ctdb/server/ctdb_lock.c

   1 /*
   2    ctdb lock handling
   3    provide API to do non-blocking locks for single or all databases
   4
   5    Copyright (C) Amitay Isaacs  2012
   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 #include "replace.h"
  21 #include "system/filesys.h"
  22 #include "system/network.h"
  23
  24 #include <talloc.h>
  25 #include <tevent.h>
  26
  27 #include "lib/tdb_wrap/tdb_wrap.h"
  28 #include "lib/util/dlinklist.h"
  29 #include "lib/util/debug.h"
  30 #include "lib/util/samba_util.h"
  31 #include "lib/util/sys_rw.h"
  32
  33 #include "ctdb_private.h"
  34
  35 #include "common/common.h"
  36 #include "common/logging.h"
  37
  38 /*
  39  * Non-blocking Locking API
  40  *
  41  * 1. Create a child process to do blocking locks.
  42  * 2. Once the locks are obtained, signal parent process via fd.
  43  * 3. Invoke registered callback routine with locking status.
  44  * 4. If the child process cannot get locks within certain time,
  45  *    execute an external script to debug.
  46  *
  47  * ctdb_lock_record()      - get a lock on a record
  48  * ctdb_lock_db()          - get a lock on a DB
  49  *
  50  *  auto_mark              - whether to mark/unmark DBs in before/after callback
  51  *                           = false is used for freezing databases for
  52  *                           recovery since the recovery cannot start till
  53  *                           databases are locked on all the nodes.
  54  *                           = true is used for record locks.
  55  */
  56
  57 enum lock_type {
  58         LOCK_RECORD,
  59         LOCK_DB,
  60 };
  61
  62 static const char * const lock_type_str[] = {
  63         "lock_record",
  64         "lock_db",
  65 };
  66
  67 struct lock_request;
  68
  69 /* lock_context is the common part for a lock request */
  70 struct lock_context {
  71         struct lock_context *next, *prev;
  72         enum lock_type type;
  73         struct ctdb_context *ctdb;
  74         struct ctdb_db_context *ctdb_db;
  75         TDB_DATA key;
  76         uint32_t priority;
  77         bool auto_mark;
  78         struct lock_request *request;
  79         pid_t child;
  80         int fd[2];
  81         struct tevent_fd *tfd;
  82         struct tevent_timer *ttimer;
  83         struct timeval start_time;
  84         uint32_t key_hash;
  85         bool can_schedule;
  86 };
  87
  88 /* lock_request is the client specific part for a lock request */
  89 struct lock_request {
  90         struct lock_context *lctx;
  91         void (*callback)(void *, bool);
  92         void *private_data;
  93 };
  94
  95
  96 int ctdb_db_iterator(struct ctdb_context *ctdb, ctdb_db_handler_t handler,
  97                      void *private_data)
  98 {
  99         struct ctdb_db_context *ctdb_db;
 100         int ret;
 101
 102         for (ctdb_db = ctdb->db_list; ctdb_db; ctdb_db = ctdb_db->next) {
 103                 ret = handler(ctdb_db, private_data);
 104                 if (ret != 0) {
 105                         return -1;
 106                 }
 107         }
 108
 109         return 0;
 110 }
 111
 112 /*
 113  * lock all databases - mark only
 114  */
 115 static int db_lock_mark_handler(struct ctdb_db_context *ctdb_db,
 116                                 void *private_data)
 117 {
 118         int tdb_transaction_write_lock_mark(struct tdb_context *);
 119
 120         DEBUG(DEBUG_INFO, ("marking locked database %s\n", ctdb_db->db_name));
 121
 122         if (tdb_transaction_write_lock_mark(ctdb_db->ltdb->tdb) != 0) {
 123                 DEBUG(DEBUG_ERR, ("Failed to mark (transaction lock) database %s\n",
 124                                   ctdb_db->db_name));
 125                 return -1;
 126         }
 127
 128         if (tdb_lockall_mark(ctdb_db->ltdb->tdb) != 0) {
 129                 DEBUG(DEBUG_ERR, ("Failed to mark (all lock) database %s\n",
 130                                   ctdb_db->db_name));
 131                 return -1;
 132         }
 133
 134         return 0;
 135 }
 136
 137 int ctdb_lockdb_mark(struct ctdb_db_context *ctdb_db)
 138 {
 139         if (!ctdb_db_frozen(ctdb_db)) {
 140                 DEBUG(DEBUG_ERR,
 141                       ("Attempt to mark database locked when not frozen\n"));
 142                 return -1;
 143         }
 144
 145         return db_lock_mark_handler(ctdb_db, NULL);
 146 }
 147
 148 /*
