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/*
* Copyright 2019 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "rtc_base/task_utils/repeating_task.h"
#include <algorithm>
#include <utility>
#include "absl/functional/any_invocable.h"
#include "api/location.h"
#include "api/scoped_refptr.h"
#include "api/sequence_checker.h"
#include "api/task_queue/pending_task_safety_flag.h"
#include "api/task_queue/task_queue_base.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "rtc_base/checks.h"
#include "rtc_base/thread_annotations.h"
#include "system_wrappers/include/clock.h"
namespace webrtc {
namespace {
class RepeatingTask {
public:
RepeatingTask(TaskQueueBase* task_queue,
TaskQueueBase::DelayPrecision precision,
TimeDelta first_delay,
absl::AnyInvocable<TimeDelta()> task,
Clock* clock,
scoped_refptr<PendingTaskSafetyFlag> alive_flag,
const Location& location);
RepeatingTask(RepeatingTask&&) = default;
RepeatingTask& operator=(RepeatingTask&&) = delete;
~RepeatingTask() = default;
void operator()() &&;
private:
TaskQueueBase* const task_queue_;
const TaskQueueBase::DelayPrecision precision_;
Clock* const clock_;
const Location location_;
absl::AnyInvocable<TimeDelta()> task_;
// This is always finite.
Timestamp next_run_time_ RTC_GUARDED_BY(task_queue_);
scoped_refptr<PendingTaskSafetyFlag> alive_flag_ RTC_GUARDED_BY(task_queue_);
};
RepeatingTask::RepeatingTask(TaskQueueBase* task_queue,
TaskQueueBase::DelayPrecision precision,
TimeDelta first_delay,
absl::AnyInvocable<TimeDelta()> task,
Clock* clock,
scoped_refptr<PendingTaskSafetyFlag> alive_flag,
const Location& location)
: task_queue_(task_queue),
precision_(precision),
clock_(clock),
location_(location),
task_(std::move(task)),
next_run_time_(clock_->CurrentTime() + first_delay),
alive_flag_(std::move(alive_flag)) {}
void RepeatingTask::operator()() && {
RTC_DCHECK_RUN_ON(task_queue_);
if (!alive_flag_->alive())
return;
webrtc_repeating_task_impl::RepeatingTaskImplDTraceProbeRun();
TimeDelta delay = task_();
RTC_DCHECK_GE(delay, TimeDelta::Zero());
// A delay of +infinity means that the task should not be run again.
// Alternatively, the closure might have stopped this task.
if (delay.IsPlusInfinity() || !alive_flag_->alive())
return;
TimeDelta lost_time = clock_->CurrentTime() - next_run_time_;
next_run_time_ += delay;
delay -= lost_time;
delay = std::max(delay, TimeDelta::Zero());
task_queue_->PostDelayedTaskWithPrecision(precision_, std::move(*this), delay,
location_);
}
} // namespace
RepeatingTaskHandle RepeatingTaskHandle::Start(
TaskQueueBase* task_queue,
absl::AnyInvocable<TimeDelta()> closure,
TaskQueueBase::DelayPrecision precision,
Clock* clock,
const Location& location) {
auto alive_flag = PendingTaskSafetyFlag::CreateDetached();
webrtc_repeating_task_impl::RepeatingTaskHandleDTraceProbeStart();
task_queue->PostTask(
RepeatingTask(task_queue, precision, TimeDelta::Zero(),
std::move(closure), clock, alive_flag, location),
location);
return RepeatingTaskHandle(std::move(alive_flag));
}
// DelayedStart is equivalent to Start except that the first invocation of the
// closure will be delayed by the given amount.
RepeatingTaskHandle RepeatingTaskHandle::DelayedStart(
TaskQueueBase* task_queue,
TimeDelta first_delay,
absl::AnyInvocable<TimeDelta()> closure,
TaskQueueBase::DelayPrecision precision,
Clock* clock,
const Location& location) {
auto alive_flag = PendingTaskSafetyFlag::CreateDetached();
webrtc_repeating_task_impl::RepeatingTaskHandleDTraceProbeDelayedStart();
task_queue->PostDelayedTaskWithPrecision(
precision,
RepeatingTask(task_queue, precision, first_delay, std::move(closure),
clock, alive_flag, location),
first_delay, location);
return RepeatingTaskHandle(std::move(alive_flag));
}
void RepeatingTaskHandle::Stop() {
if (repeating_task_) {
repeating_task_->SetNotAlive();
repeating_task_ = nullptr;
}
}
bool RepeatingTaskHandle::Running() const {
return repeating_task_ != nullptr;
}
namespace webrtc_repeating_task_impl {
// These methods are empty, but can be externally equipped with actions using
// dtrace.
void RepeatingTaskHandleDTraceProbeStart() {}
void RepeatingTaskHandleDTraceProbeDelayedStart() {}
void RepeatingTaskImplDTraceProbeRun() {}
} // namespace webrtc_repeating_task_impl
} // namespace webrtc
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