[PATCH 6/8] libqmi-glib, device: port qmi_device_release_client to use GTask

[Aleksander Morgado]

Hey Ben,

See below.

On 12/04/17 22:15, Ben Chan wrote:
> ---
>  src/libqmi-glib/qmi-device.c | 56 ++++++++++++++------------------------------
>  1 file changed, 18 insertions(+), 38 deletions(-)
> 
> diff --git a/src/libqmi-glib/qmi-device.c b/src/libqmi-glib/qmi-device.c
> index 108b605..bc9480c 100644
> --- a/src/libqmi-glib/qmi-device.c
> +++ b/src/libqmi-glib/qmi-device.c
> @@ -1120,32 +1120,18 @@ qmi_device_allocate_client (QmiDevice *self,
>  /*****************************************************************************/
>  /* Release client */
>  
> -typedef struct {
> -    QmiClient *client;
> -    GSimpleAsyncResult *result;
> -} ReleaseClientContext;
> -
> -static void
> -release_client_context_complete_and_free (ReleaseClientContext *ctx)
> -{
> -    g_simple_async_result_complete_in_idle (ctx->result);
> -    g_object_unref (ctx->result);
> -    g_object_unref (ctx->client);
> -    g_slice_free (ReleaseClientContext, ctx);
> -}
> -
>  gboolean
>  qmi_device_release_client_finish (QmiDevice *self,
>                                    GAsyncResult *res,
>                                    GError **error)
>  {
> -    return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
> +    return g_task_propagate_boolean (G_TASK (res), error);
>  }
>  
>  static void
>  client_ctl_release_cid_ready (QmiClientCtl *client_ctl,
>                                GAsyncResult *res,
> -                              ReleaseClientContext *ctx)
> +                              GTask *task)
>  {
>      GError *error = NULL;
>      QmiMessageCtlReleaseCidOutput *output;
> @@ -1156,21 +1142,21 @@ client_ctl_release_cid_ready (QmiClientCtl *client_ctl,
>      /* Check result of the async operation */
>      output = qmi_client_ctl_release_cid_finish (client_ctl, res, &error);
>      if (!output) {
> -        g_simple_async_result_take_error (ctx->result, error);
> -        release_client_context_complete_and_free (ctx);
> +        g_task_return_error (task, error);
> +        g_object_unref (task);
>          return;
>      }
>  
>      /* Check result of the QMI operation */
>      if (!qmi_message_ctl_release_cid_output_get_result (output, &error)) {
> -        g_simple_async_result_take_error (ctx->result, error);
> -        release_client_context_complete_and_free (ctx);
> +        g_task_return_error (task, error);
> +        g_object_unref (task);
>          qmi_message_ctl_release_cid_output_unref (output);
>          return;
>      }
>  
> -    g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
> -    release_client_context_complete_and_free (ctx);
> +    g_task_return_boolean (task, TRUE);
> +    g_object_unref (task);
>      qmi_message_ctl_release_cid_output_unref (output);
>  }
>  
> @@ -1183,7 +1169,7 @@ qmi_device_release_client (QmiDevice *self,
>                             GAsyncReadyCallback callback,
>                             gpointer user_data)
>  {
> -    ReleaseClientContext *ctx;
> +    GTask *task;
>      QmiService service;
>      guint8 cid;
>      gchar *flags_str;
> @@ -1206,21 +1192,15 @@ qmi_device_release_client (QmiDevice *self,
>  
>      /* NOTE! The operation must not take a reference to self, or we won't be
>       * able to use it implicitly from our dispose() */

This previous comment is misleading and obsolete, and we should remove
it. There is no explicit CID releasing done during dispose(), and
therefore we can (must I would say) take a reference to self in the GTask.

> -
> -    ctx = g_slice_new0 (ReleaseClientContext);
> -    ctx->client = g_object_ref (client);
> -    ctx->result = g_simple_async_result_new (G_OBJECT (self),
> -                                             callback,
> -                                             user_data,
> -                                             qmi_device_release_client);
> +    task = g_task_new (client, cancellable, callback, user_data);
>  

The source_object for the GTask *must* be 'self', not 'client'. This is
because during the task completion, the first argument given to the
finish() function will be this object and that would be a QmiDevice.
Now, this is really not required as the pointer is anyway not used in
the finish() method, but we should keep it consistent.

And if we do this, beware, because a bit further down in the logic there
is a unregister_client() call that will remove the internal reference to
the client (and therefore may be the last one), and just after that we
do a g_object_set() on the client object. This worked always before
because there was a client reference in the Context; but now there
isn't. We cannot remove the g_object_set() call, as we don't know
whether the caller holds a full reference or not, so the correct thing
to do would be to make sure there is an explicit valid reference to the
client object around those calls; or just set a full client reference as
task data.

>      /* Do not try to release an already released client */
>      if (cid == QMI_CID_NONE) {
> -        g_simple_async_result_set_error (ctx->result,
> -                                         QMI_CORE_ERROR,
> -                                         QMI_CORE_ERROR_INVALID_ARGS,
> -                                         "Client is already released");
> -        release_client_context_complete_and_free (ctx);
> +        g_task_return_new_error (task,
> +                                 QMI_CORE_ERROR,
> +                                 QMI_CORE_ERROR_INVALID_ARGS,
> +                                 "Client is already released");
> +        g_object_unref (task);
>          return;
>      }
>  
> @@ -1252,15 +1232,15 @@ qmi_device_release_client (QmiDevice *self,
>                                      timeout,
>                                      cancellable,
>                                      (GAsyncReadyCallback)client_ctl_release_cid_ready,
> -                                    ctx);
> +                                    task);
>  
>          qmi_message_ctl_release_cid_input_unref (input);
>          return;
>      }
>  
>      /* No need to release the CID, so just done */
> -    g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
> -    release_client_context_complete_and_free (ctx);
> +    g_task_return_boolean (task, TRUE);
> +    g_object_unref (task);
>      return;
>  }
>  
> 


-- 
Aleksander
https://aleksander.es