Rev 497: choose the most connected node first in http://samba.org/~tridge/ctdb

[tridge]

------------------------------------------------------------
revno: 497
revision-id: [EMAIL PROTECTED]
parent: [EMAIL PROTECTED]
committer: Andrew Tridgell <[EMAIL PROTECTED]>
branch nick: tridge
timestamp: Thu 2007-06-07 19:17:27 +1000
message:
  choose the most connected node first
modified:
  common/ctdb_recoverd.c         recoverd.c-20070503213540-bvxuyd9jm1f7ig90-1
=== modified file 'common/ctdb_recoverd.c'
--- a/common/ctdb_recoverd.c    2007-06-07 08:39:37 +0000
+++ b/common/ctdb_recoverd.c    2007-06-07 09:17:27 +0000
@@ -790,11 +790,67 @@
 }
 
 
+/*
+  elections are won by first checking the number of connected nodes, then
+  the priority time, then the vnn
+ */
 struct election_message {
+       uint32_t num_connected;
+       struct timeval priority_time;
        uint32_t vnn;
-       struct timeval priority_time;
 };
 
+/*
+  form this nodes election data
+ */
+static void ctdb_election_data(struct ctdb_recoverd *rec, struct 
election_message *em)
+{
+       int ret, i;
+       struct ctdb_node_map *nodemap;
+       struct ctdb_context *ctdb = rec->ctdb;
+
+       ZERO_STRUCTP(em);
+
+       em->vnn = rec->ctdb->vnn;
+       em->priority_time = rec->priority_time;
+
+       ret = ctdb_ctrl_getnodemap(ctdb, CONTROL_TIMEOUT(), CTDB_CURRENT_NODE, 
rec, &nodemap);
+       if (ret != 0) {
+               return;
+       }
+
+       for (i=0;i<nodemap->num;i++) {
+               if (!(nodemap->nodes[i].flags & NODE_FLAGS_DISCONNECTED)) {
+                       em->num_connected++;
+               }
+       }
+       talloc_free(nodemap);
+}
+
+/*
+  see if the given election data wins
+ */
+static bool ctdb_election_win(struct ctdb_recoverd *rec, struct 
election_message *em)
+{
+       struct election_message myem;
+       int cmp;
+
+       ctdb_election_data(rec, &myem);
+
+       /* try to use the most connected node */
+       cmp = (int)myem.num_connected - (int)em->num_connected;
+
+       /* then the longest running node */
+       if (cmp == 0) {
+               cmp = timeval_compare(&myem.priority_time, &em->priority_time);
+       }
+
+       if (cmp == 0) {
+               cmp = (int)myem.vnn - (int)em->vnn;
+       }
+
+       return cmp > 0;
+}
 
 /*
   send out an election request
@@ -809,8 +865,7 @@
        
        srvid = CTDB_SRVID_RECOVERY;
 
-       emsg.vnn = vnn;
-       emsg.priority_time = rec->priority_time;
+       ctdb_election_data(rec, &emsg);
 
        election_data.dsize = sizeof(struct election_message);
        election_data.dptr  = (unsigned char *)&emsg;
@@ -821,7 +876,7 @@
         */
        ret = ctdb_ctrl_setrecmaster(ctdb, CONTROL_TIMEOUT(), vnn, vnn);
        if (ret != 0) {
-               DEBUG(0, (__location__ " failed to send recmaster election 
request"));
+               DEBUG(0, (__location__ " failed to send recmaster election 
request\n"));
                return -1;
        }
 
@@ -843,16 +898,14 @@
        int ret;
        struct election_message *em = (struct election_message *)data.dptr;
        TALLOC_CTX *mem_ctx;
-       int cmp;
 
        mem_ctx = talloc_new(ctdb);
-               
+
        /* someone called an election. check their election data
           and if we disagree and we would rather be the elected node, 
           send a new election message to all other nodes
         */
-       cmp = timeval_compare(&em->priority_time, &rec->priority_time);
-       if (cmp > 0 || (cmp == 0 && em->vnn > ctdb->vnn)) {
+       if (ctdb_election_win(rec, em)) {
                ret = send_election_request(rec, mem_ctx, ctdb_get_vnn(ctdb));
                if (ret!=0) {
                        DEBUG(0, (__location__ " failed to initiate recmaster 
election"));