[gthumb] preloader: use an intern cancellable to cancel the single request only

[Paolo Bacchilega <paobac src gnome org>]

commit b10f9da58d2739819bd3f5605ff2ee2934c91391
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sat Jan 5 16:45:43 2019 +0100

    preloader: use an intern cancellable to cancel the single request only

 gthumb/gth-image-preloader.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)
---
diff --git a/gthumb/gth-image-preloader.c b/gthumb/gth-image-preloader.c
index 8a2d4bdd..c950ecb9 100644
--- a/gthumb/gth-image-preloader.c
+++ b/gthumb/gth-image-preloader.c
@@ -68,6 +68,8 @@ typedef struct {
        int                      requested_size;
        GTask                   *task;
        GCancellable            *cancellable;
+       GCancellable            *extern_cancellable;
+       gulong                   cancellable_id;
 } LoadRequest;
 
 
@@ -199,6 +201,8 @@ load_request_new (GthImagePreloader *preloader)
        request->requested_size = GTH_ORIGINAL_SIZE;
        request->task = NULL;
        request->cancellable = NULL;
+       request->extern_cancellable = NULL;
+       request->cancellable_id = 0;
 
        return request;
 }
@@ -220,6 +224,9 @@ load_request_unref (LoadRequest *request)
        if (--request->ref > 0)
                return;
 
+       if (request->cancellable_id != 0)
+               g_signal_handler_disconnect (request->extern_cancellable, request->cancellable_id);
+       _g_object_unref (request->extern_cancellable);
        _g_object_unref (request->cancellable);
        _g_object_unref (request->task);
        _g_object_list_unref (request->files);
@@ -799,6 +806,15 @@ check_file (GthFileData *file_data)
 }
 
 
+static void
+request_cancelled (GCancellable *cancellable,
+                  gpointer      user_data)
+{
+       LoadRequest *request = user_data;
+       g_cancellable_cancel (request->cancellable);
+}
+
+
 void
 gth_image_preloader_load (GthImagePreloader     *self,
                          GthFileData            *requested,
@@ -836,8 +852,12 @@ gth_image_preloader_load (GthImagePreloader         *self,
        request->files = g_list_reverse (request->files);
        request->requested_file = request->files;
        request->current_file = request->files;
-       request->cancellable = (cancellable != NULL) ? g_object_ref (cancellable) : g_cancellable_new ();
+       request->cancellable = g_cancellable_new ();
        request->task = g_task_new (G_OBJECT (self), request->cancellable, callback, user_data);
+       if (cancellable != NULL) {
+               request->extern_cancellable = g_object_ref (cancellable);
+               request->cancellable_id = g_cancellable_connect (cancellable, G_CALLBACK (request_cancelled), 
request, NULL);
+       }
 
        if ((self->priv->last_request != NULL) && (self->priv->last_request != self->priv->current_request))
                _gth_image_preloader_request_cancelled (self, self->priv->last_request);