 149  * lock all databases - unmark only
 150  */
 151 static int db_lock_unmark_handler(struct ctdb_db_context *ctdb_db,
 152                                   void *private_data)
 153 {
 154         int tdb_transaction_write_lock_unmark(struct tdb_context *);
 155
 156         DEBUG(DEBUG_INFO, ("unmarking locked database %s\n", ctdb_db->db_name));
 157
 158         if (tdb_transaction_write_lock_unmark(ctdb_db->ltdb->tdb) != 0) {
 159                 DEBUG(DEBUG_ERR, ("Failed to unmark (transaction lock) database %s\n",
 160                                   ctdb_db->db_name));
 161                 return -1;
 162         }
 163
 164         if (tdb_lockall_unmark(ctdb_db->ltdb->tdb) != 0) {
 165                 DEBUG(DEBUG_ERR, ("Failed to unmark (all lock) database %s\n",
 166                                   ctdb_db->db_name));
 167                 return -1;
 168         }
 169
 170         return 0;
 171 }
 172
 173 int ctdb_lockdb_unmark(struct ctdb_db_context *ctdb_db)
 174 {
 175         if (!ctdb_db_frozen(ctdb_db)) {
 176                 DEBUG(DEBUG_ERR,
 177                       ("Attempt to unmark database locked when not frozen\n"));
 178                 return -1;
 179         }
 180
 181         return db_lock_unmark_handler(ctdb_db, NULL);
 182 }
 183
 184 static void ctdb_lock_schedule(struct ctdb_context *ctdb);
 185
 186 /*
 187  * Destructor to kill the child locking process
 188  */
 189 static int ctdb_lock_context_destructor(struct lock_context *lock_ctx)
 190 {
 191         if (lock_ctx->request) {
 192                 lock_ctx->request->lctx = NULL;
 193         }
 194         if (lock_ctx->child > 0) {
 195                 ctdb_kill(lock_ctx->ctdb, lock_ctx->child, SIGTERM);
 196                 if (lock_ctx->type == LOCK_RECORD) {
 197                         DLIST_REMOVE(lock_ctx->ctdb_db->lock_current, lock_ctx);
 198                 } else {
 199                         DLIST_REMOVE(lock_ctx->ctdb->lock_current, lock_ctx);
 200                 }
 201                 if (lock_ctx->ctdb_db) {
 202                         lock_ctx->ctdb_db->lock_num_current--;
 203                 }
 204                 CTDB_DECREMENT_STAT(lock_ctx->ctdb, locks.num_current);
 205                 if (lock_ctx->ctdb_db) {
 206                         CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_current);
 207                 }
 208         } else {
 209                 if (lock_ctx->type == LOCK_RECORD) {
 210                         DLIST_REMOVE(lock_ctx->ctdb_db->lock_pending, lock_ctx);
 211                 } else {
 212                         DLIST_REMOVE(lock_ctx->ctdb->lock_pending, lock_ctx);
 213                 }
 214                 CTDB_DECREMENT_STAT(lock_ctx->ctdb, locks.num_pending);
 215                 if (lock_ctx->ctdb_db) {
 216                         CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_pending);
 217                 }
 218         }
 219
 220         ctdb_lock_schedule(lock_ctx->ctdb);
 221
 222         return 0;
 223 }
 224
 225
 226 /*
 227  * Destructor to remove lock request
 228  */
 229 static int ctdb_lock_request_destructor(struct lock_request *lock_request)
 230 {
 231         if (lock_request->lctx == NULL) {
 232                 return 0;
 233         }
 234
 235         lock_request->lctx->request = NULL;
 236         TALLOC_FREE(lock_request->lctx);
 237
 238         return 0;
 239 }
 240
 241 /*
 242  * Process all the callbacks waiting for lock
 243  *
 244  * If lock has failed, callback is executed with locked=false
 245  */
 246 static void process_callbacks(struct lock_context *lock_ctx, bool locked)
 247 {
 248         struct lock_request *request;
 249         bool auto_mark = lock_ctx->auto_mark;
 250
 251         if (auto_mark && locked) {
 252                 switch (lock_ctx->type) {
 253                 case LOCK_RECORD:
 254                         tdb_chainlock_mark(lock_ctx->ctdb_db->ltdb->tdb, lock_ctx->key);
 255                         break;
 256
 257                 case LOCK_DB:
 258                         ctdb_lockdb_mark(lock_ctx->ctdb_db);
 259                         break;
 260                 }
 261         }
 262
 263         request = lock_ctx->request;
 264         if (auto_mark) {
 265                 /* Since request may be freed in the callback, unset the lock
 266                  * context, so request destructor will not free lock context.
