adds ttl for twins cache in auth.go (#115)

Signed-off-by: Ashraf Fouda <ashraf.m.fouda@gmail.com>

Author: ashraffouda

pkg/provision/auth.go

@@ -2,50 +2,55 @@ package provision
 
 import (
 	"context"
-	"crypto/ed25519"
 	"fmt"
+	"time"
 
-	lru "github.com/hashicorp/golang-lru"
+	cache "github.com/patrickmn/go-cache"
 	"github.com/pkg/errors"
+	"github.com/rs/zerolog/log"
 	"github.com/threefoldtech/zosbase/pkg/stubs"
 )
 
+const (
+	keyExpiration = 60 * time.Minute
+	keyCleanup    = 10 * time.Minute
+)
+
 type substrateTwins struct {
 	substrateGateway *stubs.SubstrateGatewayStub
-	mem              *lru.Cache
+	mem              *cache.Cache
 }
 
 // NewSubstrateTwins creates a substrate users db that implements the provision.Users interface.
 func NewSubstrateTwins(substrateGateway *stubs.SubstrateGatewayStub) (Twins, error) {
-	cache, err := lru.New(1024)
-	if err != nil {
-		return nil, err
-	}
-
 	return &substrateTwins{
 		substrateGateway: substrateGateway,
-		mem:              cache,
+		mem:              cache.New(keyExpiration, keyCleanup),
 	}, nil
 }
 
 // GetKey gets twins public key
 func (s *substrateTwins) GetKey(id uint32) ([]byte, error) {
-	if value, ok := s.mem.Get(id); ok {
+	cacheKey := fmt.Sprint(id)
+	if value, ok := s.mem.Get(cacheKey); ok {
 		return value.([]byte), nil
 	}
+
+	log.Debug().Uint32("twin", id).Msg("twin public key cache expired, fetching from substrate")
 	user, err := s.substrateGateway.GetTwin(context.Background(), id)
 	if err != nil {
 		return nil, errors.Wrapf(err, "could not get user with id '%d'", id)
 	}
 
-	key := user.Account.PublicKey()
-	s.mem.Add(id, key)
-	return key, nil
+	pk := user.Account.PublicKey()
+	s.mem.Set(cacheKey, pk, cache.DefaultExpiration)
+	return pk, nil
 }
 
 type substrateAdmins struct {
-	twin uint32
-	pk   ed25519.PublicKey
+	substrateGateway *stubs.SubstrateGatewayStub
+	twin             uint32
+	mem              *cache.Cache
 }
 
 // NewSubstrateAdmins creates a substrate twins db that implements the provision.Users interface.
@@ -56,13 +61,10 @@ func NewSubstrateAdmins(substrateGateway *stubs.SubstrateGatewayStub, farmID uin
 		return nil, errors.Wrap(err, "failed to get farm")
 	}
 
-	twin, err := substrateGateway.GetTwin(context.Background(), uint32(farm.TwinID))
-	if err != nil {
-		return nil, err
-	}
 	return &substrateAdmins{
-		twin: uint32(farm.TwinID),
-		pk:   twin.Account.PublicKey(),
+		substrateGateway: substrateGateway,
+		twin:             uint32(farm.TwinID),
+		mem:              cache.New(keyExpiration, keyCleanup),
 	}, nil
 }
 
@@ -72,5 +74,18 @@ func (s *substrateAdmins) GetKey(id uint32) ([]byte, error) {
 		return nil, fmt.Errorf("twin with id '%d' is not an admin", id)
 	}
 
-	return []byte(s.pk), nil
+	cacheKey := fmt.Sprint(id)
+	if value, ok := s.mem.Get(cacheKey); ok {
+		return value.([]byte), nil
+	}
+
+	log.Debug().Uint32("twin", id).Msg("admin public key cache expired, fetching from substrate")
+	twin, err := s.substrateGateway.GetTwin(context.Background(), id)
+	if err != nil {
+		return nil, errors.Wrapf(err, "could not get admin twin with id '%d'", id)
+	}
+
+	pk := twin.Account.PublicKey()
+	s.mem.Set(cacheKey, pk, cache.DefaultExpiration)
+	return pk, nil
 }