skullc-peripherals/Threads/Inc/threads_exclusivesignal.hpp

/*
 * threads_signal.hpp
 *
 *  Created on: Jun 11, 2021
 *      Author: erki
 */

#ifndef SKULLC_THREADS_EXCLUSIVESIGNAL_HPP_
#define SKULLC_THREADS_EXCLUSIVESIGNAL_HPP_

#include <array>
#include <atomic>
#include <optional>
#include <type_traits>

#include "threads_primitivethread.hpp"
#include "threads_signal.hpp"

namespace Threads
{

template<typename T>
class ExclusiveSignal : public Signallable<T>
    , public Awaitable<std::optional<T>>
{
public:
  using value_type = T;
  using result_type = std::optional<T>;

  static_assert(
          std::is_trivially_copyable_v<value_type>, "Signal's value must be trivially copyable.");

  ExclusiveSignal()
      : current_value_(std::nullopt), waiting_thread_(std::nullopt)
  {}

  ExclusiveSignal(const ExclusiveSignal&) = delete;
  ExclusiveSignal(ExclusiveSignal&&) = delete;
  ExclusiveSignal& operator=(const ExclusiveSignal&) = delete;
  ExclusiveSignal& operator=(ExclusiveSignal&&) = delete;

#ifdef INCLUDE_xTaskGetCurrentTaskHandle
  result_type await() override
  {
    return await(PrimitiveThread::getCurrentThread());
  }

  result_type await(const long timeout) override
  {
    return await(PrimitiveThread::getCurrentThread(), timeout);
  }
#endif

  result_type await(const PrimitiveThread& currentThread) override
  {
    return await(currentThread, portMAX_DELAY);
  }

  result_type await(const PrimitiveThread& currentThread, const long timeout) override
  {
    waiting_thread_ = currentThread;

    const bool notified = currentThread.notifyWait(timeout);

    if (!notified)
    {
      return std::nullopt;
    } else
    {
      return current_value_;
    }
  }

  bool emit(const value_type& v) override
  {
    current_value_ = v;

    if (!waiting_thread_)
    {
      return false;
    } else
    {
      return waiting_thread_->notify(0, eNoAction);
    }
  }

  std::pair<bool, BaseType_t> emitFromIsr(const value_type& v) override
  {
    current_value_ = v;

    if (!waiting_thread_)
    {
      return {false, pdFALSE};
    } else
    {
      auto const [discard, was_notified] = waiting_thread_->notifyFromIsr(0, eNoAction);
      (void) discard;

      return {true, was_notified};
    }
  }

private:
  result_type current_value_;
  std::optional<PrimitiveThread> waiting_thread_;
};

template<>
struct ExclusiveSignal<void> : public Signallable<void>
    , public Awaitable<bool>
{
  using value_type = void;
  using result_type = bool;

  ExclusiveSignal()
      : waiting_thread_(std::nullopt)
  {}

  ExclusiveSignal(const ExclusiveSignal&) = delete;
  ExclusiveSignal(ExclusiveSignal&&) = delete;
  ExclusiveSignal& operator=(const ExclusiveSignal&) = delete;
  ExclusiveSignal& operator=(ExclusiveSignal&&) = delete;

#ifdef INCLUDE_xTaskGetCurrentTaskHandle
  result_type await() override
  {
    return await(PrimitiveThread::getCurrentThread());
  }

  result_type await(const long timeout) override
  {
    return await(PrimitiveThread::getCurrentThread(), timeout);
  }
#endif

  result_type await(const PrimitiveThread& currentThread) override
  {
    return await(currentThread, portMAX_DELAY);
  }

  result_type await(const PrimitiveThread& currentThread, const long timeout) override
  {
    waiting_thread_ = currentThread;
    return currentThread.notifyWait(timeout);
  }

  void emit() override
  {
    if (waiting_thread_)
    {
      auto const _ = waiting_thread_->notify(0, eNoAction);
      (void) _;
    }
  }

  BaseType_t emitFromIsr() override
  {
    if (!waiting_thread_)
    {
      return pdFALSE;
    } else
    {
      auto const [discard, was_notified] = waiting_thread_->notifyFromIsr(0, eNoAction);
      (void) discard;

      return was_notified;
    }
  }

private:
  std::optional<PrimitiveThread> waiting_thread_;
};

}// namespace Threads


#endif /* SKULLC_THREADS_EXCLUSIVESIGNAL_HPP_ */