The Tor Browser / file comparison
comparison: xpcom/base/StaticMutex.h
xpcom/base/StaticMutex.h
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
equal
deleted
inserted
replaced
| -1:000000000000 | 0:21b921a09b64 |
|---|---|
| 1 #ifndef mozilla_StaticMutex_h | |
| 2 #define mozilla_StaticMutex_h | |
| 3 | |
| 4 #include "mozilla/Atomics.h" | |
| 5 #include "mozilla/Mutex.h" | |
| 6 | |
| 7 namespace mozilla { | |
| 8 | |
| 9 /** | |
| 10 * StaticMutex is a Mutex that can (and in fact, must) be used as a | |
| 11 * global/static variable. | |
| 12 * | |
| 13 * The main reason to use StaticMutex as opposed to | |
| 14 * StaticAutoPtr<OffTheBooksMutex> is that we instantiate the StaticMutex in a | |
| 15 * thread-safe manner the first time it's used. | |
| 16 * | |
| 17 * The same caveats that apply to StaticAutoPtr apply to StaticMutex. In | |
| 18 * particular, do not use StaticMutex as a stack variable or a class instance | |
| 19 * variable, because this class relies on the fact that global variablies are | |
| 20 * initialized to 0 in order to initialize mMutex. It is only safe to use | |
| 21 * StaticMutex as a global or static variable. | |
| 22 */ | |
| 23 class StaticMutex | |
| 24 { | |
| 25 public: | |
| 26 // In debug builds, check that mMutex is initialized for us as we expect by | |
| 27 // the compiler. In non-debug builds, don't declare a constructor so that | |
| 28 // the compiler can see that the constructor is trivial. | |
| 29 #ifdef DEBUG | |
| 30 StaticMutex() | |
| 31 { | |
| 32 MOZ_ASSERT(!mMutex); | |
| 33 } | |
| 34 #endif | |
| 35 | |
| 36 void Lock() | |
| 37 { | |
| 38 Mutex()->Lock(); | |
| 39 } | |
| 40 | |
| 41 void Unlock() | |
| 42 { | |
| 43 Mutex()->Unlock(); | |
| 44 } | |
| 45 | |
| 46 void AssertCurrentThreadOwns() | |
| 47 { | |
| 48 #ifdef DEBUG | |
| 49 Mutex()->AssertCurrentThreadOwns(); | |
| 50 #endif | |
| 51 } | |
| 52 | |
| 53 private: | |
| 54 OffTheBooksMutex* Mutex() | |
| 55 { | |
| 56 if (mMutex) { | |
| 57 return mMutex; | |
| 58 } | |
| 59 | |
| 60 OffTheBooksMutex* mutex = new OffTheBooksMutex("StaticMutex"); | |
| 61 if (!mMutex.compareExchange(nullptr, mutex)) { | |
| 62 delete mutex; | |
| 63 } | |
| 64 | |
| 65 return mMutex; | |
| 66 } | |
| 67 | |
| 68 Atomic<OffTheBooksMutex*> mMutex; | |
| 69 | |
| 70 | |
| 71 // Disallow copy constructor, but only in debug mode. We only define | |
| 72 // a default constructor in debug mode (see above); if we declared | |
| 73 // this constructor always, the compiler wouldn't generate a trivial | |
| 74 // default constructor for us in non-debug mode. | |
| 75 #ifdef DEBUG | |
| 76 StaticMutex(StaticMutex &other); | |
| 77 #endif | |
| 78 | |
| 79 // Disallow these operators. | |
| 80 StaticMutex& operator=(StaticMutex* rhs); | |
| 81 static void* operator new(size_t) CPP_THROW_NEW; | |
| 82 static void operator delete(void*); | |
| 83 }; | |
| 84 | |
| 85 typedef BaseAutoLock<StaticMutex> StaticMutexAutoLock; | |
| 86 typedef BaseAutoUnlock<StaticMutex> StaticMutexAutoUnlock; | |
| 87 | |
| 88 } // namespace mozilla | |
| 89 | |
| 90 #endif |
