coroutine.hpp

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/*
 *   Copyright 2025 Huawei Technologies Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#pragma once
 
#include <functional>
#include <boost/context/continuation.hpp>
#include <hicr/core/exceptions.hpp>
 
namespace HiCR::backend::boost
{
 
class Coroutine
{
  public:
 
  using coroutineFc_t = std::function<void(void *)>;
 
  __INLINE__ void resume()
  {
    if (_hasFinished == true) HICR_THROW_RUNTIME("Attempting to resume a coroutine that has already finished");
    if (_runningContext == true) HICR_THROW_RUNTIME("Attempting to resume a coroutine that is already running");
 
    // Setting coroutine to have entered the running context
    _runningContext = true;
 
    // Resuming
    _context = _context.resume();
  }
 
  __INLINE__ void yield()
  {
    if (_hasFinished == true) HICR_THROW_RUNTIME("Attempting to suspend a coroutine that has already finished");
    if (_runningContext == false) HICR_THROW_RUNTIME("Attempting to suspend a coroutine that is not running");
 
    // Setting coroutine to have exited the running context
    _runningContext = false;
 
    // Yielding
    _context = _context.resume();
  }
 
  __INLINE__ void start(const coroutineFc_t &fc, void *const arg)
  {
    const auto coroutineFc = [this, fc, arg](::boost::context::continuation &&sink) {
      // Storing caller context
      _context = std::move(sink);
 
      // First yield allows the creation of a coroutine without running the function
      yield();
 
      // Executing coroutine function
      fc(arg);
 
      // Setting the coroutine as finished
      _hasFinished = true;
 
      // Setting coroutine to have exited the running context
      _runningContext = false;
 
      // Returning to caller context
      return std::move(_context);
    };
 
    // Setting coroutine to have entered the running context
    _runningContext = true;
 
    // Creating new context
    _context = ::boost::context::callcc(coroutineFc);
  }
 
  __INLINE__ bool hasFinished() { return _hasFinished; }
 
  private:
 
  bool _hasFinished = false;
 
  bool _runningContext = false;
 
  ::boost::context::continuation _context;
};
 
} // namespace HiCR::backend::boost