Release the forker initial key

Author: jasagredo

ouroboros-consensus/changelog.d/20251008_135933_javier.sagredo_fix_double_alloc.md

@@ -0,0 +1,24 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+### Patch
+
+- Ensure the initial handle allocated by opening a forker is deallocated in all
+  situations.
+
+<!--
+### Non-Breaking
+
+- A bullet item for the Non-Breaking category.
+
+-->
+<!--
+### Breaking
+
+- A bullet item for the Breaking category.
+
+-->

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Storage/LedgerDB/V2.hs

@@ -781,6 +781,7 @@ newForker h ldbEnv rr (st, rk) = do
           , foeSwitchVar = ldbSeq ldbEnv
           , foeTracer = tr
           , foeResourcesToRelease = (ldbOpenHandlesLock ldbEnv, k, toRelease)
+          , foeInitialHandleKey = rk
           }
   atomically $ modifyTVar (ldbForkers ldbEnv) $ Map.insert forkerKey forkerEnv
   pure $

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Storage/LedgerDB/V2/Forker.hs

@@ -19,6 +19,7 @@ module Ouroboros.Consensus.Storage.LedgerDB.V2.Forker
   , module Ouroboros.Consensus.Storage.LedgerDB.Forker
   ) where
 
+import qualified Control.Monad as Monad
 import Control.RAWLock hiding (read)
 import Control.ResourceRegistry
 import Control.Tracer
@@ -52,6 +53,9 @@ data ForkerEnv m l blk = ForkerEnv
   -- ^ Config
   , foeResourcesToRelease :: !(RAWLock m (), ResourceKey m, StrictTVar m (m ()))
   -- ^ Release the resources
+  , foeInitialHandleKey :: !(ResourceKey m)
+  -- ^ Resource key for the initial handle to ensure it is released. See
+  -- comments in 'implForkerCommit'.
   }
   deriving Generic
 
@@ -160,19 +164,12 @@ implForkerCommit env = do
                   AS.Empty _ -> pure ()
                   _ AS.:< closeOld' -> closeLedgerSeq (LedgerSeq closeOld')
                 -- Finally, close the anchor of @lseq@ (which is a duplicate of
-                -- the head of @olddb'@).
-                --
-                -- Note if the resource registry used to create the Forker is
-                -- ephemeral as the one created on each Chain selection or each
-                -- Forging loop iteration, this first duplicated state will be
-                -- closed by the resource registry closing down, so this will be
-                -- a double release, which is fine. We prefer keeping this
-                -- action just in case some client passes a registry that
-                -- outlives the forker.
-                --
-                -- The rest of the states in the forker will be closed via
-                -- @foeResourcesToRelease@ instead of via the registry.
-                close $ tables $ AS.anchor lseq
+                -- the head of @olddb'@). To close this handle, we have to
+                -- release the 'foeInitialHandleKey' as that one is registered
+                -- on the registry used to open the forker. Releasing it will
+                -- call 'close' on the handle which will call 'release' on the key
+                -- for the handle.
+                Monad.void $ release foeInitialHandleKey
           pure (closeDiscarded, LedgerSeq newdb)
       )
 
@@ -186,6 +183,7 @@ implForkerCommit env = do
     { foeLedgerSeq
     , foeSwitchVar
     , foeResourcesToRelease
+    , foeInitialHandleKey
     } = env
 
   theImpossible =