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Blocking XREAD[GROUP] should always reply with valid data (or timeout)

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This commit solves the following bug:
127.0.0.1:6379> XGROUP CREATE x grp $ MKSTREAM
OK
127.0.0.1:6379> XADD x 666 f v
"666-0"
127.0.0.1:6379> XREADGROUP GROUP grp Alice BLOCK 0 STREAMS x >
1) 1) "x"
   2) 1) 1) "666-0"
         2) 1) "f"
            2) "v"
127.0.0.1:6379> XADD x 667 f v
"667-0"
127.0.0.1:6379> XDEL x 667
(integer) 1
127.0.0.1:6379> XREADGROUP GROUP grp Alice BLOCK 0 STREAMS x >
1) 1) "x"
   2) (empty array)

The root cause is that we use s->last_id in streamCompareID
while we should use the last *valid* ID
This commit is contained in:
Guy Benoish
2019-12-26 12:19:24 +05:30
parent 324e22accf
commit a351e74fe9
3 changed files with 44 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
src/t_stream.c
View File

@ -782,6 +782,16 @@ int streamDeleteItem(stream *s, streamID *id) {
return deleted;
}
/* Get the last valid (non-tombstone) streamID of 's'. */
void streamLastValidID(stream *s, streamID *maxid)
{
streamIterator si;
streamIteratorStart(&si,s,NULL,NULL,1);
int64_t numfields;
streamIteratorGetID(&si,maxid,&numfields);
streamIteratorStop(&si);
}
/* Emit a reply in the client output buffer by formatting a Stream ID
* in the standard <ms>-<seq> format, using the simple string protocol
* of REPL. */
@ -1484,20 +1494,23 @@ void xreadCommand(client *c) {
{
serve_synchronously = 1;
serve_history = 1;
} else {
} else if (s->length) {
/* We also want to serve a consumer in a consumer group
* synchronously in case the group top item delivered is smaller
* than what the stream has inside. */
streamID *last = &groups[i]->last_id;
if (s->length && (streamCompareID(&s->last_id, last) > 0)) {
streamID maxid, *last = &groups[i]->last_id;
streamLastValidID(s, &maxid);
if (streamCompareID(&maxid, last) > 0) {
serve_synchronously = 1;
*gt = *last;
}
}
} else {
} else if (s->length) {
/* For consumers without a group, we serve synchronously if we can
* actually provide at least one item from the stream. */
if (s->length && (streamCompareID(&s->last_id, gt) > 0)) {
streamID maxid;
streamLastValidID(s, &maxid);
if (streamCompareID(&maxid, gt) > 0) {
serve_synchronously = 1;
}
}
@ -1849,11 +1862,7 @@ void xsetidCommand(client *c) {
* item, otherwise the fundamental ID monotonicity assumption is violated. */
if (s->length > 0) {
streamID maxid;
streamIterator si;
streamIteratorStart(&si,s,NULL,NULL,1);
int64_t numfields;
streamIteratorGetID(&si,&maxid,&numfields);
streamIteratorStop(&si);
streamLastValidID(s,&maxid);
if (streamCompareID(&id,&maxid) < 0) {
addReplyError(c,"The ID specified in XSETID is smaller than the "