ctdb/server/ctdb_update_record.c

   1 /*
   2    implementation of the update record control
   3
   4    Copyright (C) Andrew Tridgell  2007
   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/tevent/tevent.h"
  23 #include "db_wrap.h"
  24 #include "lib/tdb/include/tdb.h"
  25 #include "ctdb_private.h"
  26
  27 struct ctdb_persistent_write_state {
  28         struct ctdb_db_context *ctdb_db;
  29         struct ctdb_marshall_buffer *m;
  30         struct ctdb_req_control *c;
  31 };
  32
  33
  34 /*
  35   called from a child process to write the data
  36  */
  37 static int ctdb_persistent_store(struct ctdb_persistent_write_state *state)
  38 {
  39         int ret, i;
  40         struct ctdb_rec_data *rec = NULL;
  41         struct ctdb_marshall_buffer *m = state->m;
  42
  43         ret = tdb_transaction_start(state->ctdb_db->ltdb->tdb);
  44         if (ret == -1) {
  45                 DEBUG(DEBUG_ERR,("Failed to start transaction for db_id 0x%08x in ctdb_persistent_store\n",
  46                                  state->ctdb_db->db_id));
  47                 return -1;
  48         }
  49
  50         for (i=0;i<m->count;i++) {
  51                 struct ctdb_ltdb_header oldheader;
  52                 struct ctdb_ltdb_header header;
  53                 TDB_DATA key, data, olddata;
  54                 TALLOC_CTX *tmp_ctx = talloc_new(state);
  55
  56                 rec = ctdb_marshall_loop_next(m, rec, NULL, &header, &key, &data);
  57
  58                 if (rec == NULL) {
  59                         DEBUG(DEBUG_ERR,("Failed to get next record %d for db_id 0x%08x in ctdb_persistent_store\n",
  60                                          i, state->ctdb_db->db_id));
  61                         talloc_free(tmp_ctx);
  62                         goto failed;
  63                 }
  64
  65                 /* fetch the old header and ensure the rsn is less than the new rsn */
  66                 ret = ctdb_ltdb_fetch(state->ctdb_db, key, &oldheader, tmp_ctx, &olddata);
  67                 if (ret != 0) {
  68                         DEBUG(DEBUG_ERR,("Failed to fetch old record for db_id 0x%08x in ctdb_persistent_store\n",
  69                                          state->ctdb_db->db_id));
  70                         talloc_free(tmp_ctx);
  71                         goto failed;
  72                 }
  73
  74                 if (oldheader.rsn >= header.rsn &&
  75                     (olddata.dsize != data.dsize ||
  76                      memcmp(olddata.dptr, data.dptr, data.dsize) != 0)) {
  77                         DEBUG(DEBUG_CRIT,("existing header for db_id 0x%08x has larger RSN %llu than new RSN %llu in ctdb_persistent_store\n",
  78                                           state->ctdb_db->db_id,
  79                                           (unsigned long long)oldheader.rsn, (unsigned long long)header.rsn));
  80                         talloc_free(tmp_ctx);
  81                         goto failed;
  82                 }
  83
  84                 talloc_free(tmp_ctx);
  85
  86                 ret = ctdb_ltdb_store(state->ctdb_db, key, &header, data);
  87                 if (ret != 0) {
  88                         DEBUG(DEBUG_CRIT,("Failed to store record for db_id 0x%08x in ctdb_persistent_store\n",
  89                                           state->ctdb_db->db_id));
  90                         goto failed;
  91                 }
  92         }
  93
  94         ret = tdb_transaction_commit(state->ctdb_db->ltdb->tdb);
  95         if (ret == -1) {
  96                 DEBUG(DEBUG_ERR,("Failed to commit transaction for db_id 0x%08x in ctdb_persistent_store\n",
  97                                  state->ctdb_db->db_id));
  98                 return -1;
  99         }
 100
 101         return 0;
 102
 103 failed:
 104         tdb_transaction_cancel(state->ctdb_db->ltdb->tdb);
 105         return -1;
 106 }
 107
 108
 109 /*
 110   called when we the child has completed the persistent write
 111   on our behalf
 112  */
 113 static void ctdb_persistent_write_callback(int status, void *private_data)
 114 {
 115         struct ctdb_persistent_write_state *state = talloc_get_type(private_data,
