all: replace math/rand with math/rand/v2

Author: seankhliao

baggage/baggage_test.go

@@ -5,7 +5,7 @@ package baggage
 
 import (
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"slices"
 	"strings"
 	"testing"
@@ -17,12 +17,8 @@ import (
 	"go.opentelemetry.io/otel/internal/baggage"
 )
 
-var rng *rand.Rand
-
-func init() {
-	// Seed with a static value to ensure deterministic results.
-	rng = rand.New(rand.NewSource(1))
-}
+// Seed with a static value to ensure deterministic results.
+var rng = rand.New(rand.NewChaCha8([32]byte{}))
 
 func TestValidateKeyChar(t *testing.T) {
 	// ASCII only
@@ -255,7 +251,7 @@ func key(n int) string {
 
 	b := make([]rune, n)
 	for i := range b {
-		b[i] = r[rng.Intn(len(r))]
+		b[i] = r[rng.IntN(len(r))]
 	}
 	return string(b)
 }

bridge/opencensus/internal/ocmetric/metric_test.go

@@ -7,7 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"reflect"
 	"strconv"
 	"testing"
@@ -1189,7 +1189,7 @@ func BenchmarkConvertExemplar(b *testing.B) {
 	for i := range data {
 		a := make(ocmetricdata.Attachments, attchmentsN)
 		for j := 0; j < attchmentsN; j++ {
-			a[strconv.Itoa(j)] = rand.Int63()
+			a[strconv.Itoa(j)] = rand.Int64()
 		}
 		data[i] = &ocmetricdata.Exemplar{
 			Value:       rand.NormFloat64(),

bridge/opentracing/internal/mock.go

@@ -5,7 +5,8 @@ package internal // import "go.opentelemetry.io/otel/bridge/opentracing/internal
 
 import (
 	"context"
-	"math/rand"
+	crand "crypto/rand"
+	"math/rand/v2"
 	"reflect"
 	"sync"
 	"time"
@@ -44,7 +45,7 @@ type MockTracer struct {
 	TraceFlags            trace.TraceFlags
 
 	randLock sync.Mutex
-	rand     *rand.Rand
+	rand     *rand.ChaCha8
 }
 
 var (
@@ -53,13 +54,15 @@ var (
 )
 
 func NewMockTracer() *MockTracer {
+	var seed [32]byte
+	crand.Read(seed[:]) //nolint // crypto/rand never errors
 	return &MockTracer{
 		FinishedSpans:         nil,
 		SpareTraceIDs:         nil,
 		SpareSpanIDs:          nil,
 		SpareContextKeyValues: nil,
 
-		rand: rand.New(rand.NewSource(time.Now().Unix())),
+		rand: rand.NewChaCha8(seed),
 	}
 }
 

metric/example_test.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"net/http"
 	"runtime"
 	"time"
@@ -159,7 +159,7 @@ func ExampleMeter_gauge() {
 	getCPUFanSpeed := func() int64 {
 		// Generates a random fan speed for demonstration purpose.
 		// In real world applications, replace this to get the actual fan speed.
-		return int64(1500 + rand.Intn(1000))
+		return int64(1500 + rand.IntN(1000))
 	}
 
 	fanSpeedSubscription := make(chan int64, 1)
@@ -170,7 +170,7 @@ func ExampleMeter_gauge() {
 			// Synchronous gauges are used when the measurement cycle is
 			// synchronous to an external change.
 			// Simulate that external cycle here.
-			time.Sleep(time.Duration(rand.Intn(3)) * time.Second)
+			time.Sleep(time.Duration(rand.IntN(3)) * time.Second)
 			fanSpeed := getCPUFanSpeed()
 			fanSpeedSubscription <- fanSpeed
 		}

sdk/metric/exemplar/fixed_size_reservoir.go

@@ -5,8 +5,9 @@ package exemplar // import "go.opentelemetry.io/otel/sdk/metric/exemplar"
 
 import (
 	"context"
+	crand "crypto/rand"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"time"
 
 	"go.opentelemetry.io/otel/attribute"
@@ -53,9 +54,11 @@ type FixedSizeReservoir struct {
 }
 
