[PATCH] winealsa: Wait for the notify buffer to empty, rather than dropping an event.

[Andrew Eikum]

Signed-off-by: Andrew Eikum <aeikum at codeweavers.com>

On Tue, Apr 19, 2022 at 01:18:33PM +0100, Huw Davies wrote:
> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=52828
> Signed-off-by: Huw Davies <huw at codeweavers.com>
> ---
>  dlls/winealsa.drv/alsamidi.c | 42 ++++++++++++++++++++++++------------
>  1 file changed, 28 insertions(+), 14 deletions(-)
> 
> diff --git a/dlls/winealsa.drv/alsamidi.c b/dlls/winealsa.drv/alsamidi.c
> index 4f3f5538891..b226dac310f 100644
> --- a/dlls/winealsa.drv/alsamidi.c
> +++ b/dlls/winealsa.drv/alsamidi.c
> @@ -90,7 +90,8 @@ static int rec_cancel_pipe[2];
>  static pthread_t rec_thread_id;
>  
>  static pthread_mutex_t notify_mutex = PTHREAD_MUTEX_INITIALIZER;
> -static pthread_cond_t notify_cond = PTHREAD_COND_INITIALIZER;
> +static pthread_cond_t notify_read_cond = PTHREAD_COND_INITIALIZER;
> +static pthread_cond_t notify_write_cond = PTHREAD_COND_INITIALIZER;
>  static BOOL notify_quit;
>  #define NOTIFY_BUFFER_SIZE 64 + 1 /* + 1 for the sentinel */
>  static struct notify_context notify_buffer[NOTIFY_BUFFER_SIZE];
> @@ -156,19 +157,23 @@ static struct notify_context *notify_buffer_next(struct notify_context *notify)
>      return notify;
>  }
>  
> -static void notify_buffer_add(struct notify_context *notify)
> +static BOOL notify_buffer_empty(void)
>  {
> -    struct notify_context *next = notify_buffer_next(notify_write);
> +    return notify_read == notify_write;
> +}
>  
> -    if (next == notify_read) /* buffer is full - we can't issue a WARN() in a non-Win32 thread */
> -        notify_read = notify_buffer_next(notify_read); /* drop the oldest notification */
> -    *notify_write = *notify;
> -    notify_write = next;
> +static BOOL notify_buffer_full(void)
> +{
> +    return notify_buffer_next(notify_write) == notify_read;
>  }
>  
> -static BOOL notify_buffer_empty(void)
> +static BOOL notify_buffer_add(struct notify_context *notify)
>  {
> -    return notify_read == notify_write;
> +    if (notify_buffer_full()) return FALSE;
> +
> +    *notify_write = *notify;
> +    notify_write = notify_buffer_next(notify_write);
> +    return TRUE;
>  }
>  
>  static BOOL notify_buffer_remove(struct notify_context *notify)
> @@ -184,9 +189,15 @@ static void notify_post(struct notify_context *notify)
>  {
>      pthread_mutex_lock(&notify_mutex);
>  
> -    if (notify) notify_buffer_add(notify);
> +    if (notify)
> +    {
> +        while (notify_buffer_full())
> +            pthread_cond_wait(&notify_write_cond, &notify_mutex);
> +
> +        notify_buffer_add(notify);
> +    }
>      else notify_quit = TRUE;
> -    pthread_cond_signal(&notify_cond);
> +    pthread_cond_signal(&notify_read_cond);
>  
>      pthread_mutex_unlock(&notify_mutex);
>  }
> @@ -1476,11 +1487,14 @@ NTSTATUS midi_notify_wait(void *args)
>      pthread_mutex_lock(&notify_mutex);
>  
>      while (!notify_quit && notify_buffer_empty())
> -        pthread_cond_wait(&notify_cond, &notify_mutex);
> +        pthread_cond_wait(&notify_read_cond, &notify_mutex);
>  
>      *params->quit = notify_quit;
> -    if (!notify_quit) notify_buffer_remove(params->notify);
> -
> +    if (!notify_quit)
> +    {
> +        notify_buffer_remove(params->notify);
> +        pthread_cond_signal(&notify_write_cond);
> +    }
>      pthread_mutex_unlock(&notify_mutex);
>  
>      return STATUS_SUCCESS;
> -- 
> 2.25.1
> 
>