[PATCH 1/1] ntdll: Reuse old async fileio structures if possible.

[Sebastian Lackner]

From: Sebastian Lackner

This reportedly alleviates stutter when joining a match in Forza Horizon 5.
---
 dlls/ntdll/unix/file.c         | 23 +++++++++++++++++------
 dlls/ntdll/unix/unix_private.h |  1 +
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/dlls/ntdll/unix/file.c b/dlls/ntdll/unix/file.c
index eca75b2d4fb..2507120ab91 100644
--- a/dlls/ntdll/unix/file.c
+++ b/dlls/ntdll/unix/file.c
@@ -4890,18 +4890,29 @@ void release_fileio( struct async_fileio *io )
 struct async_fileio *alloc_fileio( DWORD size, async_callback_t callback, HANDLE handle )
 {
     /* first free remaining previous fileinfos */
-    struct async_fileio *io = InterlockedExchangePointer( (void **)&fileio_freelist, NULL );
+    struct async_fileio *old_io = InterlockedExchangePointer( (void **)&fileio_freelist, NULL );
+    struct async_fileio *io = NULL;

-    while (io)
+    while (old_io)
     {
-        struct async_fileio *next = io->next;
-        free( io );
-        io = next;
+        if (!io && old_io->size >= size && old_io->size <= max(4096, 4 * size))
+        {
+            io     = old_io;
+            size   = old_io->size;
+            old_io = old_io->next;
+        }
+        else
+        {
+            struct async_fileio *next = old_io->next;
+            free( old_io );
+            old_io = next;
+        }
     }

-    if ((io = malloc( size )))
+    if (io || (io = malloc( size )))
     {
         io->callback = callback;
+        io->size     = size;
         io->handle   = handle;
     }
     return io;
diff --git a/dlls/ntdll/unix/unix_private.h b/dlls/ntdll/unix/unix_private.h
index b803b1cef46..82aacbcb724 100644
--- a/dlls/ntdll/unix/unix_private.h
+++ b/dlls/ntdll/unix/unix_private.h
@@ -109,6 +109,7 @@ struct async_fileio
 {
     async_callback_t    *callback;
     struct async_fileio *next;
+    DWORD                size;
     HANDLE               handle;
 };