[sheepdog] [PATCH] sheep: let all sheeps with smaller epoch added into delayed_nodes list

[Yunkai Zhang]

From: Yunkai Zhang <qiushu.zyk at taobao.com>

Since sheeps in delayed_nodes list won't cause recovery when the cluster in
WAIT_FOR_JOIN state, it's safe to put sheeps with smaller epoch into
delayed_nodes list, regardless of whether it once belonged to the cluster.

Benifit from this change, we needn't to restart sheep in the following scenario:

1) Start [0,1,2,3] sheeps:
   epoch of [0,1,2,3] sheeps = 1

2) Kill [0] sheep, and then Shutdown [1,2,3] sheeps
   epoch of [0] sheep      = 1
   epoch of [1,2,3] sheeps = 2

3) Start [1,2] sheeps:
   epoch of [0] sheep      = 1
   epoch of [1,2,3] sheeps = 2
   cluster status = WAIT_FOR_JOIN (waits [3] sheep)

4) Start [0] sheep:
   [0] sheep will be added into delayed_nodes list, needn't to restart
   epoch of [0] sheep      = 1
   epoch of [1,2,3] sheeps = 2
   cluster status = WAIT_FOR_JOIN (waits [3] sheep)

5) Start [3] sheep:
   epoch of [0,1,2,3] sheeps = 3
   cluster status = OK
   Now cluster start working...

Signed-off-by: Yunkai Zhang <qiushu.zyk at taobao.com>
---
 sheep/group.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/sheep/group.c b/sheep/group.c
index f7c8ca7..bac371b 100644
--- a/sheep/group.c
+++ b/sheep/group.c
@@ -423,7 +423,6 @@ static bool add_delayed_node(uint32_t epoch, struct sd_node *node)
 
 	if (find_entry_list(node, &sys->delayed_nodes))
 		return false;
-	assert(!find_entry_epoch(node, epoch));
 
 	n = xmalloc(sizeof(*n));
 	n->ent = *node;
@@ -558,10 +557,6 @@ static int cluster_wait_for_join_check(struct sd_node *joined,
 		eprintf("joining node epoch too small: %"
 			PRIu32 " vs %" PRIu32 "\n",
 			jm->epoch, local_epoch);
-
-		if (bsearch(joined, local_entries, nr_local_entries,
-			    sizeof(struct sd_node), node_id_cmp))
-			return CJ_RES_FAIL;
 		return CJ_RES_JOIN_LATER;
 	}
 
-- 
1.7.11.2