mutex

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/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2016-2025 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software
 * for any purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can
 * be obtained from https://opensource.org/licenses/mit.
 */
 
/*
 * The code is inspired by LLVM libcxx and GNU libstdc++-v3.
 */
 
#ifndef CMSIS_PLUS_ESTD_MUTEX_
#define CMSIS_PLUS_ESTD_MUTEX_
 
// ----------------------------------------------------------------------------
 
// Include the next <mutex> file found in the search path.
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wgnu-include-next"
#endif
#include_next <mutex>
#pragma GCC diagnostic pop
 
#include <tuple>
#include <cerrno>
 
#include <cmsis-plus/rtos/os.h>
 
#include <cmsis-plus/estd/system_error>
#include <cmsis-plus/estd/chrono>
 
// ----------------------------------------------------------------------------
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#endif
 
// ----------------------------------------------------------------------------
 
namespace os
{
  namespace estd
  {
    // ------------------------------------------------------------------------
 
    // ========================================================================
    class mutex
    {
    private:
      using native_type = os::rtos::mutex;
 
    public:
      using native_handle_type = native_type*;
 
      /* constexpr in ISO */
      mutex () noexcept;
 
      ~mutex () = default;
 
      mutex (const mutex&) = delete;
      mutex&
      operator= (const mutex&)
          = delete;
 
      void
      lock ();
 
      bool
      try_lock ();
 
      void
      unlock ();
 
      native_handle_type
      native_handle ();
 
    protected:
      native_type nm_;
    };
 
    // ========================================================================
 
    class recursive_mutex
    {
    private:
      using native_type = os::rtos::mutex;
 
    public:
      using native_handle_type = native_type*;
 
      recursive_mutex ();
 
      ~recursive_mutex () = default;
 
      recursive_mutex (const recursive_mutex&) = delete;
      recursive_mutex&
      operator= (const recursive_mutex&)
          = delete;
 
      void
      lock ();
 
      bool
      try_lock () noexcept;
 
      void
      unlock ();
 
      native_handle_type
      native_handle ();
 
    protected:
      native_type nm_;
    };
 
    // ========================================================================
 
    class timed_mutex : public mutex
    {
    public:
      timed_mutex () = default;
 
      ~timed_mutex () = default;
 
      timed_mutex (const timed_mutex&) = delete;
      timed_mutex&
      operator= (const timed_mutex&)
          = delete;
 
      template <typename Rep_T, typename Period_T>
      bool
      try_lock_for (const std::chrono::duration<Rep_T, Period_T>& rel_time);
 
      template <typename Clock_T, typename Duration_T>
      bool
      try_lock_until (
          const std::chrono::time_point<Clock_T, Duration_T>& abs_time);
    };
 
    // ========================================================================
 
    class recursive_timed_mutex : recursive_mutex
    {
    public:
      recursive_timed_mutex () = default;
 
      ~recursive_timed_mutex () = default;
 
      recursive_timed_mutex (const recursive_timed_mutex&) = delete;
      recursive_timed_mutex&
      operator= (const recursive_timed_mutex&)
          = delete;
 
      template <typename Rep_T, typename Period_T>
      bool
      try_lock_for (const std::chrono::duration<Rep_T, Period_T>& rel_time);
 
      template <typename Clock_T, typename Duration_T>
      bool
      try_lock_until (
          const std::chrono::time_point<Clock_T, Duration_T>& abs_time);
    };
 
    // ========================================================================
    // Inline & template implementations.
    // ========================================================================
    inline mutex::mutex () noexcept
    {
    }
 
    inline mutex::native_handle_type
    mutex::native_handle ()
    {
      return &nm_;
    }
 
    // ========================================================================
 
    inline recursive_mutex::recursive_mutex ()
        : nm_{ os::rtos::mutex::initializer_recursive }
    {
    }
 
    inline recursive_mutex::native_handle_type
    recursive_mutex::native_handle ()
    {
      return &nm_;
    }
 
    // ========================================================================
 
#pragma GCC diagnostic push
#if defined(__clang__)
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Waggregate-return"
#endif
 
    template <typename Rep_T, typename Period_T>
    bool
    timed_mutex::try_lock_for (
        const std::chrono::duration<Rep_T, Period_T>& rel_time)
    {
      using namespace std::chrono;
      os::rtos::clock::duration_t ticks = 0;
      if (rel_time > duration<Rep_T, Period_T>::zero ())
        {
          ticks = static_cast<os::rtos::clock::duration_t> (
              os::estd::chrono::ceil<os::estd::chrono::systicks> (rel_time)
                  .count ());
        }
 
      os::rtos::result_t res;
      res = nm_.timed_lock (ticks);
      if (res == os::rtos::result::ok)
        {
          return true;
        }
      else if (res == ETIMEDOUT)
        {
          return false;
        }
 
      os::estd::__throw_system_error (static_cast<int> (res),
                                      "timed_mutex try_lock failed");
      return false;
    }
 
    template <typename Clock_T, typename Duration_T>
    bool
    timed_mutex::try_lock_until (
        const std::chrono::time_point<Clock_T, Duration_T>& abs_time)
    {
      using clock = Clock_T;
 
      auto now = clock::now ();
      while (now < abs_time)
        {
          if (try_lock_for (abs_time - now))
            {
              return true;
            }
          now = clock::now ();
        }
 
      return false;
    }
 
#pragma GCC diagnostic pop
 
    // ========================================================================
 
    template <typename Rep_T, typename Period_T>
    bool
    recursive_timed_mutex::try_lock_for (
        const std::chrono::duration<Rep_T, Period_T>& rel_time)
    {
      using namespace std::chrono;
      os::rtos::clock::duration_t ticks = 0;
      if (rel_time > duration<Rep_T, Period_T>::zero ())
        {
          ticks = static_cast<os::rtos::clock::duration_t> (
              os::estd::chrono::ceil<os::estd::chrono::systicks> (rel_time)
                  .count ());
        }
 
      os::rtos::result_t res;
      res = nm_.timed_lock (ticks);
      if (res == os::rtos::result::ok)
        {
          return true;
        }
      else if (res == ETIMEDOUT)
        {
          return false;
        }
 
      os::estd::__throw_system_error (static_cast<int> (res),
                                      "timed_mutex try_lock failed");
      return false;
    }
 
    template <typename Clock_T, typename Duration_T>
    bool
    recursive_timed_mutex::try_lock_until (
        const std::chrono::time_point<Clock_T, Duration_T>& abs_time)
    {
      using clock = Clock_T;
 
      auto now = clock::now ();
      while (now < abs_time)
        {
          if (try_lock_for (abs_time - now))
            {
              return true;
            }
          now = clock::now ();
        }
 
      return false;
    }
 
    // ========================================================================
  } /* namespace estd */
} /* namespace os */
 
#pragma GCC diagnostic pop
 
#if defined(OS_HAS_STD_THREADS)
 
namespace std
{
  // Redefine the objects in the std:: namespace.
 
  using mutex = os::estd::mutex;
  using recursive_mutex = os::estd::recursive_mutex;
  using timed_mutex = os::estd::timed_mutex;
  using recursive_timed_mutex = os::estd::recursive_timed_mutex;
 
} // namespace std
 
#endif
 
// ----------------------------------------------------------------------------
 
#endif /* CMSIS_PLUS_ESTD_MUTEX_ */