Remove max sample value

genesis/beacons.go

@@ -139,7 +139,7 @@ func SampleBeacons(networkID uint32, count int) ([]string, []string) {
 	sampledIDs := make([]string, 0, count)
 
 	s := sampler.NewUniform()
-	_ = s.Initialize(uint64(len(ips)))
+	s.Initialize(uint64(len(ips)))
 	indices, _ := s.Sample(count)
 	for _, index := range indices {
 		sampledIPs = append(sampledIPs, ips[int(index)])

go.mod

@@ -43,6 +43,7 @@ require (
 	github.com/stretchr/testify v1.8.1
 	github.com/supranational/blst v0.3.11-0.20220920110316-f72618070295
 	github.com/syndtr/goleveldb v1.0.1-0.20220614013038-64ee5596c38a
+	github.com/thepudds/fzgen v0.4.2
 	go.opentelemetry.io/otel v1.11.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.11.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.11.0
@@ -107,6 +108,7 @@ require (
 	github.com/prometheus/common v0.37.0 // indirect
 	github.com/prometheus/procfs v0.8.0 // indirect
 	github.com/rjeczalik/notify v0.9.3 // indirect
+	github.com/sanity-io/litter v1.5.1 // indirect
 	github.com/spf13/afero v1.8.2 // indirect
 	github.com/spf13/cast v1.5.0 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect

go.sum

@@ -114,6 +114,7 @@ github.com/cncf/xds/go v0.0.0-20210805033703-aa0b78936158/go.mod h1:eXthEFrGJvWH
 github.com/cncf/xds/go v0.0.0-20210922020428-25de7278fc84/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v0.0.0-20161028175848-04cdfd42973b/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -373,6 +374,7 @@ github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/sftp v1.13.1/go.mod h1:3HaPG6Dq1ILlpPZRO0HVMrsydcdLt6HRDccSgb87qRg=
+github.com/pmezard/go-difflib v0.0.0-20151028094244-d8ed2627bdf0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
@@ -404,9 +406,11 @@ github.com/rjeczalik/notify v0.9.3 h1:6rJAzHTGKXGj76sbRgDiDcYj/HniypXmSJo1SWakZe
 github.com/rjeczalik/notify v0.9.3/go.mod h1:gF3zSOrafR9DQEWSE8TjfI9NkooDxbyT4UgRGKZA0lc=
 github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
-github.com/rogpeppe/go-internal v1.6.1 h1:/FiVV8dS/e+YqF2JvO3yXRFbBLTIuSDkuC7aBOAvL+k=
+github.com/rogpeppe/go-internal v1.8.1 h1:geMPLpDpQOgVyCg5z5GoRwLHepNdb71NXb67XFkP+Eg=
 github.com/rs/cors v1.7.0 h1:+88SsELBHx5r+hZ8TCkggzSstaWNbDvThkVK8H6f9ik=
 github.com/rs/cors v1.7.0/go.mod h1:gFx+x8UowdsKA9AchylcLynDq+nNFfI8FkUZdN/jGCU=
+github.com/sanity-io/litter v1.5.1 h1:dwnrSypP6q56o3lFxTU+t2fwQ9A+U5qrXVO4Qg9KwVU=
+github.com/sanity-io/litter v1.5.1/go.mod h1:5Z71SvaYy5kcGtyglXOC9rrUi3c1E8CamFWjQsazTh0=
 github.com/shirou/gopsutil v3.21.11+incompatible h1:+1+c1VGhc88SSonWP6foOcLhvnKlUeu/erjjvaPEYiI=
 github.com/shirou/gopsutil v3.21.11+incompatible/go.mod h1:5b4v6he4MtMOwMlS0TUMTu2PcXUg8+E1lC7eC3UO/RA=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
@@ -432,6 +436,7 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v0.0.0-20161117074351-18a02ba4a312/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
@@ -449,6 +454,8 @@ github.com/supranational/blst v0.3.11-0.20220920110316-f72618070295/go.mod h1:jZ
 github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7/go.mod h1:q4W45IWZaF22tdD+VEXcAWRA037jwmWEB5VWYORlTpc=
 github.com/syndtr/goleveldb v1.0.1-0.20220614013038-64ee5596c38a h1:1ur3QoCqvE5fl+nylMaIr9PVV1w343YRDtsy+Rwu7XI=
 github.com/syndtr/goleveldb v1.0.1-0.20220614013038-64ee5596c38a/go.mod h1:RRCYJbIwD5jmqPI9XoAFR0OcDxqUctll6zUj/+B4S48=
+github.com/thepudds/fzgen v0.4.2 h1:HlEHl5hk2/cqEomf2uK5SA/FeJc12s/vIHmOG+FbACw=
+github.com/thepudds/fzgen v0.4.2/go.mod h1:kHCWdsv5tdnt32NIHYDdgq083m6bMtaY0M+ipiO9xWE=
 github.com/tklauser/go-sysconf v0.3.5 h1:uu3Xl4nkLzQfXNsWn15rPc/HQCJKObbt1dKJeWp3vU4=
 github.com/tklauser/go-sysconf v0.3.5/go.mod h1:MkWzOF4RMCshBAMXuhXJs64Rte09mITnppBXY/rYEFI=
 github.com/tklauser/numcpus v0.2.2 h1:oyhllyrScuYI6g+h/zUvNXNp1wy7x8qQy3t/piefldA=

