fc2e3a7421
This patch implements the new update mutex using nsProfileLock for all platforms. The logic is implemented in the new nsIUpdateMutex XPCOM component. Compability with the legacy update mutex is not preserved. Depends on D222156 Differential Revision: https://phabricator.services.mozilla.com/D222157
89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
/* -*- 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_StaticMutex_h
|
|
#define mozilla_StaticMutex_h
|
|
|
|
#include "mozilla/Atomics.h"
|
|
#include "mozilla/Mutex.h"
|
|
|
|
namespace mozilla {
|
|
|
|
/**
|
|
* StaticMutex is a Mutex that can (and in fact, must) be used as a
|
|
* global/static variable.
|
|
*
|
|
* The main reason to use StaticMutex as opposed to
|
|
* StaticAutoPtr<OffTheBooksMutex> is that we instantiate the StaticMutex in a
|
|
* thread-safe manner the first time it's used.
|
|
*
|
|
* The same caveats that apply to StaticAutoPtr apply to StaticMutex. In
|
|
* particular, do not use StaticMutex as a stack variable or a class instance
|
|
* variable, because this class relies on the fact that global variablies are
|
|
* initialized to 0 in order to initialize mMutex. It is only safe to use
|
|
* StaticMutex as a global or static variable.
|
|
*/
|
|
class MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS MOZ_CAPABILITY("mutex")
|
|
StaticMutex {
|
|
public:
|
|
// In debug builds, check that mMutex is initialized for us as we expect by
|
|
// the compiler. In non-debug builds, don't declare a constructor so that
|
|
// the compiler can see that the constructor is trivial.
|
|
#ifdef DEBUG
|
|
StaticMutex() { MOZ_ASSERT(!mMutex); }
|
|
#endif
|
|
|
|
void Lock() MOZ_CAPABILITY_ACQUIRE() { Mutex()->Lock(); }
|
|
|
|
[[nodiscard]] bool TryLock() MOZ_TRY_ACQUIRE(true) {
|
|
return Mutex()->TryLock();
|
|
}
|
|
|
|
void Unlock() MOZ_CAPABILITY_RELEASE() { Mutex()->Unlock(); }
|
|
|
|
void AssertCurrentThreadOwns() MOZ_ASSERT_CAPABILITY(this) {
|
|
#ifdef DEBUG
|
|
Mutex()->AssertCurrentThreadOwns();
|
|
#endif
|
|
}
|
|
|
|
private:
|
|
OffTheBooksMutex* Mutex() {
|
|
if (mMutex) {
|
|
return mMutex;
|
|
}
|
|
|
|
OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex");
|
|
if (!mMutex.compareExchange(nullptr, mutex)) {
|
|
delete mutex;
|
|
}
|
|
|
|
return mMutex;
|
|
}
|
|
|
|
Atomic<OffTheBooksMutex*, SequentiallyConsistent> mMutex;
|
|
|
|
// Disallow copy constructor, but only in debug mode. We only define
|
|
// a default constructor in debug mode (see above); if we declared
|
|
// this constructor always, the compiler wouldn't generate a trivial
|
|
// default constructor for us in non-debug mode.
|
|
#ifdef DEBUG
|
|
StaticMutex(StaticMutex& aOther);
|
|
#endif
|
|
|
|
// Disallow these operators.
|
|
StaticMutex& operator=(StaticMutex* aRhs);
|
|
static void* operator new(size_t) noexcept(true);
|
|
static void operator delete(void*);
|
|
};
|
|
|
|
typedef detail::BaseAutoLock<StaticMutex&> StaticMutexAutoLock;
|
|
typedef detail::BaseAutoUnlock<StaticMutex&> StaticMutexAutoUnlock;
|
|
|
|
} // namespace mozilla
|
|
|
|
#endif
|