard> makeReadGuard(bool stableEnumGuard) const override;
+
     void setInterlock(const std::shared_ptr<attribute::Interlock> &interlock);
 
     const std::shared_ptr<attribute::Interlock> &getInterlock() const {
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp
index dd089446065..62244b2c3d6 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.cpp
@@ -38,7 +38,7 @@ ImportedAttributeVector::ImportedAttributeVector(vespalib::stringref name,
 ImportedAttributeVector::~ImportedAttributeVector() {
 }
 
-std::unique_ptr<IAttributeVector>
+std::unique_ptr<AttributeReadGuard>
 ImportedAttributeVector::makeReadGuard(bool stableEnumGuard) const
 {
     return std::make_unique<ImportedAttributeVectorReadGuard>(*this, stableEnumGuard);
diff --git a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h
index 731b0bbbd19..fa5470d2449 100644
--- a/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h
+++ b/searchlib/src/vespa/searchlib/attribute/imported_attribute_vector.h
@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "readable_attribute_vector.h"
 #include "reference_attribute.h"
 #include <vespa/vespalib/stllike/string.h>
 #include <memory>
@@ -26,7 +27,7 @@ class BitVectorSearchCache;
  * Any accessor on the imported attribute for a local LID yields the same result as
  * if the same accessor were invoked with the target LID on the target attribute vector.
  */
-class ImportedAttributeVector {
+class ImportedAttributeVector : public ReadableAttributeVector {
 public:
     using SP = std::shared_ptr<ImportedAttributeVector>;
     ImportedAttributeVector(vespalib::stringref name,
@@ -58,10 +59,7 @@ public:
         return _name;
     }
 
-    /*
-     * Create an imported attribute with a snapshot of lid to lid mapping.
-     */
-    virtual std::unique_ptr<IAttributeVector> makeReadGuard(bool stableEnumGuard) const;
+    virtual std::unique_ptr<AttributeReadGuard> makeReadGuard(bool stableEnumGuard) const override;
 
 protected:
     vespalib::string                           _name;
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 da5287b6068..da404d6f904 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
@@ -12,7 +12,8 @@ namespace attribute {
 ImportedAttributeVectorReadGuard::ImportedAttributeVectorReadGuard(
         const ImportedAttributeVector &imported_attribute,
         bool stableEnumGuard)
-    : _imported_attribute(imported_attribute),
+    : AttributeReadGuard(this),
+      _imported_attribute(imported_attribute),
       _referencedLids(),
       _reference_attribute_guard(imported_attribute.getReferenceAttribute()),
       _target_attribute_guard(stableEnumGuard ? std::shared_ptr<AttributeVector>() : imported_attribute.getTargetAttribute()),
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 ad0d55cf29e..96f46fa684c 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
@@ -2,8 +2,9 @@
 
 #pragma once
 
-#include "imported_attribute_vector.h"
+#include "attribute_read_guard.h"
 #include "attributeguard.h"
+#include "imported_attribute_vector.h"
 #include <vespa/searchcommon/attribute/iattributevector.h>
 
 namespace search { class IGidToLidMapper; }
@@ -18,7 +19,8 @@ class BitVectorSearchCache;
  * Extra information for direct lid to referenced lid mapping with
  * boundary check is setup during construction.
  */
-class ImportedAttributeVectorReadGuard : public IAttributeVector
+class ImportedAttributeVectorReadGuard : public IAttributeVector,
+                                         public AttributeReadGuard
 {
 private:
     using ReferencedLids = vespalib::ConstArrayRef<uint32_t>;
diff --git a/searchlib/src/vespa/searchlib/attribute/readable_attribute_vector.h b/searchlib/src/vespa/searchlib/attribute/readable_attribute_vector.h
new file mode 100644
index 00000000000..03058362cb1
--- /dev/null
+++ b/searchlib/src/vespa/searchlib/attribute/readable_attribute_vector.h
@@ -0,0 +1,20 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#pragma once
+
+#include <memory>
+
+namespace search::attribute {
+
+class AttributeReadGuard;
+
+/**
+ * Interface for an attribute vector used to create a short-lived read guard over that attribute.
+ */
+class ReadableAttributeVector {
+public:
+    virtual ~ReadableAttributeVector() {}
+    virtual std::unique_ptr<AttributeReadGuard> makeReadGuard(bool stableEnumGuard) const = 0;
+};
+
+}
diff --git a/searchlib/src/vespa/searchlib/fef/test/attribute_map.h b/searchlib/src/vespa/searchlib/fef/test/attribute_map.h
index 8fddc0e1c41..aadca263722 100644
--- a/searchlib/src/vespa/searchlib/fef/test/attribute_map.h
+++ b/searchlib/src/vespa/searchlib/fef/test/attribute_map.h
@@ -2,14 +2,13 @@
 
 #include "mock_attribute_context.h"
 #include <vespa/searchcommon/attribute/iattributecontext.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <memory>
 #include <map>
 
 #pragma once
 
-namespace search {
-namespace fef {
-namespace test {
+namespace search::fef::test {
 
