From 06d2e05ae4dcd54dad8b0d8f21dba8970c307b7f Mon Sep 17 00:00:00 2001
From: Googol Lee <i@googol.im>
Date: Fri, 11 Jul 2025 11:16:41 +0200
Subject: [PATCH] Non-fork face detection, avoiding a race condition. (#1243)

* Non-fork face detection, avoiding a race condition.

* Update scanner test.
---
 .../scanner_tasks/face_detection_task.go      | 15 ++++----
 api/scanner/scanner_test.go                   | 38 ++++---------------
 2 files changed, 14 insertions(+), 39 deletions(-)

diff --git a/api/scanner/scanner_tasks/face_detection_task.go b/api/scanner/scanner_tasks/face_detection_task.go
index bca5f0f4..4ca8ee6e 100644
--- a/api/scanner/scanner_tasks/face_detection_task.go
+++ b/api/scanner/scanner_tasks/face_detection_task.go
@@ -18,14 +18,13 @@ func (t FaceDetectionTask) AfterProcessMedia(ctx scanner_task.TaskContext, media
 	didProcess := len(updatedURLs) > 0
 
 	if didProcess && mediaData.Media.Type == models.MediaTypePhoto {
-		go func(media *models.Media) {
-			if face_detection.GlobalFaceDetector == nil {
-				return
-			}
-			if err := face_detection.GlobalFaceDetector.DetectFaces(ctx.GetDB(), media); err != nil {
-				scanner_utils.ScannerError(ctx, "Error detecting faces in image (%s): %s", media.Path, err)
-			}
-		}(mediaData.Media)
+		media := mediaData.Media
+		if face_detection.GlobalFaceDetector == nil {
+			return nil
+		}
+		if err := face_detection.GlobalFaceDetector.DetectFaces(ctx.GetDB(), media); err != nil {
+			scanner_utils.ScannerError(ctx, "Error detecting faces in image (%s): %s", media.Path, err)
+		}
 	}
 
 	return nil
diff --git a/api/scanner/scanner_test.go b/api/scanner/scanner_test.go
index 741d7ef2..45534b70 100644
--- a/api/scanner/scanner_test.go
+++ b/api/scanner/scanner_test.go
@@ -1,14 +1,12 @@
 package scanner_test
 
 import (
-	"context"
 	"fmt"
 	"os"
 	"path/filepath"
 	"slices"
 	"strings"
 	"testing"
-	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/photoview/photoview/api/graphql/models"
@@ -178,18 +176,14 @@ func TestFullScan(t *testing.T) {
 	})
 
 	t.Run("CheckFaceGroup", func(t *testing.T) {
-		ctx, done := context.WithTimeout(t.Context(), time.Second*5)
-		defer done()
+		var allFaceGroups []*models.FaceGroup
+		if err := db.Find(&allFaceGroups).Error; err != nil {
+			t.Fatal("get face groups error:", err)
+		}
 
-		waitFor(ctx, t, time.Second/2, func() bool {
-			var allFaceGroups []*models.FaceGroup
-			if err := db.Find(&allFaceGroups).Error; err != nil {
-				t.Fatal("get face groups error:", err)
-				return false
-			}
-
-			return len(allFaceGroups) == len(wantFaceGroups)
-		})
+		if got, want := len(allFaceGroups), len(wantFaceGroups); got != want {
+			t.Errorf("len(allFaceGroups) = %d, want: %d", got, want)
+		}
 	})
 
 	t.Run("CheckFaces", func(t *testing.T) {
@@ -231,24 +225,6 @@ func equalNameWithoutSuffix(a, b string) bool {
 	return true
 }
 
-func waitFor(ctx context.Context, t *testing.T, interval time.Duration, checkFn func() bool) {
-	t.Helper()
-
-	ticker := time.NewTicker(interval)
-	for {
-		select {
-		case <-ctx.Done():
-			t.Fatal("check timeout")
-			return
-		case <-ticker.C:
-		}
-
-		if checkFn() {
-			return
-		}
-	}
-}
-
 func groupMediaWithFaces(medias []*models.ImageFace) [][]string {
 	grouped := make(map[int][]string)