--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang-tools-extra/clangd/support/Shutdown.cpp	Mon May 25 11:55:54 2020 +0900
@@ -0,0 +1,37 @@
+//===--- Shutdown.cpp - Unclean exit scenarios ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "support/Shutdown.h"
+
+#include <atomic>
+#include <cstdlib>
+#include <thread>
+
+namespace clang {
+namespace clangd {
+
+void abortAfterTimeout(std::chrono::seconds Timeout) {
+  // This is more portable than sys::WatchDog, and yields a stack trace.
+  std::thread([Timeout] {
+    std::this_thread::sleep_for(Timeout);
+    std::abort();
+  }).detach();
+}
+
+static std::atomic<bool> ShutdownRequested = {false};
+
+void requestShutdown() {
+  if (ShutdownRequested.exchange(true))
+    // This is the second shutdown request. Exit hard.
+    std::abort();
+}
+
+bool shutdownRequested() { return ShutdownRequested; }
+
+} // namespace clangd
+} // namespace clang