[gnome-software: 13/72] repos: Simplify locking slightly

[Philip Withnall <pwithnall src gnome org>]

commit 4dfce804af2ee0839891cdb626eb7d97462dba1f
Author: Philip Withnall <pwithnall endlessos org>
Date:   Fri Oct 22 15:35:47 2021 +0100

    repos: Simplify locking slightly
    
    Only `ensure_valid()` ever needs to hold the lock now, so move the mutex
    locker inside that function.
    
    Signed-off-by: Philip Withnall <pwithnall endlessos org>
    
    Helps: #1472

 plugins/repos/gs-plugin-repos.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)
---
diff --git a/plugins/repos/gs-plugin-repos.c b/plugins/repos/gs-plugin-repos.c
index bcc3f17be..c9ad73a6e 100644
--- a/plugins/repos/gs-plugin-repos.c
+++ b/plugins/repos/gs-plugin-repos.c
@@ -97,18 +97,19 @@ gs_plugin_repos_finalize (GObject *object)
        G_OBJECT_CLASS (gs_plugin_repos_parent_class)->finalize (object);
 }
 
-/* Run in a worker thread; mutex must be held */
+/* Run in multiple threads; will take the mutex */
 static gboolean
-gs_plugin_repos_ensure_valid_locked (GsPluginRepos  *self,
-                                     GHashTable    **filenames_out,
-                                     GHashTable    **urls_out,
-                                     GCancellable   *cancellable,
-                                     GError        **error)
+gs_plugin_repos_ensure_valid (GsPluginRepos  *self,
+                              GHashTable    **filenames_out,
+                              GHashTable    **urls_out,
+                              GCancellable   *cancellable,
+                              GError        **error)
 {
        g_autoptr(GDir) dir = NULL;
        const gchar *fn;
        g_autoptr(GHashTable) new_filenames = NULL;
        g_autoptr(GHashTable) new_urls = NULL;
+       g_autoptr(GMutexLocker) locker = NULL;
 
        /* Clear out args */
        if (filenames_out != NULL)
@@ -177,6 +178,8 @@ gs_plugin_repos_ensure_valid_locked (GsPluginRepos  *self,
 
        /* success; replace the hash table pointers in the object while the lock
         * is held */
+       locker = g_mutex_locker_new (&self->mutex);
+
        g_clear_pointer (&self->fns, g_hash_table_unref);
        self->fns = g_steal_pointer (&new_filenames);
        g_clear_pointer (&self->urls, g_hash_table_unref);
@@ -185,6 +188,9 @@ gs_plugin_repos_ensure_valid_locked (GsPluginRepos  *self,
        g_atomic_int_set (&self->valid, TRUE);
 
 out:
+       if (locker == NULL)
+               locker = g_mutex_locker_new (&self->mutex);
+
        g_assert (self->fns != NULL && self->urls != NULL);
 
        if (filenames_out != NULL)
@@ -216,10 +222,9 @@ setup_thread_cb (GTask        *task,
                  GCancellable *cancellable)
 {
        GsPluginRepos *self = GS_PLUGIN_REPOS (source_object);
-       g_autoptr(GMutexLocker) locker = g_mutex_locker_new (&self->mutex);
        g_autoptr(GError) local_error = NULL;
 
-       if (!gs_plugin_repos_ensure_valid_locked (self, NULL, NULL, cancellable, &local_error))
+       if (!gs_plugin_repos_ensure_valid (self, NULL, NULL, cancellable, &local_error))
                g_task_return_error (task, g_steal_pointer (&local_error));
        else
                g_task_return_boolean (task, TRUE);
@@ -347,7 +352,6 @@ gs_plugin_refine (GsPlugin             *plugin,
                  GError              **error)
 {
        GsPluginRepos *self = GS_PLUGIN_REPOS (plugin);
-       g_autoptr(GMutexLocker) locker = g_mutex_locker_new (&self->mutex);
        g_autoptr(GHashTable) filenames = NULL;  /* (element-type utf8 filename) mapping origin to filename */
        g_autoptr(GHashTable) urls = NULL;  /* (element-type utf8 utf8) mapping origin to URL */
 
@@ -358,11 +362,9 @@ gs_plugin_refine (GsPlugin             *plugin,
        /* Ensure the object state is valid, and grab a reference to it so it
         * can be accessed without holding the lock, to keep the critical
         * section small. */
-       if (!gs_plugin_repos_ensure_valid_locked (self, &filenames, &urls, cancellable, error))
+       if (!gs_plugin_repos_ensure_valid (self, &filenames, &urls, cancellable, error))
                return FALSE;
 
-       g_clear_pointer (&locker, g_mutex_locker_free);
-
        for (guint i = 0; i < gs_app_list_length (list); i++) {
                GsApp *app = gs_app_list_index (list, i);
                if (!refine_app (self, app, flags, filenames, urls, cancellable, error))