Add ExpireTime function

Signed-off-by: Devansh Singh <[email protected]>

server/generic.go

@@ -80,3 +80,12 @@ func (s *Server) persist(cmd Command) {
 		cmd.error(err)
 	}
 }
+
+func (s *Server) expireTime(cmd Command) {
+	exp, err := s.DB.ExpireTime(cmd.Args[0])
+	if err != nil {
+		cmd.error(err)
+		return
+	}
+	cmd.write(strconv.FormatInt(exp, 10))
+}

server/server.go

@@ -12,15 +12,16 @@ import (
 
 const (
 	// Generic commands
-	CMD_GET     = "GET"
-	CMD_DEL     = "DEL"
-	CMD_SET     = "SET"
-	CMD_KEYS    = "KEYS"
-	CMD_MGET    = "MGET"
-	CMD_SETEX   = "SETEX"
-	CMD_EXISTS  = "EXISTS"
-	CMD_EXPIRE  = "EXPIRE"
-	CMD_PERSIST = "PERSIST"
+	CMD_GET         = "GET"
+	CMD_DEL         = "DEL"
+	CMD_SET         = "SET"
+	CMD_KEYS        = "KEYS"
+	CMD_MGET        = "MGET"
+	CMD_SETEX       = "SETEX"
+	CMD_EXISTS      = "EXISTS"
+	CMD_EXPIRE      = "EXPIRE"
+	CMD_PERSIST     = "PERSIST"
+	CMD_EXPIRE_TIME = "EXPIRETIME"
 	// Set commands
 	CMD_SADD       = "SADD"
 	CMD_SCARD      = "SCARD"
@@ -112,6 +113,8 @@ func (s *Server) HandleCommand() {
 			s.expire(cmd)
 		case CMD_PERSIST:
 			s.persist(cmd)
+		case CMD_EXPIRE_TIME:
+			s.expireTime(cmd)
 		case CMD_SADD:
 			s.sAdd(cmd)
 		case CMD_SCARD:

store/generic.go

@@ -125,3 +125,16 @@ func (s *Store) Keys() []string {
 	}
 	return keys
 }
+
+// Returns the expiration time of a key as Unix timestamp.
+func (s *Store) ExpireTime(key string) (int64, error) {
+	s.Mutex.RLock()
+	defer s.Mutex.RUnlock()
+
+	value, ok := s.Records[key]
+	if !ok {
+		return 0, ErrKeyNotExists
+	}
+	expireTime := value.Timestamp.Add(value.Expiration)
+	return expireTime.Unix(), nil
+}