/* -*- 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 */