import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

js/ipc/CPOWTimer.h

@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=4 sw=4 et 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 CPOWTIMER_H
+#define CPOWTIMER_H
+
+#include "prinrval.h"
+#include "jsapi.h"
+
+/**
+ * A stopwatch measuring the duration of a CPOW call.
+ *
+ * As the process is consuming neither user time nor system time
+ * during a CPOW call, we measure such durations using wallclock time.
+ *
+ * This stopwatch is active iff JSRuntime::stopwatch.isActive is set.
+ * Upon destruction, update JSRuntime::stopwatch.data.totalCPOWTime.
+ */
+class MOZ_RAII CPOWTimer final {
+  public:
+    explicit inline CPOWTimer(JSContext* cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM);
+    ~CPOWTimer();
+
+  private:
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+
+    /**
+     * The context in which this timer was created, or `nullptr` if
+     * CPOW monitoring was off when the timer was created.
+     */
+    JSContext* cx_;
+
+    /**
+     * The instant at which the stopwatch was started. Undefined
+     * if CPOW monitoring was off when the timer was created.
+     */
+    int64_t startInterval_;
+};
+
+#endif