feat: cache S3 client for each regions

router.go

@@ -40,7 +40,14 @@ var (
 
 // Router represents s3-object-router application
 type Router struct {
-	s3     *s3.Client
+	awsConf aws.Config
+
+	// s3 clients for each region
+	s3 map[string]*s3.Client
+
+	// s3 bucket region cache
+	s3bucketRegion map[string]string
+
 	option *Option
 	sem    *semaphore.Weighted
 
@@ -67,9 +74,13 @@ func New(opt *Option) (*Router, error) {
 	}
 
 	return &Router{
-		s3:     s3.NewFromConfig(awsConf),
-		option: opt,
-		sem:    semaphore.NewWeighted(int64(MaxConcurrency)),
+		awsConf: awsConf,
+		s3: map[string]*s3.Client{
+			awsConf.Region: s3.NewFromConfig(awsConf),
+		},
+		s3bucketRegion: map[string]string{},
+		option:         opt,
+		sem:            semaphore.NewWeighted(int64(MaxConcurrency)),
 		genKeyPrefix: func(r *record) (string, error) {
 			var b strings.Builder
 			if err := tmpl.Execute(&b, r.parsed); err != nil {
@@ -210,7 +221,7 @@ func (r *Router) getS3Object(ctx context.Context, s3url string) (io.ReadCloser,
 		return nil, errors.New("s3:// required")
 	}
 
-	s3c, err := r.getS3Client(ctx, u.Host)
+	s3c, err := r.s3Client(ctx, u.Host)
 	if err != nil {
 		return nil, err
 	}
@@ -252,7 +263,7 @@ func (r *Router) putToS3(ctx context.Context, dest destination, body io.ReadSeek
 	r.sem.Acquire(ctx, 1)
 	defer r.sem.Release(1)
 
-	s3c, err := r.getS3Client(ctx, dest.Bucket)
+	s3c, err := r.s3Client(ctx, dest.Bucket)
 	if err != nil {
 		return err
 	}
@@ -270,26 +281,45 @@ func (r *Router) putToS3(ctx context.Context, dest destination, body io.ReadSeek
 	return err
 }
 
-// getS3Client returns s3 client for same region as the bucket
-func (r *Router) getS3Client(ctx context.Context, bucket string) (*s3.Client, error) {
-	bucketRegion, err := manager.GetBucketRegion(ctx, r.s3, bucket)
+func (r *Router) defaultS3Client() *s3.Client {
+	return r.s3[r.awsConf.Region]
+}
+
+// s3Client returns s3 client for same region as the bucket
+func (r *Router) s3Client(ctx context.Context, bucket string) (*s3.Client, error) {
+	bucketRegion, err := r.getS3BucketRegion(ctx, bucket)
 	if err != nil {
 		return nil, err
 	}
 
-	if r.s3.Options().Region == bucketRegion {
-		return r.s3, nil
+	if s3, ok := r.s3[bucketRegion]; ok {
+		return s3, nil
 	}
 
-	awsConfig, err := config.LoadDefaultConfig(
-		ctx,
-		config.WithRegion(bucketRegion),
-	)
+	awsConfig := r.awsConf.Copy()
+	awsConfig.Region = bucketRegion
+	s3 := s3.NewFromConfig(awsConfig)
+	r.s3[bucketRegion] = s3
+
+	return s3, nil
+}
+
+func (r *Router) getS3BucketRegion(ctx context.Context, bucket string) (string, error) {
+	log.Println("in getS3BucketRegion")
+	if region, ok := r.s3bucketRegion[bucket]; ok {
+		log.Printf("[debug] bucket region for %s is cached: %s\n", bucket, region)
+		return region, nil
+	}
+
+	region, err := manager.GetBucketRegion(ctx, r.defaultS3Client(), bucket)
 	if err != nil {
-		return nil, err
+		return "", err
 	}
 
-	return s3.NewFromConfig(awsConfig), nil
+	r.s3bucketRegion[bucket] = region
+	log.Printf("[debug] bucket region for %s is %s, added to cache\n", bucket, region)
+
+	return region, nil
 }
 
 type record struct {