[PATCH] Cygwin: fhandler_fifo::delete_client_handler: improve efficiency

[PATCH] Cygwin: fhandler_fifo::delete_client_handler: improve efficiency

[Ken Brown]

Delete a client handler by swapping it with the last one in the list
instead of calling memmove.
---
 winsup/cygwin/fhandler_fifo.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index b3c4c4a25..75c8406fe 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -377,14 +377,14 @@ fhandler_fifo::add_client_handler (bool new_pipe_instance)
   return 0;
 }
 
-/* Always called with fifo_client_lock in place. */
+/* Always called with fifo_client_lock in place.  Delete a
+   client_handler by swapping it with the last one in the list. */
 void
 fhandler_fifo::delete_client_handler (int i)
 {
   fc_handler[i].close ();
   if (i < --nhandlers)
-    memmove (fc_handler + i, fc_handler + i + 1,
-	     (nhandlers - i) * sizeof (fc_handler[i]));
+    fc_handler[i] = fc_handler[nhandlers];
 }
 
 /* Delete handlers that we will never read from.  Always called with
-- 
2.28.0

Re: [PATCH] Cygwin: fhandler_fifo::delete_client_handler: improve efficiency

[Corinna Vinschen]

On Aug 26 22:03, Ken Brown via Cygwin-patches wrote:
> Delete a client handler by swapping it with the last one in the list
> instead of calling memmove.
> ---
>  winsup/cygwin/fhandler_fifo.cc | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
> index b3c4c4a25..75c8406fe 100644
> --- a/winsup/cygwin/fhandler_fifo.cc
> +++ b/winsup/cygwin/fhandler_fifo.cc
> @@ -377,14 +377,14 @@ fhandler_fifo::add_client_handler (bool new_pipe_instance)
>    return 0;
>  }
>  
> -/* Always called with fifo_client_lock in place. */
> +/* Always called with fifo_client_lock in place.  Delete a
> +   client_handler by swapping it with the last one in the list. */
>  void
>  fhandler_fifo::delete_client_handler (int i)
>  {
>    fc_handler[i].close ();
>    if (i < --nhandlers)
> -    memmove (fc_handler + i, fc_handler + i + 1,
> -	     (nhandlers - i) * sizeof (fc_handler[i]));
> +    fc_handler[i] = fc_handler[nhandlers];
>  }
>  
>  /* Delete handlers that we will never read from.  Always called with
> -- 
> 2.28.0

Yup, please push.


Thanks,
Corinna