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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
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Add m-esr52 at 52.6.0
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+/* -*- 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 mozilla_ChaosMode_h
+#define mozilla_ChaosMode_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/EnumSet.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+namespace mozilla {
+
+enum ChaosFeature {
+ None = 0x0,
+ // Altering thread scheduling.
+ ThreadScheduling = 0x1,
+ // Altering network request scheduling.
+ NetworkScheduling = 0x2,
+ // Altering timer scheduling.
+ TimerScheduling = 0x4,
+ // Read and write less-than-requested amounts.
+ IOAmounts = 0x8,
+ // Iterate over hash tables in random order.
+ HashTableIteration = 0x10,
+ // Randomly refuse to use cached version of image (when allowed by spec).
+ ImageCache = 0x20,
+ Any = 0xffffffff,
+};
+
+namespace detail {
+extern MFBT_DATA Atomic<uint32_t> gChaosModeCounter;
+extern MFBT_DATA ChaosFeature gChaosFeatures;
+} // namespace detail
+
+/**
+ * When "chaos mode" is activated, code that makes implicitly nondeterministic
+ * choices is encouraged to make random and extreme choices, to test more
+ * code paths and uncover bugs.
+ */
+class ChaosMode
+{
+public:
+ static void SetChaosFeature(ChaosFeature aChaosFeature)
+ {
+ detail::gChaosFeatures = aChaosFeature;
+ }
+
+ static bool isActive(ChaosFeature aFeature)
+ {
+ if (detail::gChaosModeCounter > 0) {
+ return true;
+ }
+ return detail::gChaosFeatures & aFeature;
+ }
+
+ /**
+ * Increase the chaos mode activation level. An equivalent number of
+ * calls to leaveChaosMode must be made in order to restore the original
+ * chaos mode state. If the activation level is nonzero all chaos mode
+ * features are activated.
+ */
+ static void enterChaosMode()
+ {
+ detail::gChaosModeCounter++;
+ }
+
+ /**
+ * Decrease the chaos mode activation level. See enterChaosMode().
+ */
+ static void leaveChaosMode()
+ {
+ MOZ_ASSERT(detail::gChaosModeCounter > 0);
+ detail::gChaosModeCounter--;
+ }
+
+ /**
+ * Returns a somewhat (but not uniformly) random uint32_t < aBound.
+ * Not to be used for anything except ChaosMode, since it's not very random.
+ */
+ static uint32_t randomUint32LessThan(uint32_t aBound)
+ {
+ MOZ_ASSERT(aBound != 0);
+ return uint32_t(rand()) % aBound;
+ }
+};
+
+} /* namespace mozilla */
+
+#endif /* mozilla_ChaosMode_h */