1 files changed, 247 insertions, 0 deletions
diff --git a/vendor/github.com/armon/go-metrics/inmem.go b/vendor/github.com/armon/go-metrics/inmem.go
new file mode 100644
index 000000000..83fb6bba0
--- /dev/null
+++ b/vendor/github.com/armon/go-metrics/inmem.go
@@ -0,0 +1,247 @@
+package metrics
+
+import (
+	"fmt"
+	"math"
+	"strings"
+	"sync"
+	"time"
+)
+
+// InmemSink provides a MetricSink that does in-memory aggregation
+// without sending metrics over a network. It can be embedded within
+// an application to provide profiling information.
+type InmemSink struct {
+	// How long is each aggregation interval
+	interval time.Duration
+
+	// Retain controls how many metrics interval we keep
+	retain time.Duration
+
+	// maxIntervals is the maximum length of intervals.
+	// It is retain / interval.
+	maxIntervals int
+
+	// intervals is a slice of the retained intervals
+	intervals    []*IntervalMetrics
+	intervalLock sync.RWMutex
+	
+	rateDenom float64
+}
+
+// IntervalMetrics stores the aggregated metrics
+// for a specific interval
+type IntervalMetrics struct {
+	sync.RWMutex
+
+	// The start time of the interval
+	Interval time.Time
+
+	// Gauges maps the key to the last set value
+	Gauges map[string]float32
+
+	// Points maps the string to the list of emitted values
+	// from EmitKey
+	Points map[string][]float32
+
+	// Counters maps the string key to a sum of the counter
+	// values
+	Counters map[string]*AggregateSample
+
+	// Samples maps the key to an AggregateSample,
+	// which has the rolled up view of a sample
+	Samples map[string]*AggregateSample
+}
+
+// NewIntervalMetrics creates a new IntervalMetrics for a given interval
+func NewIntervalMetrics(intv time.Time) *IntervalMetrics {
+	return &IntervalMetrics{
+		Interval: intv,
+		Gauges:   make(map[string]float32),
+		Points:   make(map[string][]float32),
+		Counters: make(map[string]*AggregateSample),
+		Samples:  make(map[string]*AggregateSample),
+	}
+}
+
+// AggregateSample is used to hold aggregate metrics
+// about a sample
+type AggregateSample struct {
+	Count       int       // The count of emitted pairs
+	Rate	        float64   // The count of emitted pairs per time unit (usually 1 second)
+	Sum         float64   // The sum of values
+	SumSq       float64   // The sum of squared values
+	Min         float64   // Minimum value
+	Max         float64   // Maximum value
+	LastUpdated time.Time // When value was last updated
+}
+
+// Computes a Stddev of the values
+func (a *AggregateSample) Stddev() float64 {
+	num := (float64(a.Count) * a.SumSq) - math.Pow(a.Sum, 2)
+	div := float64(a.Count * (a.Count - 1))
+	if div == 0 {
+		return 0
+	}
+	return math.Sqrt(num / div)
+}
+
+// Computes a mean of the values
+func (a *AggregateSample) Mean() float64 {
+	if a.Count == 0 {
+		return 0
+	}
+	return a.Sum / float64(a.Count)
+}
+
+// Ingest is used to update a sample
+func (a *AggregateSample) Ingest(v float64, rateDenom float64) {
+	a.Count++
+	a.Sum += v
+	a.SumSq += (v * v)
+	if v < a.Min || a.Count == 1 {
+		a.Min = v
+	}
+	if v > a.Max || a.Count == 1 {
+		a.Max = v
+	}
+	a.Rate = float64(a.Count)/rateDenom
+	a.LastUpdated = time.Now()
+}
+
+func (a *AggregateSample) String() string {
+	if a.Count == 0 {
+		return "Count: 0"
+	} else if a.Stddev() == 0 {
+		return fmt.Sprintf("Count: %d Sum: %0.3f LastUpdated: %s", a.Count, a.Sum, a.LastUpdated)
+	} else {
+		return fmt.Sprintf("Count: %d Min: %0.3f Mean: %0.3f Max: %0.3f Stddev: %0.3f Sum: %0.3f LastUpdated: %s",
+			a.Count, a.Min, a.Mean(), a.Max, a.Stddev(), a.Sum, a.LastUpdated)
+	}
+}
+
+// NewInmemSink is used to construct a new in-memory sink.
