Fix for potential cyclical reference creation in RGAs

ron-rdt/CHANGELOG.md

@@ -5,6 +5,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0)
 and this project adheres to
 [Compatible Versioning](https://github.com/staltz/comver).
 
+## [0.12.1] - 2026-03-16
+* Added some duplicate operation removal to `vertexListFromOps`
+* Changed `applyPatch` to prefer new operations over existing ones when
+  updating the `HashMap UUID VertexListItem`.
+
 ## [0.12] - 2022-03-11
 - Added `Editable` typeclass which generalizes RON.Data.RGA.edit
 

ron-rdt/lib/RON/Data/LWW.hs

@@ -9,6 +9,7 @@
 {-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
 
 -- | LWW-per-field RDT
 module RON.Data.LWW (

ron-rdt/lib/RON/Data/ORSet/Experimental.hs

@@ -5,6 +5,7 @@
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
 
 module RON.Data.ORSet.Experimental (
   ORSet,

ron-rdt/lib/RON/Data/RGA.hs

@@ -48,6 +48,7 @@ import qualified Data.HashMap.Strict as HashMap
 import           Data.Map.Strict ((!?))
 import qualified Data.Map.Strict as Map
 import qualified Data.Text as Text
+import           Data.List (nubBy)
 
 import           RON.Data.Internal (MonadObjectState,
                                     Editable (..),
@@ -119,7 +120,7 @@ vertexListToOps v@VertexList {..} = go listHead listItems
        in itemValue : rest
 
 vertexListFromOps :: [Vertex] -> Maybe VertexList
-vertexListFromOps = foldr go mempty
+vertexListFromOps = foldr go mempty . nubBy (\Op{opId = opIdA} Op{opId = opIdB} -> opIdA == opIdB)
   where
     go v@Op{opId} vlist = Just VertexList{listHead = opId, listItems = vlist'}
       where
@@ -276,7 +277,7 @@ applyPatch parent patch targetItems = case parent of
           Nothing -> patch
           Just next -> VertexList next targetItems <> patch
     let item' = item {itemNext = Just next'}
-    pure $ HashMap.insert parent item' targetItems <> newItems
+    pure $ HashMap.insert parent item' newItems <> targetItems
 
 reapplyRemovalsToState :: (RgaRep, PatchSet) -> Maybe (RgaRep, PatchSet)
 reapplyRemovalsToState (RgaRep rstate, ps@PatchSet {..}) = do

ron-rdt/ron-rdt.cabal

@@ -1,7 +1,7 @@
 cabal-version:  2.2
 
 name:           ron-rdt
-version:        0.10
+version:        0.12.1
 
 bug-reports:    https://github.com/ff-notes/ron/issues
 category:       Distributed Systems, Protocol, Database