fix nits ✨

op-node/p2p/band_scorer_test.go

@@ -9,19 +9,71 @@ import (
 // TestBandScorer_ParseDefault tests the [BandScorer.Parse] function
 // on the default band scores cli flag value.
 func TestBandScorer_ParseDefault(t *testing.T) {
-	defaultScoringBands := "-40:graylist;-20:restricted;0:nopx;20:friend;"
+	// Create a new band scorer.
+	bandScorer := NewBandScorer()
+	require.NoError(t, bandScorer.Parse("-40:graylist;-20:restricted;0:nopx;20:friend;"))
 
+	// Validate the [BandScorer] internals.
+	require.ElementsMatch(t, bandScorer.bands, []scorePair{
+		{band: "graylist", threshold: -40},
+		{band: "restricted", threshold: -20},
+		{band: "nopx", threshold: 0},
+		{band: "friend", threshold: 20},
+	})
+}
+
+// TestBandScorer_BucketCorrectly tests the [BandScorer.Bucket] function
+// on a variety of scores.
+func TestBandScorer_BucketCorrectly(t *testing.T) {
 	// Create a new band scorer.
 	bandScorer := NewBandScorer()
-	require.NoError(t, bandScorer.Parse(defaultScoringBands))
+	require.NoError(t, bandScorer.Parse("-40:graylist;-20:restricted;0:nopx;20:friend;"))
+
+	// Let's validate that the [BandScorer] sorts the bands correctly.
+	require.Equal(t, bandScorer.bands, []scorePair{
+		{band: "graylist", threshold: -40},
+		{band: "restricted", threshold: -20},
+		{band: "nopx", threshold: 0},
+		{band: "friend", threshold: 20},
+	})
+
+	// Validate the [BandScorer] internals.
+	require.Equal(t, bandScorer.Bucket(-100), "graylist")
+	require.Equal(t, bandScorer.Bucket(-40), "graylist")
+	require.Equal(t, bandScorer.Bucket(-39), "restricted")
+	require.Equal(t, bandScorer.Bucket(-20), "restricted")
+	require.Equal(t, bandScorer.Bucket(-19), "nopx")
+	require.Equal(t, bandScorer.Bucket(0), "nopx")
+	require.Equal(t, bandScorer.Bucket(1), "friend")
+	require.Equal(t, bandScorer.Bucket(20), "friend")
+	require.Equal(t, bandScorer.Bucket(21), "friend")
+}
+
+// TestBandScorer_BucketInverted tests the [BandScorer.Bucket] function
+// on a variety of scores, in descending order.
+func TestBandScorer_BucketInverted(t *testing.T) {
+	// Create a new band scorer.
+	bandScorer := NewBandScorer()
+	require.NoError(t, bandScorer.Parse("20:friend;0:nopx;-20:restricted;-40:graylist;"))
+
+	// Let's validate that the [BandScorer] sorts the bands correctly.
+	require.Equal(t, bandScorer.bands, []scorePair{
+		{band: "graylist", threshold: -40},
+		{band: "restricted", threshold: -20},
+		{band: "nopx", threshold: 0},
+		{band: "friend", threshold: 20},
+	})
 
 	// Validate the [BandScorer] internals.
-	require.Len(t, bandScorer.(*bandScoreThresholds).bands, 4)
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["graylist"], float64(-40))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["restricted"], float64(-20))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["nopx"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["friend"], float64(20))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).lowestBand, "graylist")
+	require.Equal(t, bandScorer.Bucket(-100), "graylist")
+	require.Equal(t, bandScorer.Bucket(-40), "graylist")
+	require.Equal(t, bandScorer.Bucket(-39), "restricted")
+	require.Equal(t, bandScorer.Bucket(-20), "restricted")
+	require.Equal(t, bandScorer.Bucket(-19), "nopx")
+	require.Equal(t, bandScorer.Bucket(0), "nopx")
+	require.Equal(t, bandScorer.Bucket(1), "friend")
+	require.Equal(t, bandScorer.Bucket(20), "friend")
+	require.Equal(t, bandScorer.Bucket(21), "friend")
 }
 
 // TestBandScorer_ParseEmpty tests the [BandScorer.Parse] function
@@ -32,12 +84,7 @@ func TestBandScorer_ParseEmpty(t *testing.T) {
 	require.NoError(t, bandScorer.Parse(""))
 
