perf: 并发worker数可配置(默认4)与MIME检测并行化

internal/scanner/scanner.go

@@ -11,8 +11,11 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
+	"sync/atomic"
 	"time"
 
+	"kenaito-media-picker/internal/config"
 	"kenaito-media-picker/internal/probe"
 
 	"github.com/gabriel-vasile/mimetype"
@@ -106,12 +109,35 @@ func Scan(opts Options) (*Result, error) {
 	if opts.OnProgress != nil {
 		opts.OnProgress(total, total)
 	}
-	for i := range res.Files {
-		res.Files[i].Mime = detectMime(res.Files[i].Path)
-		if opts.OnProgress != nil {
-			opts.OnProgress(i+1, total)
-		}
+	// 并行认类型：每个 worker 只写自己名下那个元素（res.Files[i]），并发安全；
+	// 认类型要读文件内容，数量多时串行太慢，并行能明显提速。
+	workers := config.WorkerCount()
+	if workers > total {
+		workers = total
 	}
+	if workers < 1 {
+		workers = 1
+	}
+	var wg sync.WaitGroup
+	var done int32
+	jobs := make(chan int)
+	for w := 0; w < workers; w++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for i := range jobs {
+				res.Files[i].Mime = detectMime(res.Files[i].Path)
+				if opts.OnProgress != nil {
+					opts.OnProgress(int(atomic.AddInt32(&done, 1)), total)
+				}
+			}
+		}()
+	}
+	for i := range res.Files {
+		jobs <- i
+	}
+	close(jobs)
+	wg.Wait()
 	return res, nil
 }