YT-21402: Adjust util's IntrusiveList to support more convenient use in lockfree algorithms (and farewell SimpleIntrusiveList)

Should be done
8a7cafa1f535df785680b70b488a2e4fbb46b1b0

1 files changed, 27 insertions, 6 deletions

diff --git a/util/generic/intrlist.h b/util/generic/intrlist.h
index b5d3f2051b5..2982e3a2815 100644
--- a/util/generic/intrlist.h
+++ b/util/generic/intrlist.h
@@ -39,7 +39,7 @@ public:
         Prev_->SetNext(Next_);
         Next_->SetPrev(Prev_);
 
-        SetEnd();
+        ResetItem();
     }
 
     inline void LinkBefore(TListItem* before) noexcept {
@@ -87,11 +87,6 @@ public:
     }
 
 public:
-    inline void SetEnd() noexcept {
-        Prev_ = this;
-        Next_ = Prev_;
-    }
-
     inline void SetNext(TListItem* item) noexcept {
         Next_ = item;
     }
@@ -109,6 +104,28 @@ public:
         return static_cast<const T*>(this);
     }
 
+public:
+    // NB(arkady-e1ppa): These methods are used to implement
+    // intrusive lock-free algorithms which want to natively
+    // interact with TIntrusiveList.
+    // Assume that if you've used MutableNext/MutablePrev
+    // methods, you are not safe to use anything but
+    // MutableNext/MutablePrev/ResetItem methods until
+    // you call a ResetItem method.
+
+    inline TListItem*& MutableNext() noexcept {
+        return Next_;
+    }
+
+    inline TListItem*& MutablePrev() noexcept {
+        return Prev_;
+    }
+
+    inline void ResetItem() noexcept {
+        Next_ = this;
+        Prev_ = Next_;
+    }
+
 private:
     inline TIntrusiveListItem(const TIntrusiveListItem&) = delete;
     inline TIntrusiveListItem& operator=(const TIntrusiveListItem&) = delete;
@@ -508,6 +525,10 @@ public:
         Cut(list.Begin(), list.End(), End());
     }
 
+    inline void Append(TIntrusiveList&& list) noexcept {
+        Append(list);
+    }
+
     inline static void Cut(TIterator begin, TIterator end, TIterator pasteBefore) noexcept {
         if (begin == end) {
             return;