 267                  */
 268                 request->lctx = NULL;
 269         }
 270
 271         /* Since request may be freed in the callback, unset the request */
 272         lock_ctx->request = NULL;
 273
 274         request->callback(request->private_data, locked);
 275
 276         if (!auto_mark) {
 277                 return;
 278         }
 279
 280         if (locked) {
 281                 switch (lock_ctx->type) {
 282                 case LOCK_RECORD:
 283                         tdb_chainlock_unmark(lock_ctx->ctdb_db->ltdb->tdb, lock_ctx->key);
 284                         break;
 285
 286                 case LOCK_DB:
 287                         ctdb_lockdb_unmark(lock_ctx->ctdb_db);
 288                         break;
 289                 }
 290         }
 291
 292         talloc_free(lock_ctx);
 293 }
 294
 295
 296 static int lock_bucket_id(double t)
 297 {
 298         double ms = 1.e-3, s = 1;
 299         int id;
 300
 301         if (t < 1*ms) {
 302                 id = 0;
 303         } else if (t < 10*ms) {
 304                 id = 1;
 305         } else if (t < 100*ms) {
 306                 id = 2;
 307         } else if (t < 1*s) {
 308                 id = 3;
 309         } else if (t < 2*s) {
 310                 id = 4;
 311         } else if (t < 4*s) {
 312                 id = 5;
 313         } else if (t < 8*s) {
 314                 id = 6;
 315         } else if (t < 16*s) {
 316                 id = 7;
 317         } else if (t < 32*s) {
 318                 id = 8;
 319         } else if (t < 64*s) {
 320                 id = 9;
 321         } else {
 322                 id = 10;
 323         }
 324
 325         return id;
 326 }
 327
 328 /*
 329  * Callback routine when the required locks are obtained.
 330  * Called from parent context
 331  */
 332 static void ctdb_lock_handler(struct tevent_context *ev,
 333                             struct tevent_fd *tfd,
 334                             uint16_t flags,
 335                             void *private_data)
 336 {
 337         struct lock_context *lock_ctx;
 338         char c;
 339         bool locked;
 340         double t;
 341         int id;
 342
 343         lock_ctx = talloc_get_type_abort(private_data, struct lock_context);
 344
 345         /* cancel the timeout event */
 346         TALLOC_FREE(lock_ctx->ttimer);
 347
 348         t = timeval_elapsed(&lock_ctx->start_time);
 349         id = lock_bucket_id(t);
 350
 351         /* Read the status from the child process */
 352         if (sys_read(lock_ctx->fd[0], &c, 1) != 1) {
 353                 locked = false;
 354         } else {
 355                 locked = (c == 0 ? true : false);
 356         }
 357
 358         /* Update statistics */
 359         CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.num_calls);
 360         if (lock_ctx->ctdb_db) {
 361                 CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_calls);
 362         }
 363
 364         if (locked) {
 365                 if (lock_ctx->ctdb_db) {
 366                         CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.buckets[id]);
 367                         CTDB_UPDATE_LATENCY(lock_ctx->ctdb, lock_ctx->ctdb_db,
 368                                             lock_type_str[lock_ctx->type], locks.latency,
 369                                             lock_ctx->start_time);
 370
 371                         CTDB_UPDATE_DB_LATENCY(lock_ctx->ctdb_db, lock_type_str[lock_ctx->type], locks.latency, t);
 372                         CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.buckets[id]);
 373                 }
 374         } else {
 375                 CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.num_failed);
 376                 if (lock_ctx->ctdb_db) {
 377                         CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_failed);
 378                 }
 379         }
 380
 381         process_callbacks(lock_ctx, locked);
 382 }
 383
 384
 385 /*
