Implement AttributeVector::makeReadGuard().

2 files changed, 18 insertions, 4 deletions

diff --git a/searchlib/src/vespa/searchlib/attribute/attributevector.cpp b/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
index e94eaa3f542..2e88587337c 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
+++ b/searchlib/src/vespa/searchlib/attribute/attributevector.cpp
@@ -886,12 +886,24 @@ AttributeVector::getEstimatedShrinkLidSpaceGain() const
     return canFree;
 }
 
+class AttributeVector::ReadGuard : public attribute::AttributeReadGuard
+{
+    GenerationHandler::Guard _generationGuard;
+    using EnumGuard = std::shared_lock<std::shared_timed_mutex>;
+    EnumGuard _enumGuard;
+public:
+    ReadGuard(const 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..33b499b7400 100644
--- a/searchlib/src/vespa/searchlib/attribute/attributevector.h
+++ b/searchlib/src/vespa/searchlib/attribute/attributevector.h
@@ -590,7 +590,7 @@ 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;
@@ -625,6 +625,8 @@ private:
      */
     std::shared_timed_mutex & getEnumLock() { return _enumLock; }
 
+    class ReadGuard;
+
     friend class ComponentGuard<AttributeVector>;
     friend class AttributeEnumGuard;
     friend class AttributeValueGuard;