cancellable_task.h

// Copyright 2025 The Pigweed Authors
//
// 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
//
//     https://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 "pw_assert/assert.h"
#include "pw_async2/task.h"
#include "pw_async2/waker.h"
 
namespace pw::async2 {
 
template <typename TaskType>
class CancellableTask final : public TaskType {
 public:
  using TaskType::TaskType;
 
  void Cancel() {
    cancelled_ = true;
    std::move(cancel_waker_).Wake();
  }
 
 protected:
  Poll<> DoPend(Context& cx) final {
    if (cancelled_) {
      return Ready();
    }
 
    std::ignore = PW_ASYNC_TRY_STORE_WAKER(
        cx, cancel_waker_, "CancellableTask waiting for cancellation");
    return TaskType::DoPend(cx);
  }
 
 private:
  Waker cancel_waker_;
  bool cancelled_ = false;
};
 
}  // namespace pw::async2