Line data    Source code

       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:
      73        7618 :     explicit StdLockGuard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {}
      74        7618 :     ~StdLockGuard() UNLOCK_FUNCTION() {}
      75             : };
      76             : 
      77             : #endif // BITCOIN_THREADSAFETY_H