1 files changed, 60 insertions, 0 deletions
diff --git a/xpcom/threads/MainThreadUtils.h b/xpcom/threads/MainThreadUtils.h
new file mode 100644
index 0000000000..152805eb66
--- /dev/null
+++ b/xpcom/threads/MainThreadUtils.h
@@ -0,0 +1,60 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MainThreadUtils_h_
+#define MainThreadUtils_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/ThreadSafety.h"
+#include "nscore.h"
+
+class nsIThread;
+
+/**
+ * Get a reference to the main thread.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ */
+extern nsresult NS_GetMainThread(nsIThread** aResult);
+
+#ifdef MOZILLA_INTERNAL_API
+bool NS_IsMainThreadTLSInitialized();
+extern "C" {
+bool NS_IsMainThread();
+}
+
+namespace mozilla {
+
+/**
+ * A dummy static capability for the thread safety analysis which can be
+ * required by functions and members using `MOZ_REQUIRE(sMainThreadCapability)`
+ * and `MOZ_GUARDED_BY(sMainThreadCapability)` and asserted using
+ * `AssertIsOnMainThread()`.
+ *
+ * If you want a thread-safety-analysis capability for a non-main thread,
+ * consider using the `EventTargetCapability` type.
+ */
+class MOZ_CAPABILITY("main thread") MainThreadCapability final {};
+constexpr MainThreadCapability sMainThreadCapability;
+
+#  ifdef DEBUG
+void AssertIsOnMainThread() MOZ_ASSERT_CAPABILITY(sMainThreadCapability);
+#  else
+inline void AssertIsOnMainThread()
+    MOZ_ASSERT_CAPABILITY(sMainThreadCapability) {}
+#  endif
+
+inline void ReleaseAssertIsOnMainThread()
+    MOZ_ASSERT_CAPABILITY(sMainThreadCapability) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+}
+
+}  // namespace mozilla
+
+#endif
+
+#endif  // MainThreadUtils_h_