[gnome-boxes] downloader: Loop instead of recursing

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 1b2138b16e2e40521aa851321748349db75eae7d
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Mon Sep 24 23:51:09 2012 +0300

    downloader: Loop instead of recursing
    
    Vala currently doesn't optimize tail-call recursion and since it has to
    unref/free passed arguments after the call in the generated code, its
    not exactly tail call in generated code and therefore gcc's
    '-foptimize-sibling-calls' can't help us either.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=683403

 src/downloader.vala |   53 +++++++++++++++++++++++++++++++-------------------
 1 files changed, 33 insertions(+), 20 deletions(-)
---
diff --git a/src/downloader.vala b/src/downloader.vala
index f5d96e4..6f12126 100644
--- a/src/downloader.vala
+++ b/src/downloader.vala
@@ -15,6 +15,25 @@ private class Boxes.Downloader : GLib.Object {
         return downloader;
     }
 
+    private static string fetch_os_logo_url (Osinfo.Os os) {
+        if (os.logo != null)
+            return os.logo;
+
+        string logo_url = null;
+        var derived = os.get_related (Osinfo.ProductRelationship.DERIVES_FROM);
+        while (derived.get_length () > 0 && logo_url == null) {
+            // FIXME: Does Osinfo allows deriving from multiple OSs?
+            var parent = derived.get_nth (0) as Osinfo.Os;
+
+            if (parent.logo != null)
+                logo_url = parent.logo;
+            else
+                derived = parent.get_related (Osinfo.ProductRelationship.DERIVES_FROM);
+        }
+
+        return logo_url;
+    }
+
     private Downloader () {
         downloads = new GLib.HashTable <string,File> (str_hash, str_equal);
     }
@@ -52,26 +71,20 @@ private class Boxes.Downloader : GLib.Object {
     }
 
     public static async void fetch_os_logo (Gtk.Image image, Osinfo.Os os, int size) {
-        if (os.logo != null) {
-            debug ("%s has logo '%s'.", os.name, os.logo);
-
-            var remote_file = File.new_for_uri (os.logo);
-            var cached_path = get_logo_cache (remote_file.get_basename ());
-            try {
-                var cached_file = yield get_instance ().download (remote_file, cached_path);
-                var pixbuf = new Gdk.Pixbuf.from_file_at_size (cached_file.get_path (), size, size);
-                image.set_from_pixbuf (pixbuf);
-            } catch (GLib.Error error) {
-                warning ("Error loading logo file '%s': %s", os.logo, error.message);
-            }
-        } else {
-            var derived = os.get_related (Osinfo.ProductRelationship.DERIVES_FROM);
-            if (derived.get_length () > 0) {
-                // FIXME: Does Osinfo allows deriving from multiple OSs?
-                var parent = derived.get_nth (0) as Osinfo.Os;
-
-                yield fetch_os_logo (image, parent, size);
-            }
+        var logo_url = fetch_os_logo_url (os);
+        if (logo_url == null)
+            return;
+
+        debug ("%s has logo '%s'.", os.name, logo_url);
+
+        var remote_file = File.new_for_uri (logo_url);
+        var cached_path = get_logo_cache (remote_file.get_basename ());
+        try {
+            var cached_file = yield get_instance ().download (remote_file, cached_path);
+            var pixbuf = new Gdk.Pixbuf.from_file_at_size (cached_file.get_path (), size, size);
+            image.set_from_pixbuf (pixbuf);
+        } catch (GLib.Error error) {
+            warning ("Error loading logo file '%s': %s", logo_url, error.message);
         }
     }