context.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_async2/poll.h"
#include "pw_async2/waker.h"
#include "pw_log/tokenized_args.h"
 
namespace pw::async2 {
 
class Context;
class Dispatcher;
class NativeDispatcherBase;
 
namespace internal {
 
class WakerQueueBase;
 
bool StoreWaker(Context& cx, Waker& waker_out, log::Token wait_reason);
 
// Overload of StoreWaker taking a queue, allowing PW_ASYNC_STORE_WAKER to be
// used with a WakerQueue as the target.
bool StoreWaker(Context& cx, WakerQueueBase& queue, log::Token wait_reason);
 
}  // namespace internal
 
class Context {
 public:
  Context(Dispatcher& dispatcher, Waker& waker)
      : dispatcher_(&dispatcher), waker_(&waker), requires_waker_(true) {}
 
  Dispatcher& dispatcher() { return *dispatcher_; }
 
  void ReEnqueue();
 
  // removed from the dispatcher, requiring it to be manually re-posted to run
  // again.
  template <typename T = ReadyType>
  Poll<T> Unschedule() {
    requires_waker_ = false;
    return Pending();
  }
 
 private:
  friend class NativeDispatcherBase;
  friend bool internal::StoreWaker(Context& cx,
                                   Waker& waker_out,
                                   log::Token wait_reason);
  friend bool internal::StoreWaker(Context& cx,
                                   internal::WakerQueueBase& queue,
                                   log::Token wait_reason);
 
  Dispatcher* dispatcher_;
  Waker* waker_;
  bool requires_waker_;
};
 
}  // namespace pw::async2