server/ctdb_monitor.c

   1 /*
   2    monitoring links to all other nodes to detect dead nodes
   3
   4
   5    Copyright (C) Ronnie Sahlberg 2007
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22 #include "lib/events/events.h"
  23 #include "system/filesys.h"
  24 #include "system/wait.h"
  25 #include "../include/ctdb_private.h"
  26
  27 /*
  28   see if any nodes are dead
  29  */
  30 static void ctdb_check_for_dead_nodes(struct event_context *ev, struct timed_event *te,
  31                                       struct timeval t, void *private_data)
  32 {
  33         struct ctdb_context *ctdb = talloc_get_type(private_data, struct ctdb_context);
  34         int i;
  35
  36         if (ctdb->monitoring_mode == CTDB_MONITORING_DISABLED) {
  37                 event_add_timed(ctdb->ev, ctdb->monitor_context,
  38                         timeval_current_ofs(ctdb->tunable.keepalive_interval, 0),
  39                         ctdb_check_for_dead_nodes, ctdb);
  40                 return;
  41         }
  42
  43         /* send a keepalive to all other nodes, unless */
  44         for (i=0;i<ctdb->num_nodes;i++) {
  45                 struct ctdb_node *node = ctdb->nodes[i];
  46                 if (node->pnn == ctdb->pnn) {
  47                         continue;
  48                 }
  49
  50                 if (node->flags & NODE_FLAGS_DISCONNECTED) {
  51                         /* it might have come alive again */
  52                         if (node->rx_cnt != 0) {
  53                                 ctdb_node_connected(node);
  54                         }
  55                         continue;
  56                 }
  57
  58
  59                 if (node->rx_cnt == 0) {
  60                         node->dead_count++;
  61                 } else {
  62                         node->dead_count = 0;
  63                 }
  64
  65                 node->rx_cnt = 0;
  66
  67                 if (node->dead_count >= ctdb->tunable.keepalive_limit) {
  68                         DEBUG(0,("dead count reached for node %u\n", node->pnn));
  69                         ctdb_node_dead(node);
  70                         ctdb_send_keepalive(ctdb, node->pnn);
  71                         /* maybe tell the transport layer to kill the
  72                            sockets as well?
  73                         */
  74                         continue;
  75                 }
  76
  77                 if (node->tx_cnt == 0) {
  78                         DEBUG(5,("sending keepalive to %u\n", node->pnn));
  79                         ctdb_send_keepalive(ctdb, node->pnn);
  80                 }
  81
  82                 node->tx_cnt = 0;
  83         }
  84
  85         event_add_timed(ctdb->ev, ctdb->monitor_context,
  86                         timeval_current_ofs(ctdb->tunable.keepalive_interval, 0),
  87                         ctdb_check_for_dead_nodes, ctdb);
  88 }
  89
  90 static void ctdb_check_health(struct event_context *ev, struct timed_event *te,
  91                               struct timeval t, void *private_data);
  92
  93 /*
  94   called when a health monitoring event script finishes
  95  */
  96 static void ctdb_health_callback(struct ctdb_context *ctdb, int status, void *p)
  97 {
  98         struct ctdb_node *node = ctdb->nodes[ctdb->pnn];
  99         TDB_DATA data;
 100         struct ctdb_node_flag_change c;
 101         uint32_t next_interval;
 102
 103         c.pnn = ctdb->pnn;
 104         c.old_flags = node->flags;
 105
 106         if (status != 0 && !(node->flags & NODE_FLAGS_UNHEALTHY)) {
 107                 DEBUG(0,("monitor event failed - disabling node\n"));
 108                 node->flags |= NODE_FLAGS_UNHEALTHY;
 109         } else if (status == 0 && (node->flags & NODE_FLAGS_UNHEALTHY)) {
 110                 DEBUG(0,("monitor event OK - node re-enabled\n"));
 111                 node->flags &= ~NODE_FLAGS_UNHEALTHY;
 112         }
 113
 114         if (node->flags & NODE_FLAGS_UNHEALTHY) {
 115                 next_interval = ctdb->tunable.monitor_retry;
 116         } else {
 117                 next_interval = ctdb->tunable.monitor_interval;
 118         }
 119
 120         event_add_timed(ctdb->ev, ctdb->monitor_context,
 121                         timeval_current_ofs(next_interval, 0),
 122                         ctdb_check_health, ctdb);
 123
 124         if (c.old_flags == node->flags) {
 125                 return;
 126         }
 127
 128         c.new_flags = node->flags;
 129
 130         data.dptr = (uint8_t *)&c;
 131         data.dsize = sizeof(c);
 132
 133         /* tell the other nodes that something has changed */
 134         ctdb_daemon_send_message(ctdb, CTDB_BROADCAST_CONNECTED,
 135                                  CTDB_SRVID_NODE_FLAGS_CHANGED, data);
 136
 137 }
 138
 139
 140 /*
 141   called when the startup event script finishes
 142  */
 143 static void ctdb_startup_callback(struct ctdb_context *ctdb, int status, void *p)
 144 {
 145         if (status != 0) {
 146                 DEBUG(0,("startup event failed\n"));
 147         } else if (status == 0) {
 148                 DEBUG(0,("startup event OK - enabling monitoring\n"));
 149                 ctdb->done_startup = true;
 150         }
 151
 152         if (ctdb->done_startup) {
