From 13133148dc5943db1cd8beb2987abfd6397d0b03 Mon Sep 17 00:00:00 2001
From: voidlizard <dzuikov@gmail.com>
Date: Sun, 12 Jan 2025 09:32:47 +0300
Subject: [PATCH] wip, works but mem O(k)

---
 hbs2-git3/app/Main.hs                     |  9 ++++++
 hbs2-git3/lib/HBS2/Data/Log/Structured.hs | 25 ++++++++++++++++
 hbs2-git3/lib/HBS2/Git3/State/Index.hs    | 36 +++++++++++------------
 3 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/hbs2-git3/app/Main.hs b/hbs2-git3/app/Main.hs
index 78aa80dd..dfcb6412 100644
--- a/hbs2-git3/app/Main.hs
+++ b/hbs2-git3/app/Main.hs
@@ -924,6 +924,15 @@ theDict = do
 
               liftIO $ hPrint stdout $ pretty sha1 <+> pretty blake
 
+        entry $ bindMatch "test:reflog:file:check" $ nil_ $ \case
+          [ StringLike fn ] -> lift do
+            bs <- liftIO $ mmapFileByteString fn Nothing
+
+            unless (validateSorted bs) do
+              error "malformed"
+
+          _ -> throwIO (BadFormException @C nil)
+
         entry $ bindMatch "test:git:reflog:index:sqlite" $ nil_ $ \syn -> lift $ connectedDo do
 
           reflog <- getGitRemoteKey >>= orThrowUser "reflog not set"
diff --git a/hbs2-git3/lib/HBS2/Data/Log/Structured.hs b/hbs2-git3/lib/HBS2/Data/Log/Structured.hs
index 049fc483..51bd4e99 100644
--- a/hbs2-git3/lib/HBS2/Data/Log/Structured.hs
+++ b/hbs2-git3/lib/HBS2/Data/Log/Structured.hs
@@ -17,6 +17,8 @@ import Codec.Compression.Zstd.Streaming qualified as Zstd
 import Codec.Compression.Zstd.Streaming (Result(..))
 
 import Control.Exception
+import Control.Monad.Trans.Maybe
+import Lens.Micro.Platform
 
 -- import UnliftIO
 
@@ -97,6 +99,29 @@ instance Monad m => BytesReader (ConsumeBS m) where
     put $! b
     pure (LBS.fromStrict a)
 
+{- HLINT ignore "Eta reduce"-}
+toSectionList :: BS.ByteString -> [BS.ByteString]
+toSectionList source = go source
+  where
+    go bs | BS.length bs < 4 = []
+          | otherwise = go1 (BS.splitAt 4 bs & over _1 (fromIntegral . N.word32))
+
+    go1 (len,rest) | BS.length rest < len = []
+
+    go1 (len,rest) = do
+      let (sect, rest1) = BS.splitAt len rest
+      sect : go rest1
+
+validateSorted :: BS.ByteString -> Bool
+validateSorted bs = do
+    let sections = toSectionList bs
+    let r = flip fix (Nothing, sections, 0) $ \next -> \case
+              (_, [], e) -> e
+              (Nothing, x:xs, e) -> next (Just x, xs, e)
+              (Just v, x:_, e) | v > x -> (e+1)
+              (Just _, x:xs, e)  -> next (Just x, xs, e)
+    r == 0
+
 scanBS :: Monad m => BS.ByteString -> ( BS.ByteString -> m () ) -> m ()
 scanBS bs action = do
   let hsz = 4
diff --git a/hbs2-git3/lib/HBS2/Git3/State/Index.hs b/hbs2-git3/lib/HBS2/Git3/State/Index.hs
index e65b541f..35f145eb 100644
--- a/hbs2-git3/lib/HBS2/Git3/State/Index.hs
+++ b/hbs2-git3/lib/HBS2/Git3/State/Index.hs
@@ -102,32 +102,30 @@ mergeSortedFilesN _ [_] out = rm out
 mergeSortedFilesN getKey inputFiles outFile = do
 
   mmaped <- for inputFiles $ \fn -> do
-     liftIO (mmapFileByteString fn Nothing)
+     bs <- liftIO (mmapFileByteString fn Nothing)
+     pure $ toSectionList bs
 
   liftIO $ UIO.withBinaryFileAtomic outFile WriteMode $ \hOut -> do
-    flip fix (mmaped, Heap.empty) $ \next (mmf, win) -> do
-      let (entries, files) = fmap readEntry mmf & unzip
-      let values = [ Entry (getKey e) e | e <- catMaybes entries ]
-      let e' = (win <> Heap.fromList values) & Heap.uncons
-      maybe1 e' none $ \(Entry _ e, newWin) -> do
+
+    let seed = HPSQ.empty @BS.ByteString @BS.ByteString @BS.ByteString
+
+    flip fix (mmaped, seed) $ \next (files, win) -> do
+
+      let (vals,rests) = unzip (mapMaybe L.uncons files)
+
+      let newWin = flip fix (win, vals) $ \l -> \case
+                      (w, [])   -> w
+                      (w, e:es) -> let k = getKey e in l (HPSQ.insert k k e w, es)
+
+      maybe1 (HPSQ.minView newWin) none $ \(k,_,e, nextWin) -> do
         liftIO $ writeSection (LBS.fromStrict e) (LBS.hPutStr hOut)
-        next (catMaybes files, newWin)
+        next (L.filter (not . L.null) $ fmap (dropDupes k) rests, nextWin)
 
     mapM_ rm inputFiles
 
   where
-    readEntry :: BS.ByteString -> (Maybe BS.ByteString, Maybe BS.ByteString)
+    dropDupes k = L.dropWhile ( (== k) . getKey )
 
-    readEntry src | BS.length src < 4 = (mzero, mzero)
-
-    readEntry src = do
-      let (size, rest) = BS.splitAt 4 src & over _1 ( fromIntegral . N.word32 )
-      let (e, rest2) = BS.splitAt size rest
-
-      if BS.length e < size then
-        (mzero, mzero)
-      else
-        (Just e, Just rest2)
 
 compactIndex :: forall m . (Git3Perks m, MonadReader Git3Env m) => Natural -> m ()
 compactIndex maxSize = do
@@ -356,5 +354,5 @@ updateReflogIndex = do
             -- notice $ pretty sha1 <+> pretty tx
             writeSection ( LBS.fromChunks [key,value] ) (LBS.hPutStr wh)
 
-      lift $ compactIndex ( 32 * 1024 * 1024 )
+      -- lift $ compactIndex ( 32 * 1024 * 1024 )