From 6e23bad39778cba848dee17921c9d92a56958e59 Mon Sep 17 00:00:00 2001
From: voidlizard <dzuikov@gmail.com>
Date: Mon, 21 Jul 2025 20:38:40 +0300
Subject: [PATCH] scan-for-tombs

---
 hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs | 20 ++++----
 hbs2-tests/test/TestNCQ.hs                | 57 +++++++++++++++++++++++
 2 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs b/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs
index 63191767..67959e08 100644
--- a/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs
+++ b/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs
@@ -281,6 +281,9 @@ ncqNewUniqFileName  me@NCQStorage2{..} pref suff = liftIO $ withSem ncqMiscSem d
     False -> pure n
     True  -> next (succ i)
 
+ncqEmptyKey :: ByteString
+ncqEmptyKey = BS.replicate ncqKeyLen 0
+
 ncqGetNewFossilName :: MonadIO m => NCQStorage2 -> m FilePath
 ncqGetNewFossilName me = ncqNewUniqFileName me "fossil-" ".data"
 
@@ -514,15 +517,16 @@ ncqLookupIndex :: MonadUnliftIO m
                -> m (Maybe ( NCQOffset, NCQSize ))
 ncqLookupIndex hx (mmaped, nway) = do
   fmap decodeEntry <$> nwayHashLookup nway mmaped (coerce hx)
-  where
-    {-# INLINE decodeEntry #-}
-    decodeEntry entryBs = do
-      let (p,r) = BS.splitAt 8 entryBs
-      let off = fromIntegral (N.word64 p)
-      let size = fromIntegral (N.word32 (BS.take 4 r))
-      ( off, size )
 {-# INLINE ncqLookupIndex #-}
 
+decodeEntry :: ByteString -> ( NCQOffset, NCQSize )
+decodeEntry entryBs = do
+    let (p,r) = BS.splitAt 8 entryBs
+    let off = fromIntegral (N.word64 p)
+    let size = fromIntegral (N.word32 (BS.take 4 r))
+    ( off, size )
+{-# INLINE decodeEntry #-}
+
 ncqLocateActually :: MonadUnliftIO m => NCQStorage2 -> HashRef -> m (Maybe Location)
 ncqLocateActually ncq href = do
   inMem      <- ncqLookupEntry ncq href <&> fmap (InMemory . ncqEntryData)
@@ -749,7 +753,7 @@ ncqStorageRun2 ncq@NCQStorage2{..} = flip runContT pure do
 
   where
 
-    emptyKey = BS.replicate ncqKeyLen 0
+    emptyKey = ncqEmptyKey
 
     openNewDataFile :: forall mx . MonadIO mx => mx (FileKey, Fd)
     openNewDataFile = do
diff --git a/hbs2-tests/test/TestNCQ.hs b/hbs2-tests/test/TestNCQ.hs
index 219124e9..33d9ac9b 100644
--- a/hbs2-tests/test/TestNCQ.hs
+++ b/hbs2-tests/test/TestNCQ.hs
@@ -1628,6 +1628,63 @@ main = do
 
           e -> throwIO (BadFormException (mkList e))
 
+
+        entry $ bindMatch "test:ncq2:del2" $ nil_ $ \syn -> do
+
+          runTest $ \TestEnv{..} -> do
+            g <- liftIO MWC.createSystemRandom
+            let dir = testEnvDir
+
+            let (_, argz) = splitOpts [] syn
+            let n = headDef 50000 [ fromIntegral x | LitIntVal x <- argz ]
+            let p0 = headDef 0.25  [ realToFrac x   | LitScientificVal x <- drop 1 argz ]
+
+            thashes <- newTVarIO mempty
+
+            ncqWithStorage dir $ \sto@NCQStorage2{..} -> do
+
+              sizes <- replicateM n $ uniformRM (32*1024, 256*1024) g
+
+              notice $ "write" <+> pretty n <+> "blocks"
+              pooledForConcurrentlyN_ 16 sizes $ \s -> do
+                h <- ncqPutBS sto (Just B) Nothing =<< genRandomBS g s
+
+                p1 <- uniformRM @Double (0, 1) g
+
+                when (p1 < p0) do
+                  ncqDelEntry sto h
+                  atomically $ modifyTVar thashes (HS.insert h)
+
+              deleted <- readTVarIO thashes
+
+              tombs <- for (HS.toList deleted) $ \d -> do
+                         ncqLocate2 sto d <&>  maybe False (N2.ncqIsTomb sto)
+
+              let tnum = sum [ 1 | x <- tombs, x ]
+
+              notice $ "should be deleted" <+> pretty (HS.size deleted) <+> "/" <+> pretty tnum
+
+              useVersion sto $ const do
+                tfs <- N2.ncqListTrackedFiles sto <&> filter (isNotPending . view _2) . V.toList
+
+                for_ tfs $ \(fk,_,_)  -> void $ runMaybeT do
+
+                  let idxf = N2.ncqGetFileName sto $ toFileName (IndexFile fk)
+
+                  (idxBs, nway) <- liftIO $ nwayHashMMapReadOnly idxf
+                                        >>= orThrowUser "can't mmap index"
+
+                  stat' <- S.toList_ $ nwayHashScanAll nway idxBs $ \_ k v -> do
+                    unless (k == ncqEmptyKey) do
+                      let (o,s) = decodeEntry v
+                      when ( s == ncqSLen + ncqKeyLen + ncqPrefixLen ) do
+                        let hk = coerce @_ @HashRef k
+                        S.yield (fk, 1)
+
+                  let stat = HM.fromListWith (+) stat'
+                  for_ (HM.toList stat) $ \(k, num) -> do
+                    notice $ pretty k <+> pretty num
+
         entry $ bindMatch "test:ncq2:del1" $ nil_ $ \syn -> do
 
           runTest $ \TestEnv{..} -> do