network/network.go

@@ -683,9 +683,7 @@ func (n *network) Peers(peerID ids.NodeID) ([]ips.ClaimedIPPort, error) {
 	// We select a random sample of validators to gossip to avoid starving out a
 	// validator from being gossiped for an extended period of time.
 	s := sampler.NewUniform()
-	if err := s.Initialize(uint64(len(unknownValidators))); err != nil {
-		return nil, err
-	}
+	s.Initialize(uint64(len(unknownValidators)))
 
 	// Calculate the unknown information we need to send to this peer.
 	validatorIPs := make([]ips.ClaimedIPPort, 0, int(n.config.PeerListNumValidatorIPs))

network/peer/set.go

@@ -120,9 +120,7 @@ func (s *peerSet) Sample(n int, precondition func(Peer) bool) []Peer {
 	}
 
 	sampler := sampler.NewUniform()
-	// It is impossible for the sampler to report an error here. Since
-	// [len(s.peersSlice)] <= MaxInt64.
-	_ = sampler.Initialize(uint64(len(s.peersSlice)))
+	sampler.Initialize(uint64(len(s.peersSlice)))
 
 	peers := make([]Peer, 0, n)
 	for len(peers) < n {

snow/consensus/snowball/network_test.go

@@ -28,7 +28,7 @@ func (n *Network) Initialize(params Parameters, numColors int) {
 
 func (n *Network) AddNode(sb Consensus) {
 	s := sampler.NewUniform()
-	_ = s.Initialize(uint64(len(n.colors)))
+	s.Initialize(uint64(len(n.colors)))
 	indices, _ := s.Sample(len(n.colors))
 	sb.Initialize(n.params, n.colors[int(indices[0])])
 	for _, index := range indices[1:] {
@@ -70,7 +70,7 @@ func (n *Network) Round() {
 		running := n.running[runningInd]
 
 		s := sampler.NewUniform()
-		_ = s.Initialize(uint64(len(n.nodes)))
+		s.Initialize(uint64(len(n.nodes)))
 		count := len(n.nodes)
 		if count > n.params.K {
 			count = n.params.K

snow/consensus/snowman/network_test.go

@@ -24,7 +24,7 @@ type Network struct {
 
 func (n *Network) shuffleColors() {
 	s := sampler.NewUniform()
-	_ = s.Initialize(uint64(len(n.colors)))
+	s.Initialize(uint64(len(n.colors)))
 	indices, _ := s.Sample(len(n.colors))
 	colors := []*TestBlock(nil)
 	for _, index := range indices {
@@ -105,7 +105,7 @@ func (n *Network) Round() error {
 	running := n.running[runningInd]
 
 	s := sampler.NewUniform()
-	_ = s.Initialize(uint64(len(n.nodes)))
+	s.Initialize(uint64(len(n.nodes)))
 	indices, _ := s.Sample(n.params.K)
 	sampledColors := bag.Bag[ids.ID]{}
 	for _, index := range indices {

snow/consensus/snowstorm/network_test.go

@@ -24,7 +24,7 @@ type Network struct {
 
 func (n *Network) shuffleConsumers() {
 	s := sampler.NewUniform()
-	_ = s.Initialize(uint64(len(n.consumers)))
+	s.Initialize(uint64(len(n.consumers)))
 	indices, _ := s.Sample(len(n.consumers))
 	consumers := []*TestTx(nil)
 	for _, index := range indices {
@@ -56,7 +56,7 @@ func (n *Network) Initialize(
 	for len(colors) > 0 {
 		selected := []ids.ID{}
 		s := sampler.NewUniform()
-		_ = s.Initialize(uint64(len(colors)))
+		s.Initialize(uint64(len(colors)))
 		size := len(colors)
 		if size > colorsPerConsumer {
 			size = colorsPerConsumer
@@ -134,12 +134,12 @@ func (n *Network) Round() error {
 	}
 
 	s := sampler.NewUniform()
-	_ = s.Initialize(uint64(len(n.running)))
+	s.Initialize(uint64(len(n.running)))
 	runningInd, _ := s.Next()
 
 	running := n.running[runningInd]
 
-	_ = s.Initialize(uint64(len(n.nodes)))
+	s.Initialize(uint64(len(n.nodes)))
 	indices, _ := s.Sample(n.params.K)
 	sampledColors := bag.Bag[ids.ID]{}
 	sampledColors.SetThreshold(n.params.Alpha)

snow/engine/avalanche/transitive.go

@@ -345,9 +345,7 @@ func (t *Transitive) Gossip(ctx context.Context) error {
 		return nil
 	}
 
