mutex.hpp

// Based on https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
#ifndef SIMPLE_WEB_MUTEX_HPP
#define SIMPLE_WEB_MUTEX_HPP

#include <mutex>

// Enable thread safety attributes only with clang.
#if defined(__clang__) && (!defined(SWIG))
#define THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x))
#else
#define THREAD_ANNOTATION_ATTRIBUTE__(x) // no-op
#endif

#define CAPABILITY(x) \
  THREAD_ANNOTATION_ATTRIBUTE__(capability(x))

#define SCOPED_CAPABILITY \
  THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)

#define GUARDED_BY(x) \
  THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))

#define PT_GUARDED_BY(x) \
  THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))

#define ACQUIRED_BEFORE(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(__VA_ARGS__))

#define ACQUIRED_AFTER(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(__VA_ARGS__))

#define REQUIRES(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(requires_capability(__VA_ARGS__))

#define REQUIRES_SHARED(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(requires_shared_capability(__VA_ARGS__))

#define ACQUIRE(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(acquire_capability(__VA_ARGS__))

#define ACQUIRE_SHARED(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(acquire_shared_capability(__VA_ARGS__))

#define RELEASE(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(release_capability(__VA_ARGS__))

#define RELEASE_SHARED(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(release_shared_capability(__VA_ARGS__))

#define TRY_ACQUIRE(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_capability(__VA_ARGS__))

#define TRY_ACQUIRE_SHARED(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_shared_capability(__VA_ARGS__))

#define EXCLUDES(...) \
  THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__))

#define ASSERT_CAPABILITY(x) \
  THREAD_ANNOTATION_ATTRIBUTE__(assert_capability(x))

#define ASSERT_SHARED_CAPABILITY(x) \
  THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_capability(x))

#define RETURN_CAPABILITY(x) \
  THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))

#define NO_THREAD_SAFETY_ANALYSIS \
  THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)

namespace SimpleWeb {
  /// Defines an annotated interface for mutexes.
  class CAPABILITY("mutex") Mutex {
    std::mutex mutex;

  public:
    void lock() ACQUIRE() {
      mutex.lock();
    }

    void unlock() RELEASE() {
      mutex.unlock();
    }
  };

  class SCOPED_CAPABILITY LockGuard {
    Mutex &mutex;
    bool locked = true;

  public:
    LockGuard(Mutex &mutex_) ACQUIRE(mutex_) : mutex(mutex_) {
      mutex.lock();
    }
    void unlock() RELEASE() {
      mutex.unlock();
      locked = false;
    }
    ~LockGuard() RELEASE() {
      if(locked)
        mutex.unlock();
    }
  };

} // namespace SimpleWeb

#endif // SIMPLE_WEB_MUTEX_HPP