add support cache for query

cache.go

@@ -9,9 +9,9 @@ import (
 // Cache interface
 type Cache interface {
 	Get(*datastore.Key, interface{}) error
-	GetMulti([]*datastore.Key, []interface{}) error
+	GetMulti([]*datastore.Key, interface{}) error
 	Set(*datastore.Key, interface{}) error
-	SetMulti([]*datastore.Key, []interface{}) error
+	SetMulti([]*datastore.Key, interface{}) error
 	Del(*datastore.Key) error
 	DelMulti([]*datastore.Key) error
 }

cache/redis/redis.go

@@ -3,6 +3,7 @@ package redis
 import (
 	"bytes"
 	"encoding/gob"
+	"reflect"
 	"time"
 
 	"cloud.google.com/go/datastore"
@@ -45,7 +46,25 @@ func (cache *Cache) Get(key *datastore.Key, dst interface{}) error {
 }
 
 // GetMulti gets multi data
-func (cache *Cache) GetMulti(keys []*datastore.Key, dst []interface{}) error {
+func (cache *Cache) GetMulti(keys []*datastore.Key, dst interface{}) error {
+	db := cache.Pool.Get()
+	defer db.Close()
+	for _, key := range keys {
+		db.Send("GET", cache.Prefix+key.String())
+	}
+	err := db.Flush()
+	if err != nil {
+		return err
+	}
+	for i := range keys {
+		b, err := redis.Bytes(db.Receive())
+		if err != nil {
+			return err
+		}
+		if len(b) > 0 {
+			decode(b, reflect.Indirect(reflect.ValueOf(dst)).Index(i).Interface())
+		}
+	}
 	return nil
 }
 
@@ -67,7 +86,21 @@ func (cache *Cache) Set(key *datastore.Key, src interface{}) error {
 
 // SetMulti sets data
 func (cache *Cache) SetMulti(keys []*datastore.Key, src interface{}) error {
-	return nil
+	db := cache.Pool.Get()
+	defer db.Close()
+	db.Send("MULTI")
+	for i, key := range keys {
+		b, err := encode(reflect.Indirect(reflect.ValueOf(src)).Index(i).Interface())
+		if err != nil {
+			return err
+		}
+		if cache.TTL > 0 {
+			db.Send("SETEX", cache.Prefix+key.String(), int(cache.TTL/time.Second), b)
+		}
+		db.Send("SET", cache.Prefix+key.String(), b)
+	}
+	_, err := db.Do("EXEC")
+	return err
 }
 
 // Del dels data
@@ -82,8 +115,10 @@ func (cache *Cache) Del(key *datastore.Key) error {
 func (cache *Cache) DelMulti(keys []*datastore.Key) error {
 	db := cache.Pool.Get()
 	defer db.Close()
+	db.Send("MULTI")
 	for _, key := range keys {
 		db.Send("DEL", cache.Prefix+key.String())
 	}
-	return db.Flush()
+	_, err := db.Do("EXEC")
+	return err
 }

get.go

@@ -32,6 +32,32 @@ func (client *Client) GetByKeys(ctx context.Context, keys []*datastore.Key, dst
 		dst = rs.Interface()
 	}
 
+	if client.Cache != nil {
+		err := client.Cache.GetMulti(keys, dst)
+		if err == nil {
+			nfKeys := []*datastore.Key{}
+			nfMap := []int{}
+			rf := valueOf(dst)
+			for i := 0; i < rf.Len(); i++ {
+				if rf.Index(i).IsNil() {
+					nfKeys = append(nfKeys, keys[i])
+					nfMap = append(nfMap, i)
+				}
+			}
+			l := len(nfKeys)
+			nfDstRf := reflect.MakeSlice(rf.Type(), l, l)
+			err := client.GetMulti(ctx, keys, nfDstRf.Interface())
+			for i, k := range nfMap {
+				rf.Index(k).Set(nfDstRf.Index(i))
+			}
+			SetKeys(keys, dst)
+			if err != nil {
+				return err
+			}
+			return nil
+		}
+	}
+
 	err := client.GetMulti(ctx, keys, dst)
 	SetKeys(keys, dst)
 	if err != nil {

query.go

@@ -17,12 +17,13 @@ func (client *Client) Query(ctx context.Context, kind string, dst interface{}, q
 	for _, setter := range qs {
 		q = setter(q)
 	}
+	q = q.KeysOnly()
 
-	_, err := client.GetAll(ctx, q, dst)
+	keys, err := client.GetAll(ctx, q, nil)
 	if err != nil {
 		return err
 	}
-	return nil
+	return client.GetByKeys(ctx, keys, dst)
 }
 
 // QueryFirst run Get to get the first result
@@ -31,12 +32,13 @@ func (client *Client) QueryFirst(ctx context.Context, kind string, dst interface
 	for _, setter := range qs {
 		q = setter(q)
 	}
+	q = q.Limit(1).KeysOnly()
 
-	_, err := client.Run(ctx, q).Next(dst)
+	key, err := client.Run(ctx, q).Next(nil)
 	if err != nil {
 		return err
 	}
-	return nil
+	return client.GetByKey(ctx, key, dst)
 }
 
 // QueryKeys queries only key