[gnome-shell/wip/cosimoc/cache-issue] StTextureCache: use right event to detect file changes

[Cosimo Cecchi <cosimoc src gnome org>]

commit 90798cebfdce182cfc702c4d90cdfc16a460299a
Author: Cosimo Cecchi <cosimo endlessm com>
Date:   Fri Nov 9 13:55:53 2018 -0800

    StTextureCache: use right event to detect file changes
    
    StTextureCache installs file monitors that invalidate caches when
    contents of the underlying file change.
    At the moment, the cache uses the Gio.FileMonitorEvent.CHANGED event
    type to make that determination.
    
    However, that is suboptimal for at least two reasons:
    - while a file is being written to disk, many CHANGED events will be
      emitted in sequence. That will cause needless cache invalidations,
      and we will risk loading the file before it's fully loaded.
    - if an existing file is replaced, e.g. with g_file_replace(), we may
      not get a CHANGED event but a CREATED one instead, so the cache ends
      up never getting invalidated.
    
    The good news is that in both of those cases GFileMonitor will send a
    CHANGES_DONE_HINT event after changes have settled, or after the file
    is replaced.
    
    This commit fixes both cases by switching from the CHANGED event to
    CHANGES_DONE_HINT to determine that a file has in fact changed.

 src/st/st-texture-cache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/st/st-texture-cache.c b/src/st/st-texture-cache.c
index 3bf3a5e97..621907111 100644
--- a/src/st/st-texture-cache.c
+++ b/src/st/st-texture-cache.c
@@ -984,7 +984,7 @@ file_changed_cb (GFileMonitor      *monitor,
   char *key;
   guint file_hash;
 
-  if (event_type != G_FILE_MONITOR_EVENT_CHANGED)
+  if (event_type != G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT)
     return;
 
   file_hash = g_file_hash (file);