Does the nested

launch

block around

taskDao.increaseMillisCompletedToday

(which is a database operation) look dangerous? I use this to measure time but without the nested

launch

, I think the length of the database operation itself is causing imprecision. The tick interval is every 1s.

fun startTimer() {
    timerJob?.cancel()
    timerJob = applicationScope.launch {
        val selectedTask = selectedTask.first()
        if (selectedTask != null) {
            taskDao.updateLastActiveTimestamp(selectedTask.id, System.currentTimeMillis())
            startTimerService()
            timerRunningFlow.value = true
            while (true) {
                val timeBefore = SystemClock.elapsedRealtime()
                delay(TICK_DELAY)
                val timeAfter = SystemClock.elapsedRealtime()
                val elapsedTime = timeAfter - timeBefore
                launch {
                    taskDao.increaseMillisCompletedToday(selectedTask.id, elapsedTime)
                }
            }
        }
    }
}

Right I think you hit the nail on the head. In old java terms

Delay

works as

ScheduledExecutorService.scheduleWithFixedDelay

where Im guessing what you want is

ScheduledExecutorService.scheduleAtFixedRate

@groostav Thank you for your answer. Is there something in Java or Kotlin world that gives me a fixed delay that is not affected by the time in the device's settings?

If fixed delay is ok, but you just want the reported time to be accurate, then you could track the total time instead of just the delay. Something like:

val startTime = SystemClock.elapsedRealtime()
var lastReportedTime = 0
while(true) {
    delay(TICK_DELAY)
    val totalElapsedTime = SystemClock.elapsedRealtime() - startTime
    taskDao.increaseMillisCompletedToday(selectedTask.id, totalElapsedTime - lastReportedTime)
    lastReportedTime = totalElapsedTime
}

@Nick Allen that's a great idea!