Introduce runAsync() to run main loops without blocking module resolution

All modules are promises. If Gtk.Application.run() or
GLib.MainLoop.run() is called within a module it will block all other
promises as run() is a synchronous, blocking function. To work around
this there is now a setMainLoopHook function exposed which runs a
callback after module resolution is complete. This allows APIs to
"install" a mainloop asynchronously.

For Gio.Application and GLib.MainLoop there are now runAsync() versions
of their run() functions. runAsync() returns a Promise which will
resolve once the mainloop has exited.

Fixes #468

1 files changed, 2 insertions, 0 deletions

diff --git a/gjs/mainloop.cpp b/gjs/mainloop.cpp
index 91109d61..b69d45a8 100644
--- a/gjs/mainloop.cpp
+++ b/gjs/mainloop.cpp
@@ -40,6 +40,8 @@ bool MainLoop::spin(GjsContextPrivate* gjs) {
             return false;
         }
     } while (
+        // and there is not a pending main loop hook
+        !gjs->has_main_loop_hook() &&
         // and there are pending sources or the job queue is not empty
         // continue spinning the event loop.
         (can_block() || !gjs->empty()));