[gnome-software: 12/29] repos: Clarify threading behaviour

[Philip Withnall <pwithnall src gnome org>]

commit 6612f0e91d5892c04107b1300b9ea1c38318b744
Author: Philip Withnall <pwithnall endlessos org>
Date:   Fri Oct 15 13:57:28 2021 +0100

    repos: Clarify threading behaviour
    
    Rename the setup method to clarify its functionality, and the fact that
    it should only be run with the plugin’s mutex held.
    
    Ensure accesses to `valid` are atomic, since it’s used from multiple
    threads.
    
    Signed-off-by: Philip Withnall <pwithnall endlessos org>

 plugins/repos/gs-plugin-repos.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)
---
diff --git a/plugins/repos/gs-plugin-repos.c b/plugins/repos/gs-plugin-repos.c
index 0b956bc43..b4babc394 100644
--- a/plugins/repos/gs-plugin-repos.c
+++ b/plugins/repos/gs-plugin-repos.c
@@ -21,7 +21,7 @@ struct _GsPluginRepos {
        GFileMonitor    *monitor;
        GMutex           mutex;
        gchar           *reposdir;
-       gboolean         valid;
+       gboolean         valid;         /* (atomic) */
 };
 
 G_DEFINE_TYPE (GsPluginRepos, gs_plugin_repos, GS_TYPE_PLUGIN)
@@ -76,17 +76,17 @@ gs_plugin_repos_finalize (GObject *object)
        G_OBJECT_CLASS (gs_plugin_repos_parent_class)->finalize (object);
 }
 
-/* mutex must be held */
+/* Run in a worker thread; mutex must be held */
 static gboolean
-gs_plugin_repos_setup (GsPluginRepos  *self,
-                       GCancellable   *cancellable,
-                       GError        **error)
+gs_plugin_repos_ensure_valid_locked (GsPluginRepos  *self,
+                                     GCancellable   *cancellable,
+                                     GError        **error)
 {
        g_autoptr(GDir) dir = NULL;
        const gchar *fn;
 
        /* already valid */
-       if (self->valid)
+       if (g_atomic_int_get (&self->valid))
                return TRUE;
 
        /* clear existing */
@@ -146,7 +146,8 @@ gs_plugin_repos_setup (GsPluginRepos  *self,
        }
 
        /* success */
-       self->valid = TRUE;
+       g_atomic_int_set (&self->valid, TRUE);
+
        return TRUE;
 }
 
@@ -159,7 +160,7 @@ gs_plugin_repos_changed_cb (GFileMonitor      *monitor,
 {
        GsPluginRepos *self = GS_PLUGIN_REPOS (user_data);
 
-       self->valid = FALSE;
+       g_atomic_int_set (&self->valid, FALSE);
 }
 
 gboolean
@@ -179,7 +180,7 @@ gs_plugin_setup (GsPlugin *plugin, GCancellable *cancellable, GError **error)
                          G_CALLBACK (gs_plugin_repos_changed_cb), self);
 
        /* unconditionally at startup */
-       return gs_plugin_repos_setup (self, cancellable, error);
+       return gs_plugin_repos_ensure_valid_locked (self, cancellable, error);
 }
 
 static gboolean
@@ -202,7 +203,7 @@ refine_app_locked (GsPluginRepos        *self,
                return TRUE;
 
        /* ensure valid */
-       if (!gs_plugin_repos_setup (self, cancellable, error))
+       if (!gs_plugin_repos_ensure_valid_locked (self, cancellable, error))
                return FALSE;
 
        /* find hostname */