[Cluster-devel] [PATCH] rgmanager: Randomize node list when relocating with no target

[Ryan McCabe]

Randomize the node list when choosing a node to which to forward
a start request to when relocating a service with no specified
target. The current behavior causes the service to bounce between
the two nodes with the highest node IDs when relocating in a loop.

Resolves: rhbz#831648

Signed-off-by: Ryan McCabe <rmccabe at redhat.com>
---
 rgmanager/include/members.h      |  1 +
 rgmanager/src/clulib/members.c   | 20 ++++++++++++++++++++
 rgmanager/src/daemons/rg_state.c |  1 +
 3 files changed, 22 insertions(+)

diff --git a/rgmanager/include/members.h b/rgmanager/include/members.h
index 7e99e17..09f7a9a 100644
--- a/rgmanager/include/members.h
+++ b/rgmanager/include/members.h
@@ -27,6 +27,7 @@ char * memb_id_to_name(cluster_member_list_t *ml, int nodeid);
 cman_node_t * memb_id_to_p(cluster_member_list_t *ml, int nodeid);
 cman_node_t * memb_name_to_p(cluster_member_list_t *ml, char *name);
 void free_member_list(cluster_member_list_t *ml);
+void member_list_shuffle(cluster_member_list_t *ml);
 cluster_member_list_t *memb_gained(cluster_member_list_t *old,
 		 		   cluster_member_list_t *new);
 cluster_member_list_t *memb_lost(cluster_member_list_t *old,
diff --git a/rgmanager/src/clulib/members.c b/rgmanager/src/clulib/members.c
index 5f98708..715fe39 100644
--- a/rgmanager/src/clulib/members.c
+++ b/rgmanager/src/clulib/members.c
@@ -11,6 +11,7 @@
 #include <signal.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <sys/time.h>
 #include <rg_types.h>
 #include <pthread.h>
 #include <errno.h>
@@ -501,3 +502,22 @@ member_list_dup(cluster_member_list_t *orig)
 	return ret;
 }
 
+void member_list_shuffle(cluster_member_list_t *ml) {
+    int i;
+    unsigned st;
+    struct timeval tv;
+
+    gettimeofday(&tv, NULL);
+    st = (int)(tv.tv_usec);
+
+
+    for (i = 0 ; i < ml->cml_count ; i++) {
+        cman_node_t temp;
+        int newidx = rand_r(&st) % ml->cml_count;
+        if (newidx == i)
+            continue;
+        memcpy(&temp, &ml->cml_members[i], sizeof(cman_node_t));
+        memcpy(&ml->cml_members[i], &ml->cml_members[newidx], sizeof(cman_node_t));
+        memcpy(&ml->cml_members[newidx], &temp, sizeof(cman_node_t));
+    }
+}
diff --git a/rgmanager/src/daemons/rg_state.c b/rgmanager/src/daemons/rg_state.c
index 80e8667..59454bf 100644
--- a/rgmanager/src/daemons/rg_state.c
+++ b/rgmanager/src/daemons/rg_state.c
@@ -1924,6 +1924,7 @@ handle_relocate_req(char *svcName, int orig_request, int preferred_target,
 		allowed_nodes = member_list();
 		//count_resource_groups(allowed_nodes);
 	}
+	member_list_shuffle(allowed_nodes);
 
 	if (preferred_target > 0)
 		memb_mark_down(allowed_nodes, preferred_target);
-- 
1.7.11.7