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Diffstat (limited to 'xpcom/glue/Mutex.h')
| -rw-r--r-- | xpcom/glue/Mutex.h | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/xpcom/glue/Mutex.h b/xpcom/glue/Mutex.h new file mode 100644 index 0000000000..16ad44f4c1 --- /dev/null +++ b/xpcom/glue/Mutex.h @@ -0,0 +1,229 @@ +/* -*- 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_Mutex_h +#define mozilla_Mutex_h + +#include "prlock.h" + +#include "mozilla/BlockingResourceBase.h" +#include "mozilla/GuardObjects.h" + +// +// Provides: +// +// - Mutex, a non-recursive mutex +// - MutexAutoLock, an RAII class for ensuring that Mutexes are properly +// locked and unlocked +// - MutexAutoUnlock, complementary sibling to MutexAutoLock +// +// - OffTheBooksMutex, a non-recursive mutex that doesn't do leak checking +// - OffTheBooksMutexAuto{Lock,Unlock} - Like MutexAuto{Lock,Unlock}, but for +// an OffTheBooksMutex. +// +// Using MutexAutoLock/MutexAutoUnlock etc. is MUCH preferred to making bare +// calls to Lock and Unlock. +// +namespace mozilla { + +/** + * OffTheBooksMutex is identical to Mutex, except that OffTheBooksMutex doesn't + * include leak checking. Sometimes you want to intentionally "leak" a mutex + * until shutdown; in these cases, OffTheBooksMutex is for you. + */ +class OffTheBooksMutex : BlockingResourceBase +{ +public: + /** + * @param aName A name which can reference this lock + * @returns If failure, nullptr + * If success, a valid Mutex* which must be destroyed + * by Mutex::DestroyMutex() + **/ + explicit OffTheBooksMutex(const char* aName) + : BlockingResourceBase(aName, eMutex) + { + mLock = PR_NewLock(); + if (!mLock) { + NS_RUNTIMEABORT("Can't allocate mozilla::Mutex"); + } + } + + ~OffTheBooksMutex() + { + NS_ASSERTION(mLock, + "improperly constructed Lock or double free"); + // NSPR does consistency checks for us + PR_DestroyLock(mLock); + mLock = 0; + } + +#ifndef DEBUG + /** + * Lock + * @see prlock.h + **/ + void Lock() { PR_Lock(mLock); } + + /** + * Unlock + * @see prlock.h + **/ + void Unlock() { PR_Unlock(mLock); } + + /** + * AssertCurrentThreadOwns + * @see prlock.h + **/ + void AssertCurrentThreadOwns() const {} + + /** + * AssertNotCurrentThreadOwns + * @see prlock.h + **/ + void AssertNotCurrentThreadOwns() const {} + +#else + void Lock(); + void Unlock(); + + void AssertCurrentThreadOwns() const + { + PR_ASSERT_CURRENT_THREAD_OWNS_LOCK(mLock); + } + + void AssertNotCurrentThreadOwns() const + { + // FIXME bug 476536 + } + +#endif // ifndef DEBUG + +private: + OffTheBooksMutex(); + OffTheBooksMutex(const OffTheBooksMutex&); + OffTheBooksMutex& operator=(const OffTheBooksMutex&); + + PRLock* mLock; + + friend class CondVar; + + // MozPromise needs to access mLock for debugging purpose. + template<typename, typename, bool> + friend class MozPromise; +}; + +/** + * Mutex + * When possible, use MutexAutoLock/MutexAutoUnlock to lock/unlock this + * mutex within a scope, instead of calling Lock/Unlock directly. + */ +class Mutex : public OffTheBooksMutex +{ +public: + explicit Mutex(const char* aName) + : OffTheBooksMutex(aName) + { + MOZ_COUNT_CTOR(Mutex); + } + + ~Mutex() + { + MOZ_COUNT_DTOR(Mutex); + } + +private: + Mutex(); + Mutex(const Mutex&); + Mutex& operator=(const Mutex&); +}; + +/** + * MutexAutoLock + * Acquires the Mutex when it enters scope, and releases it when it leaves + * scope. + * + * MUCH PREFERRED to bare calls to Mutex.Lock and Unlock. + */ +template<typename T> +class MOZ_RAII BaseAutoLock +{ +public: + /** + * Constructor + * The constructor aquires the given lock. The destructor + * releases the lock. + * + * @param aLock A valid mozilla::Mutex* returned by + * mozilla::Mutex::NewMutex. + **/ + explicit BaseAutoLock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM) + : mLock(&aLock) + { + MOZ_GUARD_OBJECT_NOTIFIER_INIT; + NS_ASSERTION(mLock, "null mutex"); + mLock->Lock(); + } + + ~BaseAutoLock(void) + { + mLock->Unlock(); + } + +private: + BaseAutoLock(); + BaseAutoLock(BaseAutoLock&); + BaseAutoLock& operator=(BaseAutoLock&); + static void* operator new(size_t) CPP_THROW_NEW; + + T* mLock; + MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER +}; + +typedef BaseAutoLock<Mutex> MutexAutoLock; +typedef BaseAutoLock<OffTheBooksMutex> OffTheBooksMutexAutoLock; + +/** + * MutexAutoUnlock + * Releases the Mutex when it enters scope, and re-acquires it when it leaves + * scope. + * + * MUCH PREFERRED to bare calls to Mutex.Unlock and Lock. + */ +template<typename T> +class MOZ_RAII BaseAutoUnlock +{ +public: + explicit BaseAutoUnlock(T& aLock MOZ_GUARD_OBJECT_NOTIFIER_PARAM) + : mLock(&aLock) + { + MOZ_GUARD_OBJECT_NOTIFIER_INIT; + NS_ASSERTION(mLock, "null lock"); + mLock->Unlock(); + } + + ~BaseAutoUnlock() + { + mLock->Lock(); + } + +private: + BaseAutoUnlock(); + BaseAutoUnlock(BaseAutoUnlock&); + BaseAutoUnlock& operator=(BaseAutoUnlock&); + static void* operator new(size_t) CPP_THROW_NEW; + + T* mLock; + MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER +}; + +typedef BaseAutoUnlock<Mutex> MutexAutoUnlock; +typedef BaseAutoUnlock<OffTheBooksMutex> OffTheBooksMutexAutoUnlock; + +} // namespace mozilla + + +#endif // ifndef mozilla_Mutex_h |