org.opentripplanner.framework.time.CountdownTimer Maven / Gradle / Ivy
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package org.opentripplanner.framework.time;
import java.time.Duration;
import java.util.function.LongSupplier;
/**
* This class will track time and is useful when for example throttling something. It does NOT
* notify anyone, but the caller must regularly check if the timer is finished.
*/
public class CountdownTimer {
private final LongSupplier clock;
private final long countDownDuration;
private long timeLimit;
/**
* Create new timer with the given count-down-duration time.
*/
public CountdownTimer(Duration countDownDuration) {
this(countDownDuration, System::currentTimeMillis);
}
/**
* This constructor allows us to unit test the timer without using
* {@code System::currentTimeMillis}.
*
* The timer is started, no need to explicit call {@link #restart()} right
* after the construction.
*/
CountdownTimer(Duration countDownDuration, LongSupplier clock) {
this.clock = clock;
this.countDownDuration = countDownDuration.toMillis();
restart();
}
/**
* Start/restart the counting down the time.
*/
public void restart() {
restart(now());
}
/**
* The timer has past the count-down-limit (startTime + countDownDuration)
*/
public boolean timeIsUp() {
return timeIsUp(now());
}
/**
* Return {@code true} if time is up, and then immediately start the timer again.
*/
public boolean nextLap() {
long time = now();
if (timeIsUp(time)) {
restart(time);
return true;
}
return false;
}
private boolean timeIsUp(long time) {
return time >= timeLimit;
}
private void restart(long time) {
this.timeLimit = time + countDownDuration;
}
private long now() {
return clock.getAsLong();
}
}