[#179] api: Add cache for ListObjectsV1/V2

Refactored cache for ListObjects:
made cache common for all versions,
simplified: remove dependendence on token/startafter
add mitable cachelifetime.

Refactored listobjects

Signed-off-by: Angira Kekteeva <kira@nspcc.ru>

api/layer/layer.go

@@ -24,7 +24,7 @@ type (
 	layer struct {
 		pool  pool.Pool
 		log   *zap.Logger
-		cache ObjectsListV2Cache
+		cache ObjectsListCache
 	}
 
 	// Params stores basic API parameters.
@@ -131,7 +131,7 @@ func NewLayer(log *zap.Logger, conns pool.Pool) Client {
 	return &layer{
 		pool:  conns,
 		log:   log,
-		cache: newListObjectsCache(),
+		cache: newListObjectsCache(defaultCacheLifetime),
 	}
 }
 

api/layer/object.go

@@ -13,7 +13,6 @@ import (
 	cid "github.com/nspcc-dev/neofs-api-go/pkg/container/id"
 	"github.com/nspcc-dev/neofs-api-go/pkg/object"
 	"github.com/nspcc-dev/neofs-s3-gw/api"
-	"github.com/nspcc-dev/neofs-s3-gw/creds/accessbox"
 	"go.uber.org/zap"
 )
 
@@ -59,7 +58,6 @@ type (
 		Bucket    *BucketInfo
 		Delimiter string
 		Prefix    string
-		StartAfter string
 	}
 )
 
@@ -211,43 +209,32 @@ func (n *layer) ListObjectsV1(ctx context.Context, p *ListObjectsParamsV1) (*Lis
 	var (
 		err        error
 		result     ListObjectsInfoV1
-		bkt    *BucketInfo
+		allObjects []*ObjectInfo
 	)
 
 	if p.MaxKeys == 0 {
 		return &result, nil
 	}
 
-	if bkt, err = n.GetBucketInfo(ctx, p.Bucket); err != nil {
+	if allObjects, err = n.listAllObjects(ctx, p.ListObjectsParamsCommon); err != nil {
 		return nil, err
 	}
 
-	allObjects, err := n.listSortedAllObjects(ctx, allObjectParams{
+	if len(allObjects) == 0 {
-		Bucket:     bkt,
+		return &result, nil
-		Prefix:     p.Prefix,
+	}
-		Delimiter:  p.Delimiter,
+
-		StartAfter: p.Marker,
+	if p.Marker != "" {
-	})
+		allObjects = trimAfterObjectName(p.Marker, allObjects)
-	if err != nil {
-		return nil, err
 	}
 
 	if len(allObjects) > p.MaxKeys {
 		result.IsTruncated = true
-
-		nextObject := allObjects[p.MaxKeys-1]
-		result.NextMarker = nextObject.Name
-
 		allObjects = allObjects[:p.MaxKeys]
+		result.NextMarker = allObjects[len(allObjects)-1].Name
 	}
 
-	for _, ov := range allObjects {
+	result.Prefixes, result.Objects = triageObjects(allObjects)
-		if ov.isDir {
-			result.Prefixes = append(result.Prefixes, ov.Name)
-		} else {
-			result.Objects = append(result.Objects, ov)
-		}
-	}
 
 	return &result, nil
 }
@@ -258,67 +245,40 @@ func (n *layer) ListObjectsV2(ctx context.Context, p *ListObjectsParamsV2) (*Lis
 		err        error
 		result     ListObjectsInfoV2
 		allObjects []*ObjectInfo
-		bkt        *BucketInfo
-		cacheKey   string
-		box        *accessbox.Box
 	)
 
 	if p.MaxKeys == 0 {
 		return &result, nil
 	}
 
-	if bkt, err = n.GetBucketInfo(ctx, p.Bucket); err != nil {
+	if allObjects, err = n.listAllObjects(ctx, p.ListObjectsParamsCommon); err != nil {
 		return nil, err
 	}
 
