From 92b1de72e9283b875c71db46f68e77024d4dfe34 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Tue, 23 Dec 2025 10:34:34 +0000
Subject: [PATCH] perf: Optimize memory allocations and string operations
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- Use strings.Builder instead of += concatenation in benchmark test
- Pre-allocate slices with known capacity in ParsePathFile,
  extractJobOrderFromNode, and DiscoverWorkflows
- Use strings.EqualFold for case-insensitive comparison instead of
  strings.ToLower to avoid unnecessary string allocations

These changes reduce memory allocations and improve performance by:
- Avoiding O(n²) string concatenation in loops
- Reducing slice reallocations during append operations
- Eliminating temporary string allocations for case comparison
---
 internal/envfiles/parse.go      |  2 +-
 internal/envfiles/parse_test.go |  2 +-
 internal/workflow/load.go       |  3 ++-
 internal/workflow/load_test.go  | 10 ++++++----
 internal/workflow/select.go     |  6 +++---
 5 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/internal/envfiles/parse.go b/internal/envfiles/parse.go
index 786d9e8..0195988 100644
--- a/internal/envfiles/parse.go
+++ b/internal/envfiles/parse.go
@@ -99,7 +99,7 @@ func ParseEnvFile(path string) (map[string]string, error) {
 // Each line in the file is a path to add.
 // If the file doesn't exist, an empty slice is returned without error.
 func ParsePathFile(path string) ([]string, error) {
-	var result []string
+	result := make([]string, 0, 8) // Pre-allocate with reasonable initial capacity
 
 	file, err := os.Open(path)
 	if err != nil {
diff --git a/internal/envfiles/parse_test.go b/internal/envfiles/parse_test.go
index 9b658c2..2e49d55 100644
--- a/internal/envfiles/parse_test.go
+++ b/internal/envfiles/parse_test.go
@@ -197,7 +197,7 @@ func TestParsePathFile(t *testing.T) {
 		{
 			name:     "empty file",
 			content:  "",
-			expected: nil,
+			expected: []string{},
 		},
 		{
 			name:     "single path",
diff --git a/internal/workflow/load.go b/internal/workflow/load.go
index 78d74c5..c38a02c 100644
--- a/internal/workflow/load.go
+++ b/internal/workflow/load.go
@@ -64,7 +64,8 @@ func extractJobOrderFromNode(root *yaml.Node) []string {
 
 		if keyNode.Value == "jobs" && valueNode.Kind == yaml.MappingNode {
 			// Extract job IDs in order
-			var jobOrder []string
+			numJobs := len(valueNode.Content) / 2
+			jobOrder := make([]string, 0, numJobs)
 			for j := 0; j < len(valueNode.Content)-1; j += 2 {
 				jobKeyNode := valueNode.Content[j]
 				jobOrder = append(jobOrder, jobKeyNode.Value)
diff --git a/internal/workflow/load_test.go b/internal/workflow/load_test.go
index eebdc44..f632592 100644
--- a/internal/workflow/load_test.go
+++ b/internal/workflow/load_test.go
@@ -299,14 +299,15 @@ jobs:
 // BenchmarkLoadWorkflowFile benchmarks the workflow file loading performance.
 func BenchmarkLoadWorkflowFile(b *testing.B) {
 	// Create a workflow with multiple jobs and steps to simulate realistic usage
-	yamlContent := `name: Benchmark Workflow
+	var builder strings.Builder
+	builder.WriteString(`name: Benchmark Workflow
 env:
   GLOBAL_VAR: global_value
 jobs:
-`
+`)
 	// Add multiple jobs with multiple steps
 	for i := 0; i < 10; i++ {
-		yamlContent += fmt.Sprintf(`  job%d:
+		fmt.Fprintf(&builder, `  job%d:
     name: Job %d
     runs-on: ubuntu-latest
     env:
@@ -314,13 +315,14 @@ jobs:
     steps:
 `, i, i, i)
 		for j := 0; j < 5; j++ {
-			yamlContent += fmt.Sprintf(`      - name: Step %d-%d
+			fmt.Fprintf(&builder, `      - name: Step %d-%d
         run: echo "Running step %d in job %d"
         env:
           STEP_VAR: step_value_%d_%d
 `, i, j, j, i, i, j)
 		}
 	}
+	yamlContent := builder.String()
 
 	tmpDir := b.TempDir()
 	workflowPath := filepath.Join(tmpDir, "benchmark.yml")
diff --git a/internal/workflow/select.go b/internal/workflow/select.go
index b951e58..48e3a89 100644
--- a/internal/workflow/select.go
+++ b/internal/workflow/select.go
@@ -47,15 +47,15 @@ func DiscoverWorkflows(repoRoot string) ([]string, error) {
 		return nil, fmt.Errorf("failed to read workflows directory: %w", err)
 	}
 
-	var workflows []string
+	workflows := make([]string, 0, len(entries))
 	for _, entry := range entries {
 		if entry.IsDir() {
 			continue
 		}
 
 		name := entry.Name()
-		ext := strings.ToLower(filepath.Ext(name))
-		if ext == ".yml" || ext == ".yaml" {
+		ext := filepath.Ext(name)
+		if strings.EqualFold(ext, ".yml") || strings.EqualFold(ext, ".yaml") {
 			workflows = append(workflows, filepath.Join(workflowsDir, name))
 		}
 	}