Streams: rewrite empty streams with XADD MAXLEN 0. Use XSETID.

Related to #5426.
This commit is contained in:
antirez 2018-10-16 16:48:31 +02:00
parent ea78a1db32
commit c1689166b7

View File

@ -1158,22 +1158,28 @@ int rewriteStreamObject(rio *r, robj *key, robj *o) {
if (rioWriteBulkString(r,(char*)value,value_len) == 0) return 0;
}
}
/* Append XSTREAM SETID after XADD, make sure lastid is correct,
* in case of XDEL lastid. */
if (rioWriteBulkCount(r,'*',4) == 0) return 0;
if (rioWriteBulkString(r,"XSTREAM",7) == 0) return 0;
if (rioWriteBulkString(r,"SETID",5) == 0) return 0;
if (rioWriteBulkObject(r,key) == 0) return 0;
if (rioWriteBulkStreamID(r,&s->last_id) == 0) return 0;
} else {
/* Using XSTREAM CREATE if the stream is empty. */
if (rioWriteBulkCount(r,'*',4) == 0) return 0;
if (rioWriteBulkString(r,"XSTREAM",7) == 0) return 0;
if (rioWriteBulkString(r,"CREATE",6) == 0) return 0;
/* Use the XADD MAXLEN 0 trick to generate an empty stream if
* the key we are serializing is an empty string, which is possible
* for the Stream type. */
if (rioWriteBulkCount(r,'*',7) == 0) return 0;
if (rioWriteBulkString(r,"XADD",4) == 0) return 0;
if (rioWriteBulkObject(r,key) == 0) return 0;
if (rioWriteBulkStreamID(r,&s->last_id) == 0) return 0;
if (rioWriteBulkString(r,"MAXLEN",6) == 0) return 0;
if (rioWriteBulkString(r,"0",1) == 0) return 0;
if (rioWriteBulkString(r,"*",1) == 0) return 0;
if (rioWriteBulkString(r,"x",1) == 0) return 0;
if (rioWriteBulkString(r,"y",1) == 0) return 0;
}
/* Append XSETID after XADD, make sure lastid is correct,
* in case of XDEL lastid. */
if (rioWriteBulkCount(r,'*',3) == 0) return 0;
if (rioWriteBulkString(r,"XSETID",6) == 0) return 0;
if (rioWriteBulkObject(r,key) == 0) return 0;
if (rioWriteBulkStreamID(r,&s->last_id) == 0) return 0;
/* Create all the stream consumer groups. */
if (s->cgroups) {
raxIterator ri;