[sheepdog] [PATCH 3/3] sheep: remove check_majority()

[Yunkai Zhang]

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

When sheep receives LEAVE event, check_majority() will be executed in
__sd_leave(), it'll make network very busy as it try to connect all
sheeps each other.

I don't think this checking is necessary, that is driver's work. Driver
will tell us which sheep is alive and which have left. So let's remove
this checking.

Signed-off-by: Yunkai Zhang <qiushu.zyk at taobao.com>
---
 sheep/group.c |   36 ++----------------------------------
 1 files changed, 2 insertions(+), 34 deletions(-)

diff --git a/sheep/group.c b/sheep/group.c
index e37e049..69c6b71 100644
--- a/sheep/group.c
+++ b/sheep/group.c
@@ -668,39 +668,6 @@ void sd_notify_handler(struct sd_node *sender, void *msg, size_t msg_len)
 	process_request_event_queues();
 }
 
-/*
- * Check whether the majority of Sheepdog nodes are still alive or not
- */
-static int check_majority(struct sd_node *nodes, int nr_nodes)
-{
-	int nr_majority, nr_reachable = 0, fd, i;
-	char name[INET6_ADDRSTRLEN];
-
-	nr_majority = nr_nodes / 2 + 1;
-
-	/* we need at least 3 nodes to handle network partition
-	 * failure */
-	if (nr_nodes < 3)
-		return 1;
-
-	for (i = 0; i < nr_nodes; i++) {
-		addr_to_str(name, sizeof(name), nodes[i].addr, 0);
-		fd = connect_to(name, nodes[i].port);
-		if (fd < 0)
-			continue;
-
-		close(fd);
-		nr_reachable++;
-		if (nr_reachable >= nr_majority) {
-			dprintf("the majority of nodes are alive\n");
-			return 1;
-		}
-	}
-	dprintf("%d, %d, %d\n", nr_nodes, nr_majority, nr_reachable);
-	eprintf("the majority of nodes are not alive\n");
-	return 0;
-}
-
 static void __sd_join(struct event_struct *cevent)
 {
 	struct work_join *w = container_of(cevent, struct work_join, cev);
@@ -731,7 +698,8 @@ static void __sd_leave(struct event_struct *cevent)
 {
 	struct work_leave *w = container_of(cevent, struct work_leave, cev);
 
-	if (!check_majority(w->member_list, w->member_list_entries)) {
+	/* we need at least 3 nodes to handle network partition failure */
+	if (w->member_list_entries < 3) {
 		eprintf("perhaps a network partition has occurred?\n");
 		abort();
 	}
-- 
1.7.7.6