1 files changed, 112 insertions, 0 deletions
diff --git a/vendor/github.com/facebookgo/stats/counter.go b/vendor/github.com/facebookgo/stats/counter.go
new file mode 100644
index 00000000..59a0ed1e
--- /dev/null
+++ b/vendor/github.com/facebookgo/stats/counter.go
@@ -0,0 +1,112 @@
+package stats
+
+import "fmt"
+
+// Type is the type of aggregation of apply
+type Type int
+
+const (
+	AggregateAvg Type = iota
+	AggregateSum
+	AggregateHistogram
+)
+
+var (
+	// HistogramPercentiles is used to determine which percentiles to return for
+	// SimpleCounter.Aggregate
+	HistogramPercentiles = map[string]float64{
+		"p50": 0.5,
+		"p95": 0.95,
+		"p99": 0.99,
+	}
+
+	// MinSamplesForPercentiles is used by SimpleCounter.Aggregate to determine
+	// what the minimum number of samples is required for percentile analysis
+	MinSamplesForPercentiles = 10
+)
+
+// Aggregates can be used to merge counters together. This is not goroutine safe
+type Aggregates map[string]Counter
+
+// Add adds the counter for aggregation. This is not goroutine safe
+func (a Aggregates) Add(c Counter) error {
+	key := c.FullKey()
+	if counter, ok := a[key]; ok {
+		if counter.GetType() != c.GetType() {
+			return fmt.Errorf("stats: mismatched aggregation type for: %s", key)
+		}
+		counter.AddValues(c.GetValues()...)
+	} else {
+		a[key] = c
+	}
+	return nil
+}
+
+// Counter is the interface used by Aggregates to merge counters together
+type Counter interface {
+	// FullKey is used to uniquely identify the counter
+	FullKey() string
+
+	// AddValues adds values for aggregation
+	AddValues(...float64)
+
+	// GetValues returns the values for aggregation
+	GetValues() []float64
+
+	// GetType returns the type of aggregation to apply
+	GetType() Type
+}
+
+// SimpleCounter is a basic implementation of the Counter interface
+type SimpleCounter struct {
+	Key    string
+	Values []float64
+	Type   Type
+}
+
+// FullKey is part of the Counter interace
+func (s *SimpleCounter) FullKey() string {
+	return s.Key
+}
+
+// GetValues is part of the Counter interface
+func (s *SimpleCounter) GetValues() []float64 {
+	return s.Values
+}
+
+// AddValues is part of the Counter interface
+func (s *SimpleCounter) AddValues(vs ...float64) {
+	s.Values = append(s.Values, vs...)
+}
+
+// GetType is part of the Counter interface
+func (s *SimpleCounter) GetType() Type {
+	return s.Type
+}
+
+// Aggregate aggregates the provided values appropriately, returning a map
+// from key to value. If AggregateHistogram is specified, the map will contain
+// the relevant percentiles as specified by HistogramPercentiles
+func (s *SimpleCounter) Aggregate() map[string]float64 {
+	switch s.Type {
+	case AggregateAvg:
+		return map[string]float64{
+			s.Key: Average(s.Values),
+		}
+	case AggregateSum:
+		return map[string]float64{
+			s.Key: Sum(s.Values),
+		}
+	case AggregateHistogram:
+		histogram := map[string]float64{
+			s.Key: Average(s.Values),
+		}
+		if len(s.Values) > MinSamplesForPercentiles {
+			for k, v := range Percentiles(s.Values, HistogramPercentiles) {
+				histogram[fmt.Sprintf("%s.%s", s.Key, k)] = v
+			}
+		}
+		return histogram
+	}
+	panic("stats: unsupported aggregation type")
+}