/**
* Obtains a clock that returns instants from the specified clock truncated
* to the nearest occurrence of the specified duration.
* <p>
* This clock will only tick as per the specified duration. Thus, if the duration
* is half a second, the clock will return instants truncated to the half second.
* <p>
* The tick duration must be positive. If it has a part smaller than a whole
* millisecond, then the whole duration must divide into one second without
* leaving a remainder. All normal tick durations will match these criteria,
* including any multiple of hours, minutes, seconds and milliseconds, and
* sensible nanosecond durations, such as 20ns, 250,000ns and 500,000ns.
* <p>
* A duration of zero or one nanosecond would have no truncation effect.
* Passing one of these will return the underlying clock.
* <p>
* Implementations may use a caching strategy for performance reasons.
* As such, it is possible that the start of the requested duration observed
* via this clock will be later than that observed directly via the underlying clock.
* <p>
* The returned implementation is immutable, thread-safe and {@code Serializable}
* providing that the base clock is.
*
* @param Clock $baseClock the base clock to base the ticking clock on, not null
* @param Duration $tickDuration the duration of each visible tick, not negative, not null
* @return Clock clock that ticks in whole units of the duration, not null
* @throws \InvalidArgumentException if the duration is negative, or has a
* part smaller than a whole millisecond such that the whole duration is not
* divisible into one second
* @throws ArithmeticException if the duration is too large to be represented as nanos
*/
public static function tick(Clock $baseClock, Duration $tickDuration)
{
if ($tickDuration->isNegative()) {
throw new \InvalidArgumentException("Tick duration must not be negative");
}
$tickNanos = $tickDuration->toNanos();
if ($tickNanos % 1000000 == 0) {
// ok, no fraction of millisecond
} else {
if (1000000000 % $tickNanos == 0) {
// ok, divides into one second without remainder
} else {
throw new \InvalidArgumentException("Invalid tick duration");
}
}
if ($tickNanos <= 1) {
return $baseClock;
}
return new TickClock($baseClock, $tickNanos);
}
