vendor: bump beorn7/perks v1.0.1

full diff: 4c0e84591b...v1.0.1

- beorn7/perks#3 Avoid iterating on maps
    - Speed up InsertTargeted* functions by at least 2x by avoiding iterating on maps.
- beorn7/perks#4 Fixed format error
- Use 1000000 instead of 1e6 for int constant
- Add go module support

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor/github.com/beorn7/perks/go.mod

@@ -0,0 +1,3 @@
+module github.com/beorn7/perks
+
+go 1.11

vendor/github.com/beorn7/perks/quantile/stream.go

@@ -77,15 +77,20 @@ func NewHighBiased(epsilon float64) *Stream {
 // is guaranteed to be within (Quantile±Epsilon).
 //
 // See http://www.cs.rutgers.edu/~muthu/bquant.pdf for time, space, and error properties.
-func NewTargeted(targets map[float64]float64) *Stream {
+func NewTargeted(targetMap map[float64]float64) *Stream {
+	// Convert map to slice to avoid slow iterations on a map.
+	// ƒ is called on the hot path, so converting the map to a slice
+	// beforehand results in significant CPU savings.
+	targets := targetMapToSlice(targetMap)
+
 	ƒ := func(s *stream, r float64) float64 {
 		var m = math.MaxFloat64
 		var f float64
-		for quantile, epsilon := range targets {
-			if quantile*s.n <= r {
-				f = (2 * epsilon * r) / quantile
+		for _, t := range targets {
+			if t.quantile*s.n <= r {
+				f = (2 * t.epsilon * r) / t.quantile
 			} else {
-				f = (2 * epsilon * (s.n - r)) / (1 - quantile)
+				f = (2 * t.epsilon * (s.n - r)) / (1 - t.quantile)
 			}
 			if f < m {
 				m = f
@@ -96,6 +101,25 @@ func NewTargeted(targets map[float64]float64) *Stream {
 	return newStream(ƒ)
 }
 
+type target struct {
+	quantile float64
+	epsilon  float64
+}
+
+func targetMapToSlice(targetMap map[float64]float64) []target {
+	targets := make([]target, 0, len(targetMap))
+
+	for quantile, epsilon := range targetMap {
+		t := target{
+			quantile: quantile,
+			epsilon:  epsilon,
+		}
+		targets = append(targets, t)
+	}
+
+	return targets
+}
+
 // Stream computes quantiles for a stream of float64s. It is not thread-safe by
 // design. Take care when using across multiple goroutines.
 type Stream struct {