[gnome-software] Fix thread safety issues in the plugin loader

[Giovanni Campagna <gcampagna src gnome org>]

commit 180e8d6e24799086a314531ed5562b6b5b5ef6c2
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Sat Aug 31 15:59:04 2013 +0200

    Fix thread safety issues in the plugin loader
    
    Protect with mutexes all the struct members that are accessed from
    multiple threads, and make sure that signals handled by the view
    are emitted in the main thread.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=707185

 src/gs-plugin-loader.c |   32 ++++++++++++++++++++++++++++++--
 1 files changed, 30 insertions(+), 2 deletions(-)
---
diff --git a/src/gs-plugin-loader.c b/src/gs-plugin-loader.c
index def4e70..1242e24 100644
--- a/src/gs-plugin-loader.c
+++ b/src/gs-plugin-loader.c
@@ -35,7 +35,11 @@ struct GsPluginLoaderPrivate
        GPtrArray               *plugins;
        gchar                   *location;
        GsPluginStatus           status_last;
+
+       GMutex                   pending_apps_mutex;
        GPtrArray               *pending_apps;
+
+       GMutex                   app_cache_mutex;
        GHashTable              *app_cache;
 };
 
@@ -71,6 +75,8 @@ gs_plugin_loader_dedupe (GsPluginLoader *plugin_loader, GsApp *app)
        GsApp *new_app;
        GsPluginLoaderPrivate *priv = plugin_loader->priv;
 
+       g_mutex_lock (&plugin_loader->priv->app_cache_mutex);
+
        /* not yet set */
        if (gs_app_get_id (app) == NULL) {
                new_app = app;
@@ -80,6 +86,8 @@ gs_plugin_loader_dedupe (GsPluginLoader *plugin_loader, GsApp *app)
        /* already exists */
        new_app = g_hash_table_lookup (priv->app_cache, gs_app_get_id (app));
        if (new_app != NULL) {
+               /* already exists */
+
                /* this looks a little odd to unref the method parameter,
                 * but it allows us to do:
                 * app = gs_plugin_loader_dedupe (cache, app);
@@ -98,6 +106,7 @@ gs_plugin_loader_dedupe (GsPluginLoader *plugin_loader, GsApp *app)
        /* no ref */
        new_app = app;
 out:
+       g_mutex_unlock (&plugin_loader->priv->app_cache_mutex);
        return new_app;
 }
 
@@ -1423,6 +1432,15 @@ typedef struct {
        gpointer         func_user_data;
 } GsPluginLoaderThreadHelper;
 
+static gboolean
+emit_pending_apps_idle (gpointer loader)
+{
+       g_signal_emit (loader, signals[SIGNAL_PENDING_APPS_CHANGED], 0);
+       g_object_unref (loader);
+
+       return G_SOURCE_REMOVE;
+}
+
 /**
  * gs_plugin_loader_thread_func:
  **/
@@ -1435,8 +1453,10 @@ gs_plugin_loader_thread_func (gpointer user_data)
 
        /* add to list */
        gs_app_set_state (helper->app, helper->state_progress);
+       g_mutex_lock (&helper->plugin_loader->priv->pending_apps_mutex);
        g_ptr_array_add (helper->plugin_loader->priv->pending_apps, helper->app);
-       g_signal_emit (helper->plugin_loader, signals[SIGNAL_PENDING_APPS_CHANGED], 0);
+       g_mutex_unlock (&helper->plugin_loader->priv->pending_apps_mutex);
+       g_idle_add (emit_pending_apps_idle, g_object_ref (helper->plugin_loader));
 
        /* run action */
        ret = gs_plugin_loader_run_action (helper->plugin_loader,
@@ -1453,8 +1473,10 @@ gs_plugin_loader_thread_func (gpointer user_data)
        }
 
        /* remove from list */
+       g_mutex_lock (&helper->plugin_loader->priv->pending_apps_mutex);
        g_ptr_array_remove (helper->plugin_loader->priv->pending_apps, helper->app);
-       g_signal_emit (helper->plugin_loader, signals[SIGNAL_PENDING_APPS_CHANGED], 0);
+       g_mutex_unlock (&helper->plugin_loader->priv->pending_apps_mutex);
+       g_idle_add (emit_pending_apps_idle, g_object_ref (helper->plugin_loader));
 
        /* fire finished func */
        if (helper->func != NULL) {
@@ -1840,6 +1862,9 @@ gs_plugin_loader_init (GsPluginLoader *plugin_loader)
                                                                 g_str_equal,
                                                                 NULL,
                                                                 (GFreeFunc) g_object_unref);
+
+       g_mutex_init (&plugin_loader->priv->pending_apps_mutex);
+       g_mutex_init (&plugin_loader->priv->app_cache_mutex);
 }
 
 /**
@@ -1866,6 +1891,9 @@ gs_plugin_loader_finalize (GObject *object)
        g_ptr_array_unref (plugin_loader->priv->plugins);
        g_free (plugin_loader->priv->location);
 
+       g_mutex_clear (&plugin_loader->priv->pending_apps_mutex);
+       g_mutex_clear (&plugin_loader->priv->app_cache_mutex);
+
        G_OBJECT_CLASS (gs_plugin_loader_parent_class)->finalize (object);
 }