 386  * Callback routine when required locks are not obtained within timeout
 387  * Called from parent context
 388  */
 389 static void ctdb_lock_timeout_handler(struct tevent_context *ev,
 390                                     struct tevent_timer *ttimer,
 391                                     struct timeval current_time,
 392                                     void *private_data)
 393 {
 394         static char debug_locks[PATH_MAX+1] = "";
 395         static struct timeval last_debug_time;
 396         struct lock_context *lock_ctx;
 397         struct ctdb_context *ctdb;
 398         struct timeval now;
 399         pid_t pid;
 400         double elapsed_time;
 401         int new_timer;
 402
 403         lock_ctx = talloc_get_type_abort(private_data, struct lock_context);
 404         ctdb = lock_ctx->ctdb;
 405
 406         elapsed_time = timeval_elapsed(&lock_ctx->start_time);
 407         DEBUG(DEBUG_WARNING,
 408               ("Unable to get %s lock on database %s for %.0lf seconds\n",
 409                (lock_ctx->type == LOCK_RECORD ? "RECORD" : "DB"),
 410                lock_ctx->ctdb_db->db_name, elapsed_time));
 411
 412         /* If a node stopped/banned, don't spam the logs */
 413         if (ctdb->nodes[ctdb->pnn]->flags & NODE_FLAGS_INACTIVE) {
 414                 goto skip_lock_debug;
 415         }
 416
 417         /* Restrict log debugging to once per second */
 418         now = timeval_current();
 419         if (last_debug_time.tv_sec == now.tv_sec) {
 420                 goto skip_lock_debug;
 421         }
 422
 423         last_debug_time.tv_sec = now.tv_sec;
 424
 425         if (ctdb_set_helper("lock debugging helper",
 426                             debug_locks, sizeof(debug_locks),
 427                             "CTDB_DEBUG_LOCKS",
 428                             getenv("CTDB_BASE"), "debug_locks.sh")) {
 429                 pid = vfork();
 430                 if (pid == 0) {
 431                         execl(debug_locks, debug_locks, NULL);
 432                         _exit(0);
 433                 }
 434                 ctdb_track_child(ctdb, pid);
 435         } else {
 436                 DEBUG(DEBUG_WARNING,
 437                       (__location__
 438                        " Unable to setup lock debugging\n"));
 439         }
 440
 441 skip_lock_debug:
 442
 443         /* Back-off logging if lock is not obtained for a long time */
 444         if (elapsed_time < 100.0) {
 445                 new_timer = 10;
 446         } else if (elapsed_time < 1000.0) {
 447                 new_timer = 100;
 448         } else {
 449                 new_timer = 1000;
 450         }
 451
 452         /* reset the timeout timer */
 453         // talloc_free(lock_ctx->ttimer);
 454         lock_ctx->ttimer = tevent_add_timer(ctdb->ev,
 455                                             lock_ctx,
 456                                             timeval_current_ofs(new_timer, 0),
 457                                             ctdb_lock_timeout_handler,
 458                                             (void *)lock_ctx);
 459 }
 460
 461 static int db_flags(struct ctdb_db_context *ctdb_db)
 462 {
 463         int tdb_flags = TDB_DEFAULT;
 464
 465 #ifdef TDB_MUTEX_LOCKING
 466         if (!ctdb_db->persistent && ctdb_db->ctdb->tunable.mutex_enabled) {
 467                 tdb_flags = (TDB_MUTEX_LOCKING | TDB_CLEAR_IF_FIRST);
 468         }
 469 #endif
 470         return tdb_flags;
 471 }
 472
 473 static bool lock_helper_args(TALLOC_CTX *mem_ctx,
 474                              struct lock_context *lock_ctx, int fd,
 475                              int *argc, const char ***argv)
 476 {
 477         const char **args = NULL;
 478         int nargs = 0, i;
 479
 480         switch (lock_ctx->type) {
 481         case LOCK_RECORD:
 482                 nargs = 6;
 483                 break;
 484
 485         case LOCK_DB:
 486                 nargs = 5;
 487                 break;
 488         }
 489
 490         /* Add extra argument for null termination */
