xpcom/base/StaticMutex.h@129ffea94266 (annotated)
xpcom/base/StaticMutex.h
Sat, 03 Jan 2015 20:18:00 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Sat, 03 Jan 2015 20:18:00 +0100
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
- permissions
- -rw-r--r--
Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.
| michael@0 | 1 | #ifndef mozilla_StaticMutex_h |
| michael@0 | 2 | #define mozilla_StaticMutex_h |
| michael@0 | 3 | |
| michael@0 | 4 | #include "mozilla/Atomics.h" |
| michael@0 | 5 | #include "mozilla/Mutex.h" |
| michael@0 | 6 | |
| michael@0 | 7 | namespace mozilla { |
| michael@0 | 8 | |
| michael@0 | 9 | /** |
| michael@0 | 10 | * StaticMutex is a Mutex that can (and in fact, must) be used as a |
| michael@0 | 11 | * global/static variable. |
| michael@0 | 12 | * |
| michael@0 | 13 | * The main reason to use StaticMutex as opposed to |
| michael@0 | 14 | * StaticAutoPtr<OffTheBooksMutex> is that we instantiate the StaticMutex in a |
| michael@0 | 15 | * thread-safe manner the first time it's used. |
| michael@0 | 16 | * |
| michael@0 | 17 | * The same caveats that apply to StaticAutoPtr apply to StaticMutex. In |
| michael@0 | 18 | * particular, do not use StaticMutex as a stack variable or a class instance |
| michael@0 | 19 | * variable, because this class relies on the fact that global variablies are |
| michael@0 | 20 | * initialized to 0 in order to initialize mMutex. It is only safe to use |
| michael@0 | 21 | * StaticMutex as a global or static variable. |
| michael@0 | 22 | */ |
| michael@0 | 23 | class StaticMutex |
| michael@0 | 24 | { |
| michael@0 | 25 | public: |
| michael@0 | 26 | // In debug builds, check that mMutex is initialized for us as we expect by |
| michael@0 | 27 | // the compiler. In non-debug builds, don't declare a constructor so that |
| michael@0 | 28 | // the compiler can see that the constructor is trivial. |
| michael@0 | 29 | #ifdef DEBUG |
| michael@0 | 30 | StaticMutex() |
| michael@0 | 31 | { |
| michael@0 | 32 | MOZ_ASSERT(!mMutex); |
| michael@0 | 33 | } |
| michael@0 | 34 | #endif |
| michael@0 | 35 | |
| michael@0 | 36 | void Lock() |
| michael@0 | 37 | { |
| michael@0 | 38 | Mutex()->Lock(); |
| michael@0 | 39 | } |
| michael@0 | 40 | |
| michael@0 | 41 | void Unlock() |
| michael@0 | 42 | { |
| michael@0 | 43 | Mutex()->Unlock(); |
| michael@0 | 44 | } |
| michael@0 | 45 | |
| michael@0 | 46 | void AssertCurrentThreadOwns() |
| michael@0 | 47 | { |
| michael@0 | 48 | #ifdef DEBUG |
| michael@0 | 49 | Mutex()->AssertCurrentThreadOwns(); |
| michael@0 | 50 | #endif |
| michael@0 | 51 | } |
| michael@0 | 52 | |
| michael@0 | 53 | private: |
| michael@0 | 54 | OffTheBooksMutex* Mutex() |
| michael@0 | 55 | { |
| michael@0 | 56 | if (mMutex) { |
| michael@0 | 57 | return mMutex; |
| michael@0 | 58 | } |
| michael@0 | 59 | |
| michael@0 | 60 | OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex"); |
| michael@0 | 61 | if (!mMutex.compareExchange(nullptr, mutex)) { |
| michael@0 | 62 | delete mutex; |
| michael@0 | 63 | } |
| michael@0 | 64 | |
| michael@0 | 65 | return mMutex; |
| michael@0 | 66 | } |
| michael@0 | 67 | |
| michael@0 | 68 | Atomic<OffTheBooksMutex*> mMutex; |
| michael@0 | 69 | |
| michael@0 | 70 | |
| michael@0 | 71 | // Disallow copy constructor, but only in debug mode. We only define |
| michael@0 | 72 | // a default constructor in debug mode (see above); if we declared |
| michael@0 | 73 | // this constructor always, the compiler wouldn't generate a trivial |
| michael@0 | 74 | // default constructor for us in non-debug mode. |
| michael@0 | 75 | #ifdef DEBUG |
| michael@0 | 76 | StaticMutex(StaticMutex &other); |
| michael@0 | 77 | #endif |
| michael@0 | 78 | |
| michael@0 | 79 | // Disallow these operators. |
| michael@0 | 80 | StaticMutex& operator=(StaticMutex* rhs); |
| michael@0 | 81 | static void* operator new(size_t) CPP_THROW_NEW; |
| michael@0 | 82 | static void operator delete(void*); |
| michael@0 | 83 | }; |
| michael@0 | 84 | |
| michael@0 | 85 | typedef BaseAutoLock<StaticMutex> StaticMutexAutoLock; |
| michael@0 | 86 | typedef BaseAutoUnlock<StaticMutex> StaticMutexAutoUnlock; |
| michael@0 | 87 | |
| michael@0 | 88 | } // namespace mozilla |
| michael@0 | 89 | |
| michael@0 | 90 | #endif |
