1 files changed, 55 insertions, 0 deletions
diff --git a/gjs/mainloop.cpp b/gjs/mainloop.cpp
new file mode 100644
index 00000000..efe9d05a
--- /dev/null
+++ b/gjs/mainloop.cpp
@@ -0,0 +1,55 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
+// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
+// SPDX-FileCopyrightText: 2021 Evan Welsh <contact@evanwelsh.com>
+
+#include <gio/gio.h>
+#include <glib.h>
+
+#include "gjs/context-private.h"
+#include "gjs/mainloop.h"
+
+namespace Gjs {
+
+MainLoop::MainLoop() { m_refcount = 0; }
+
+void MainLoop::ref() { m_refcount++; }
+
+bool MainLoop::unref() {
+    if (m_refcount == 0)
+        return false;
+
+    m_refcount--;
+    return true;
+}
+
+void MainLoop::spin(GjsContext* context) {
+    auto priv = GjsContextPrivate::from_object(context);
+
+    // Check if System.exit() has been called.
+    if (priv->should_exit(nullptr))
+        return;
+
+    GjsAutoPointer<GMainContext, GMainContext, g_main_context_unref>
+        main_context(g_main_context_ref_thread_default());
+
+    do {
+        if (priv->should_exit(nullptr))
+            break;
+
+        // Allow the loop to block if the event loop is referenced.
+        bool can_block = m_refcount > 0;
+        // Only run the loop if there are pending jobs.
+        if (g_main_context_pending(main_context))
+            g_main_context_iteration(main_context, can_block);
+
+        // Check if System.exit() has been called.
+        if (priv->should_exit(nullptr))
+            break;
+    } while (
+        // If there are pending sources or the job queue is not empty
+        (m_refcount > 0 || !priv->empty()) &&
+        // and System.exit() has not been called
+        // continue spinning the event loop.
+        !priv->should_exit(nullptr));
+}
+};  // namespace Gjs