 491         nargs++;
 492
 493         args = talloc_array(mem_ctx, const char *, nargs);
 494         if (args == NULL) {
 495                 return false;
 496         }
 497
 498         args[0] = talloc_asprintf(args, "%d", getpid());
 499         args[1] = talloc_asprintf(args, "%d", fd);
 500
 501         switch (lock_ctx->type) {
 502         case LOCK_RECORD:
 503                 args[2] = talloc_strdup(args, "RECORD");
 504                 args[3] = talloc_strdup(args, lock_ctx->ctdb_db->db_path);
 505                 args[4] = talloc_asprintf(args, "0x%x",
 506                                           db_flags(lock_ctx->ctdb_db));
 507                 if (lock_ctx->key.dsize == 0) {
 508                         args[5] = talloc_strdup(args, "NULL");
 509                 } else {
 510                         args[5] = hex_encode_talloc(args, lock_ctx->key.dptr, lock_ctx->key.dsize);
 511                 }
 512                 break;
 513
 514         case LOCK_DB:
 515                 args[2] = talloc_strdup(args, "DB");
 516                 args[3] = talloc_strdup(args, lock_ctx->ctdb_db->db_path);
 517                 args[4] = talloc_asprintf(args, "0x%x",
 518                                           db_flags(lock_ctx->ctdb_db));
 519                 break;
 520         }
 521
 522         /* Make sure last argument is NULL */
 523         args[nargs-1] = NULL;
 524
 525         for (i=0; i<nargs-1; i++) {
 526                 if (args[i] == NULL) {
 527                         talloc_free(args);
 528                         return false;
 529                 }
 530         }
 531
 532         *argc = nargs;
 533         *argv = args;
 534         return true;
 535 }
 536
 537 /*
 538  * Find a lock request that can be scheduled
 539  */
 540 static struct lock_context *ctdb_find_lock_context(struct ctdb_context *ctdb)
 541 {
 542         struct lock_context *lock_ctx, *next_ctx;
 543         struct ctdb_db_context *ctdb_db;
 544
 545         /* First check if there are database lock requests */
 546
 547         for (lock_ctx = ctdb->lock_pending; lock_ctx != NULL;
 548              lock_ctx = next_ctx) {
 549
 550                 if (lock_ctx->request != NULL) {
 551                         /* Found a lock context with a request */
 552                         return lock_ctx;
 553                 }
 554
 555                 next_ctx = lock_ctx->next;
 556
 557                 DEBUG(DEBUG_INFO, ("Removing lock context without lock "
 558                                    "request\n"));
 559                 DLIST_REMOVE(ctdb->lock_pending, lock_ctx);
 560                 CTDB_DECREMENT_STAT(ctdb, locks.num_pending);
 561                 if (lock_ctx->ctdb_db) {
 562                         CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db,
 563                                                locks.num_pending);
 564                 }
 565                 talloc_free(lock_ctx);
 566         }
 567
 568         /* Next check database queues */
 569         for (ctdb_db = ctdb->db_list; ctdb_db; ctdb_db = ctdb_db->next) {
 570                 if (ctdb_db->lock_num_current ==
 571                     ctdb->tunable.lock_processes_per_db) {
 572                         continue;
 573                 }
 574
 575                 for (lock_ctx = ctdb_db->lock_pending; lock_ctx != NULL;
 576                      lock_ctx = next_ctx) {
 577
 578                         next_ctx = lock_ctx->next;
 579
 580                         if (lock_ctx->request != NULL) {
 581                                 return lock_ctx;
 582                         }
 583
 584                         DEBUG(DEBUG_INFO, ("Removing lock context without "
 585                                            "lock request\n"));
 586                         DLIST_REMOVE(ctdb_db->lock_pending, lock_ctx);
 587                         CTDB_DECREMENT_STAT(ctdb, locks.num_pending);
 588                         CTDB_DECREMENT_DB_STAT(ctdb_db, locks.num_pending);
