Tiny refactoring

src/Interpreters/Cache/FileCache.cpp

@@ -771,8 +771,7 @@ bool FileCache::tryReserve(FileSegment & file_segment, const size_t size, FileCa
         reserve_stat.stat_by_kind.clear();
     }
 
-    /// A file_segment_metadata acquires a LRUQueue iterator on first successful space reservation attempt,
+    /// A file_segment_metadata acquires a priority iterator on first successful space reservation attempt,
-    /// e.g. queue_iteratir is std::nullopt here if no space has been reserved yet.
     auto queue_iterator = file_segment.getQueueIterator();
     chassert(!queue_iterator || file_segment.getReservedSize() > 0);
 

src/Interpreters/Cache/FileCacheSettings.cpp

@@ -3,6 +3,7 @@
 #include <Poco/Util/AbstractConfiguration.h>
 #include <Common/Exception.h>
 #include <Common/NamedCollections/NamedCollections.h>
+#include <boost/algorithm/string/case_conv.hpp>
 #include <IO/ReadHelpers.h>
 
 namespace DB
@@ -63,7 +64,10 @@ void FileCacheSettings::loadImpl(FuncHas has, FuncGetUInt get_uint, FuncGetStrin
         throw Exception(ErrorCodes::BAD_ARGUMENTS, "Setting `boundary_alignment` cannot exceed `max_file_segment_size`");
 
     if (has("cache_policy"))
+    {
         cache_policy = get_string("cache_policy");
+        boost::to_upper(cache_policy);
+    }
 
     if (has("slru_size_ratio"))
         slru_size_ratio = get_double("slru_size_ratio");

src/Interpreters/Cache/LRUFileCachePriority.cpp

@@ -32,10 +32,10 @@ IFileCachePriority::IteratorPtr LRUFileCachePriority::add(
     size_t size,
     const CacheGuard::Lock & lock)
 {
-    return add(Entry(key_metadata->key, offset, size, key_metadata), lock);
+    return std::make_shared<LRUIterator>(add(Entry(key_metadata->key, offset, size, key_metadata), lock));
 }
 
-std::unique_ptr<LRUFileCachePriority::LRUIterator> LRUFileCachePriority::add(Entry && entry, const CacheGuard::Lock &)
+LRUFileCachePriority::LRUIterator LRUFileCachePriority::add(Entry && entry, const CacheGuard::Lock &)
 {
     if (entry.size == 0)
     {
@@ -76,7 +76,7 @@ std::unique_ptr<LRUFileCachePriority::LRUIterator> LRUFileCachePriority::add(Ent
         log, "Added entry into LRU queue, key: {}, offset: {}, size: {}",
         entry.key, entry.offset, entry.size);
 
-    return std::make_unique<LRUIterator>(this, iterator);
+    return LRUIterator(this, iterator);
 }
 
 LRUFileCachePriority::LRUQueue::iterator LRUFileCachePriority::remove(LRUQueue::iterator it, const CacheGuard::Lock &)
@@ -115,6 +115,26 @@ LRUFileCachePriority::LRUIterator::LRUIterator(
 {
 }
 
+LRUFileCachePriority::LRUIterator::LRUIterator(const LRUIterator & other)
+{
+    *this = other;
+}
+
+LRUFileCachePriority::LRUIterator & LRUFileCachePriority::LRUIterator::operator =(const LRUIterator & other)
+{
+    if (this == &other)
+        return *this;
+
+    cache_priority = other.cache_priority;
+    iterator = other.iterator;
+    return *this;
+}
+
+bool LRUFileCachePriority::LRUIterator::operator ==(const LRUIterator & other) const
+{
+    return cache_priority == other.cache_priority && iterator == other.iterator;
+}
+
 void LRUFileCachePriority::iterate(IterateFunc && func, const CacheGuard::Lock & lock)
 {
     for (auto it = queue.begin(); it != queue.end();)
@@ -223,8 +243,7 @@ bool LRUFileCachePriority::collectCandidatesForEviction(
     return can_fit();
 }
 
