threadsafety.h raw

   1  // Copyright (c) 2009-2010 Satoshi Nakamoto
   2  // Copyright (c) 2009-2020 The Limenka 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 LIMENKA_THREADSAFETY_H
   7  #define LIMENKA_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      explicit StdLockGuard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {}
  74      ~StdLockGuard() UNLOCK_FUNCTION() = default;
  75  };
  76  
  77  #endif // LIMENKA_THREADSAFETY_H
  78