Structure, refactor and clean up trace messages

.github/workflows/ci.yml

@@ -122,6 +122,7 @@ jobs:
           --project-file="${{ matrix.cabal-project-file || env.DEFAULT_CABAL_PROJECT_FILE }}"
 
     - name: 🧪 Test
+      id: test
       if: ${{ !matrix.cabal-skip-tests }}
       run: |
         cabal test all \
@@ -131,6 +132,19 @@ jobs:
       env:
         TASTY_TIMEOUT: "5m"
 
+    # Golden test output is not printed to the screen, so if a golden test fails
+    # then it is not clear from the logs why the test fails. Uploading the
+    # directory containing the golden files after running the goldens tests
+    # allows us to diff the expected and actual golden file contents.
+    - name: 📦 Upload golden files
+      if: ${{ !matrix.cabal-skip-tests && steps.test.outcome != 'success' && always() }}
+      uses: actions/upload-artifact@v4
+      with:
+        name: golden-files-${{ runner.os }}-ghc-${{ steps.setup-haskell.outputs.ghc-version }}-cabal-${{ steps.setup-haskell.outputs.cabal-version }}-plan-${{ hashFiles('dist-newstyle/cache/plan.json') }}
+        path: test/golden-file-data
+        if-no-files-found: error
+        retention-days: 1
+
     - name: 🛠️ Setup cabal-docspec (Linux)
       if: ${{ !matrix.cabal-skip-tests && runner.os == 'Linux' }}
       uses: ./.github/actions/setup-cabal-docspec

lsm-tree.cabal

@@ -811,6 +811,7 @@ test-suite lsm-tree-test
     Test.Database.LSMTree.StateMachine
     Test.Database.LSMTree.StateMachine.DL
     Test.Database.LSMTree.StateMachine.Op
+    Test.Database.LSMTree.Tracer.Golden
     Test.Database.LSMTree.UnitTests
     Test.FS
     Test.Util.Arbitrary

src/Database/LSMTree.hs

@@ -175,11 +175,13 @@ module Database.LSMTree (
   -- * Traces #traces#
   Tracer,
   LSMTreeTrace (..),
+  SessionTrace (..),
   TableTrace (..),
   CursorTrace (..),
   MergeTrace (..),
-  CursorId (..),
+  SessionId (..),
   TableId (..),
+  CursorId (..),
   AtLevel (..),
   LevelNo (..),
   NumEntries (..),
@@ -251,7 +253,8 @@ import           Database.LSMTree.Internal.Unsafe (BlobRefInvalidError (..),
                      ResolveSerialisedValue, SessionClosedError (..),
                      SessionDirCorruptedError (..),
                      SessionDirDoesNotExistError (..),
-                     SessionDirLockedError (..), SnapshotCorruptedError (..),
+                     SessionDirLockedError (..), SessionId (..),
+                     SessionTrace (..), SnapshotCorruptedError (..),
                      SnapshotDoesNotExistError (..), SnapshotExistsError (..),
                      SnapshotNotCompatibleError (..), TableClosedError (..),
                      TableCorruptedError (..), TableTooLargeError (..),

src/Database/LSMTree/Internal/RunReader.hs

@@ -90,6 +90,7 @@ data RunReader m h = RunReader {
     }
 
 data OffsetKey = NoOffsetKey | OffsetKey !SerialisedKey
+  deriving stock Show
 
 {-# SPECIALISE new ::
      OffsetKey

src/Database/LSMTree/Internal/UniqCounter.hs

@@ -11,6 +11,7 @@ module Database.LSMTree.Internal.UniqCounter (
   uniqueToCursorId,
 ) where
 
+import           Control.DeepSeq (NFData (..))
 import           Control.Monad.Primitive (PrimMonad, PrimState)
 import           Data.Primitive.PrimVar as P
 import           Database.LSMTree.Internal.RunNumber
@@ -35,6 +36,9 @@ uniqueToCursorId (Unique n) = CursorId n
 --
 newtype UniqCounter m = UniqCounter (PrimVar (PrimState m) Int)
 
+instance NFData (UniqCounter m) where
+  rnf (UniqCounter (P.PrimVar mba)) = rnf mba
+
 {-# INLINE newUniqCounter #-}
 newUniqCounter :: PrimMonad m => Int -> m (UniqCounter m)
 newUniqCounter = fmap UniqCounter . P.newPrimVar