From fc53015811b3e0169f3627d71086db26ef0f3c2a Mon Sep 17 00:00:00 2001
From: sven-n <sven-n@users.noreply.github.com>
Date: Thu, 21 May 2026 08:19:25 +0200
Subject: [PATCH] Fix WAL file-handle leak in disk store recovery

RecoverFromWalOrIndex in both BasicDiskVocabularyStore and
BasicDiskVectorStore opened the WAL file with `using var fs`, which
keeps the handle alive until the end of the method. The subsequent
File.WriteAllBytes(_walPath, ...) call then raced against that handle
on Windows and threw IOException("The process cannot access the file
... because it is being used by another process."), causing
AddAndGetText_PersistsToDisk and Delete_RemovesFromIndexButKeepsFile to
fail intermittently.

Scope the FileStream/BinaryReader in an explicit `using (...)` block so
they are disposed before the truncating write.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 .../VectorStore/BasicDiskVectorStore.cs       | 53 +++++++++++--------
 .../Vocabulary/BasicDiskVocabularyStore.cs    | 29 ++++++----
 2 files changed, 48 insertions(+), 34 deletions(-)

diff --git a/src/Build5Nines.SharpVector/VectorStore/BasicDiskVectorStore.cs b/src/Build5Nines.SharpVector/VectorStore/BasicDiskVectorStore.cs
index 137d725..5cabe01 100644
--- a/src/Build5Nines.SharpVector/VectorStore/BasicDiskVectorStore.cs
+++ b/src/Build5Nines.SharpVector/VectorStore/BasicDiskVectorStore.cs
@@ -191,33 +191,40 @@ private void RecoverFromWalOrIndex()
 
         // Replay WAL to recover any operations after the last checkpoint
         if (!File.Exists(_walPath)) return;
-        using var fs = new FileStream(_walPath, FileMode.Open, FileAccess.Read, FileShare.Read);
-        using var br = new BinaryReader(fs);
-        while (fs.Position < fs.Length)
+
+        // Scope the read handles so the file is closed before we overwrite it
+        // below; `using var` would otherwise hold the handle until the end of
+        // the method and File.WriteAllBytes would race against it on Windows.
+        using (var fs = new FileStream(_walPath, FileMode.Open, FileAccess.Read, FileShare.Read))
+        using (var br = new BinaryReader(fs))
         {
-            bool isDelete = br.ReadBoolean();
-            var idJson = br.ReadString();
-            var id = JsonSerializer.Deserialize<TId>(idJson)!;
-            if (isDelete)
-            {
-                _index.TryRemove(id, out _);
-                _cache.TryRemove(id, out _);
-            }
-            else
+            while (fs.Position < fs.Length)
             {
-                var itemJson = br.ReadString();
-                var item = JsonSerializer.Deserialize<VectorTextItem<TVocabularyKey, TMetadata>>(itemJson)!;
-
-                // Append item to items file to bring storage up-to-date
-                using var ofs = new FileStream(_itemsPath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.Read);
-                ofs.Seek(0, SeekOrigin.End);
-                var offset = ofs.Position;
-                WriteItem(ofs, item);
-                ofs.Flush(true);
-                _index[id] = offset;
-                _cache[id] = item;
+                bool isDelete = br.ReadBoolean();
+                var idJson = br.ReadString();
+                var id = JsonSerializer.Deserialize<TId>(idJson)!;
+                if (isDelete)
+                {
+                    _index.TryRemove(id, out _);
+                    _cache.TryRemove(id, out _);
+                }
+                else
+                {
+                    var itemJson = br.ReadString();
+                    var item = JsonSerializer.Deserialize<VectorTextItem<TVocabularyKey, TMetadata>>(itemJson)!;
+
+                    // Append item to items file to bring storage up-to-date
+                    using var ofs = new FileStream(_itemsPath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.Read);
+                    ofs.Seek(0, SeekOrigin.End);
+                    var offset = ofs.Position;
+                    WriteItem(ofs, item);
+                    ofs.Flush(true);
+                    _index[id] = offset;
+                    _cache[id] = item;
+                }
             }
         }
+
         // After successful replay, truncate WAL (commit)
         File.WriteAllBytes(_walPath, Array.Empty<byte>());
         PersistIndex();
diff --git a/src/Build5Nines.SharpVector/Vocabulary/BasicDiskVocabularyStore.cs b/src/Build5Nines.SharpVector/Vocabulary/BasicDiskVocabularyStore.cs
index 2b1c6cd..3552c18 100644
--- a/src/Build5Nines.SharpVector/Vocabulary/BasicDiskVocabularyStore.cs
+++ b/src/Build5Nines.SharpVector/Vocabulary/BasicDiskVocabularyStore.cs
@@ -118,23 +118,30 @@ private void RecoverFromWalOrIndex()
     {
         LoadIfExists();
         if (!File.Exists(_walPath)) return;
-        using var fs = new FileStream(_walPath, FileMode.Open, FileAccess.Read, FileShare.Read);
-        using var br = new BinaryReader(fs);
-        while (fs.Position < fs.Length)
+
+        // Scope the read handles so the file is closed before we overwrite it
+        // below; `using var` would otherwise hold the handle until the end of
+        // the method and File.WriteAllBytes would race against it on Windows.
+        using (var fs = new FileStream(_walPath, FileMode.Open, FileAccess.Read, FileShare.Read))
+        using (var br = new BinaryReader(fs))
         {
-            int count = br.ReadInt32();
-            for (int i = 0; i < count; i++)
+            while (fs.Position < fs.Length)
             {
-                var tokenJson = br.ReadString();
-                var token = JsonSerializer.Deserialize<TKey>(tokenJson)!;
-                if (!_vocab.ContainsKey(token))
+                int count = br.ReadInt32();
+                for (int i = 0; i < count; i++)
                 {
-                    var idx = _vocab.Count;
-                    _vocab[token] = idx;
-                    _cache[token] = idx;
+                    var tokenJson = br.ReadString();
+                    var token = JsonSerializer.Deserialize<TKey>(tokenJson)!;
+                    if (!_vocab.ContainsKey(token))
+                    {
+                        var idx = _vocab.Count;
+                        _vocab[token] = idx;
+                        _cache[token] = idx;
+                    }
                 }
             }
         }
+
         File.WriteAllBytes(_walPath, Array.Empty<byte>());
         Persist();
     }