 116                                                                    struct ctdb_persistent_write_state);
 117
 118
 119         ctdb_request_control_reply(state->ctdb_db->ctdb, state->c, NULL, status, NULL);
 120
 121         talloc_free(state);
 122 }
 123
 124 /*
 125   called if our lockwait child times out
 126  */
 127 static void ctdb_persistent_lock_timeout(struct event_context *ev, struct timed_event *te,
 128                                          struct timeval t, void *private_data)
 129 {
 130         struct ctdb_persistent_write_state *state = talloc_get_type(private_data,
 131                                                                    struct ctdb_persistent_write_state);
 132         ctdb_request_control_reply(state->ctdb_db->ctdb, state->c, NULL, -1, "timeout in ctdb_persistent_lock");
 133         talloc_free(state);
 134 }
 135
 136 struct childwrite_handle {
 137         struct ctdb_context *ctdb;
 138         struct ctdb_db_context *ctdb_db;
 139         struct fd_event *fde;
 140         int fd[2];
 141         pid_t child;
 142         void *private_data;
 143         void (*callback)(int, void *);
 144         struct timeval start_time;
 145 };
 146
 147 static int childwrite_destructor(struct childwrite_handle *h)
 148 {
 149         CTDB_DECREMENT_STAT(h->ctdb, pending_childwrite_calls);
 150         kill(h->child, SIGKILL);
 151         return 0;
 152 }
 153
 154 /* called when the child process has finished writing the record to the
 155    database
 156 */
 157 static void childwrite_handler(struct event_context *ev, struct fd_event *fde,
 158                              uint16_t flags, void *private_data)
 159 {
 160         struct childwrite_handle *h = talloc_get_type(private_data,
 161                                                      struct childwrite_handle);
 162         void *p = h->private_data;
 163         void (*callback)(int, void *) = h->callback;
 164         pid_t child = h->child;
 165         TALLOC_CTX *tmp_ctx = talloc_new(ev);
 166         int ret;
 167         char c;
 168
 169         CTDB_UPDATE_LATENCY(h->ctdb, h->ctdb_db, "persistent", childwrite_latency, h->start_time);
 170         CTDB_DECREMENT_STAT(h->ctdb, pending_childwrite_calls);
 171
 172         /* the handle needs to go away when the context is gone - when
 173            the handle goes away this implicitly closes the pipe, which
 174            kills the child */
 175         talloc_steal(tmp_ctx, h);
 176
 177         talloc_set_destructor(h, NULL);
 178
 179         ret = read(h->fd[0], &c, 1);
 180         if (ret < 1) {
 181                 DEBUG(DEBUG_ERR, (__location__ " Read returned %d. Childwrite failed\n", ret));
 182                 c = 1;
 183         }
 184
 185         callback(c, p);
 186
 187         kill(child, SIGKILL);
 188         talloc_free(tmp_ctx);
 189 }
 190
 191 /* this creates a child process which will take out a tdb transaction
 192    and write the record to the database.
 193 */
 194 struct childwrite_handle *ctdb_childwrite(struct ctdb_db_context *ctdb_db,
 195                                 void (*callback)(int, void *private_data),
 196                                 struct ctdb_persistent_write_state *state)
 197 {
 198         struct childwrite_handle *result;
 199         int ret;
 200         pid_t parent = getpid();
 201
 202         CTDB_INCREMENT_STAT(ctdb_db->ctdb, childwrite_calls);
 203         CTDB_INCREMENT_STAT(ctdb_db->ctdb, pending_childwrite_calls);
 204
 205         if (!(result = talloc_zero(state, struct childwrite_handle))) {
 206                 CTDB_DECREMENT_STAT(ctdb_db->ctdb, pending_childwrite_calls);
 207                 return NULL;
 208         }
 209
 210         ret = pipe(result->fd);
 211
 212         if (ret != 0) {
 213                 talloc_free(result);
 214                 CTDB_DECREMENT_STAT(ctdb_db->ctdb, pending_childwrite_calls);
 215                 return NULL;
 216         }
 217
 218         result->child = ctdb_fork(ctdb_db->ctdb);
 219
 220         if (result->child == (pid_t)-1) {
 221                 close(result->fd[0]);
 222                 close(result->fd[1]);
 223                 talloc_free(result);
 224                 CTDB_DECREMENT_STAT(ctdb_db->ctdb, pending_childwrite_calls);
 225                 return NULL;