-	if err := t.uniformSampler.Initialize(uint64(len(edge))); err != nil {
-		return err // Should never happen
-	}
+	t.uniformSampler.Initialize(uint64(len(edge)))
 	indices, err := t.uniformSampler.Sample(1)
 	if err != nil {
 		return err // Also should never really happen because the edge has positive length
@@ -734,9 +732,7 @@ func (t *Transitive) issueBatch(ctx context.Context, txs []snowstorm.Tx) error {
 	// Randomly select parents of this vertex from among the virtuous set
 	virtuousIDs := t.Consensus.Virtuous().CappedList(t.Params.Parents)
 	numVirtuousIDs := len(virtuousIDs)
-	if err := t.uniformSampler.Initialize(uint64(numVirtuousIDs)); err != nil {
-		return err
-	}
+	t.uniformSampler.Initialize(uint64(numVirtuousIDs))
 
 	indices, err := t.uniformSampler.Sample(numVirtuousIDs)
 	if err != nil {

utils/sampler/rand.go

@@ -4,58 +4,94 @@
 package sampler
 
 import (
-	"math/rand"
+	"math"
 	"sync"
 	"time"
 
 	"gonum.org/v1/gonum/mathext/prng"
 )
 
-var (
-	int63Mask uint64 = 1<<63 - 1
-	globalRNG        = newRNG()
-)
+var globalRNG = newRNG()
 
-func newRNG() rng {
-	source := prng.NewMT19937()
-	source.Seed(uint64(time.Now().UnixNano()))
+func newRNG() *rng {
 	// We don't use a cryptographically secure source of randomness here, as
 	// there's no need to ensure a truly random sampling.
-	return rand.New(&syncSource{rng: source}) // #nosec G404
+	source := prng.NewMT19937()
+	source.Seed(uint64(time.Now().UnixNano()))
+	return &rng{rng: source}
 }
 
 func Seed(seed int64) {
 	globalRNG.Seed(seed)
 }
 
-type rng interface {
-	// Seed uses the provided seed value to initialize the generator to a
-	// deterministic state.
-	Seed(seed int64)
-
-	// Int63n returns, as an int64, a non-negative pseudo-random number in
-	// [0,n). It panics if n <= 0.
-	Int63n(n int64) int64
+type source interface {
+	Seed(uint64)
+	Uint64() uint64
 }
 
-type syncSource struct {
+type rng struct {
 	lock sync.Mutex
-	rng  *prng.MT19937
+	rng  source
+}
+
+// Seed uses the provided seed value to initialize the generator to a
+// deterministic state.
+func (r *rng) Seed(seed int64) {
+	r.lock.Lock()
+	r.rng.Seed(uint64(seed))
+	r.lock.Unlock()
 }
 
-func (s *syncSource) Seed(seed int64) {
-	s.lock.Lock()
-	s.rng.Seed(uint64(seed))
-	s.lock.Unlock()
+// Uint64Inclusive returns a pseudo-random number in [0,n].
+//
+// Invariant: The result of this function is stored in chain state, so any
+// modifications are considered breaking.
+func (r *rng) Uint64Inclusive(n uint64) uint64 {
+	switch {
+	// n+1 is power of two, so we can just mask
+	//
+	// Note: This does work for MaxUint64 as overflow is explicitly part of the
+	// compiler specification: https://go.dev/ref/spec#Integer_overflow
+	case n&(n+1) == 0:
+		return r.uint64() & n
+
+	// n is greater than MaxUint64/2 so we need to just iterate until we get a
+	// number in the requested range.
+	case n > math.MaxInt64:
+		v := r.uint64()
+		for v > n {
+			v = r.uint64()
+		}
+		return v
+
+	// n is less than MaxUint64/2 so we generate a number in the range
+	// [0, k*(n+1)) where k is the largest integer such that k*(n+1) is less
+	// than or equal to MaxUint64/2. We can't easily find k such that k*(n+1) is
+	// less than or equal to MaxUint64 because the calculation would overflow.
+	//
+	// ref: https://github.com/golang/go/blob/ce10e9d84574112b224eae88dc4e0f43710808de/src/math/rand/rand.go#L127-L132
+	default:
+		max := (1 << 63) - 1 - (1<<63)%(n+1)
+		v := r.uint63()
+		for v > max {
+			v = r.uint63()
+		}
+		return v % (n + 1)
+	}
 }
 
-func (s *syncSource) Int63() int64 {
-	return int64(s.Uint64() & int63Mask)
+// uint63 returns a random number in [0, MaxInt64]
+func (r *rng) uint63() uint64 {
+	return r.uint64() & math.MaxInt64
 }
 
-func (s *syncSource) Uint64() uint64 {
-	s.lock.Lock()
-	n := s.rng.Uint64()
-	s.lock.Unlock()
+// uint64 returns a random number in [0, MaxUint64]
+func (r *rng) uint64() uint64 {
+	// Note: We must grab a write lock here because rng.Uint64 internally
+	// modifies state.
+	r.lock.Lock()
+	n := r.rng.Uint64()
+	r.lock.Unlock()
 	return n
 }