snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

benchmark/stats/curve.go

@@ -0,0 +1,179 @@
+/*
+ *
+ * Copyright 2019 gRPC authors.
+ *
+ * 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 stats
+
+import (
+	"crypto/sha256"
+	"encoding/csv"
+	"encoding/hex"
+	"fmt"
+	"math"
+	rand "math/rand/v2"
+	"os"
+	"sort"
+	"strconv"
+)
+
+// payloadCurveRange represents a line within a payload curve CSV file.
+type payloadCurveRange struct {
+	from, to int32
+	weight   float64
+}
+
+// newPayloadCurveRange receives a line from a payload curve CSV file and
+// returns a *payloadCurveRange if the values are acceptable.
+func newPayloadCurveRange(line []string) (*payloadCurveRange, error) {
+	if len(line) != 3 {
+		return nil, fmt.Errorf("invalid number of entries in line %v (expected 3)", line)
+	}
+
+	var from, to int64
+	var weight float64
+	var err error
+	if from, err = strconv.ParseInt(line[0], 10, 32); err != nil {
+		return nil, err
+	}
+	if from <= 0 {
+		return nil, fmt.Errorf("line %v: field (%d) must be in (0, %d]", line, from, math.MaxInt32)
+	}
+	if to, err = strconv.ParseInt(line[1], 10, 32); err != nil {
+		return nil, err
+	}
+	if to <= 0 {
+		return nil, fmt.Errorf("line %v: field %d must be in (0, %d]", line, to, math.MaxInt32)
+	}
+	if from > to {
+		return nil, fmt.Errorf("line %v: from (%d) > to (%d)", line, from, to)
+	}
+	if weight, err = strconv.ParseFloat(line[2], 64); err != nil {
+		return nil, err
+	}
+	return &payloadCurveRange{from: int32(from), to: int32(to), weight: weight}, nil
+}
+
+// chooseRandom picks a payload size (in bytes) for a particular range. This is
+// done with a uniform distribution.
+func (pcr *payloadCurveRange) chooseRandom() int {
+	if pcr.from == pcr.to { // fast path
+		return int(pcr.from)
+	}
+
+	return int(rand.Int32N(pcr.to-pcr.from+1) + pcr.from)
+}
+
+// sha256file is a helper function that returns a hex string matching the
+// SHA-256 sum of the input file.
+func sha256file(file string) (string, error) {
+	data, err := os.ReadFile(file)
+	if err != nil {
+		return "", err
+	}
+	sum := sha256.Sum256(data)
+	return hex.EncodeToString(sum[:]), nil
+}
+
+// PayloadCurve is an internal representation of a weighted random distribution
+// CSV file. Once a *PayloadCurve is created with NewPayloadCurve, the
+// ChooseRandom function should be called to generate random payload sizes.
+type PayloadCurve struct {
+	pcrs []*payloadCurveRange
+	// Sha256 must be a public field so that the gob encoder can write it to
+	// disk. This will be needed at decode-time by the Hash function.
+	Sha256 string
+}
+
+// NewPayloadCurve parses a .csv file and returns a *PayloadCurve if no errors
+// were encountered in parsing and initialization.
+func NewPayloadCurve(file string) (*PayloadCurve, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	r := csv.NewReader(f)
+	lines, err := r.ReadAll()
+	if err != nil {
+		return nil, err
+	}
+
+	ret := &PayloadCurve{}
+	var total float64
+	for _, line := range lines {
+		pcr, err := newPayloadCurveRange(line)
+		if err != nil {
+			return nil, err
+		}
+
+		ret.pcrs = append(ret.pcrs, pcr)
+		total += pcr.weight
+	}
+
+	ret.Sha256, err = sha256file(file)
+	if err != nil {
+		return nil, err
+	}
+	for _, pcr := range ret.pcrs {
+		pcr.weight /= total
+	}
+
+	sort.Slice(ret.pcrs, func(i, j int) bool {
+		if ret.pcrs[i].from == ret.pcrs[j].from {
+			return ret.pcrs[i].to < ret.pcrs[j].to
+		}
+		return ret.pcrs[i].from < ret.pcrs[j].from
+	})
+
+	var lastTo int32
+	for _, pcr := range ret.pcrs {
+		if lastTo >= pcr.from {
+			return nil, fmt.Errorf("[%d, %d] overlaps with a different line", pcr.from, pcr.to)
+		}
+		lastTo = pcr.to
+	}
+
+	return ret, nil
+}
+
+// ChooseRandom picks a random payload size (in bytes) that follows the
+// underlying weighted random distribution.
+func (pc *PayloadCurve) ChooseRandom() int {
+	target := rand.Float64()
+	var seen float64
+	for _, pcr := range pc.pcrs {
+		seen += pcr.weight
+		if seen >= target {
+			return pcr.chooseRandom()
+		}
+	}
+
+	// This should never happen, but if it does, return a sane default.
+	return 1
+}
+
+// Hash returns a string uniquely identifying a payload curve file for feature
+// matching purposes.
+func (pc *PayloadCurve) Hash() string {
+	return pc.Sha256
+}
+
+// ShortHash returns a shortened version of Hash for display purposes.
+func (pc *PayloadCurve) ShortHash() string {
+	return pc.Sha256[:8]
+}