[gnome-software: 1/2] appstream: Ensure XbBuilders are constructed in the right context

[Milan Crha <mcrha src gnome org>]

commit 68b955bb7ff94244793c8ae41e7fe78156b48937
Author: Philip Withnall <pwithnall endlessos org>
Date:   Mon Sep 20 16:36:17 2021 +0100

    appstream: Ensure XbBuilders are constructed in the right context
    
    This is a follow-up to commit 6fb78f853b8183501fb. While that commit was
    complete, it will not be sufficient once libxmlb is modified to store
    the `GMainContext` at construction time of an `XbSilo`, which is a
    long-term solution to the libxmlb side of the threading problem.
    
    Specifically, `xb_builder_new()` constructs a new `XbSilo`, which may
    have a long life. Therefore, `xb_builder_new()` needs to be called in
    the correct `GMainContext`.
    
    Signed-off-by: Philip Withnall <pwithnall endlessos org>
    
    Helps: #1422

 plugins/core/gs-plugin-appstream.c | 13 ++++++++++++-
 plugins/flatpak/gs-flatpak.c       | 26 ++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 3 deletions(-)
---
diff --git a/plugins/core/gs-plugin-appstream.c b/plugins/core/gs-plugin-appstream.c
index 18743c1c8..5d61c5b6a 100644
--- a/plugins/core/gs-plugin-appstream.c
+++ b/plugins/core/gs-plugin-appstream.c
@@ -505,7 +505,7 @@ gs_plugin_appstream_check_silo (GsPlugin *plugin,
        GsPluginData *priv = gs_plugin_get_data (plugin);
        const gchar *test_xml;
        g_autofree gchar *blobfn = NULL;
-       g_autoptr(XbBuilder) builder = xb_builder_new ();
+       g_autoptr(XbBuilder) builder = NULL;
        g_autoptr(XbNode) n = NULL;
        g_autoptr(GFile) file = NULL;
        g_autoptr(GRWLockReaderLocker) reader_locker = NULL;
@@ -525,6 +525,17 @@ gs_plugin_appstream_check_silo (GsPlugin *plugin,
        writer_locker = g_rw_lock_writer_locker_new (&priv->silo_lock);
        g_clear_object (&priv->silo);
 
+       /* FIXME: https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1422 */
+       old_thread_default = g_main_context_ref_thread_default ();
+       if (old_thread_default == g_main_context_default ())
+               g_clear_pointer (&old_thread_default, g_main_context_unref);
+       if (old_thread_default != NULL)
+               g_main_context_pop_thread_default (old_thread_default);
+       builder = xb_builder_new ();
+       if (old_thread_default != NULL)
+               g_main_context_push_thread_default (old_thread_default);
+       g_clear_pointer (&old_thread_default, g_main_context_unref);
+
        /* verbose profiling */
        if (g_getenv ("GS_XMLB_VERBOSE") != NULL) {
                xb_builder_set_profile_flags (builder,
diff --git a/plugins/flatpak/gs-flatpak.c b/plugins/flatpak/gs-flatpak.c
index 55a91af2a..af7369be8 100644
--- a/plugins/flatpak/gs-flatpak.c
+++ b/plugins/flatpak/gs-flatpak.c
@@ -959,7 +959,7 @@ gs_flatpak_rescan_appstream_store (GsFlatpak *self,
        g_autoptr(GPtrArray) xremotes = NULL;
        g_autoptr(GRWLockReaderLocker) reader_locker = NULL;
        g_autoptr(GRWLockWriterLocker) writer_locker = NULL;
-       g_autoptr(XbBuilder) builder = xb_builder_new ();
+       g_autoptr(XbBuilder) builder = NULL;
        g_autoptr(GMainContext) old_thread_default = NULL;
 
        reader_locker = g_rw_lock_reader_locker_new (&self->silo_lock);
@@ -972,6 +972,17 @@ gs_flatpak_rescan_appstream_store (GsFlatpak *self,
        writer_locker = g_rw_lock_writer_locker_new (&self->silo_lock);
        g_clear_object (&self->silo);
 
+       /* FIXME: https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1422 */
+       old_thread_default = g_main_context_ref_thread_default ();
+       if (old_thread_default == g_main_context_default ())
+               g_clear_pointer (&old_thread_default, g_main_context_unref);
+       if (old_thread_default != NULL)
+               g_main_context_pop_thread_default (old_thread_default);
+       builder = xb_builder_new ();
+       if (old_thread_default != NULL)
+               g_main_context_push_thread_default (old_thread_default);
+       g_clear_pointer (&old_thread_default, g_main_context_unref);
+
        /* verbose profiling */
        if (g_getenv ("GS_XMLB_VERBOSE") != NULL) {
                xb_builder_set_profile_flags (builder,
@@ -2691,7 +2702,7 @@ gs_flatpak_refine_appstream_from_bytes (GsFlatpak *self,
 {
        const gchar *const *locales = g_get_language_names ();
        g_autofree gchar *xpath = NULL;
-       g_autoptr(XbBuilder) builder = xb_builder_new ();
+       g_autoptr(XbBuilder) builder = NULL;
        g_autoptr(XbBuilderSource) source = xb_builder_source_new ();
        g_autoptr(XbNode) component_node = NULL;
        g_autoptr(XbNode) n = NULL;
@@ -2703,6 +2714,17 @@ gs_flatpak_refine_appstream_from_bytes (GsFlatpak *self,
        g_autoptr(GZlibDecompressor) decompressor = NULL;
        g_autoptr(GMainContext) old_thread_default = NULL;
 
+       /* FIXME: https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1422 */
+       old_thread_default = g_main_context_ref_thread_default ();
+       if (old_thread_default == g_main_context_default ())
+               g_clear_pointer (&old_thread_default, g_main_context_unref);
+       if (old_thread_default != NULL)
+               g_main_context_pop_thread_default (old_thread_default);
+       builder = xb_builder_new ();
+       if (old_thread_default != NULL)
+               g_main_context_push_thread_default (old_thread_default);
+       g_clear_pointer (&old_thread_default, g_main_context_unref);
+
        /* add current locales */
        for (guint i = 0; locales[i] != NULL; i++)
                xb_builder_add_locale (builder, locales[i]);