-std::unique_ptr<LRUFileCachePriority::LRUIterator>
+LRUFileCachePriority::LRUIterator LRUFileCachePriority::move(LRUIterator & it, LRUFileCachePriority & other, const CacheGuard::Lock &)
-LRUFileCachePriority::move(LRUIterator & it, LRUFileCachePriority & other, const CacheGuard::Lock &)
 {
     const auto & entry = it.getEntry();
     if (entry.size == 0)
@@ -254,7 +273,7 @@ LRUFileCachePriority::move(LRUIterator & it, LRUFileCachePriority & other, const
 
     other.updateSize(-entry.size);
     other.updateElementsCount(-1);
-    return std::make_unique<LRUIterator>(this, it.iterator);
+    return LRUIterator(this, it.iterator);
 }
 
 FileSegments LRUFileCachePriority::dump(const CacheGuard::Lock & lock)

src/Interpreters/Cache/LRUFileCachePriority.h

@@ -67,17 +67,22 @@ private:
     using IterateFunc = std::function<IterationResult(LockedKey &, const FileSegmentMetadataPtr &)>;
     void iterate(IterateFunc && func, const CacheGuard::Lock &);
 
-    std::unique_ptr<LRUIterator> move(LRUIterator & it, LRUFileCachePriority & other, const CacheGuard::Lock &);
+    LRUIterator move(LRUIterator & it, LRUFileCachePriority & other, const CacheGuard::Lock &);
-    std::unique_ptr<LRUIterator> add(Entry && entry, const CacheGuard::Lock &);
+    LRUIterator add(Entry && entry, const CacheGuard::Lock &);
 };
 
 class LRUFileCachePriority::LRUIterator : public IFileCachePriority::Iterator
 {
     friend class LRUFileCachePriority;
     friend class SLRUFileCachePriority;
+
 public:
     LRUIterator(LRUFileCachePriority * cache_priority_, LRUQueue::iterator iterator_);
 
+    LRUIterator(const LRUIterator & other);
+    LRUIterator & operator =(const LRUIterator & other);
+    bool operator ==(const LRUIterator & other) const;
+
     const Entry & getEntry() const override { return *iterator; }
 
     size_t increasePriority(const CacheGuard::Lock &) override;

src/Interpreters/Cache/SLRUFileCachePriority.cpp

@@ -109,7 +109,7 @@ bool SLRUFileCachePriority::collectCandidatesForEviction(
             for (const auto & candidate : key_candidates.candidates)
             {
                 auto * candidate_it = assert_cast<SLRUIterator *>(candidate->getQueueIterator().get());
-                candidate_it->lru_iterator = probationary_queue.move(*candidate_it->lru_iterator, protected_queue, lk);
+                candidate_it->lru_iterator = probationary_queue.move(candidate_it->lru_iterator, protected_queue, lk);
                 candidate_it->is_protected = false;
             }
         }
@@ -124,7 +124,7 @@ void SLRUFileCachePriority::increasePriority(SLRUIterator & iterator, const Cach
     /// we only need to increase its priority within the protected queue.
     if (iterator.is_protected)
     {
-        iterator.lru_iterator->increasePriority(lock);
+        iterator.lru_iterator.increasePriority(lock);
         return;
     }
 
@@ -137,7 +137,7 @@ void SLRUFileCachePriority::increasePriority(SLRUIterator & iterator, const Cach
         /// Entry size is bigger than the whole protected queue limit.
         /// This is only possible if protected_queue_size_limit is less than max_file_segment_size,
         /// which is not possible in any realistic cache configuration.
-        iterator.lru_iterator->increasePriority(lock);
+        iterator.lru_iterator.increasePriority(lock);
         return;
     }
 
@@ -153,7 +153,7 @@ void SLRUFileCachePriority::increasePriority(SLRUIterator & iterator, const Cach
         /// We cannot make space for entry to be moved to protected queue
         /// (not enough releasable file segments).
         /// Then just increase its priority within probationary queue.
-        iterator.lru_iterator->increasePriority(lock);
+        iterator.lru_iterator.increasePriority(lock);
         return;
     }
 