 589                         talloc_free(lock_ctx);
 590                 }
 591         }
 592
 593         return NULL;
 594 }
 595
 596 /*
 597  * Schedule a new lock child process
 598  * Set up callback handler and timeout handler
 599  */
 600 static void ctdb_lock_schedule(struct ctdb_context *ctdb)
 601 {
 602         struct lock_context *lock_ctx;
 603         int ret, argc;
 604         TALLOC_CTX *tmp_ctx;
 605         static char prog[PATH_MAX+1] = "";
 606         const char **args;
 607
 608         if (!ctdb_set_helper("lock helper",
 609                              prog, sizeof(prog),
 610                              "CTDB_LOCK_HELPER",
 611                              CTDB_HELPER_BINDIR, "ctdb_lock_helper")) {
 612                 ctdb_die(ctdb, __location__
 613                          " Unable to set lock helper\n");
 614         }
 615
 616         /* Find a lock context with requests */
 617         lock_ctx = ctdb_find_lock_context(ctdb);
 618         if (lock_ctx == NULL) {
 619                 return;
 620         }
 621
 622         lock_ctx->child = -1;
 623         ret = pipe(lock_ctx->fd);
 624         if (ret != 0) {
 625                 DEBUG(DEBUG_ERR, ("Failed to create pipe in ctdb_lock_schedule\n"));
 626                 return;
 627         }
 628
 629         set_close_on_exec(lock_ctx->fd[0]);
 630
 631         /* Create data for child process */
 632         tmp_ctx = talloc_new(lock_ctx);
 633         if (tmp_ctx == NULL) {
 634                 DEBUG(DEBUG_ERR, ("Failed to allocate memory for helper args\n"));
 635                 close(lock_ctx->fd[0]);
 636                 close(lock_ctx->fd[1]);
 637                 return;
 638         }
 639
 640         if (! ctdb->do_setsched) {
 641                 ret = setenv("CTDB_NOSETSCHED", "1", 1);
 642                 if (ret != 0) {
 643                         DEBUG(DEBUG_WARNING,
 644                               ("Failed to set CTDB_NOSETSCHED variable\n"));
 645                 }
 646         }
 647
 648         /* Create arguments for lock helper */
 649         if (!lock_helper_args(tmp_ctx, lock_ctx, lock_ctx->fd[1],
 650                               &argc, &args)) {
 651                 DEBUG(DEBUG_ERR, ("Failed to create lock helper args\n"));
 652                 close(lock_ctx->fd[0]);
 653                 close(lock_ctx->fd[1]);
 654                 talloc_free(tmp_ctx);
 655                 return;
 656         }
 657
 658         lock_ctx->child = ctdb_vfork_exec(lock_ctx, ctdb, prog, argc,
 659                                           (const char **)args);
 660         if (lock_ctx->child == -1) {
 661                 DEBUG(DEBUG_ERR, ("Failed to create a child in ctdb_lock_schedule\n"));
 662                 close(lock_ctx->fd[0]);
 663                 close(lock_ctx->fd[1]);
 664                 talloc_free(tmp_ctx);
 665                 return;
 666         }
 667
 668         /* Parent process */
 669         close(lock_ctx->fd[1]);
 670
 671         talloc_free(tmp_ctx);
 672
 673         /* Set up timeout handler */
 674         lock_ctx->ttimer = tevent_add_timer(ctdb->ev,
 675                                             lock_ctx,
 676                                             timeval_current_ofs(10, 0),
 677                                             ctdb_lock_timeout_handler,
 678                                             (void *)lock_ctx);
 679         if (lock_ctx->ttimer == NULL) {
 680                 ctdb_kill(ctdb, lock_ctx->child, SIGTERM);
 681                 lock_ctx->child = -1;
 682                 close(lock_ctx->fd[0]);
 683                 return;
 684         }
 685
 686         /* Set up callback */
 687         lock_ctx->tfd = tevent_add_fd(ctdb->ev,
 688                                       lock_ctx,
 689                                       lock_ctx->fd[0],
 690                                       TEVENT_FD_READ,
 691                                       ctdb_lock_handler,
 692                                       (void *)lock_ctx);
