From e164d9a531addc326ac563eb7a082ed146f268b9 Mon Sep 17 00:00:00 2001
From: David Guida <1432872+mizrael@users.noreply.github.com>
Date: Fri, 7 Jun 2024 16:45:29 -0400
Subject: [PATCH] added semaphore to writer

---
 src/EvenireDB/Persistence/EventsProvider.cs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/EvenireDB/Persistence/EventsProvider.cs b/src/EvenireDB/Persistence/EventsProvider.cs
index 58297d7..906b083 100644
--- a/src/EvenireDB/Persistence/EventsProvider.cs
+++ b/src/EvenireDB/Persistence/EventsProvider.cs
@@ -41,7 +41,17 @@ public async ValueTask AppendAsync(
     {
         var extentInfo = _extentInfoProvider.Get(streamId);
 
-        var inHeaders = _dataRepo.AppendAsync(extentInfo, events, cancellationToken);
-        await _headersRepo.AppendAsync(extentInfo, inHeaders, cancellationToken);
+        var semaphore = _streamLocks.GetOrAdd(streamId, _ => new SemaphoreSlim(1, 1));
+        await semaphore.WaitAsync(cancellationToken);
+
+        try
+        {
+            var inHeaders = _dataRepo.AppendAsync(extentInfo, events, cancellationToken);
+            await _headersRepo.AppendAsync(extentInfo, inHeaders, cancellationToken);
+        }
+        finally
+        {
+            semaphore.Release();
+        }   
     }
 }
\ No newline at end of file