[gnome-settings-daemon/wip/chergert/mem-reduce: 7/8] datetime: release weather tzdb information

[Benjamin Berg <bberg src gnome org>]

commit a9043a749b1f8db42c71ef90465cc903278ed2c9
Author: Christian Hergert <chergert redhat com>
Date:   Tue Mar 10 19:05:25 2020 -0700

    datetime: release weather tzdb information
    
    We only need this once when starting up, so this tries to reduce the
    memory footprint by dropping that memory after caching a copy of the
    information we actually care about.

 plugins/datetime/meson.build  |  3 ++-
 plugins/datetime/weather-tz.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)
---
diff --git a/plugins/datetime/meson.build b/plugins/datetime/meson.build
index ed2d433f..0913ddcb 100644
--- a/plugins/datetime/meson.build
+++ b/plugins/datetime/meson.build
@@ -23,7 +23,8 @@ deps = plugins_deps + [
   libgeoclue_dep,
   libnotify_dep,
   m_dep,
-  polkit_gobject_dep
+  polkit_gobject_dep,
+  cc.find_library('dl', required: false),
 ]
 
 cflags += ['-DGNOMECC_DATA_DIR="@0@"'.format(gsd_pkgdatadir)]
diff --git a/plugins/datetime/weather-tz.c b/plugins/datetime/weather-tz.c
index 09995ea4..f4afdaca 100644
--- a/plugins/datetime/weather-tz.c
+++ b/plugins/datetime/weather-tz.c
@@ -19,6 +19,12 @@
 
 #include "config.h"
 
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+
+#include <dlfcn.h>
+
 #include "weather-tz.h"
 #include "tz.h"
 
@@ -88,6 +94,30 @@ weather_tz_db_populate_locations (WeatherTzDB *tzdb,
         }
 }
 
+static void
+release_world (void)
+{
+       void (*release_world_func) (void) = NULL;
+
+       /* libgweather holds on to a great deal of memory in the default
+        * world instance. We do not need this after parsing, so we can release
+        * it all by finding the exported _gweather_location_reset_world() symbol
+        * and calling it.
+        *
+        * This should really be fixed in libgweather, but to prove it's an issue,
+        * we can test things here first.
+        */
+
+       release_world_func = dlsym (RTLD_NEXT, "_gweather_location_reset_world");
+       if (release_world_func != NULL) {
+               g_debug ("Releasing Locations.xml data");
+               release_world_func ();
+       }
+       else {
+               g_debug ("Cannot locate symbol _gweather_location_reset_world()");
+       }
+}
+
 WeatherTzDB *
 weather_tz_db_new (void)
 {
@@ -97,6 +127,8 @@ weather_tz_db_new (void)
         tzdb->tz_locations = g_array_new (FALSE, FALSE, sizeof (TzLocation));
         load_timezones (tzdb->tz_locations, gweather_location_get_world ());
 
+       release_world ();
+
         return tzdb;
 }