refactor profiler: introduce safeMemoryDelta for accurate memory delta calculations

mattdholloway · mattdholloway · commit a43b03c67c40 · 2025-08-15T16:41:05.000+01:00
diff --git a/pkg/github/actions_test.go b/pkg/github/actions_test.go
@@ -1251,7 +1251,7 @@ func Test_MemoryUsage_SlidingWindow_vs_NoWindow(t *testing.T) {
 		if err != nil {
 			return 0, 0, err
 		}
-		defer resp1.Body.Close()
+		defer resp1.Body.Close() //nolint:bodyclose // Response body is closed in downloadLogContent, but we need to return httpResp
 		content, totalLines, _, err := buffer.ProcessResponseAsRingBufferToEnd(resp1, bufferSize)
 		return totalLines, int64(len(content)), err
 	})
@@ -1263,7 +1263,7 @@ func Test_MemoryUsage_SlidingWindow_vs_NoWindow(t *testing.T) {
 		if err != nil {
 			return 0, 0, err
 		}
-		defer resp2.Body.Close()
+		defer resp2.Body.Close() //nolint:bodyclose // Response body is closed in downloadLogContent, but we need to return httpResp
 		content, err := io.ReadAll(resp2.Body)
 		if err != nil {
 			return 0, 0, err
diff --git a/pkg/profiler/profiler.go b/pkg/profiler/profiler.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"log/slog"
+	"math"
 )
 
 // Profile represents performance metrics for an operation
@@ -35,6 +36,26 @@ func (p *Profile) String() string {
 	)
 }
 
+func safeMemoryDelta(after, before uint64) int64 {
+	if after > math.MaxInt64 || before > math.MaxInt64 {
+		if after >= before {
+			diff := after - before
+			if diff > math.MaxInt64 {
+				return math.MaxInt64
+			}
+			return int64(diff)
+		} else {
+			diff := before - after
+			if diff > math.MaxInt64 {
+				return -math.MaxInt64
+			}
+			return -int64(diff)
+		}
+	}
+
+	return int64(after) - int64(before)
+}
+
 // Profiler provides minimal performance profiling capabilities
 type Profiler struct {
 	logger  *slog.Logger
@@ -71,7 +92,7 @@ func (p *Profiler) ProfileFunc(ctx context.Context, operation string, fn func()
 	var memAfter runtime.MemStats
 	runtime.ReadMemStats(&memAfter)
 	profile.MemoryAfter = memAfter.Alloc
-	profile.MemoryDelta = int64(memAfter.Alloc) - int64(memBefore.Alloc)
+	profile.MemoryDelta = safeMemoryDelta(memAfter.Alloc, memBefore.Alloc)
 
 	if p.logger != nil {
 		p.logger.InfoContext(ctx, "Performance profile", "profile", profile.String())
@@ -105,7 +126,7 @@ func (p *Profiler) ProfileFuncWithMetrics(ctx context.Context, operation string,
 	var memAfter runtime.MemStats
 	runtime.ReadMemStats(&memAfter)
 	profile.MemoryAfter = memAfter.Alloc
-	profile.MemoryDelta = int64(memAfter.Alloc) - int64(memBefore.Alloc)
+	profile.MemoryDelta = safeMemoryDelta(memAfter.Alloc, memBefore.Alloc)
 
 	if p.logger != nil {
 		p.logger.InfoContext(ctx, "Performance profile", "profile", profile.String())
@@ -139,7 +160,7 @@ func (p *Profiler) Start(ctx context.Context, operation string) func(lines int,
 		var memAfter runtime.MemStats
 		runtime.ReadMemStats(&memAfter)
 		profile.MemoryAfter = memAfter.Alloc
-		profile.MemoryDelta = int64(memAfter.Alloc) - int64(memBefore.Alloc)
+		profile.MemoryDelta = safeMemoryDelta(memAfter.Alloc, memBefore.Alloc)
 
 		if p.logger != nil {
 			p.logger.InfoContext(ctx, "Performance profile", "profile", profile.String())
