Review fixes

src/Interpreters/Cache/EvictionCandidates.cpp

@@ -39,7 +39,7 @@ EvictionCandidates::~EvictionCandidates()
         // Reset the evicting state
         // (as the corresponding file segments were not yet removed).
         for (const auto & candidate : key_candidates.candidates)
-            candidate->setEvicting(false, nullptr, nullptr);
+            candidate->resetEvictingFlag();
     }
 }
 
@@ -53,7 +53,7 @@ void EvictionCandidates::add(
         it->second.key_metadata = locked_key.getKeyMetadata();
 
     it->second.candidates.push_back(candidate);
-    candidate->setEvicting(true, &locked_key, &lock);
+    candidate->setEvictingFlag(locked_key, lock);
     ++candidates_size;
 }
 

src/Interpreters/Cache/IFileCachePriority.cpp

@@ -13,7 +13,6 @@ namespace DB
 namespace ErrorCodes
 {
     extern const int LOGICAL_ERROR;
-    extern const int NOT_IMPLEMENTED;
 }
 
 IFileCachePriority::IFileCachePriority(size_t max_size_, size_t max_elements_)
@@ -52,13 +51,4 @@ void IFileCachePriority::check(const CachePriorityGuard::Lock & lock) const
     }
 }
 
-void IFileCachePriority::holdImpl(size_t, size_t, const CachePriorityGuard::Lock &)
-{
-    throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method holdImpl() is not implemented");
-}
-
-void IFileCachePriority::releaseImpl(size_t, size_t)
-{
-    throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method holdImpl() is not implemented");
-}
 }

src/Interpreters/Cache/IFileCachePriority.h

@@ -52,14 +52,18 @@ public:
         /// a separate lock `EntryGuard::Lock`, it will make this part of code more coherent,
         /// but it will introduce one more mutex while it is avoidable.
         /// Introducing one more mutex just for coherency does not win the trade-off (isn't it?).
-        void setEvicting(bool evicting_, const LockedKey * locked_key, const CachePriorityGuard::Lock * lock) const
+        void setEvictingFlag(const LockedKey &, const CachePriorityGuard::Lock &) const
         {
-            if (evicting_ && (!locked_key || !lock))
-                throw Exception(ErrorCodes::LOGICAL_ERROR,
-                                "Setting evicting state to `true` can be done only under lock");
+            auto prev = evicting.exchange(true, std::memory_order_relaxed);
+            chassert(!prev);
+            UNUSED(prev);
+        }
 
-            chassert(evicting.load() != evicting_);
-            evicting.store(evicting_);
+        void resetEvictingFlag() const
+        {
+            auto prev = evicting.exchange(false, std::memory_order_relaxed);
+            chassert(prev);
+            UNUSED(prev);
         }
 
     private:
@@ -189,12 +193,9 @@ public:
 protected:
     IFileCachePriority(size_t max_size_, size_t max_elements_);
 
-    virtual void holdImpl(
-        size_t size,
-        size_t elements,
-        const CachePriorityGuard::Lock & lock);
+    virtual void holdImpl(size_t /* size */, size_t /* elements */, const CachePriorityGuard::Lock &) {}
 
-    virtual void releaseImpl(size_t size, size_t elements);
+    virtual void releaseImpl(size_t /* size */, size_t /* elements */) {}
 
     size_t max_size = 0;
     size_t max_elements = 0;

src/Interpreters/Cache/Metadata.h

@@ -50,12 +50,20 @@ struct FileSegmentMetadata : private boost::noncopyable
         return iterator->getEntry()->isEvicting(lock);
     }
 
-    void setEvicting(bool evicting, const LockedKey * locked_key, const CachePriorityGuard::Lock * lock) const
+    void setEvictingFlag(const LockedKey & locked_key, const CachePriorityGuard::Lock & lock) const
     {
         auto iterator = getQueueIterator();
         if (!iterator)
             throw Exception(ErrorCodes::LOGICAL_ERROR, "Iterator is not set");
-        iterator->getEntry()->setEvicting(evicting, locked_key, lock);
+        iterator->getEntry()->setEvictingFlag(locked_key, lock);
+    }
+
+    void resetEvictingFlag() const
+    {
+        auto iterator = getQueueIterator();
+        if (!iterator)
+            throw Exception(ErrorCodes::LOGICAL_ERROR, "Iterator is not set");
+        iterator->getEntry()->resetEvictingFlag();
     }
 
     Priority::IteratorPtr getQueueIterator() const { return file_segment->getQueueIterator(); }