func profileSample(clk clock.Clock, w io.Writer, r io.Reader, res time.Duration) (io.Writer, io.Reader, func() SamplingProfile) {
samplingWriter := &samplingTimeWriter{w: w}
samplingReader := &samplingTimeReader{r: r}
start := clk.Now()
done := make(chan struct{})
samples := SamplingProfile{}
go func() {
ticker := clk.Ticker(res)
defer ticker.Stop()
for {
select {
case <-ticker.C:
isWriting := atomic.LoadUint32(&samplingWriter.state) == stateBlocked
isReading := atomic.LoadUint32(&samplingReader.state) == stateBlocked
if isWriting {
samples.Writing++
} else {
samples.NotWriting++
}
if isReading {
samples.Reading++
} else {
samples.NotReading++
}
case <-done:
return
}
}
}()
return samplingWriter, samplingReader, func() SamplingProfile {
close(done)
total := clk.Now().Sub(start)
samples.TimeProfile = TimeProfile{
Total: total,
WaitRead: time.Duration(float64(samples.Reading) / float64(samples.Reading+samples.NotReading) * float64(total)),
WaitWrite: time.Duration(float64(samples.Writing) / float64(samples.Writing+samples.NotWriting) * float64(total)),
}
return samples
}
}
// GetAlignedTicker returns a ticker so that, let's say interval is a second
// then it will tick at every whole second, or if it's 60s than it's every whole
// minute. Note that in my testing this is about .0001 to 0.0002 seconds off due
// to scheduling etc.
func GetAlignedTicker(c clock.Clock, period time.Duration) *clock.Ticker {
unix := c.Now().UnixNano()
diff := time.Duration(period - (time.Duration(unix) % period))
return c.Ticker(diff)
}