152 lines
3.4 KiB
C++
152 lines
3.4 KiB
C++
/*
|
|
* Copyright 2003-2022 The Music Player Daemon Project
|
|
* http://www.musicpd.org
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with this program; if not, write to the Free Software Foundation, Inc.,
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
*/
|
|
|
|
#ifndef MPD_PERIOD_CLOCK_HXX
|
|
#define MPD_PERIOD_CLOCK_HXX
|
|
|
|
#include <chrono>
|
|
|
|
/**
|
|
* This is a stopwatch which saves the timestamp of an event, and can
|
|
* check whether a specified time span has passed since then.
|
|
*/
|
|
class PeriodClock {
|
|
public:
|
|
typedef std::chrono::steady_clock::duration Duration;
|
|
typedef Duration Delta;
|
|
typedef std::chrono::steady_clock::time_point Stamp;
|
|
|
|
private:
|
|
Stamp last;
|
|
|
|
public:
|
|
/**
|
|
* Initializes the object, setting the last time stamp to "0",
|
|
* i.e. a Check() will always succeed. If you do not want this
|
|
* default behaviour, call Update() immediately after creating the
|
|
* object.
|
|
*/
|
|
constexpr
|
|
PeriodClock():last() {}
|
|
|
|
protected:
|
|
static Stamp GetNow() {
|
|
return std::chrono::steady_clock::now();
|
|
}
|
|
|
|
constexpr Delta Elapsed(Stamp now) const {
|
|
return last == Stamp()
|
|
? Delta(-1)
|
|
: Delta(now - last);
|
|
}
|
|
|
|
constexpr bool Check(Stamp now, Duration duration) const {
|
|
return now >= last + duration;
|
|
}
|
|
|
|
void Update(Stamp now) {
|
|
last = now;
|
|
}
|
|
|
|
public:
|
|
constexpr bool IsDefined() const {
|
|
return last > Stamp();
|
|
}
|
|
|
|
/**
|
|
* Resets the clock.
|
|
*/
|
|
void Reset() {
|
|
last = Stamp();
|
|
}
|
|
|
|
/**
|
|
* Returns the time elapsed since the last update(). Returns
|
|
* a negative value if update() was never called.
|
|
*/
|
|
Delta Elapsed() const {
|
|
return Elapsed(GetNow());
|
|
}
|
|
|
|
/**
|
|
* Combines a call to Elapsed() and Update().
|
|
*/
|
|
Delta ElapsedUpdate() {
|
|
const auto now = GetNow();
|
|
const auto result = Elapsed(now);
|
|
Update(now);
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Checks whether the specified duration has passed since the last
|
|
* update.
|
|
*
|
|
* @param duration the duration
|
|
*/
|
|
bool Check(Duration duration) const {
|
|
return Check(GetNow(), duration);
|
|
}
|
|
|
|
/**
|
|
* Updates the time stamp, setting it to the current clock.
|
|
*/
|
|
void Update() {
|
|
Update(GetNow());
|
|
}
|
|
|
|
/**
|
|
* Updates the time stamp, setting it to the current clock plus the
|
|
* specified offset.
|
|
*/
|
|
void UpdateWithOffset(Delta offset) {
|
|
Update(GetNow() + offset);
|
|
}
|
|
|
|
/**
|
|
* Checks whether the specified duration has passed since the last
|
|
* update. If yes, it updates the time stamp.
|
|
*
|
|
* @param duration the duration in milliseconds
|
|
*/
|
|
bool CheckUpdate(Duration duration) {
|
|
Stamp now = GetNow();
|
|
if (Check(now, duration)) {
|
|
Update(now);
|
|
return true;
|
|
} else
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Checks whether the specified duration has passed since the last
|
|
* update. After that, it updates the time stamp.
|
|
*
|
|
* @param duration the duration in milliseconds
|
|
*/
|
|
bool CheckAlwaysUpdate(Duration duration) {
|
|
Stamp now = GetNow();
|
|
bool ret = Check(now, duration);
|
|
Update(now);
|
|
return ret;
|
|
}
|
|
};
|
|
|
|
#endif
|