perf(alias): narrow cached backend paths

Author: syscc

drivers/alias/driver.go

@@ -201,12 +201,12 @@ func (d *Alias) List(ctx context.Context, dir model.Obj, args model.ListArgs) ([
 		dirPath := dirPaths[dirIndex]
 		for _, obj := range tmp {
 			name := obj.GetName()
-			if _, exists := resolveMap[name]; !exists {
-				paths := make([]string, 0, len(dirPaths)-dirIndex)
-				for _, path := range dirPaths[dirIndex:] {
-					paths = append(paths, stdpath.Join(path, name))
-				}
-				resolveMap[name] = newAliasResolved(paths, dirIndex > 0, obj)
+			childPath := stdpath.Join(dirPath, name)
+			if resolved, exists := resolveMap[name]; exists {
+				resolved.paths = append(resolved.paths, childPath)
+				resolveMap[name] = resolved
+			} else {
+				resolveMap[name] = newAliasResolved([]string{childPath}, dirIndex > 0, obj)
 			}
 			if _, exists := objMap[name]; exists {
 				continue

drivers/alias/index.go

@@ -22,24 +22,28 @@ func (d *Alias) getResolvedFromSearchIndex(ctx context.Context, roots []string,
 		return aliasResolved{}, false
 	}
 	known := make(map[string]aliasSearchIndexState)
+	paths := make([]string, 0, len(roots))
+	firstIndex := -1
 	for idx, root := range roots {
 		rawPath := stdpath.Join(root, sub)
 		_, exists, reliable := aliasSearchIndexPath(ctx, rawPath, known)
 		if exists {
-			paths := make([]string, 0, len(roots)-idx)
-			for _, root := range roots[idx:] {
-				paths = append(paths, stdpath.Join(root, sub))
+			if firstIndex < 0 {
+				firstIndex = idx
 			}
-			return aliasResolved{
-				paths:   paths,
-				skipped: idx > 0,
-			}, true
+			paths = append(paths, rawPath)
 		}
 		if !reliable {
 			return aliasResolved{}, false
 		}
 	}
-	return aliasResolved{}, false
+	if len(paths) == 0 {
+		return aliasResolved{}, false
+	}
+	return aliasResolved{
+		paths:   paths,
+		skipped: firstIndex > 0,
+	}, true
 }
 
 func aliasSearchIndexReady() bool {

drivers/alias/meta.go

@@ -16,7 +16,7 @@ type Addition struct {
 	ProviderPassThrough  bool   `json:"provider_pass_through" type:"bool" default:"false"`
 	DetailsPassThrough   bool   `json:"details_pass_through" type:"bool" default:"false"`
 	AliasCacheEnabled    bool   `json:"alias_cache_enabled" type:"bool" default:"false" help:"Cache aggregated Alias directory listings and resolved backend paths"`
-	AliasCacheExpiration int    `json:"alias_cache_expiration" default:"30" required:"false" type:"number" help:"Alias cache expiration in minutes"`
+	AliasCacheExpiration int    `json:"alias_cache_expiration" default:"30" required:"false" type:"number" help:"Alias cache expiration time (minutes)"`
 	AliasCacheMaxEntries int    `json:"alias_cache_max_entries" default:"0" required:"false" type:"number" help:"Maximum Alias cache entries. 0 means unlimited"`
 	AliasListConcurrency int    `json:"alias_list_concurrency" default:"1" required:"false" type:"number" help:"Maximum number of backend folders to list concurrently. 1 or less means serial listing"`
 }