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clock.go
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clock.go
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package hare
import (
"math"
"time"
)
// Wakeup has a value of -2 because it occurs exactly two round durations before the end of round 0.
// This accounts for the duration of round zero and the preround.
const Wakeup = math.MaxUint32 - 1 // -2
// SimpleRoundClock is a simple Hare-round clock. Repeated calls to AwaitEndOfRound() will each return a new channel
// and will be backed by a new timer which will not be garbage collected until it expires. To avoid leaking resources,
// callers should avoid calling AwaitEndOfRound() more than once for a given round (e.g. by storing the resulting
// channel and reusing it).
type SimpleRoundClock struct {
LayerTime time.Time
WakeupDelta time.Duration
RoundDuration time.Duration
}
// NewSimpleRoundClock returns a new SimpleRoundClock, given the provided configuration.
func NewSimpleRoundClock(layerTime time.Time, wakeupDelta, roundDuration time.Duration) *SimpleRoundClock {
return &SimpleRoundClock{
LayerTime: layerTime,
WakeupDelta: wakeupDelta,
RoundDuration: roundDuration,
}
}
// AwaitWakeup returns a channel that gets closed when the Hare wakeup delay has passed.
func (c *SimpleRoundClock) AwaitWakeup() <-chan struct{} {
return c.AwaitEndOfRound(Wakeup)
}
// AwaitEndOfRound returns a channel that gets closed when the given round ends. Repeated calls to this method will
// return new instances of the channel and use new underlying timers which will not be garbage collected until they
// expire. To avoid leaking resources, callers should avoid calling AwaitEndOfRound() more than once for a given round
// (e.g. by storing the resulting channel and reusing it).
func (c *SimpleRoundClock) AwaitEndOfRound(round uint32) <-chan struct{} {
ch := make(chan struct{})
time.AfterFunc(time.Until(c.RoundEnd(round)), func() {
close(ch)
})
return ch
}
// RoundEnd returns the time at which round ends, passing round-1 will return
// the time at which round starts.
func (c *SimpleRoundClock) RoundEnd(round uint32) time.Time {
// The pre-round (which has a value of MaxUInt32) ends one RoundDuration after the WakeupDelta. Rounds, in general, are
// zero-based. By adding 2 to the round number and multiplying by the RoundDuration we get the correct number of
// RoundDurations to wait.
duration := c.WakeupDelta + (c.RoundDuration * time.Duration(round+2))
return c.LayerTime.Add(duration)
}