-	if box, err = GetBoxData(ctx); err != nil {
+	if len(allObjects) == 0 {
-		return nil, err
+		return &result, nil
-	}
-
-	cacheKey = createKey(box.Gate.AccessKey, bkt.CID)
-
-	if p.ContinuationToken != "" {
-		allObjects = n.cache.Get(p.ContinuationToken, cacheKey)
-		allObjects = trimStartAfter(p.StartAfter, allObjects)
-	}
-
-	if allObjects == nil {
-		allObjects, err = n.listSortedAllObjects(ctx, allObjectParams{
-			Bucket:     bkt,
-			Prefix:     p.Prefix,
-			Delimiter:  p.Delimiter,
-			StartAfter: p.StartAfter,
-		})
-		if err != nil {
-			return nil, err
 	}
 
 	if p.ContinuationToken != "" {
 		allObjects = trimAfterObjectID(p.ContinuationToken, allObjects)
 	}
+
+	if p.StartAfter != "" {
+		allObjects = trimAfterObjectName(p.StartAfter, allObjects)
 	}
 
 	if len(allObjects) > p.MaxKeys {
 		result.IsTruncated = true
-
-		restObjects := allObjects[p.MaxKeys:]
-		n.cache.Put(cacheKey, restObjects)
-		result.NextContinuationToken = restObjects[0].id.String()
-
 		allObjects = allObjects[:p.MaxKeys]
+		result.NextContinuationToken = allObjects[len(allObjects)-1].id.String()
 	}
 
-	for _, ov := range allObjects {
+	result.Prefixes, result.Objects = triageObjects(allObjects)
-		if ov.isDir {
+
-			result.Prefixes = append(result.Prefixes, ov.Name)
-		} else {
-			result.Objects = append(result.Objects, ov)
-		}
-	}
 	return &result, nil
 }
 
-func (n *layer) listSortedAllObjects(ctx context.Context, p allObjectParams) ([]*ObjectInfo, error) {
+func (n *layer) listSortedObjectsFromNeoFS(ctx context.Context, p allObjectParams) ([]*ObjectInfo, error) {
 	var (
 		err       error
 		ids       []*object.ID
@@ -346,9 +306,6 @@ func (n *layer) listSortedAllObjects(ctx context.Context, p allObjectParams) ([]
 			if _, ok := uniqNames[oi.Name]; ok {
 				continue
 			}
-			if len(p.StartAfter) > 0 && oi.Name <= p.StartAfter {
-				continue
-			}
 
 			uniqNames[oi.Name] = oi.isDir
 
@@ -363,22 +320,75 @@ func (n *layer) listSortedAllObjects(ctx context.Context, p allObjectParams) ([]
 	return objects, nil
 }
 
-func trimStartAfter(startAfter string, objects []*ObjectInfo) []*ObjectInfo {
+func trimAfterObjectName(startAfter string, objects []*ObjectInfo) []*ObjectInfo {
-	if objects != nil && len(startAfter) != 0 && objects[0].Name <= startAfter {
+	if len(objects) != 0 && objects[len(objects)-1].Name <= startAfter {
+		return nil
+	}
 	for i := range objects {
 		if objects[i].Name > startAfter {
 			return objects[i:]
 		}
 	}
-	}
+
-	return objects
+	return nil
 }
 
 func trimAfterObjectID(id string, objects []*ObjectInfo) []*ObjectInfo {
+	if len(objects) != 0 && objects[len(objects)-1].id.String() == id {
+		return []*ObjectInfo{}
+	}
 	for i, obj := range objects {
 		if obj.ID().String() == id {
-			return objects[i:]
+			return objects[i+1:]
 		}
 	}
-	return objects
+
+	return nil
+}
+
+func triageObjects(allObjects []*ObjectInfo) (prefixes []string, objects []*ObjectInfo) {
+	for _, ov := range allObjects {
+		if ov.isDir {
+			prefixes = append(prefixes, ov.Name)
+		} else {
+			objects = append(objects, ov)
+		}
+	}
+
+	return
+}
+
+func (n *layer) listAllObjects(ctx context.Context, p ListObjectsParamsCommon) ([]*ObjectInfo, error) {
+	var (
+		err        error
+		bkt        *BucketInfo
+		cacheKey   cacheOptions
+		allObjects []*ObjectInfo
+	)
+
+	if bkt, err = n.GetBucketInfo(ctx, p.Bucket); err != nil {
+		return nil, err
+	}
+
+	if cacheKey, err = createKey(ctx, bkt.CID, p.Prefix, p.Delimiter); err != nil {
+		return nil, err
+	}
+
+	allObjects = n.cache.Get(cacheKey)
+
+	if allObjects == nil {
+		allObjects, err = n.listSortedObjectsFromNeoFS(ctx, allObjectParams{
+			Bucket:    bkt,
+			Prefix:    p.Prefix,
+			Delimiter: p.Delimiter,
+		})
+		if err != nil {
+			return nil, err
+		}
+
+		// putting to cache a copy of allObjects because allObjects can be modified further
+		n.cache.Put(cacheKey, append([]*ObjectInfo(nil), allObjects...))
+	}
+
+	return allObjects, nil
 }

api/layer/object_cache.go

@@ -1,6 +1,7 @@
 package layer
 
 import (
+	"context"
 	"sync"
 	"time"
 
