source: vendor/current/ctdb/server/ipalloc_deterministic.c

/*
   ctdb ip takeover code

   Copyright (C) Ronnie Sahlberg  2007
   Copyright (C) Andrew Tridgell  2007
   Copyright (C) Martin Schwenke  2011

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <http://www.gnu.org/licenses/>.
*/

#include "replace.h"
#include "system/network.h"

#include "lib/util/debug.h"
#include "common/logging.h"

#include "server/ipalloc_private.h"

bool ipalloc_deterministic(struct ipalloc_state *ipalloc_state)
{
        struct public_ip_list *t;
        int i, numnodes;

        numnodes = ipalloc_state->num;

        DEBUG(DEBUG_NOTICE,("Deterministic IPs enabled. Resetting all ip allocations\n"));
       /* Allocate IPs to nodes in a modulo fashion so that IPs will
        *  always be allocated the same way for a specific set of
        *  available/unavailable nodes.
        */

        for (i = 0, t = ipalloc_state->all_ips; t!= NULL; t = t->next, i++) {
                t->pnn = i % numnodes;
        }

        /* IP failback doesn't make sense with deterministic
         * IPs, since the modulo step above implicitly fails
         * back IPs to their "home" node.
         */
        if (1 == ipalloc_state->no_ip_failback) {
                DEBUG(DEBUG_WARNING, ("WARNING: 'NoIPFailback' set but ignored - incompatible with 'DeterministicIPs\n"));
        }

        unassign_unsuitable_ips(ipalloc_state);

        basic_allocate_unassigned(ipalloc_state);

        /* No failback here! */

        return true;
}