[glib/wip/antoniof/fallback-timezone-cache-lookup: 2/3] Revert "gtimezone: Cache timezones based on the identifier they were created by"

[Philip Withnall <pwithnall src gnome org>]

commit 36e7b48ad519c18ef3b4e1b4825b68088bd99dd9
Author: António Fernandes <antoniof gnome org>
Date:   Wed Sep 23 19:36:49 2020 +0100

    Revert "gtimezone: Cache timezones based on the identifier they were created by"
    
    This reverts commit 851241f19a3fd9ec693b3dd8f37a84c7f970984a.
    
    That commit avoids a performance regression but introduces a behavior regression:
    changes to /etc/localtime have no effect for the remaining of the application's
    runtime.
    
    With the optimization introduced by the previous commit, we can pass NULL to
    g_time_zone_new() repeatedly with no performance drawback, so we no longer have
    to workaround this case.
    
    Fixes: #2224

 glib/gtimezone.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)
---
diff --git a/glib/gtimezone.c b/glib/gtimezone.c
index ff9972502..3c555dbc7 100644
--- a/glib/gtimezone.c
+++ b/glib/gtimezone.c
@@ -198,7 +198,6 @@ static GHashTable/*<string?, GTimeZone>*/ *time_zones;
 G_LOCK_DEFINE_STATIC (tz_default);
 static GTimeZone *tz_default = NULL;
 G_LOCK_DEFINE_STATIC (tz_local);
-static gchar *tzenv_cached = NULL;
 static GTimeZone *tz_local = NULL;
 
 #define MIN_TZYEAR 1916 /* Daylight Savings started in WWI */
@@ -1869,17 +1868,11 @@ g_time_zone_new_local (void)
   G_LOCK (tz_local);
 
   /* Is time zone changed and must be flushed? */
-  if (tz_local && g_strcmp0 (tzenv, tzenv_cached) != 0)
-    {
-      g_clear_pointer (&tz_local, g_time_zone_unref);
-      g_clear_pointer (&tzenv_cached, g_free);
-    }
+  if (tz_local && g_strcmp0 (g_time_zone_get_identifier (tz_local), tzenv))
+    g_clear_pointer (&tz_local, g_time_zone_unref);
 
   if (tz_local == NULL)
-    {
-      tz_local = g_time_zone_new (tzenv);
-      tzenv_cached = g_strdup (tzenv);
-    }
+    tz_local = g_time_zone_new (tzenv);
 
   tz = g_time_zone_ref (tz_local);