 	// Validate the [BandScorer] internals.
-	require.Len(t, bandScorer.(*bandScoreThresholds).bands, 0)
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["graylist"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["restricted"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["nopx"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["friend"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).lowestBand, "")
+	require.Len(t, bandScorer.bands, 0)
 }
 
 // TestBandScorer_ParseWhitespace tests the [BandScorer.Parse] function
@@ -48,10 +95,5 @@ func TestBandScorer_ParseWhitespace(t *testing.T) {
 	require.NoError(t, bandScorer.Parse("  ;  ;  ;  "))
 
 	// Validate the [BandScorer] internals.
-	require.Len(t, bandScorer.(*bandScoreThresholds).bands, 0)
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["graylist"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["restricted"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["nopx"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).bands["friend"], float64(0))
-	require.Equal(t, bandScorer.(*bandScoreThresholds).lowestBand, "")
+	require.Len(t, bandScorer.bands, 0)
 }

op-node/p2p/peer_scorer.go

@@ -2,6 +2,7 @@ package p2p
 
 import (
 	"fmt"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -18,11 +19,15 @@ type scorer struct {
 	bandScoreThresholds BandScorer
 }
 
-// bandScoreThresholds holds the thresholds for classifying peers
+type scorePair struct {
+	band      string
+	threshold float64
+}
+
+// BandScoreThresholds holds the thresholds for classifying peers
 // into different score bands.
-type bandScoreThresholds struct {
-	bands      map[string]float64
-	lowestBand string
+type BandScoreThresholds struct {
+	bands []scorePair
 }
 
 // BandScorer is an interface for placing peer scores
@@ -40,21 +45,20 @@ type BandScorer interface {
 }
 
 // NewBandScorer constructs a new [BandScorer] instance.
-func NewBandScorer() BandScorer {
-	return &bandScoreThresholds{
-		bands: make(map[string]float64),
+func NewBandScorer() *BandScoreThresholds {
+	return &BandScoreThresholds{
+		bands: make([]scorePair, 0),
 	}
 }
 
 // Reset wipes the internal state of the [BandScorer].
-func (s *bandScoreThresholds) Reset() {
-	s.bands = make(map[string]float64)
+func (s *BandScoreThresholds) Reset() {
+	s.bands = s.bands[:0]
 }
 
 // Parse creates a [BandScorer] from a given string.
-func (s *bandScoreThresholds) Parse(str string) error {
-	var lowestThreshold float64
-	for i, band := range strings.Split(str, ";") {
+func (s *BandScoreThresholds) Parse(str string) error {
+	for _, band := range strings.Split(str, ";") {
 		// Skip empty band strings.
 		band := strings.TrimSpace(band)
 		if band == "" {
@@ -68,25 +72,33 @@ func (s *bandScoreThresholds) Parse(str string) error {
 		if err != nil {
 			return err
 		}
-		s.bands[split[1]] = threshold
-		if threshold < lowestThreshold || i == 0 {
-			s.lowestBand = split[1]
-			lowestThreshold = threshold
-		}
+		s.bands = append(s.bands, scorePair{
+			band:      split[1],
+			threshold: threshold,
+		})
 	}
+
+	// Order the bands by threshold in ascending order.
+	sort.Slice(s.bands, func(i, j int) bool {
+		return s.bands[i].threshold < s.bands[j].threshold
+	})
+
 	return nil
 }
 
 // Bucket returns the appropriate band for a given score.
-func (s *bandScoreThresholds) Bucket(score float64) string {
-	for band, threshold := range s.bands {
-		if score >= threshold {
-			return band
+func (s *BandScoreThresholds) Bucket(score float64) string {
+	for _, pair := range s.bands {
+		if score <= pair.threshold {
+			return pair.band
+		}
 	}
+	// If there is no band threshold higher than the score,
+	// the peer must be placed in the highest bucket.
+	if len(s.bands) > 0 {
+		return s.bands[len(s.bands)-1].band
 	}
-	// If there is no band threshold lower than the score,
-	// the peer must be placed in the lowest bucket.
-	return s.lowestBand
+	return ""
 }
 
 // Peerstore is a subset of the libp2p peerstore.Peerstore interface.