mpd/src/event/CoarseTimerEvent.hxx
2023-11-21 20:47:25 +01:00

79 lines
1.8 KiB
C++

// SPDX-License-Identifier: BSD-2-Clause
// Copyright CM4all GmbH
// author: Max Kellermann <mk@cm4all.com>
#pragma once
#include "Chrono.hxx"
#include "util/BindMethod.hxx"
#include "util/IntrusiveList.hxx"
class EventLoop;
/**
* This class invokes a callback function after a certain amount of
* time. Use Schedule() to start the timer or Cancel() to cancel it.
*
* Unlike #FineTimerEvent, this class has a granularity of about 1
* second, and is optimized for timeouts between 1 and 60 seconds
* which are often canceled before they expire (i.e. optimized for
* fast insertion and deletion, at the cost of granularity).
*
* This class is not thread-safe, all methods must be called from the
* thread that runs the #EventLoop, except where explicitly documented
* as thread-safe.
*/
class CoarseTimerEvent final : AutoUnlinkIntrusiveListHook
{
friend class TimerWheel;
friend struct IntrusiveListBaseHookTraits<CoarseTimerEvent>;
EventLoop &loop;
using Callback = BoundMethod<void() noexcept>;
const Callback callback;
/**
* When is this timer due? This is only valid if IsPending()
* returns true.
*/
Event::TimePoint due;
public:
CoarseTimerEvent(EventLoop &_loop, Callback _callback) noexcept
:loop(_loop), callback(_callback) {}
auto &GetEventLoop() const noexcept {
return loop;
}
constexpr auto GetDue() const noexcept {
return due;
}
/**
* Was this timer scheduled?
*/
bool IsPending() const noexcept {
return is_linked();
}
void Schedule(Event::Duration d) noexcept;
/**
* Like Schedule(), but is a no-op if there is a due time
* earlier than the given one.
*/
void ScheduleEarlier(Event::Duration d) noexcept;
void Cancel() noexcept {
if (IsPending())
unlink();
}
private:
void Run() noexcept {
callback();
}
};