add async lookup to hmget

Former-commit-id: a967b47b60e3f4efbc945dc44a0903f47e07993f

src/server.cpp

@@ -607,7 +607,7 @@ struct redisCommand redisCommandTable[] = {
      0,NULL,1,1,1,0,0,0},
 
     {"hmget",hmgetCommand,-3,
-     "read-only fast @hash",
+     "read-only fast async @hash",
      0,NULL,1,1,1,0,0,0},
 
     {"hincrby",hincrbyCommand,4,

src/t_hash.cpp

@@ -812,7 +812,7 @@ void hmgetCommand(client *c) {
 
     /* Don't abort when the key cannot be found. Non-existing keys are empty
      * hashes, where HMGET should respond with a series of null bulks. */
-    o = lookupKeyRead(c->db, c->argv[1]);
+    o = lookupKeyRead(c->db, c->argv[1], c->mvccCheckpoint);
     if (checkType(c,o,OBJ_HASH)) return;
 
     addReplyArrayLen(c, c->argc-2);