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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.
#include "pw_async_basic/dispatcher.h"
#include "pw_assert/check.h"
#include "pw_chrono/system_clock.h"
#include "pw_log/log.h"
using namespace std::chrono_literals;
namespace pw::async {
const chrono::SystemClock::duration SLEEP_DURATION = 5s;
BasicDispatcher::~BasicDispatcher() {
RequestStop();
lock_.lock();
DrainTaskQueue();
lock_.unlock();
}
void BasicDispatcher::Run() {
lock_.lock();
while (!stop_requested_) {
MaybeSleep();
ExecuteDueTasks();
}
DrainTaskQueue();
lock_.unlock();
}
void BasicDispatcher::RunUntilIdle() {
lock_.lock();
ExecuteDueTasks();
if (stop_requested_) {
DrainTaskQueue();
}
lock_.unlock();
}
void BasicDispatcher::RunUntil(chrono::SystemClock::time_point end_time) {
lock_.lock();
while (end_time < now() && !stop_requested_) {
MaybeSleep();
ExecuteDueTasks();
}
if (stop_requested_) {
DrainTaskQueue();
}
lock_.unlock();
}
void BasicDispatcher::RunFor(chrono::SystemClock::duration duration) {
RunUntil(now() + duration);
}
void BasicDispatcher::MaybeSleep() {
if (task_queue_.empty() || task_queue_.front().due_time_ > now()) {
// Sleep until a notification is received or until the due time of the
// next task. Notifications are sent when tasks are posted or 'stop' is
// requested.
chrono::SystemClock::time_point wake_time =
task_queue_.empty() ? now() + SLEEP_DURATION
: task_queue_.front().due_time_;
lock_.unlock();
PW_LOG_DEBUG("no task due; waiting for signal");
timed_notification_.try_acquire_until(wake_time);
lock_.lock();
}
}
void BasicDispatcher::ExecuteDueTasks() {
while (!task_queue_.empty() && task_queue_.front().due_time_ <= now() &&
!stop_requested_) {
backend::NativeTask& task = task_queue_.front();
task_queue_.pop_front();
if (task.interval().has_value()) {
PostTaskInternal(task, task.due_time_ + task.interval().value());
}
lock_.unlock();
PW_LOG_DEBUG("running task");
Context ctx{this, &task.task_};
task(ctx, OkStatus());
lock_.lock();
}
}
void BasicDispatcher::RequestStop() {
std::lock_guard lock(lock_);
PW_LOG_DEBUG("stop requested");
stop_requested_ = true;
timed_notification_.release();
}
void BasicDispatcher::DrainTaskQueue() {
PW_LOG_DEBUG("draining task queue");
while (!task_queue_.empty()) {
backend::NativeTask& task = task_queue_.front();
task_queue_.pop_front();
lock_.unlock();
PW_LOG_DEBUG("running cancelled task");
Context ctx{this, &task.task_};
task(ctx, Status::Cancelled());
lock_.lock();
}
}
void BasicDispatcher::Post(Task& task) { PostAt(task, now()); }
void BasicDispatcher::PostAfter(Task& task,
chrono::SystemClock::duration delay) {
PostAt(task, now() + delay);
}
void BasicDispatcher::PostAt(Task& task, chrono::SystemClock::time_point time) {
lock_.lock();
PW_LOG_DEBUG("posting task");
PostTaskInternal(task.native_type(), time);
lock_.unlock();
}
void BasicDispatcher::PostPeriodic(Task& task,
chrono::SystemClock::duration interval) {
PostPeriodicAt(task, interval, now());
}
void BasicDispatcher::PostPeriodicAt(
Task& task,
chrono::SystemClock::duration interval,
chrono::SystemClock::time_point start_time) {
PW_DCHECK(interval != chrono::SystemClock::duration::zero());
task.native_type().set_interval(interval);
PostAt(task, start_time);
}
bool BasicDispatcher::Cancel(Task& task) {
std::lock_guard lock(lock_);
return task_queue_.remove(task.native_type());
}
void BasicDispatcher::PostTaskInternal(
backend::NativeTask& task, chrono::SystemClock::time_point time_due) {
task.due_time_ = time_due;
auto it_front = task_queue_.begin();
auto it_behind = task_queue_.before_begin();
while (it_front != task_queue_.end() && time_due > it_front->due_time_) {
++it_front;
++it_behind;
}
task_queue_.insert_after(it_behind, task);
timed_notification_.release();
}
} // namespace pw::async
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