 153                 event_add_timed(ctdb->ev, ctdb->monitor_context,
 154                                 timeval_zero(),
 155                                 ctdb_check_health, ctdb);
 156         } else {
 157                 event_add_timed(ctdb->ev, ctdb->monitor_context,
 158                                 timeval_current_ofs(ctdb->tunable.monitor_interval, 0),
 159                                 ctdb_check_health, ctdb);
 160         }
 161
 162 }
 163
 164
 165 /*
 166   see if the event scripts think we are healthy
 167  */
 168 static void ctdb_check_health(struct event_context *ev, struct timed_event *te,
 169                               struct timeval t, void *private_data)
 170 {
 171         struct ctdb_context *ctdb = talloc_get_type(private_data, struct ctdb_context);
 172         int ret;
 173
 174         if (ctdb->monitoring_mode == CTDB_MONITORING_DISABLED && ctdb->done_startup) {
 175                 event_add_timed(ctdb->ev, ctdb->monitor_context,
 176                                 timeval_current_ofs(ctdb->tunable.monitor_interval, 0),
 177                                 ctdb_check_health, ctdb);
 178                 return;
 179         }
 180
 181         if (!ctdb->done_startup) {
 182                 ret = ctdb_event_script_callback(ctdb,
 183                                                  timeval_current_ofs(ctdb->tunable.script_timeout, 0),
 184                                                  ctdb->monitor_context, ctdb_startup_callback,
 185                                                  ctdb, "startup");
 186         } else {
 187                 ret = ctdb_event_script_callback(ctdb,
 188                                                  timeval_current_ofs(ctdb->tunable.script_timeout, 0),
 189                                                  ctdb->monitor_context, ctdb_health_callback,
 190                                                  ctdb, "monitor");
 191         }
 192
 193         if (ret != 0) {
 194                 DEBUG(0,("Unable to launch monitor event script\n"));
 195                 event_add_timed(ctdb->ev, ctdb->monitor_context,
 196                                 timeval_current_ofs(ctdb->tunable.monitor_retry, 0),
 197                                 ctdb_check_health, ctdb);
 198         }
 199 }
 200
 201 /* stop any monitoring */
 202 void ctdb_stop_monitoring(struct ctdb_context *ctdb)
 203 {
 204         talloc_free(ctdb->monitor_context);
 205         ctdb->monitor_context = talloc_new(ctdb);
 206         CTDB_NO_MEMORY_FATAL(ctdb, ctdb->monitor_context);
 207 }
 208
 209 /*
 210   start watching for nodes that might be dead
 211  */
 212 void ctdb_start_monitoring(struct ctdb_context *ctdb)
 213 {
 214         struct timed_event *te;
 215
 216         ctdb_stop_monitoring(ctdb);
 217
 218         te = event_add_timed(ctdb->ev, ctdb->monitor_context,
 219                              timeval_current_ofs(ctdb->tunable.keepalive_interval, 0),
 220                              ctdb_check_for_dead_nodes, ctdb);
 221         CTDB_NO_MEMORY_FATAL(ctdb, te);
 222
 223         te = event_add_timed(ctdb->ev, ctdb->monitor_context,
 224                              timeval_current_ofs(ctdb->tunable.monitor_retry, 0),
 225                              ctdb_check_health, ctdb);
 226         CTDB_NO_MEMORY_FATAL(ctdb, te);
 227 }
 228
 229
 230 /*
 231   modify flags on a node
 232  */
 233 int32_t ctdb_control_modflags(struct ctdb_context *ctdb, TDB_DATA indata)
 234 {
 235         struct ctdb_node_modflags *m = (struct ctdb_node_modflags *)indata.dptr;
 236         TDB_DATA data;
 237         struct ctdb_node_flag_change c;
 238         struct ctdb_node *node = ctdb->nodes[ctdb->pnn];
 239         uint32_t old_flags = node->flags;
 240
 241         node->flags |= m->set;
 242         node->flags &= ~m->clear;
 243
 244         if (node->flags == old_flags) {
 245                 /* no change */
 246                 return 0;
 247         }
 248
 249         DEBUG(0, ("Control modflags on node %u - flags now 0x%x\n", ctdb->pnn, node->flags));
 250
 251         /* if we have been banned, go into recovery mode */
 252         c.pnn = ctdb->pnn;
 253         c.old_flags = old_flags;
 254         c.new_flags = node->flags;
 255
 256         data.dptr = (uint8_t *)&c;
 257         data.dsize = sizeof(c);
 258
 259         /* tell the other nodes that something has changed */
 260         ctdb_daemon_send_message(ctdb, CTDB_BROADCAST_CONNECTED,
 261                                  CTDB_SRVID_NODE_FLAGS_CHANGED, data);
 262
 263         if ((node->flags & NODE_FLAGS_BANNED) && !(old_flags & NODE_FLAGS_BANNED)) {
 264                 /* make sure we are frozen */
 265                 DEBUG(0,("This node has been banned - forcing freeze and recovery\n"));
 266                 /* Reset the generation id to 1 to make us ignore any
 267                    REQ/REPLY CALL/DMASTER someone sends to us.
 268                    We are now banned so we shouldnt service database calls
 269                    anymore.
 270                 */
 271                 ctdb->vnn_map->generation = INVALID_GENERATION;
 272
 273                 ctdb_start_freeze(ctdb);
 274                 ctdb_release_all_ips(ctdb);
 275                 ctdb->recovery_mode = CTDB_RECOVERY_ACTIVE;
 276         }
 277
 278         return 0;
 279 }