From fa5020a1eab7497303b742dca03080476973cc95 Mon Sep 17 00:00:00 2001
From: Todd Neal <tnealt@amazon.com>
Date: Wed, 19 Feb 2025 15:24:26 -0600
Subject: [PATCH] perf: remove the edit distance helper for identifying typos
 (#2008)

---
 pkg/scheduling/requirements.go      | 43 ++---------------------------
 pkg/scheduling/requirements_test.go | 13 ---------
 2 files changed, 2 insertions(+), 54 deletions(-)

diff --git a/pkg/scheduling/requirements.go b/pkg/scheduling/requirements.go
index 949f4edccb..a082f693a1 100644
--- a/pkg/scheduling/requirements.go
+++ b/pkg/scheduling/requirements.go
@@ -189,45 +189,6 @@ func (r Requirements) Compatible(requirements Requirements, options ...option.Fu
 	return multierr.Append(errs, r.Intersects(requirements))
 }
 
-// editDistance is an implementation of edit distance from Algorithms/DPV
-func editDistance(s, t string) int {
-	min := func(a, b, c int) int {
-		m := a
-		if b < m {
-			m = b
-		}
-		if c < m {
-			m = c
-		}
-		return m
-	}
-
-	m := len(s)
-	n := len(t)
-	if m == 0 {
-		return n
-	}
-	if n == 0 {
-		return m
-	}
-	prevRow := make([]int, n)
-	curRow := make([]int, n)
-	for j := 1; j < n; j++ {
-		prevRow[j] = j
-	}
-	for i := 1; i < m; i++ {
-		for j := 1; j < n; j++ {
-			diff := 0
-			if s[i] != t[j] {
-				diff = 1
-			}
-			curRow[j] = min(prevRow[j]+1, curRow[j-1]+1, prevRow[j-1]+diff)
-		}
-		prevRow, curRow = curRow, prevRow
-	}
-	return prevRow[n-1]
-}
-
 func getSuffix(key string) string {
 	before, after, found := strings.Cut(key, "/")
 	return lo.Ternary(found, after, before)
@@ -235,7 +196,7 @@ func getSuffix(key string) string {
 
 func labelHint(r Requirements, key string, allowedUndefined sets.Set[string]) string {
 	for wellKnown := range allowedUndefined {
-		if strings.Contains(wellKnown, key) || editDistance(key, wellKnown) < len(wellKnown)/5 {
+		if strings.Contains(wellKnown, key) {
 			return fmt.Sprintf(" (typo of %q?)", wellKnown)
 		}
 		if strings.HasSuffix(wellKnown, getSuffix(key)) {
@@ -243,7 +204,7 @@ func labelHint(r Requirements, key string, allowedUndefined sets.Set[string]) st
 		}
 	}
 	for existing := range r {
-		if strings.Contains(existing, key) || editDistance(key, existing) < len(existing)/5 {
+		if strings.Contains(existing, key) {
 			return fmt.Sprintf(" (typo of %q?)", existing)
 		}
 		if strings.HasSuffix(existing, getSuffix(key)) {
diff --git a/pkg/scheduling/requirements_test.go b/pkg/scheduling/requirements_test.go
index dff6ea3de6..aa6a97ef75 100644
--- a/pkg/scheduling/requirements_test.go
+++ b/pkg/scheduling/requirements_test.go
@@ -561,10 +561,8 @@ var _ = Describe("Requirements", func() {
 		},
 			Entry("Zone Label #1", "topology.kubernetesio/zone", `label "topology.kubernetesio/zone" does not have known values (typo of "topology.kubernetes.io/zone"?)`),
 			Entry("Zone Label #1", "node.io/zone", `label "node.io/zone" does not have known values (typo of "topology.kubernetes.io/zone"?)`),
-			Entry("Zone Label #1", "topology.kubernetesiozone", `label "topology.kubernetesiozone" does not have known values (typo of "topology.kubernetes.io/zone"?)`),
 			Entry("Region Label #1", "topology.kubernetes.io/regio", `label "topology.kubernetes.io/regio" does not have known values (typo of "topology.kubernetes.io/region"?)`),
 			Entry("Region Label #2", "node.kubernetes.io/region", `label "node.kubernetes.io/region" does not have known values (typo of "topology.kubernetes.io/region"?)`),
-			Entry("NodePool Label #1", "karpenter.shnodepool", `label "karpenter.shnodepool" does not have known values (typo of "karpenter.sh/nodepool"?)`),
 			Entry("NodePool Label #2", "karpenter/nodepool", `label "karpenter/nodepool" does not have known values (typo of "karpenter.sh/nodepool"?)`),
 		)
 		It("should display an error message for unknown labels", func() {
@@ -699,17 +697,6 @@ var _ = Describe("Requirements", func() {
 	})
 })
 
-// Keeping this in case we need it, I ran for 1m+ samples and had no issues
-// fuzz: elapsed: 2m27s, execs: 1002748 (6130/sec), new interesting: 30 (total: 33)
-func FuzzEditDistance(f *testing.F) {
-	f.Add("foo", "bar")
-	f.Add("foo", "")
-	f.Add("", "foo")
-	f.Fuzz(func(t *testing.T, lhs, rhs string) {
-		editDistance(lhs, rhs)
-	})
-}
-
 // TestSchedulingProfile is used to gather profiling metrics, benchmarking is primarily done with standard
 // Go benchmark functions
 // go test -tags=test_performance -run=RequirementsProfile