Add cache to store UID to UserID mapping in EOS

changelog/unreleased/eos-user-cache.md

@@ -0,0 +1,7 @@
+Enhancement: Add cache to store UID to UserID mapping in EOS
+
+Previously, we used to send an RPC to the user provider service for every lookup
+of user IDs from the UID stored in EOS. This PR adds an in-memory lock-protected
+cache to store this mapping.
+
+https://github.com/cs3org/reva/pull/1340

pkg/storage/utils/eosfs/eosfs.go

@@ -29,6 +29,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 
 	userpb "github.com/cs3org/go-cs3apis/cs3/identity/user/v1beta1"
 	rpc "github.com/cs3org/go-cs3apis/cs3/rpc/v1beta1"
@@ -179,6 +180,12 @@ type eosfs struct {
 	chunkHandler  *chunking.ChunkHandler
 	singleUserUID string
 	singleUserGID string
+	userIDCache   *userCache
+}
+
+type userCache struct {
+	*sync.RWMutex
+	cache map[string]*userpb.UserId
 }
 
 // NewEOSFS returns a storage.FS interface implementation that connects to an
@@ -213,6 +220,10 @@ func NewEOSFS(c *Config) (storage.FS, error) {
 		c:            eosClient,
 		conf:         c,
 		chunkHandler: chunking.NewChunkHandler(c.CacheDirectory),
+		userIDCache: &userCache{
+			&sync.RWMutex{},
+			make(map[string]*userpb.UserId),
+		},
 	}
 
 	return eosfs, nil
@@ -1455,6 +1466,12 @@ func (fs *eosfs) getUIDGateway(ctx context.Context, u *userpb.UserId) (string, s
 }
 
 func (fs *eosfs) getUserIDGateway(ctx context.Context, uid string) (*userpb.UserId, error) {
+	fs.userIDCache.RLock()
+	if userID, ok := fs.userIDCache.cache[uid]; ok {
+		fs.userIDCache.RUnlock()
+		return userID, nil
+	}
+	fs.userIDCache.RUnlock()
 	client, err := pool.GetGatewayServiceClient(fs.conf.GatewaySvc)
 	if err != nil {
 		return nil, errors.Wrap(err, "eos: error getting gateway grpc client")
@@ -1469,6 +1486,9 @@ func (fs *eosfs) getUserIDGateway(ctx context.Context, uid string) (*userpb.User
 	if getUserResp.Status.Code != rpc.Code_CODE_OK {
 		return nil, errors.Wrap(err, "eos: grpc get user failed")
 	}
+	fs.userIDCache.Lock()
+	fs.userIDCache.cache[uid] = getUserResp.User.Id
+	fs.userIDCache.Unlock()
 	return getUserResp.User.Id, nil
 }