[PATCH wayland v5] client: extend error handling
Jason Ekstrand
jason at jlekstrand.net
Tue Jul 22 19:44:00 PDT 2014
Sorry for not looking at it. I'm mostly ok with the API so it's fine that
you pushed it. I did have a question or two though.
On Mon, Jul 7, 2014 at 7:28 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> From: Marek Chalupa <mchqwerty at gmail.com>
>
> When an error occurs, wl_display_get_error() does not
> provide any way of getting know if it was a local error or if it was
> an error event, respectively what object caused the error and what
> the error was.
>
> This patch introduces a new function wl_display_get_protocol_error()
> which will return error code, interface and id of the object that
> generated the error.
> wl_display_get_error() will work the same way as before.
>
> wl_display_get_protocol_error() DOES NOT indicate that a non-protocol
> error happened. It returns valid information only in that case that
> (protocol) error occurred, so it should be used after calling
> wl_display_get_error() with positive result.
>
> [Pekka Paalanen] Applied another hunk of Bryce's comments to docs,
> added libtool version bump.
>
> Reviewed-by: Pekka Paalanen <ppaalanen at gmail.com>
> Reviewed-by: Bryce Harrington <b.harrington at samsung.com>
> ---
> Makefile.am | 2 +-
> src/wayland-client.c | 137
> ++++++++++++++++++++++++++++++++++++++++++++-------
> src/wayland-client.h | 3 ++
> 3 files changed, 123 insertions(+), 19 deletions(-)
>
> diff --git a/Makefile.am b/Makefile.am
> index c15d8b8..fee19ab 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -51,7 +51,7 @@ nodist_libwayland_server_la_SOURCES = \
>
> libwayland_client_la_CFLAGS = $(FFI_CFLAGS) $(GCC_CFLAGS) -pthread
> libwayland_client_la_LIBADD = $(FFI_LIBS) libwayland-util.la -lrt -lm
> -libwayland_client_la_LDFLAGS = -version-info 2:0:2
> +libwayland_client_la_LDFLAGS = -version-info 3:0:3
> libwayland_client_la_SOURCES = \
> src/wayland-client.c
>
> diff --git a/src/wayland-client.c b/src/wayland-client.c
> index e8aab7e..19b5694 100644
> --- a/src/wayland-client.c
> +++ b/src/wayland-client.c
> @@ -78,7 +78,24 @@ struct wl_event_queue {
> struct wl_display {
> struct wl_proxy proxy;
> struct wl_connection *connection;
> +
> + /* errno of the last wl_display error */
> int last_error;
> +
> + /* When display gets an error event from some object, it stores
> + * information about it here, so that client can get this
> + * information afterwards */
> + struct {
> + /* Code of the error. It can be compared to
> + * the interface's errors enumeration. */
> + uint32_t code;
> + /* interface (protocol) in which the error occurred */
> + const struct wl_interface *interface;
> + /* id of the proxy that caused the error. There's no
> warranty
> + * that the proxy is still valid. It's up to client how it
> will
> + * use it */
> + uint32_t id;
> + } protocol_error;
> int fd;
> pthread_t display_thread;
> struct wl_map objects;
> @@ -96,6 +113,14 @@ struct wl_display {
>
> static int debug_client = 0;
>
> +/**
> + * This function is called for local errors (no memory, server hung up)
> + *
> + * \param display
> + * \param error error value (EINVAL, EFAULT, ...)
> + *
> + * \note this function is called with display mutex locked
> + */
> static void
> display_fatal_error(struct wl_display *display, int error)
> {
> @@ -105,7 +130,7 @@ display_fatal_error(struct wl_display *display, int
> error)
> return;
>
> if (!error)
> - error = 1;
> + error = EFAULT;
>
> display->last_error = error;
>
> @@ -113,11 +138,56 @@ display_fatal_error(struct wl_display *display, int
> error)
> pthread_cond_broadcast(&iter->cond);
> }
>
> +/**
> + * This function is called for error events
> + * and indicates that in some object an error occured.
> + * Difference between this function and display_fatal_error()
> + * is that this one handles errors that will come by wire,
> + * whereas display_fatal_error() is called for local errors.
