Coverage Report

Created: 2018-09-25 14:53

/work/obj-fuzz/dist/include/mozilla/StaticMutex.h
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/* -*- 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_StaticMutex_h
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#define mozilla_StaticMutex_h
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#include "mozilla/Atomics.h"
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#include "mozilla/Mutex.h"
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namespace mozilla {
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/**
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 * StaticMutex is a Mutex that can (and in fact, must) be used as a
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 * global/static variable.
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 *
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 * The main reason to use StaticMutex as opposed to
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 * StaticAutoPtr<OffTheBooksMutex> is that we instantiate the StaticMutex in a
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 * thread-safe manner the first time it's used.
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 *
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 * The same caveats that apply to StaticAutoPtr apply to StaticMutex.  In
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 * particular, do not use StaticMutex as a stack variable or a class instance
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 * variable, because this class relies on the fact that global variablies are
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 * initialized to 0 in order to initialize mMutex.  It is only safe to use
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 * StaticMutex as a global or static variable.
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 */
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template <recordreplay::Behavior Recording>
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class MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS BaseStaticMutex
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{
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public:
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  // In debug builds, check that mMutex is initialized for us as we expect by
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  // the compiler.  In non-debug builds, don't declare a constructor so that
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  // the compiler can see that the constructor is trivial.
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#ifdef DEBUG
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  BaseStaticMutex()
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  {
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    MOZ_ASSERT(!mMutex);
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  }
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#endif
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  void Lock()
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  {
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    Mutex()->Lock();
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  }
mozilla::BaseStaticMutex<(mozilla::recordreplay::Behavior)1>::Lock()
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  {
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    Mutex()->Lock();
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  }
mozilla::BaseStaticMutex<(mozilla::recordreplay::Behavior)0>::Lock()
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  {
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    Mutex()->Lock();
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  }
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  void Unlock()
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  {
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    Mutex()->Unlock();
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  }
mozilla::BaseStaticMutex<(mozilla::recordreplay::Behavior)1>::Unlock()
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  {
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    Mutex()->Unlock();
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  }
mozilla::BaseStaticMutex<(mozilla::recordreplay::Behavior)0>::Unlock()
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  {
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    Mutex()->Unlock();
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  }
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  void AssertCurrentThreadOwns()
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  {
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#ifdef DEBUG
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    Mutex()->AssertCurrentThreadOwns();
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#endif
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  }
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private:
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  OffTheBooksMutex* Mutex()
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  {
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    if (mMutex) {
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      return mMutex;
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    }
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    OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex", Recording);
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    if (!mMutex.compareExchange(nullptr, mutex)) {
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      delete mutex;
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    }
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    return mMutex;
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  }
mozilla::BaseStaticMutex<(mozilla::recordreplay::Behavior)1>::Mutex()
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  {
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    if (mMutex) {
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      return mMutex;
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    }
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    OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex", Recording);
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    if (!mMutex.compareExchange(nullptr, mutex)) {
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      delete mutex;
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    }
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    return mMutex;
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  }
mozilla::BaseStaticMutex<(mozilla::recordreplay::Behavior)0>::Mutex()
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  {
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    if (mMutex) {
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      return mMutex;
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    }
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    OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex", Recording);
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    if (!mMutex.compareExchange(nullptr, mutex)) {
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      delete mutex;
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    }
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    return mMutex;
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  }
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  Atomic<OffTheBooksMutex*, SequentiallyConsistent, Recording> mMutex;
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  // Disallow copy constructor, but only in debug mode.  We only define
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  // a default constructor in debug mode (see above); if we declared
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  // this constructor always, the compiler wouldn't generate a trivial
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  // default constructor for us in non-debug mode.
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#ifdef DEBUG
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  BaseStaticMutex(BaseStaticMutex& aOther);
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#endif
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  // Disallow these operators.
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  BaseStaticMutex& operator=(BaseStaticMutex* aRhs);
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  static void* operator new(size_t) CPP_THROW_NEW;
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  static void operator delete(void*);
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};
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typedef BaseStaticMutex<recordreplay::Behavior::Preserve> StaticMutex;
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typedef BaseStaticMutex<recordreplay::Behavior::DontPreserve> StaticMutexNotRecorded;
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// Helper for StaticMutexAutoLock/Unlock.
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class MOZ_STACK_CLASS AnyStaticMutex
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{
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public:
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  MOZ_IMPLICIT AnyStaticMutex(StaticMutex& aMutex)
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    : mStaticMutex(&aMutex), mStaticMutexNotRecorded(nullptr)
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  {}
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  MOZ_IMPLICIT AnyStaticMutex(StaticMutexNotRecorded& aMutex)
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    : mStaticMutex(nullptr), mStaticMutexNotRecorded(&aMutex)
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  {}
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  void Lock()
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  {
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    if (mStaticMutex) {
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      mStaticMutex->Lock();
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    } else {
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      mStaticMutexNotRecorded->Lock();
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    }
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  }
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  void Unlock()
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  {
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    if (mStaticMutex) {
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      mStaticMutex->Unlock();
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    } else {
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      mStaticMutexNotRecorded->Unlock();
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    }
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  }
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private:
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  StaticMutex* mStaticMutex;
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  StaticMutexNotRecorded* mStaticMutexNotRecorded;
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};
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typedef BaseAutoLock<AnyStaticMutex> StaticMutexAutoLock;
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typedef BaseAutoUnlock<AnyStaticMutex> StaticMutexAutoUnlock;
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} // namespace mozilla
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#endif