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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.
*/
#ifndef RTC_BASE_TASK_UTILS_REPEATING_TASK_H_
#define RTC_BASE_TASK_UTILS_REPEATING_TASK_H_
#include <memory>
#include <type_traits>
#include <utility>
#include "absl/functional/any_invocable.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 "system_wrappers/include/clock.h"
namespace webrtc {
namespace webrtc_repeating_task_impl {
// Methods simplifying external tracing of RepeatingTaskHandle operations.
void RepeatingTaskHandleDTraceProbeStart();
void RepeatingTaskHandleDTraceProbeDelayedStart();
void RepeatingTaskImplDTraceProbeRun();
} // namespace webrtc_repeating_task_impl
// Allows starting tasks that repeat themselves on a TaskQueue indefinately
// until they are stopped or the TaskQueue is destroyed. It allows starting and
// stopping multiple times, but you must stop one task before starting another
// and it can only be stopped when in the running state. The public interface is
// not thread safe.
class RepeatingTaskHandle {
public:
RepeatingTaskHandle() = default;
~RepeatingTaskHandle() = default;
RepeatingTaskHandle(RepeatingTaskHandle&& other) = default;
RepeatingTaskHandle& operator=(RepeatingTaskHandle&& other) = default;
RepeatingTaskHandle(const RepeatingTaskHandle&) = delete;
RepeatingTaskHandle& operator=(const RepeatingTaskHandle&) = delete;
// Start can be used to start a task that will be reposted with a delay
// determined by the return value of the provided closure. The actual task is
// owned by the TaskQueue and will live until it has been stopped or the
// TaskQueue deletes it. It's perfectly fine to destroy the handle while the
// task is running, since the repeated task is owned by the TaskQueue.
// The tasks are scheduled onto the task queue using the specified precision.
static RepeatingTaskHandle Start(
TaskQueueBase* task_queue,
absl::AnyInvocable<TimeDelta()> closure,
TaskQueueBase::DelayPrecision precision =
TaskQueueBase::DelayPrecision::kLow,
Clock* clock = Clock::GetRealTimeClockRaw(),
const Location& location = Location::Current());
// DelayedStart is equivalent to Start except that the first invocation of the
// closure will be delayed by the given amount.
static RepeatingTaskHandle DelayedStart(
TaskQueueBase* task_queue,
TimeDelta first_delay,
absl::AnyInvocable<TimeDelta()> closure,
TaskQueueBase::DelayPrecision precision =
TaskQueueBase::DelayPrecision::kLow,
Clock* clock = Clock::GetRealTimeClockRaw(),
const Location& location = Location::Current());
// Stops future invocations of the repeating task closure. Can only be called
// from the TaskQueue where the task is running. The closure is guaranteed to
// not be running after Stop() returns unless Stop() is called from the
// closure itself.
void Stop();
// Returns true until Stop() was called.
// Can only be called from the TaskQueue where the task is running.
bool Running() const;
private:
explicit RepeatingTaskHandle(
rtc::scoped_refptr<PendingTaskSafetyFlag> alive_flag)
: repeating_task_(std::move(alive_flag)) {}
rtc::scoped_refptr<PendingTaskSafetyFlag> repeating_task_;
};
} // namespace webrtc
#endif // RTC_BASE_TASK_UTILS_REPEATING_TASK_H_
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