[gthumb] preloader: save the request in a queue

[Paolo Bacchilega <paobac src gnome org>]

commit 70de652135549a814a71503cc39359d4626cf4ad
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sat Jan 5 16:47:10 2019 +0100

    preloader: save the request in a queue
    
    make sure the previous requests are cancelled

 gthumb/gth-image-preloader.c | 73 ++++++++++++++++++++++++++++++++------------
 1 file changed, 53 insertions(+), 20 deletions(-)
---
diff --git a/gthumb/gth-image-preloader.c b/gthumb/gth-image-preloader.c
index c950ecb9..22dc3c25 100644
--- a/gthumb/gth-image-preloader.c
+++ b/gthumb/gth-image-preloader.c
@@ -74,7 +74,7 @@ typedef struct {
 
 
 struct _GthImagePreloaderPrivate {
-       GList                   *requests;              /* List of LoadRequest */
+       GList                   *requests;              /* List of queued LoadRequest */
        LoadRequest             *current_request;
        LoadRequest             *last_request;
        GthImageLoader          *loader;
@@ -374,9 +374,13 @@ _gth_image_preloader_request_finished (GthImagePreloader *self,
                load_request_unref (self->priv->current_request);
                self->priv->current_request = NULL;
        }
+       self->priv->requests = g_list_remove (self->priv->requests, load_request);
        load_request_unref (load_request);
 }
 
+static void
+_gth_image_preloader_cancel_request (GthImagePreloader *self,
+                                    LoadRequest       *request);
 
 static void
 _gth_image_preloader_load_current_file (GthImagePreloader *self,
@@ -391,11 +395,16 @@ load_current_file (gpointer user_data)
 
        g_return_val_if_fail (request->current_file != NULL, FALSE);
 
-       if (self->priv->load_next_id > 0) {
-               g_source_remove (self->priv->load_next_id);
-               self->priv->load_next_id = 0;
+       if (self->priv->last_request != request) {
+               _gth_image_preloader_cancel_request (self, request);
+       }
+       else {
+               if (self->priv->load_next_id > 0) {
+                       g_source_remove (self->priv->load_next_id);
+                       self->priv->load_next_id = 0;
+               }
+               _gth_image_preloader_load_current_file (self, request);
        }
-       _gth_image_preloader_load_current_file (self, request);
 
        return FALSE;
 }
@@ -470,8 +479,7 @@ _gth_image_preloader_request_completed (GthImagePreloader *self,
 
 
 static void
-_gth_image_preloader_start_request (GthImagePreloader *self,
-                                   LoadRequest       *request);
+_gth_image_preloader_start_last_request (GthImagePreloader *self);
 
 
 static void
@@ -546,8 +554,7 @@ image_scale_ready_cb (GObject      *source_object,
                cairo_surface_destroy (surface);
                _gth_image_preloader_request_finished (self, request);
 
-               if (self->priv->last_request != NULL)
-                       _gth_image_preloader_start_request (self, self->priv->last_request);
+               _gth_image_preloader_start_last_request (self);
 
                return;
        }
@@ -608,16 +615,21 @@ _gth_image_preloader_resize_at_requested_size (GthImagePreloader *self,
 
 
 static void
-_gth_image_preloader_request_cancelled (GthImagePreloader *self,
-                                       LoadRequest       *request)
+_gth_image_preloader_cancel_request (GthImagePreloader *self,
+                                    LoadRequest       *request)
 {
        if (request->current_file == request->requested_file)
                g_task_return_error (request->task, g_error_new_literal (G_IO_ERROR, G_IO_ERROR_CANCELLED, 
""));
-
        _gth_image_preloader_request_finished (self, request);
+}
 
-       if (self->priv->last_request != NULL)
-               _gth_image_preloader_start_request (self, self->priv->last_request);
+
+static void
+_gth_image_preloader_request_cancelled (GthImagePreloader *self,
+                                       LoadRequest       *request)
+{
+       _gth_image_preloader_cancel_request (self, request);
+       _gth_image_preloader_start_last_request (self);
 }
 
 
@@ -642,7 +654,7 @@ image_loader_ready_cb (GObject      *source_object,
 
        if (request->finalized) {
 #ifdef DEBUG_PRELOADER
-               g_print (" --> cancelled\n");
+               g_print (" --> cancelled [0]\n");
 #endif
                load_data_free (load_data);
                return;
@@ -660,7 +672,7 @@ image_loader_ready_cb (GObject      *source_object,
            || (self->priv->last_request != request))
        {
 #ifdef DEBUG_PRELOADER
-               g_print (" --> cancelled\n");
+               g_print (" --> cancelled [1] %s\n", g_file_get_uri (GTH_FILE_DATA 
(request->current_file->data)->file));
 #endif
                load_data_free (load_data);
                if (error != NULL)
@@ -764,11 +776,33 @@ static void
 _gth_image_preloader_start_request (GthImagePreloader *self,
                                    LoadRequest       *request)
 {
+       if (request == NULL)
+               return
+
        load_request_unref (self->priv->current_request);
        self->priv->current_request = load_request_ref (request);
 
        request->current_file = request->files;
        _gth_image_preloader_load_current_file (self, request);
+
+}
+
+
+static void
+_gth_image_preloader_start_last_request (GthImagePreloader *self)
+{
+       GList *tmp_requests;
+       GList *scan;
+
+       tmp_requests = g_list_copy (self->priv->requests);
+       for (scan = tmp_requests; scan; scan = scan->next) {
+               LoadRequest *request = scan->data;
+               if (request != self->priv->last_request)
+                       _gth_image_preloader_cancel_request (self, request);
+       }
+       g_list_free (tmp_requests);
+
+       _gth_image_preloader_start_request (self, self->priv->last_request);
 }
 
 
@@ -859,14 +893,13 @@ gth_image_preloader_load (GthImagePreloader        *self,
                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);
-
+       self->priv->requests = g_list_prepend (self->priv->requests, request);
        self->priv->last_request = request;
+
        if (self->priv->current_request != NULL)
                _gth_image_preloader_cancel_current_request (self);
        else
-               _gth_image_preloader_start_request (self, self->priv->last_request);
+               _gth_image_preloader_start_last_request (self);
 }