 func newFixedSizeReservoir(s *storage) *FixedSizeReservoir {
+	var seed [32]byte
+	crand.Read(seed[:]) //nolint // crypto/rand never errors
 	r := &FixedSizeReservoir{
 		storage: s,
-		rng:     rand.New(rand.NewSource(time.Now().UnixNano())),
+		rng:     rand.New(rand.NewChaCha8(seed)),
 	}
 	r.reset()
 	return r
@@ -64,26 +67,9 @@ func newFixedSizeReservoir(s *storage) *FixedSizeReservoir {
 // randomFloat64 returns, as a float64, a uniform pseudo-random number in the
 // open interval (0.0,1.0).
 func (r *FixedSizeReservoir) randomFloat64() float64 {
-	// TODO: This does not return a uniform number. rng.Float64 returns a
-	// uniformly random int in [0,2^53) that is divided by 2^53. Meaning it
-	// returns multiples of 2^-53, and not all floating point numbers between 0
-	// and 1 (i.e. for values less than 2^-4 the 4 last bits of the significand
-	// are always going to be 0).
-	//
-	// An alternative algorithm should be considered that will actually return
-	// a uniform number in the interval (0,1). For example, since the default
-	// rand source provides a uniform distribution for Int63, this can be
-	// converted following the prototypical code of Mersenne Twister 64 (Takuji
-	// Nishimura and Makoto Matsumoto:
-	// http://www.math.sci.hiroshima-u.ac.jp/m-mat/MT/VERSIONS/C-LANG/mt19937-64.c)
-	//
-	//   (float64(rng.Int63()>>11) + 0.5) * (1.0 / 4503599627370496.0)
-	//
-	// There are likely many other methods to explore here as well.
-
-	f := r.rng.Float64()
+	f := rand.Float64()
 	for f == 0 {
-		f = r.rng.Float64()
+		f = rand.Float64()
 	}
 	return f
 }
@@ -146,7 +132,7 @@ func (r *FixedSizeReservoir) Offer(ctx context.Context, t time.Time, n Value, a
 	} else {
 		if r.count == r.next {
 			// Overwrite a random existing measurement with the one offered.
-			idx := int(r.rng.Int63n(int64(cap(r.store))))
+			idx := int(rand.Int64N(int64(cap(r.store))))
 			r.store[idx] = newMeasurement(ctx, t, n, a)
 			r.advance()
 		}

sdk/metric/exemplar/fixed_size_reservoir_test.go

@@ -5,11 +5,11 @@ package exemplar
 
 import (
 	"context"
+	crand "crypto/rand"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"slices"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -28,7 +28,9 @@ func TestNewFixedSizeReservoirSamplingCorrectness(t *testing.T) {
 	intensity := 0.1
 	sampleSize := 1000
 
-	rng := rand.New(rand.NewSource(time.Now().UnixNano()))
+	var seed [32]byte
+	crand.Read(seed[:]) //nolint // crypto/rand never errors
+	rng := rand.New(rand.NewChaCha8(seed))
 
 	data := make([]float64, sampleSize*1000)
 	for i := range data {

sdk/resource/benchmark_test.go

@@ -5,7 +5,7 @@ package resource_test
 
 import (
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"testing"
 
 	"go.opentelemetry.io/otel/attribute"
@@ -21,18 +21,18 @@ func makeAttrs(n int) (_, _ *resource.Resource) {
 	for i := 0; i < n; i++ {
 		var k string
 		for {
-			k = fmt.Sprint("k", rand.Intn(1000000000))
+			k = fmt.Sprint("k", rand.IntN(1000000000))
 			if !used[k] {
 				used[k] = true
 				break
 			}
 		}
-		l1[i] = attribute.String(k, fmt.Sprint("v", rand.Intn(1000000000)))
+		l1[i] = attribute.String(k, fmt.Sprint("v", rand.IntN(1000000000)))
 
 		if rand.Float64() < conflict {
 			l2[i] = l1[i]
 		} else {
-			l2[i] = attribute.String(k, fmt.Sprint("v", rand.Intn(1000000000)))
+			l2[i] = attribute.String(k, fmt.Sprint("v", rand.IntN(1000000000)))
 		}
 	}
 	return resource.NewSchemaless(l1...), resource.NewSchemaless(l2...)

sdk/trace/id_generator.go

@@ -6,8 +6,7 @@ package trace // import "go.opentelemetry.io/otel/sdk/trace"
 import (
 	"context"
 	crand "crypto/rand"
-	"encoding/binary"
-	"math/rand"
+	"math/rand/v2"
 	"sync"
 
 	"go.opentelemetry.io/otel/trace"
@@ -31,7 +30,7 @@ type IDGenerator interface {
 
 type randomIDGenerator struct {
 	sync.Mutex
-	randSource *rand.Rand
+	randSource *rand.ChaCha8
 }
 
 var _ IDGenerator = &randomIDGenerator{}
@@ -73,9 +72,9 @@ func (gen *randomIDGenerator) NewIDs(ctx context.Context) (trace.TraceID, trace.
 }
 
 func defaultIDGenerator() IDGenerator {
-	gen := &randomIDGenerator{}
-	var rngSeed int64
-	_ = binary.Read(crand.Reader, binary.LittleEndian, &rngSeed)
-	gen.randSource = rand.New(rand.NewSource(rngSeed))
-	return gen
+	var seed [32]byte
+	crand.Read(seed[:]) //nolint // crypto/rand never errors
+	return &randomIDGenerator{
+		randSource: rand.NewChaCha8(seed),
+	}
 }

sdk/trace/id_generator_test.go

@@ -39,3 +39,15 @@ func TestNewSpanIDWithInvalidTraceID(t *testing.T) {
 	spanID := gen.NewSpanID(context.Background(), trace.TraceID{})
 	assert.Truef(t, spanID.IsValid(), "span id: %s", spanID.String())
 }
+
+var (
+	_traceID trace.TraceID
+	_spanID  trace.SpanID
+)
+
+func BenchmarkIDGenerator(b *testing.B) {
+	var gen IDGenerator = defaultIDGenerator()
+	for range b.N {
+		_traceID, _spanID = gen.NewIDs(context.Background())
+	}
+}

sdk/trace/provider_test.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"math/rand"
+	"math/rand/v2"
 	"testing"
 
 	"github.com/stretchr/testify/assert"