internal: remove fastrand

This package is no longer necessary, as in `math/rand/v2` the
`rand.Uint32` function is equivalent.

internal/arenaskl/skl.go

@@ -45,13 +45,13 @@ package arenaskl // import "github.com/cockroachdb/pebble/internal/arenaskl"
 
 import (
 	"math"
+	"math/rand/v2"
 	"runtime"
 	"sync/atomic"
 	"unsafe"
 
 	"github.com/cockroachdb/errors"
 	"github.com/cockroachdb/pebble/internal/base"
-	"github.com/cockroachdb/pebble/internal/fastrand"
 )
 
 const (
@@ -337,7 +337,7 @@ func (s *Skiplist) newNode(
 }
 
 func (s *Skiplist) randomHeight() uint32 {
-	rnd := fastrand.Uint32()
+	rnd := rand.Uint32()
 
 	h := uint32(1)
 	for h < maxHeight && rnd <= probabilities[h] {

internal/invariants/utils.go

@@ -4,10 +4,10 @@
 
 package invariants
 
-import "github.com/cockroachdb/pebble/internal/fastrand"
+import "math/rand/v2"
 
 // Sometimes returns true percent% of the time if we were built with the
 // "invariants" of "race" build tags
 func Sometimes(percent int) bool {
-	return Enabled && fastrand.Uint32()%100 < uint32(percent)
+	return Enabled && rand.Uint32N(100) < uint32(percent)
 }

iterator.go

@@ -8,13 +8,13 @@ import (
 	"bytes"
 	"context"
 	"io"
+	"math/rand/v2"
 	"sync"
 	"unsafe"
 
 	"github.com/cockroachdb/errors"
 	"github.com/cockroachdb/pebble/internal/base"
 	"github.com/cockroachdb/pebble/internal/bytealloc"
-	"github.com/cockroachdb/pebble/internal/fastrand"
 	"github.com/cockroachdb/pebble/internal/humanize"
 	"github.com/cockroachdb/pebble/internal/invariants"
 	"github.com/cockroachdb/pebble/internal/keyspan"
@@ -810,14 +810,14 @@ func (i *Iterator) maybeSampleRead() {
 	}
 	bytesRead := uint64(len(i.key) + i.value.Len())
 	for i.readSampling.bytesUntilReadSampling < bytesRead {
-		i.readSampling.bytesUntilReadSampling += uint64(fastrand.Uint32n(2 * uint32(samplingPeriod)))
+		i.readSampling.bytesUntilReadSampling += uint64(rand.Uint32N(2 * uint32(samplingPeriod)))
 		// The block below tries to adjust for the case where this is the
 		// first read in a newly-opened iterator. As bytesUntilReadSampling
 		// starts off at zero, we don't want to sample the first read of
 		// every newly-opened iterator, but we do want to sample some of them.
 		if !i.readSampling.initialSamplePassed {
 			i.readSampling.initialSamplePassed = true
-			if fastrand.Uint32n(uint32(i.readSampling.bytesUntilReadSampling)) > uint32(bytesRead) {
+			if rand.Uint32N(uint32(i.readSampling.bytesUntilReadSampling)) > uint32(bytesRead) {
 				continue
 			}
 		}