/
rate.go
83 lines (64 loc) · 1.82 KB
/
rate.go
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package udp
import (
"time"
)
type RateStats struct {
SleepDuration time.Duration // total time slept
UnderrunCount uint // count of timing underruns (no sleep)
Count uint // count of timing ticks
}
type RateClock struct {
rateChan chan time.Time
stats *RateStats
start time.Time
rate uint
stop uint // stop once offset
offset uint
}
func (self *RateClock) init() {
self.stats = &RateStats{}
}
func (self *RateClock) initStats(stats *RateStats) {
self.stats = stats
}
func (self *RateClock) run() {
defer close(self.rateChan)
for ; self.stop == 0 || self.offset < self.stop; self.offset++ {
if self.rate != 0 {
// scheduled time for next packet
targetClock := time.Duration(self.offset) * time.Second / time.Duration(self.rate)
currentClock := time.Since(self.start)
skew := targetClock - currentClock
if skew > 0 {
// slow down
time.Sleep(skew)
self.stats.SleepDuration += skew
} else {
// catch up
self.stats.UnderrunCount++
}
}
self.rateChan <- time.Now()
self.stats.Count++
}
}
func (self *RateClock) Start(rate uint, count uint) chan time.Time {
self.rateChan = make(chan time.Time)
self.Set(rate, count)
// start
go self.run()
return self.rateChan
}
// change running timer
func (self *RateClock) Set(rate uint, count uint) {
// XXX: unsafe if running...
self.start = time.Now()
self.rate = rate
self.stop = count
self.offset = 0
}
// Stop running, closing the chan returned by Start()
func (self *RateClock) Stop() {
// XXX
self.stop = self.offset
}