1 // Copyright (c) 2009-2010 Satoshi Nakamoto 2 // Copyright (c) 2009-2020 The Bitcoin Core developers 3 // Distributed under the MIT software license, see the accompanying 4 // file COPYING or http://www.opensource.org/licenses/mit-license.php. 5 6 #ifndef BITCOIN_THREADSAFETY_H 7 #define BITCOIN_THREADSAFETY_H 8 9 #include <mutex> 10 11 #ifdef __clang__ 12 // TL;DR Add GUARDED_BY(mutex) to member variables. The others are 13 // rarely necessary. Ex: int nFoo GUARDED_BY(cs_foo); 14 // 15 // See https://clang.llvm.org/docs/ThreadSafetyAnalysis.html 16 // for documentation. The clang compiler can do advanced static analysis 17 // of locking when given the -Wthread-safety option. 18 #define LOCKABLE __attribute__((lockable)) 19 #define SCOPED_LOCKABLE __attribute__((scoped_lockable)) 20 #define GUARDED_BY(x) __attribute__((guarded_by(x))) 21 #define PT_GUARDED_BY(x) __attribute__((pt_guarded_by(x))) 22 #define ACQUIRED_AFTER(...) __attribute__((acquired_after(__VA_ARGS__))) 23 #define ACQUIRED_BEFORE(...) __attribute__((acquired_before(__VA_ARGS__))) 24 #define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__((exclusive_lock_function(__VA_ARGS__))) 25 #define SHARED_LOCK_FUNCTION(...) __attribute__((shared_lock_function(__VA_ARGS__))) 26 #define EXCLUSIVE_TRYLOCK_FUNCTION(...) __attribute__((exclusive_trylock_function(__VA_ARGS__))) 27 #define SHARED_TRYLOCK_FUNCTION(...) __attribute__((shared_trylock_function(__VA_ARGS__))) 28 #define UNLOCK_FUNCTION(...) __attribute__((unlock_function(__VA_ARGS__))) 29 #define LOCK_RETURNED(x) __attribute__((lock_returned(x))) 30 #define LOCKS_EXCLUDED(...) __attribute__((locks_excluded(__VA_ARGS__))) 31 #define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((exclusive_locks_required(__VA_ARGS__))) 32 #define SHARED_LOCKS_REQUIRED(...) __attribute__((shared_locks_required(__VA_ARGS__))) 33 #define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis)) 34 #define ASSERT_EXCLUSIVE_LOCK(...) __attribute__((assert_exclusive_lock(__VA_ARGS__))) 35 #else 36 #define LOCKABLE 37 #define SCOPED_LOCKABLE 38 #define GUARDED_BY(x) 39 #define PT_GUARDED_BY(x) 40 #define ACQUIRED_AFTER(...) 41 #define ACQUIRED_BEFORE(...) 42 #define EXCLUSIVE_LOCK_FUNCTION(...) 43 #define SHARED_LOCK_FUNCTION(...) 44 #define EXCLUSIVE_TRYLOCK_FUNCTION(...) 45 #define SHARED_TRYLOCK_FUNCTION(...) 46 #define UNLOCK_FUNCTION(...) 47 #define LOCK_RETURNED(x) 48 #define LOCKS_EXCLUDED(...) 49 #define EXCLUSIVE_LOCKS_REQUIRED(...) 50 #define SHARED_LOCKS_REQUIRED(...) 51 #define NO_THREAD_SAFETY_ANALYSIS 52 #define ASSERT_EXCLUSIVE_LOCK(...) 53 #endif // __GNUC__ 54 55 // StdMutex provides an annotated version of std::mutex for us, 56 // and should only be used when sync.h Mutex/LOCK/etc are not usable. 57 class LOCKABLE StdMutex : public std::mutex 58 { 59 public: 60 #ifdef __clang__ 61 //! For negative capabilities in the Clang Thread Safety Analysis. 62 //! A negative requirement uses the EXCLUSIVE_LOCKS_REQUIRED attribute, in conjunction 63 //! with the ! operator, to indicate that a mutex should not be held. 64 const StdMutex& operator!() const { return *this; } 65 #endif // __clang__ 66 }; 67 68 // StdLockGuard provides an annotated version of std::lock_guard for us, 69 // and should only be used when sync.h Mutex/LOCK/etc are not usable. 70 class SCOPED_LOCKABLE StdLockGuard : public std::lock_guard<StdMutex> 71 { 72 public: StdLockGuard(StdMutex & cs)73 explicit StdLockGuard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {} UNLOCK_FUNCTION()74 ~StdLockGuard() UNLOCK_FUNCTION() {} 75 }; 76 77 #endif // BITCOIN_THREADSAFETY_H 78