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// Copyright 2023 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_async/dispatcher.h"
#include "pw_async/task.h"
#include "pw_sync/interrupt_spin_lock.h"
#include "pw_sync/lock_annotations.h"
#include "pw_sync/timed_thread_notification.h"
#include "pw_thread/thread_core.h"
namespace pw::async {
/// BasicDispatcher is a generic implementation of Dispatcher.
class BasicDispatcher final : public Dispatcher, public thread::ThreadCore {
public:
explicit BasicDispatcher() = default;
~BasicDispatcher() override;
/// Execute all runnable tasks and return without waiting.
void RunUntilIdle();
/// Run the dispatcher until Now() has reached `end_time`, executing all tasks
/// that come due before then.
void RunUntil(chrono::SystemClock::time_point end_time);
/// Run the dispatcher until `duration` has elapsed, executing all tasks that
/// come due in that period.
void RunFor(chrono::SystemClock::duration duration);
/// Stop processing tasks. If the dispatcher is serving a task loop, break out
/// of the loop, dequeue all waiting tasks, and call their TaskFunctions with
/// a PW_STATUS_CANCELLED status. If no task loop is being served, execute the
/// dequeueing procedure the next time the Dispatcher is run.
void RequestStop() PW_LOCKS_EXCLUDED(lock_);
// ThreadCore overrides:
/// Run the dispatcher until RequestStop() is called. Overrides
/// ThreadCore::Run() so that BasicDispatcher is compatible with
/// pw::thread::Thread.
void Run() override PW_LOCKS_EXCLUDED(lock_);
// Dispatcher overrides:
void PostAt(Task& task, chrono::SystemClock::time_point time) override;
bool Cancel(Task& task) override PW_LOCKS_EXCLUDED(lock_);
// VirtualSystemClock overrides:
chrono::SystemClock::time_point now() override {
return chrono::SystemClock::now();
}
private:
// Insert |task| into task_queue_ maintaining its min-heap property, keyed by
// |time_due|.
void PostTaskInternal(backend::NativeTask& task,
chrono::SystemClock::time_point time_due)
PW_LOCKS_EXCLUDED(lock_);
// If no tasks are due, sleep until a notification is received, the next task
// comes due, or a timeout elapses; whichever occurs first.
void MaybeSleep() PW_EXCLUSIVE_LOCKS_REQUIRED(lock_);
// Dequeue and run each task that is due.
void ExecuteDueTasks() PW_EXCLUSIVE_LOCKS_REQUIRED(lock_);
// Dequeue each task and call each TaskFunction with a PW_STATUS_CANCELLED
// status.
void DrainTaskQueue() PW_EXCLUSIVE_LOCKS_REQUIRED(lock_);
sync::InterruptSpinLock lock_;
sync::TimedThreadNotification timed_notification_;
bool stop_requested_ PW_GUARDED_BY(lock_) = false;
// A priority queue of scheduled Tasks sorted by earliest due times first.
IntrusiveList<backend::NativeTask> task_queue_ PW_GUARDED_BY(lock_);
};
} // namespace pw::async
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