libcxx/utils/google-benchmark/src/mutex.h

#ifndef BENCHMARK_MUTEX_H_
#define BENCHMARK_MUTEX_H_

#include <mutex>
#include <condition_variable>

// Enable thread safety attributes only with clang.
// The attributes can be safely erased when compiling with other compilers.
#if defined(HAVE_THREAD_SAFETY_ATTRIBUTES)
#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 benchmark {

typedef std::condition_variable Condition;

// NOTE: Wrappers for std::mutex and std::unique_lock are provided so that
// we can annotate them with thread safety attributes and use the
// -Wthread-safety warning with clang. The standard library types cannot be
// used directly because they do not provided the required annotations.
class CAPABILITY("mutex") Mutex
{
public:
  Mutex() {}

  void lock() ACQUIRE() { mut_.lock(); }
  void unlock() RELEASE() { mut_.unlock(); }
  std::mutex& native_handle() {
    return mut_;
  }
private:
  std::mutex mut_;
};


class SCOPED_CAPABILITY MutexLock
{
  typedef std::unique_lock<std::mutex> MutexLockImp;
public:
  MutexLock(Mutex& m) ACQUIRE(m) : ml_(m.native_handle())
  { }
  ~MutexLock() RELEASE() {}
  MutexLockImp& native_handle() { return ml_; }
private:
  MutexLockImp ml_;
};


class Notification
{
public:
  Notification() : notified_yet_(false) { }

  void WaitForNotification() const EXCLUDES(mutex_) {
    MutexLock m_lock(mutex_);
    auto notified_fn = [this]() REQUIRES(mutex_) {
                            return this->HasBeenNotified();
                        };
    cv_.wait(m_lock.native_handle(), notified_fn);
  }

  void Notify() EXCLUDES(mutex_) {
    {
      MutexLock lock(mutex_);
      notified_yet_ = 1;
    }
    cv_.notify_all();
  }

private:
  bool HasBeenNotified() const REQUIRES(mutex_) {
    return notified_yet_;
  }

  mutable Mutex mutex_;
  mutable std::condition_variable cv_;
  bool notified_yet_ GUARDED_BY(mutex_);
};

} // end namespace benchmark

#endif // BENCHMARK_MUTEX_H_