+// Uses an aggregation interval and maximum retention period.
+func NewInmemSink(interval, retain time.Duration) *InmemSink {
+	rateTimeUnit := time.Second
+	i := &InmemSink{
+		interval:     interval,
+		retain:       retain,
+		maxIntervals: int(retain / interval),
+		rateDenom: float64(interval.Nanoseconds()) / float64(rateTimeUnit.Nanoseconds()),
+	}
+	i.intervals = make([]*IntervalMetrics, 0, i.maxIntervals)
+	return i
+}
+
+func (i *InmemSink) SetGauge(key []string, val float32) {
+	k := i.flattenKey(key)
+	intv := i.getInterval()
+
+	intv.Lock()
+	defer intv.Unlock()
+	intv.Gauges[k] = val
+}
+
+func (i *InmemSink) EmitKey(key []string, val float32) {
+	k := i.flattenKey(key)
+	intv := i.getInterval()
+
+	intv.Lock()
+	defer intv.Unlock()
+	vals := intv.Points[k]
+	intv.Points[k] = append(vals, val)
+}
+
+func (i *InmemSink) IncrCounter(key []string, val float32) {
+	k := i.flattenKey(key)
+	intv := i.getInterval()
+
+	intv.Lock()
+	defer intv.Unlock()
+
+	agg := intv.Counters[k]
+	if agg == nil {
+		agg = &AggregateSample{}
+		intv.Counters[k] = agg
+	}
+	agg.Ingest(float64(val), i.rateDenom)
+}
+
+func (i *InmemSink) AddSample(key []string, val float32) {
+	k := i.flattenKey(key)
+	intv := i.getInterval()
+
+	intv.Lock()
+	defer intv.Unlock()
+
+	agg := intv.Samples[k]
+	if agg == nil {
+		agg = &AggregateSample{}
+		intv.Samples[k] = agg
+	}
+	agg.Ingest(float64(val), i.rateDenom)
+}
+
+// Data is used to retrieve all the aggregated metrics
+// Intervals may be in use, and a read lock should be acquired
+func (i *InmemSink) Data() []*IntervalMetrics {
+	// Get the current interval, forces creation
+	i.getInterval()
+
+	i.intervalLock.RLock()
+	defer i.intervalLock.RUnlock()
+
+	intervals := make([]*IntervalMetrics, len(i.intervals))
+	copy(intervals, i.intervals)
+	return intervals
+}
+
+func (i *InmemSink) getExistingInterval(intv time.Time) *IntervalMetrics {
+	i.intervalLock.RLock()
+	defer i.intervalLock.RUnlock()
+
+	n := len(i.intervals)
+	if n > 0 && i.intervals[n-1].Interval == intv {
+		return i.intervals[n-1]
+	}
+	return nil
+}
+
+func (i *InmemSink) createInterval(intv time.Time) *IntervalMetrics {
+	i.intervalLock.Lock()
+	defer i.intervalLock.Unlock()
+
+	// Check for an existing interval
+	n := len(i.intervals)
+	if n > 0 && i.intervals[n-1].Interval == intv {
+		return i.intervals[n-1]
+	}
+
+	// Add the current interval
+	current := NewIntervalMetrics(intv)
+	i.intervals = append(i.intervals, current)
+	n++
+
+	// Truncate the intervals if they are too long
+	if n >= i.maxIntervals {
+		copy(i.intervals[0:], i.intervals[n-i.maxIntervals:])
+		i.intervals = i.intervals[:i.maxIntervals]
+	}
+	return current
+}
+
+// getInterval returns the current interval to write to
+func (i *InmemSink) getInterval() *IntervalMetrics {
+	intv := time.Now().Truncate(i.interval)
+	if m := i.getExistingInterval(intv); m != nil {
+		return m
+	}
+	return i.createInterval(intv)
+}
+
+// Flattens the key for formatting, removes spaces
+func (i *InmemSink) flattenKey(parts []string) string {
+	joined := strings.Join(parts, ".")
+	return strings.Replace(joined, " ", "_", -1)
+}