 226         }
 227
 228         result->callback = callback;
 229         result->private_data = state;
 230         result->ctdb = ctdb_db->ctdb;
 231         result->ctdb_db = ctdb_db;
 232
 233         if (result->child == 0) {
 234                 char c = 0;
 235
 236                 close(result->fd[0]);
 237                 debug_extra = talloc_asprintf(NULL, "childwrite-%s:", ctdb_db->db_name);
 238                 ret = ctdb_persistent_store(state);
 239                 if (ret != 0) {
 240                         DEBUG(DEBUG_ERR, (__location__ " Failed to write persistent data\n"));
 241                         c = 1;
 242                 }
 243
 244                 write(result->fd[1], &c, 1);
 245
 246                 /* make sure we die when our parent dies */
 247                 while (kill(parent, 0) == 0 || errno != ESRCH) {
 248                         sleep(5);
 249                 }
 250                 _exit(0);
 251         }
 252
 253         close(result->fd[1]);
 254         set_close_on_exec(result->fd[0]);
 255
 256         talloc_set_destructor(result, childwrite_destructor);
 257
 258         DEBUG(DEBUG_DEBUG, (__location__ " Created PIPE FD:%d for ctdb_childwrite\n", result->fd[0]));
 259
 260         result->fde = event_add_fd(ctdb_db->ctdb->ev, result, result->fd[0],
 261                                    EVENT_FD_READ, childwrite_handler,
 262                                    (void *)result);
 263         if (result->fde == NULL) {
 264                 talloc_free(result);
 265                 CTDB_DECREMENT_STAT(ctdb_db->ctdb, pending_childwrite_calls);
 266                 return NULL;
 267         }
 268         tevent_fd_set_auto_close(result->fde);
 269
 270         result->start_time = timeval_current();
 271
 272         return result;
 273 }
 274
 275 /*
 276    update a record on this node if the new record has a higher rsn than the
 277    current record
 278  */
 279 int32_t ctdb_control_update_record(struct ctdb_context *ctdb,
 280                                    struct ctdb_req_control *c, TDB_DATA recdata,
 281                                    bool *async_reply)
 282 {
 283         struct ctdb_db_context *ctdb_db;
 284         struct ctdb_persistent_write_state *state;
 285         struct childwrite_handle *handle;
 286         struct ctdb_marshall_buffer *m = (struct ctdb_marshall_buffer *)recdata.dptr;
 287
 288         if (ctdb->recovery_mode != CTDB_RECOVERY_NORMAL) {
 289                 DEBUG(DEBUG_INFO,("rejecting ctdb_control_update_record when recovery active\n"));
 290                 return -1;
 291         }
 292
 293         ctdb_db = find_ctdb_db(ctdb, m->db_id);
 294         if (ctdb_db == NULL) {
 295                 DEBUG(DEBUG_ERR,("Unknown database 0x%08x in ctdb_control_update_record\n", m->db_id));
 296                 return -1;
 297         }
 298
 299         if (ctdb_db->unhealthy_reason) {
 300                 DEBUG(DEBUG_ERR,("db(%s) unhealty in ctdb_control_update_record: %s\n",
 301                                  ctdb_db->db_name, ctdb_db->unhealthy_reason));
 302                 return -1;
 303         }
 304
 305         state = talloc(ctdb, struct ctdb_persistent_write_state);
 306         CTDB_NO_MEMORY(ctdb, state);
 307
 308         state->ctdb_db = ctdb_db;
 309         state->c       = c;
 310         state->m       = m;
 311
 312         /* create a child process to take out a transaction and
 313            write the data.
 314         */
 315         handle = ctdb_childwrite(ctdb_db, ctdb_persistent_write_callback, state);
 316         if (handle == NULL) {
 317                 DEBUG(DEBUG_ERR,("Failed to setup childwrite handler in ctdb_control_update_record\n"));
 318                 talloc_free(state);
 319                 return -1;
 320         }
 321
 322         /* we need to wait for the replies */
 323         *async_reply = true;
 324
 325         /* need to keep the control structure around */
 326         talloc_steal(state, c);
 327
 328         /* but we won't wait forever */
 329         event_add_timed(ctdb->ev, state, timeval_current_ofs(ctdb->tunable.control_timeout, 0),
 330                         ctdb_persistent_lock_timeout, state);
 331
 332         return 0;
 333 }
 334