 /**
  * Simple mapping from attribute name to IAttributeVector which can be used for tests
@@ -21,6 +20,7 @@ namespace test {
  */
 class AttributeMap {
     std::map<vespalib::string, std::shared_ptr<attribute::IAttributeVector>> _attributes;
+    std::map<vespalib::string, std::unique_ptr<attribute::AttributeReadGuard>> _guards;
 public:
     using IAttributeVector = attribute::IAttributeVector;
 
@@ -28,15 +28,29 @@ public:
         _attributes.emplace(attr->getName(), std::move(attr));
     }
 
+    void add(std::unique_ptr<attribute::AttributeReadGuard> guard) {
+        _guards.emplace(guard->attribute()->getName(), std::move(guard));
+    }
+
     const IAttributeVector * getAttribute(const vespalib::string & name) const {
-        auto iter = _attributes.find(name);
-        return (iter != _attributes.end() ? iter->second.get() : nullptr);
+        auto attrItr = _attributes.find(name);
+        if (attrItr != _attributes.end()) {
+            return attrItr->second.get();
+        }
+        auto guardItr = _guards.find(name);
+        if (guardItr != _guards.end()) {
+            return guardItr->second->attribute();
+        }
+        return nullptr;
     }
 
     void getAttributeList(std::vector<const IAttributeVector *> & list) const {
         for (const auto& attr : _attributes) {
             list.emplace_back(attr.second.get());
         }
+        for (const auto &guard : _guards) {
+            list.emplace_back(guard.second->attribute());
+        }
     }
 
     attribute::IAttributeContext::UP createContext() const {
@@ -44,6 +58,4 @@ public:
     }
 };
 
-} // test
-} // fef
-} // search
+}
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 aeaa153ef1c..90c9c9b7f33 100644
--- a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.cpp
+++ b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.cpp
@@ -38,7 +38,7 @@ ImportedTensorAttributeVector::~ImportedTensorAttributeVector()
 {
 }
 
-std::unique_ptr<attribute::IAttributeVector>
+std::unique_ptr<attribute::AttributeReadGuard>
 ImportedTensorAttributeVector::makeReadGuard(bool stableEnumGuard) const
 {
     return std::make_unique<ImportedTensorAttributeVectorReadGuard>(*this, stableEnumGuard);
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 c94b0469e93..93155a2defc 100644
--- a/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.h
+++ b/searchlib/src/vespa/searchlib/tensor/imported_tensor_attribute_vector.h
@@ -29,7 +29,7 @@ public:
                                   std::shared_ptr<BitVectorSearchCache> search_cache);
     ~ImportedTensorAttributeVector();
 
-    virtual std::unique_ptr<attribute::IAttributeVector> makeReadGuard(bool stableEnumGuard) const override;
+    virtual std::unique_ptr<attribute::AttributeReadGuard> makeReadGuard(bool stableEnumGuard) const override;
     virtual std::unique_ptr<Tensor> getTensor(uint32_t docId) const override;
     virtual std::unique_ptr<Tensor> getEmptyTensor() const override;
     virtual void getTensor(uint32_t docId, vespalib::tensor::MutableDenseTensorView &tensor) const override;
diff --git a/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h b/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h
index 6245e0304fb..339060bbfc3 100644
--- a/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h
+++ b/searchlib/src/vespa/searchlib/test/imported_attribute_fixture.h
@@ -5,6 +5,7 @@
 #include "mock_gid_to_lid_mapping.h"
 #include <vespa/document/base/documentid.h>
 #include <vespa/document/base/globalid.h>
+#include <vespa/searchlib/attribute/attribute_read_guard.h>
 #include <vespa/searchlib/attribute/attributefactory.h>
 #include <vespa/searchlib/attribute/attributeguard.h>
 #include <vespa/searchlib/attribute/floatbase.h>
@@ -137,6 +138,13 @@ std::unique_ptr<QueryTermSimple> word_term(vespalib::stringref term) {
     return std::make_unique<QueryTermSimple>(term, QueryTerm::WORD);
 }
 
+struct ReadGuardWrapper {
+    std::unique_ptr<AttributeReadGuard> guard;
+    ReadGuardWrapper(std::unique_ptr<AttributeReadGuard> guard_) : guard(std::move(guard_)) {}
+    const IAttributeVector *operator->() const { return guard->operator->(); }
+    const IAttributeVector &operator*() const { return guard->operator*(); }
+};
+
 struct ImportedAttributeFixture {
     bool use_search_cache;
     std::shared_ptr<AttributeVector> target_attr;
@@ -149,8 +157,8 @@ struct ImportedAttributeFixture {
 
     virtual ~ImportedAttributeFixture();
 
-    std::unique_ptr<IAttributeVector> get_imported_attr() const {
-        return imported_attr->makeReadGuard(false);
+    ReadGuardWrapper get_imported_attr() const {
+        return ReadGuardWrapper(imported_attr->makeReadGuard(false));
     }
 
     void map_reference(DocId from_lid, GlobalId via_gid, DocId to_lid) {