@@ -8,72 +9,84 @@ import (
 )
 
 /*
-	This is an implementation of a cache for ListObjectsV2 which we return to users by ContinuationToken.
+	This is an implementation of a cache for ListObjectsV2/V1 which we can return to users when we receive a ListObjects
+	request.
 
-	The cache is a map which has a key: (access_key from AccessBox) + container_id and a value: list of objects with
+	The cache is a map which has a key: cacheOptions struct and a value: list of objects. After putting a record we
-	creation time. After putting a record we start a timer (via time.AfterFunc) that removes the record after
+	start a timer (via time.AfterFunc) that removes the record after defaultCacheLifetime value.
-	defaultCacheLifetime value.
 
-	ContinuationToken in our gateway is an objectID in NeoFS.
+	When we get a request from the user we just try to find the suitable and non-expired cache and then we return
-
+	the list of objects. Otherwise we send the request to NeoFS.
-	We don't keep ContinuationToken in this structure because we assume that users who received the token can reconnect
-	to other gateways and they should be able to get a list of objects.
-	When we receive the token from the user we just try to find the cache and then we return the list of objects which
-	starts from this token (i.e. objectID).
 */
 
-// ObjectsListV2Cache provides interface for cache of ListObjectsV2 in a layer struct.
+// ObjectsListCache provides interface for cache of ListObjectsV2 in a layer struct.
 type (
-	ObjectsListV2Cache interface {
+	ObjectsListCache interface {
-		Get(token string, key string) []*ObjectInfo
+		Get(key cacheOptions) []*ObjectInfo
-		Put(key string, objects []*ObjectInfo)
+		Put(key cacheOptions, objects []*ObjectInfo)
 	}
 )
 
-var (
+const defaultCacheLifetime = time.Second * 60
-	defaultCacheLifetime = time.Second * 60
-)
 
 type (
 	listObjectsCache struct {
-		caches map[string]cache
+		cacheLifetime time.Duration
+		caches        map[cacheOptions]cache
 		mtx           sync.RWMutex
 	}
 	cache struct {
 		list []*ObjectInfo
 	}
+	cacheOptions struct {
+		key       string
+		delimiter string
+		prefix    string
+	}
 )
 
-func newListObjectsCache() *listObjectsCache {
+func newListObjectsCache(lifetime time.Duration) *listObjectsCache {
 	return &listObjectsCache{
-		caches: make(map[string]cache),
+		caches:        make(map[cacheOptions]cache),
+		cacheLifetime: lifetime,
 	}
 }
 
-func (l *listObjectsCache) Get(token, key string) []*ObjectInfo {
+func (l *listObjectsCache) Get(key cacheOptions) []*ObjectInfo {
 	l.mtx.RLock()
 	defer l.mtx.RUnlock()
 	if val, ok := l.caches[key]; ok {
-		return trimAfterObjectID(token, val.list)
+		return val.list
 	}
-
 	return nil
 }
 
-func (l *listObjectsCache) Put(key string, objects []*ObjectInfo) {
+func (l *listObjectsCache) Put(key cacheOptions, objects []*ObjectInfo) {
+	if len(objects) == 0 {
+		return
+	}
 	var c cache
-
 	l.mtx.Lock()
 	defer l.mtx.Unlock()
 	c.list = objects
 	l.caches[key] = c
-	time.AfterFunc(defaultCacheLifetime, func() {
+	time.AfterFunc(l.cacheLifetime, func() {
 		l.mtx.Lock()
 		delete(l.caches, key)
 		l.mtx.Unlock()
 	})
 }
 
-func createKey(accessKey string, cid *cid.ID) string {
+func createKey(ctx context.Context, cid *cid.ID, prefix, delimiter string) (cacheOptions, error) {
-	return accessKey + cid.String()
+	box, err := GetBoxData(ctx)
+	if err != nil {
+		return cacheOptions{}, err
+	}
+	p := cacheOptions{
+		key:       box.Gate.AccessKey + cid.String(),
+		delimiter: delimiter,
+		prefix:    prefix,
+	}
+
+	return p, nil
 }