> + *
> + * \param display
> + * \param code error code
> + * \param id id of the object that generated the error
> + * \param intf protocol interface
> + */
> static void
> -wl_display_fatal_error(struct wl_display *display, int error)
> +display_protocol_error(struct wl_display *display, uint32_t code,
> + uint32_t id, const struct wl_interface *intf)
> {
> + struct wl_event_queue *iter;
> + int err;
> +
> + if (display->last_error)
> + return;
> +
> + /* set correct errno */
> + if (wl_interface_equal(intf, &wl_display_interface)) {
> + switch (code) {
> + case WL_DISPLAY_ERROR_INVALID_OBJECT:
> + case WL_DISPLAY_ERROR_INVALID_METHOD:
> + err = EINVAL;
> + break;
> + case WL_DISPLAY_ERROR_NO_MEMORY:
> + err = ENOMEM;
> + break;
> + default:
> + err = EFAULT;
> + }
> + } else {
> + err = EPROTO;
> + }
> +
> pthread_mutex_lock(&display->mutex);
> - display_fatal_error(display, error);
> +
> + display->last_error = err;
> +
> + display->protocol_error.code = code;
> + display->protocol_error.id = id;
> + display->protocol_error.interface = intf;
> +
> + wl_list_for_each(iter, &display->event_queue_list, link)
> + pthread_cond_broadcast(&iter->cond);
>
Why are you doing this? Is someone waiting on you to display an error or
waiting for the error code? I don't really see what there is to wake up
here.
> +
> pthread_mutex_unlock(&display->mutex);
> }
>
> @@ -579,25 +649,12 @@ display_handle_error(void *data,
> uint32_t code, const char *message)
> {
> struct wl_proxy *proxy = object;
> - int err;
>
> wl_log("%s@%u: error %d: %s\n",
> proxy->object.interface->name, proxy->object.id, code,
> message);
>
> - switch (code) {
> - case WL_DISPLAY_ERROR_INVALID_OBJECT:
> - case WL_DISPLAY_ERROR_INVALID_METHOD:
> - err = EINVAL;
> - break;
> - case WL_DISPLAY_ERROR_NO_MEMORY:
> - err = ENOMEM;
> - break;
> - default:
> - err = EFAULT;
> - break;
> - }
> -
> - wl_display_fatal_error(display, err);
> + display_protocol_error(display, code, proxy->object.id,
> + proxy->object.interface);
> }
>
> static void
> @@ -1486,6 +1543,50 @@ wl_display_get_error(struct wl_display *display)
> return ret;
> }
>
> +/**
> + * Retrieves the information about a protocol error:
> + *
> + * \param display The Wayland display
> + * \param interface if not NULL, stores the interface where the error
> occurred
> + * \param id if not NULL, stores the object id that generated
> + * the error. There's no guarantee the object is
> + * still valid; the client must know if it deleted the
> object.
>
Does the client even know what to do with the ID? I mean, sure, they could
print it in an error message, but how useful is it? I suppose they could
check to see if wl_proxy_get_id(my_proxy) == id to see if it happend at
that point in the stream. Is this what you intend?
> + * \return The error code as defined in the interface
> specification.
> + *
> + * \code
> + * int err = wl_display_get_error(display);
> + *
> + * if (err == EPROTO) {
> + * code = wl_display_get_protocol_error(display, &interface, &id);
> + * handle_error(code, interface, id);
> + * }
> + *
> + * ...
> + *
> + * \endcode
> + */
> +WL_EXPORT uint32_t
> +wl_display_get_protocol_error(struct wl_display *display,
> + const struct wl_interface **interface,
> + uint32_t *id)
> +{
> + uint32_t ret;
> +
> + pthread_mutex_lock(&display->mutex);
> +
> + ret = display->protocol_error.code;
> +
> + if (interface)
> + *interface = display->protocol_error.interface;
> + if (id)
> + *id = display->protocol_error.id;
> +
> + pthread_mutex_unlock(&display->mutex);
> +
> + return ret;
> +}
> +
> +
> /** Send all buffered requests on the display to the server
> *
> * \param display The display context object
> diff --git a/src/wayland-client.h b/src/wayland-client.h
> index 2a32785..dc4df53 100644
> --- a/src/wayland-client.h
> +++ b/src/wayland-client.h
> @@ -161,6 +161,9 @@ int wl_display_dispatch_queue_pending(struct
> wl_display *display,
> struct wl_event_queue *queue);
> int wl_display_dispatch_pending(struct wl_display *display);
> int wl_display_get_error(struct wl_display *display);
> +uint32_t wl_display_get_protocol_error(struct wl_display *display,
> + const struct wl_interface
> **interface,
> + uint32_t *id);
>
> int wl_display_flush(struct wl_display *display);
> int wl_display_roundtrip(struct wl_display *display);
> --
> 1.8.5.5
>
> _______________________________________________
> wayland-devel mailing list
> wayland-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/wayland-devel
>
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