1 files changed, 13 insertions, 0 deletions
diff --git a/src/replication.c b/src/replication.c
index 6e89d8739..06cfe89ae 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -588,6 +588,19 @@ void replconfCommand(redisClient *c) {
                     &port,NULL) != REDIS_OK))
                 return;
             c->slave_listening_port = port;
+        } else if (!strcasecmp(c->argv[j]->ptr,"ack")) {
+            /* REPLCONF ACK is used by slave to inform the master the amount
+             * of replication stream that it processed so far. It is an
+             * internal only command that normal clients should never use. */
+            long long offset;
+
+            if (!(c->flags & REDIS_SLAVE)) return;
+            if ((getLongLongFromObject(c->argv[j+1], &offset) != REDIS_OK))
+                return;
+            if (offset > c->repl_ack_off)
+                c->repl_ack_off = offset;
+            c->repl_ack_time = server.unixtime;
+            /* Note: this command does not reply anything! */
         } else {
             addReplyErrorFormat(c,"Unrecognized REPLCONF option: %s",
                 (char*)c->argv[j]->ptr);