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/*
* Copyright (c) 2021 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.
*/
#ifndef NET_DCSCTP_TIMER_TASK_QUEUE_TIMEOUT_H_
#define NET_DCSCTP_TIMER_TASK_QUEUE_TIMEOUT_H_
#include <memory>
#include <utility>
#include "api/task_queue/pending_task_safety_flag.h"
#include "api/task_queue/task_queue_base.h"
#include "api/units/timestamp.h"
#include "net/dcsctp/public/timeout.h"
namespace dcsctp {
// The TaskQueueTimeoutFactory creates `Timeout` instances, which schedules
// itself to be triggered on the provided `task_queue`, which may be a thread,
// an actual TaskQueue or something else which supports posting a delayed task.
//
// Note that each `DcSctpSocket` must have its own `TaskQueueTimeoutFactory`,
// as the `TimeoutID` are not unique among sockets.
//
// This class must outlive any created Timeout that it has created. Note that
// the `DcSctpSocket` will ensure that all Timeouts are deleted when the socket
// is destructed, so this means that this class must outlive the `DcSctpSocket`.
//
// This class, and the timeouts created it, are not thread safe.
class TaskQueueTimeoutFactory {
public:
// The `get_time` function must return the current time, relative to any
// epoch. Whenever a timeout expires, the `on_expired` callback will be
// triggered, and then the client should provided `timeout_id` to
// `DcSctpSocketInterface::HandleTimeout`.
TaskQueueTimeoutFactory(webrtc::TaskQueueBase& task_queue,
std::function<TimeMs()> get_time,
std::function<void(TimeoutID timeout_id)> on_expired)
: task_queue_(task_queue),
get_time_(std::move(get_time)),
on_expired_(std::move(on_expired)) {}
// Creates an implementation of `Timeout`.
std::unique_ptr<Timeout> CreateTimeout(
webrtc::TaskQueueBase::DelayPrecision precision =
webrtc::TaskQueueBase::DelayPrecision::kLow) {
return std::make_unique<TaskQueueTimeout>(*this, precision);
}
private:
class TaskQueueTimeout : public Timeout {
public:
TaskQueueTimeout(TaskQueueTimeoutFactory& parent,
webrtc::TaskQueueBase::DelayPrecision precision);
~TaskQueueTimeout();
void Start(DurationMs duration_ms, TimeoutID timeout_id) override;
void Stop() override;
private:
TaskQueueTimeoutFactory& parent_;
const webrtc::TaskQueueBase::DelayPrecision precision_;
// A safety flag to ensure that posted tasks to the task queue don't
// reference these object when they go out of scope. Note that this safety
// flag will be re-created if the scheduled-but-not-yet-expired task is not
// to be run. This happens when there is a posted delayed task with an
// expiration time _further away_ than what is now the expected expiration
// time. In this scenario, a new delayed task has to be posted with a
// shorter duration and the old task has to be forgotten.
rtc::scoped_refptr<webrtc::PendingTaskSafetyFlag> pending_task_safety_flag_;
// The time when the posted delayed task is set to expire. Will be set to
// the infinite future if there is no such task running.
webrtc::Timestamp posted_task_expiration_ =
webrtc::Timestamp::PlusInfinity();
// The time when the timeout expires. It will be set to the infinite future
// if the timeout is not running/not started.
webrtc::Timestamp timeout_expiration_ = webrtc::Timestamp::PlusInfinity();
// The current timeout ID that will be reported when expired.
TimeoutID timeout_id_ = TimeoutID(0);
};
webrtc::Timestamp Now() { return webrtc::Timestamp::Millis(*get_time_()); }
RTC_NO_UNIQUE_ADDRESS webrtc::SequenceChecker thread_checker_;
webrtc::TaskQueueBase& task_queue_;
const std::function<TimeMs()> get_time_;
const std::function<void(TimeoutID)> on_expired_;
};
} // namespace dcsctp
#endif // NET_DCSCTP_TIMER_TASK_QUEUE_TIMEOUT_H_
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