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101 lines
2.7 KiB
C++
101 lines
2.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_ChaosMode_h
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#define mozilla_ChaosMode_h
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#include "mozilla/Atomics.h"
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#include "mozilla/EnumSet.h"
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#include <stdint.h>
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#include <stdlib.h>
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namespace mozilla {
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enum ChaosFeature {
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None = 0x0,
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// Altering thread scheduling.
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ThreadScheduling = 0x1,
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// Altering network request scheduling.
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NetworkScheduling = 0x2,
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// Altering timer scheduling.
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TimerScheduling = 0x4,
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// Read and write less-than-requested amounts.
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IOAmounts = 0x8,
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// Iterate over hash tables in random order.
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HashTableIteration = 0x10,
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// Randomly refuse to use cached version of image (when allowed by spec).
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ImageCache = 0x20,
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// Delay dispatching threads to encourage dispatched tasks to run.
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TaskDispatching = 0x40,
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// Delay task running to encourage sending threads to run.
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TaskRunning = 0x80,
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Any = 0xffffffff,
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};
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namespace detail {
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extern MFBT_DATA Atomic<uint32_t,
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SequentiallyConsistent,
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recordreplay::Behavior::DontPreserve> gChaosModeCounter;
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extern MFBT_DATA ChaosFeature gChaosFeatures;
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} // namespace detail
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/**
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* When "chaos mode" is activated, code that makes implicitly nondeterministic
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* choices is encouraged to make random and extreme choices, to test more
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* code paths and uncover bugs.
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*/
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class ChaosMode
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{
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public:
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static void SetChaosFeature(ChaosFeature aChaosFeature)
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{
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detail::gChaosFeatures = aChaosFeature;
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}
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static bool isActive(ChaosFeature aFeature)
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{
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if (detail::gChaosModeCounter > 0) {
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return true;
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}
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return detail::gChaosFeatures & aFeature;
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}
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/**
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* Increase the chaos mode activation level. An equivalent number of
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* calls to leaveChaosMode must be made in order to restore the original
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* chaos mode state. If the activation level is nonzero all chaos mode
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* features are activated.
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*/
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static void enterChaosMode()
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{
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detail::gChaosModeCounter++;
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}
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/**
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* Decrease the chaos mode activation level. See enterChaosMode().
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*/
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static void leaveChaosMode()
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{
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MOZ_ASSERT(detail::gChaosModeCounter > 0);
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detail::gChaosModeCounter--;
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}
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/**
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* Returns a somewhat (but not uniformly) random uint32_t < aBound.
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* Not to be used for anything except ChaosMode, since it's not very random.
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*/
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static uint32_t randomUint32LessThan(uint32_t aBound)
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{
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MOZ_ASSERT(aBound != 0);
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return uint32_t(rand()) % aBound;
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}
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};
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} /* namespace mozilla */
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#endif /* mozilla_ChaosMode_h */
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