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

/* 
   monitoring links to all other nodes to detect dead nodes


   Copyright (C) Ronnie Sahlberg 2007

   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/filesys.h"
#include "system/network.h"
#include "system/time.h"
#include "system/wait.h"

#include <talloc.h>
#include <tevent.h>

#include "lib/util/debug.h"
#include "lib/util/samba_util.h"

#include "ctdb_private.h"

#include "common/common.h"
#include "common/logging.h"


/*
  see if any nodes are dead
 */
static void ctdb_check_for_dead_nodes(struct tevent_context *ev,
                                      struct tevent_timer *te,
                                      struct timeval t, void *private_data)
{
        struct ctdb_context *ctdb = talloc_get_type(private_data, struct ctdb_context);
        int i;

        /* send a keepalive to all other nodes, unless */
        for (i=0;i<ctdb->num_nodes;i++) {
                struct ctdb_node *node = ctdb->nodes[i];

                if (node->flags & NODE_FLAGS_DELETED) {
                        continue;
                }

                if (node->pnn == ctdb->pnn) {
                        continue;
                }
                
                if (node->flags & NODE_FLAGS_DISCONNECTED) {
                        /* it might have come alive again */
                        if (node->rx_cnt != 0) {
                                ctdb_node_connected(node);
                        }
                        continue;
                }


                if (node->rx_cnt == 0) {
                        node->dead_count++;
                } else {
                        node->dead_count = 0;
                }

                node->rx_cnt = 0;

                if (node->dead_count >= ctdb->tunable.keepalive_limit) {
                        DEBUG(DEBUG_NOTICE,("dead count reached for node %u\n", node->pnn));
                        ctdb_node_dead(node);
                        ctdb_send_keepalive(ctdb, node->pnn);
                        /* maybe tell the transport layer to kill the
                           sockets as well?
                        */
                        continue;
                }
                
                DEBUG(DEBUG_DEBUG,("sending keepalive to %u\n", node->pnn));
                ctdb_send_keepalive(ctdb, node->pnn);

                node->tx_cnt = 0;
        }

        tevent_add_timer(ctdb->ev, ctdb->keepalive_ctx,
                         timeval_current_ofs(ctdb->tunable.keepalive_interval, 0),
                         ctdb_check_for_dead_nodes, ctdb);
}


void ctdb_start_keepalive(struct ctdb_context *ctdb)
{
        struct tevent_timer *te;

        ctdb->keepalive_ctx = talloc_new(ctdb);
        CTDB_NO_MEMORY_FATAL(ctdb, ctdb->keepalive_ctx);

        te = tevent_add_timer(ctdb->ev, ctdb->keepalive_ctx,
                              timeval_current_ofs(ctdb->tunable.keepalive_interval, 0),
                              ctdb_check_for_dead_nodes, ctdb);
        CTDB_NO_MEMORY_FATAL(ctdb, te);

        DEBUG(DEBUG_NOTICE,("Keepalive monitoring has been started\n"));
}

void ctdb_stop_keepalive(struct ctdb_context *ctdb)
{
        talloc_free(ctdb->keepalive_ctx);
        ctdb->keepalive_ctx = NULL;
}