Add pushover notifications, this should be a super basic MVP

vendor/github.com/dgraph-io/ristretto/z/histogram.go

@@ -0,0 +1,151 @@
+/*
+ * Copyright 2020 Dgraph Labs, Inc. and Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package z
+
+import (
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/dustin/go-humanize"
+)
+
+// Creates bounds for an histogram. The bounds are powers of two of the form
+// [2^min_exponent, ..., 2^max_exponent].
+func HistogramBounds(minExponent, maxExponent uint32) []float64 {
+	var bounds []float64
+	for i := minExponent; i <= maxExponent; i++ {
+		bounds = append(bounds, float64(int(1)<<i))
+	}
+	return bounds
+}
+
+// HistogramData stores the information needed to represent the sizes of the keys and values
+// as a histogram.
+type HistogramData struct {
+	Bounds         []float64
+	Count          int64
+	CountPerBucket []int64
+	Min            int64
+	Max            int64
+	Sum            int64
+}
+
+// NewHistogramData returns a new instance of HistogramData with properly initialized fields.
+func NewHistogramData(bounds []float64) *HistogramData {
+	return &HistogramData{
+		Bounds:         bounds,
+		CountPerBucket: make([]int64, len(bounds)+1),
+		Max:            0,
+		Min:            math.MaxInt64,
+	}
+}
+
+func (histogram *HistogramData) Copy() *HistogramData {
+	if histogram == nil {
+		return nil
+	}
+	return &HistogramData{
+		Bounds:         append([]float64{}, histogram.Bounds...),
+		CountPerBucket: append([]int64{}, histogram.CountPerBucket...),
+		Count:          histogram.Count,
+		Min:            histogram.Min,
+		Max:            histogram.Max,
+		Sum:            histogram.Sum,
+	}
+}
+
+// Update changes the Min and Max fields if value is less than or greater than the current values.
+func (histogram *HistogramData) Update(value int64) {
+	if histogram == nil {
+		return
+	}
+	if value > histogram.Max {
+		histogram.Max = value
+	}
+	if value < histogram.Min {
+		histogram.Min = value
+	}
+
+	histogram.Sum += value
+	histogram.Count++
+
+	for index := 0; index <= len(histogram.Bounds); index++ {
+		// Allocate value in the last buckets if we reached the end of the Bounds array.
+		if index == len(histogram.Bounds) {
+			histogram.CountPerBucket[index]++
+			break
+		}
+
+		if value < int64(histogram.Bounds[index]) {
+			histogram.CountPerBucket[index]++
+			break
+		}
+	}
+}
+
+// Mean returns the mean value for the histogram.
+func (histogram *HistogramData) Mean() float64 {
+	if histogram.Count == 0 {
+		return 0
+	}
+	return float64(histogram.Sum) / float64(histogram.Count)
+}
+
+// String converts the histogram data into human-readable string.
+func (histogram *HistogramData) String() string {
+	if histogram == nil {
+		return ""
+	}
+	var b strings.Builder
+
+	b.WriteString("\n -- Histogram: \n")
+	b.WriteString(fmt.Sprintf("Min value: %d \n", histogram.Min))
+	b.WriteString(fmt.Sprintf("Max value: %d \n", histogram.Max))
+	b.WriteString(fmt.Sprintf("Mean: %.2f \n", histogram.Mean()))
+	b.WriteString(fmt.Sprintf("Count: %d \n", histogram.Count))
+
+	numBounds := len(histogram.Bounds)
+	for index, count := range histogram.CountPerBucket {
+		if count == 0 {
+			continue
+		}
+
+		// The last bucket represents the bucket that contains the range from
+		// the last bound up to infinity so it's processed differently than the
+		// other buckets.
+		if index == len(histogram.CountPerBucket)-1 {
+			lowerBound := uint64(histogram.Bounds[numBounds-1])
+			page := float64(count*100) / float64(histogram.Count)
+			b.WriteString(fmt.Sprintf("[%s, %s) %d %.2f%% \n",
+				humanize.IBytes(lowerBound), "infinity", count, page))
+			continue
+		}
+
+		upperBound := uint64(histogram.Bounds[index])
+		lowerBound := uint64(0)
+		if index > 0 {
+			lowerBound = uint64(histogram.Bounds[index-1])
+		}
+
+		page := float64(count*100) / float64(histogram.Count)
+		b.WriteString(fmt.Sprintf("[%s, %s) %d %.2f%% \n",
+			humanize.IBytes(lowerBound), humanize.IBytes(upperBound), count, page))
+	}
+	b.WriteString(" --\n")
+	return b.String()
+}