add a flag to request exptime in reply

Summary: if the flag is set on the request, reply will have exptime attached to the reply

Reviewed By: stuclar

Differential Revision: D64145438

fbshipit-source-id: 3e25ad2736513a4e4e4d1171ef6e4e9923f6bead

mcrouter/lib/mc/msg.h

@@ -265,6 +265,7 @@ enum mc_msg_flags_t {
   MC_MSG_FLAG_ASCII_INT_SERIALIZED = 0x10,
   MC_MSG_FLAG_SIZE_SPLIT = 0x20,
   MC_MSG_FLAG_KEY_CLIENT_BINDING_ENABLED = 0x40,
+  MC_MSG_FLAG_REQUEST_EXPTIME = 0x80,
   MC_MSG_FLAG_NZLIB_COMPRESSED = 0x800,
   MC_MSG_FLAG_QUICKLZ_COMPRESSED = 0x2000,
   MC_MSG_FLAG_SNAPPY_COMPRESSED = 0x4000,
@@ -308,6 +309,8 @@ static inline const char* mc_flag_to_string(const enum mc_msg_flags_t flag) {
       return "SIZE_SPLIT";
     case MC_MSG_FLAG_KEY_CLIENT_BINDING_ENABLED:
       return "MC_MSG_FLAG_KEY_CLIENT_BINDING_ENABLED";
+    case MC_MSG_FLAG_REQUEST_EXPTIME:
+      return "MC_MSG_FLAG_REQUEST_EXPTIME";
     case MC_MSG_FLAG_NZLIB_COMPRESSED:
       return "NZLIB_COMPRESSED";
     case MC_MSG_FLAG_QUICKLZ_COMPRESSED: