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       1                 :             : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2                 :             : // Copyright (c) 2009-present 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_UTIL_STDMUTEX_H
       7                 :             : #define BITCOIN_UTIL_STDMUTEX_H
       8                 :             : 
       9                 :             : // This header declares threading primitives compatible with Clang
      10                 :             : // Thread Safety Analysis and provides appropriate annotation macros.
      11                 :             : #include <threadsafety.h> // IWYU pragma: export
      12                 :             : 
      13                 :             : #include <util/macros.h>
      14                 :             : 
      15                 :             : #include <mutex>
      16                 :             : 
      17                 :             : // StdMutex provides an annotated version of std::mutex for us,
      18                 :             : // and should only be used when sync.h Mutex/LOCK/etc are not usable.
      19                 :           3 : class LOCKABLE StdMutex : public std::mutex
      20                 :             : {
      21                 :             : public:
      22                 :             : #ifdef __clang__
      23                 :             :     //! For negative capabilities in the Clang Thread Safety Analysis.
      24                 :             :     //! A negative requirement uses the EXCLUSIVE_LOCKS_REQUIRED attribute, in conjunction
      25                 :             :     //! with the ! operator, to indicate that a mutex should not be held.
      26                 :             :     const StdMutex& operator!() const { return *this; }
      27                 :             : #endif // __clang__
      28                 :             : 
      29                 :             :     // StdMutex::Guard provides an annotated version of std::lock_guard for us.
      30                 :             :     class SCOPED_LOCKABLE Guard : public std::lock_guard<StdMutex>
      31                 :             :     {
      32                 :             :     public:
      33   [ +  -  +  -  :      995638 :         explicit Guard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {}
          #  #  #  #  #  
          #  #  #  #  #  
           #  # ][ +  -  
          +  -  +  -  +  
          -  -  -  +  +  
             -  +  +  + ]
                 [ +  - ]
      34                 :      995638 :         ~Guard() UNLOCK_FUNCTION() = default;
      35                 :             :     };
      36                 :             : 
      37                 :             :     static inline StdMutex& CheckNotHeld(StdMutex& cs) EXCLUSIVE_LOCKS_REQUIRED(!cs) LOCK_RETURNED(cs) { return cs; }
      38                 :             : };
      39                 :             : 
      40                 :             : // Provide STDLOCK(..) wrapper around StdMutex::Guard that checks the lock is not already held
      41                 :             : #define STDLOCK(cs) StdMutex::Guard UNIQUE_NAME(criticalblock){StdMutex::CheckNotHeld(cs)}
      42                 :             : 
      43                 :             : using StdLockGuard = StdMutex::Guard; // TODO: remove, provided for backwards compat only
      44                 :             : 
      45                 :             : #endif // BITCOIN_UTIL_STDMUTEX_H