@@ -176,7 +176,7 @@ void SLRUFileCachePriority::increasePriority(SLRUIterator & iterator, const Cach
             /// "downgrade" candidates cannot be moved to probationary queue,
             /// so entry cannot be moved to protected queue as well.
             /// Then just increase its priority within probationary queue.
-            iterator.lru_iterator->increasePriority(lock);
+            iterator.lru_iterator.increasePriority(lock);
             return;
         }
         /// Make space for "downgrade" candidates.
@@ -186,14 +186,14 @@ void SLRUFileCachePriority::increasePriority(SLRUIterator & iterator, const Cach
     /// All checks passed, now we can move downgrade candidates to
     /// probationary queue and our entry to protected queue.
     Entry entry_copy = iterator.getEntry();
-    iterator.lru_iterator->remove(lock);
+    iterator.lru_iterator.remove(lock);
 
     for (const auto & [key, key_candidates] : downgrade_candidates)
     {
         for (const auto & candidate : key_candidates.candidates)
         {
             auto * candidate_it = assert_cast<SLRUIterator *>(candidate->getQueueIterator().get());
-            candidate_it->lru_iterator = probationary_queue.move(*candidate_it->lru_iterator, protected_queue, lock);
+            candidate_it->lru_iterator = probationary_queue.move(candidate_it->lru_iterator, protected_queue, lock);
             candidate_it->is_protected = false;
         }
     }
@@ -218,10 +218,10 @@ void SLRUFileCachePriority::shuffle(const CacheGuard::Lock & lock)
 
 SLRUFileCachePriority::SLRUIterator::SLRUIterator(
     SLRUFileCachePriority * cache_priority_,
-    std::unique_ptr<LRUFileCachePriority::LRUIterator> lru_iterator_,
+    LRUFileCachePriority::LRUIterator && lru_iterator_,
     bool is_protected_)
     : cache_priority(cache_priority_)
-    , lru_iterator(std::move(lru_iterator_))
+    , lru_iterator(lru_iterator_)
     , is_protected(is_protected_)
 {
 }
@@ -229,7 +229,7 @@ SLRUFileCachePriority::SLRUIterator::SLRUIterator(
 const SLRUFileCachePriority::Entry & SLRUFileCachePriority::SLRUIterator::getEntry() const
 {
     assertValid();
-    return lru_iterator->getEntry();
+    return lru_iterator.getEntry();
 }
 
 size_t SLRUFileCachePriority::SLRUIterator::increasePriority(const CacheGuard::Lock & lock)
@@ -242,26 +242,24 @@ size_t SLRUFileCachePriority::SLRUIterator::increasePriority(const CacheGuard::L
 void SLRUFileCachePriority::SLRUIterator::updateSize(int64_t size)
 {
     assertValid();
-    lru_iterator->updateSize(size);
+    lru_iterator.updateSize(size);
 }
 
 void SLRUFileCachePriority::SLRUIterator::invalidate()
 {
     assertValid();
-    lru_iterator->invalidate();
+    lru_iterator.invalidate();
 }
 
 void SLRUFileCachePriority::SLRUIterator::remove(const CacheGuard::Lock & lock)
 {
     assertValid();
-    lru_iterator->remove(lock);
+    lru_iterator.remove(lock);
-    lru_iterator = nullptr;
 }
 
 void SLRUFileCachePriority::SLRUIterator::assertValid() const
 {
-    if (!lru_iterator)
+    lru_iterator.assertValid();
-        throw Exception(ErrorCodes::LOGICAL_ERROR, "Attempt to use invalid iterator");
 }
 
 }

src/Interpreters/Cache/SLRUFileCachePriority.h

@@ -52,7 +52,7 @@ class SLRUFileCachePriority::SLRUIterator : public IFileCachePriority::Iterator
 public:
     SLRUIterator(
         SLRUFileCachePriority * cache_priority_,
-        std::unique_ptr<LRUIterator> lru_iterator_,
+        LRUIterator && lru_iterator_,
         bool is_protected_);
 
     const Entry & getEntry() const override;
@@ -71,7 +71,7 @@ private:
     void assertValid() const;
 
     SLRUFileCachePriority * cache_priority;
-    mutable std::unique_ptr<LRUIterator> lru_iterator;
+    mutable LRUIterator lru_iterator;
     bool is_protected;
 };