 693         if (lock_ctx->tfd == NULL) {
 694                 TALLOC_FREE(lock_ctx->ttimer);
 695                 ctdb_kill(ctdb, lock_ctx->child, SIGTERM);
 696                 lock_ctx->child = -1;
 697                 close(lock_ctx->fd[0]);
 698                 return;
 699         }
 700         tevent_fd_set_auto_close(lock_ctx->tfd);
 701
 702         /* Move the context from pending to current */
 703         if (lock_ctx->type == LOCK_RECORD) {
 704                 DLIST_REMOVE(lock_ctx->ctdb_db->lock_pending, lock_ctx);
 705                 DLIST_ADD_END(lock_ctx->ctdb_db->lock_current, lock_ctx);
 706         } else {
 707                 DLIST_REMOVE(ctdb->lock_pending, lock_ctx);
 708                 DLIST_ADD_END(ctdb->lock_current, lock_ctx);
 709         }
 710         CTDB_DECREMENT_STAT(lock_ctx->ctdb, locks.num_pending);
 711         CTDB_INCREMENT_STAT(lock_ctx->ctdb, locks.num_current);
 712         if (lock_ctx->ctdb_db) {
 713                 lock_ctx->ctdb_db->lock_num_current++;
 714                 CTDB_DECREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_pending);
 715                 CTDB_INCREMENT_DB_STAT(lock_ctx->ctdb_db, locks.num_current);
 716         }
 717 }
 718
 719
 720 /*
 721  * Lock record / db depending on type
 722  */
 723 static struct lock_request *ctdb_lock_internal(TALLOC_CTX *mem_ctx,
 724                                                struct ctdb_context *ctdb,
 725                                                struct ctdb_db_context *ctdb_db,
 726                                                TDB_DATA key,
 727                                                uint32_t priority,
 728                                                void (*callback)(void *, bool),
 729                                                void *private_data,
 730                                                enum lock_type type,
 731                                                bool auto_mark)
 732 {
 733         struct lock_context *lock_ctx = NULL;
 734         struct lock_request *request;
 735
 736         if (callback == NULL) {
 737                 DEBUG(DEBUG_WARNING, ("No callback function specified, not locking\n"));
 738                 return NULL;
 739         }
 740
 741         lock_ctx = talloc_zero(ctdb, struct lock_context);
 742         if (lock_ctx == NULL) {
 743                 DEBUG(DEBUG_ERR, ("Failed to create a new lock context\n"));
 744                 return NULL;
 745         }
 746
 747         if ((request = talloc_zero(mem_ctx, struct lock_request)) == NULL) {
 748                 talloc_free(lock_ctx);
 749                 return NULL;
 750         }
 751
 752         lock_ctx->type = type;
 753         lock_ctx->ctdb = ctdb;
 754         lock_ctx->ctdb_db = ctdb_db;
 755         lock_ctx->key.dsize = key.dsize;
 756         if (key.dsize > 0) {
 757                 lock_ctx->key.dptr = talloc_memdup(lock_ctx, key.dptr, key.dsize);
 758                 if (lock_ctx->key.dptr == NULL) {
 759                         DEBUG(DEBUG_ERR, (__location__ "Memory allocation error\n"));
 760                         talloc_free(lock_ctx);
 761                         talloc_free(request);
 762                         return NULL;
 763                 }
 764                 lock_ctx->key_hash = ctdb_hash(&key);
 765         } else {
 766                 lock_ctx->key.dptr = NULL;
 767         }
 768         lock_ctx->priority = priority;
 769         lock_ctx->auto_mark = auto_mark;
 770
 771         lock_ctx->request = request;
 772         lock_ctx->child = -1;
 773
 774         /* Non-record locks are required by recovery and should be scheduled
 775          * immediately, so keep them at the head of the pending queue.
 776          */
 777         if (lock_ctx->type == LOCK_RECORD) {
 778                 DLIST_ADD_END(ctdb_db->lock_pending, lock_ctx);
 779         } else {
 780                 DLIST_ADD_END(ctdb->lock_pending, lock_ctx);
 781         }
 782         CTDB_INCREMENT_STAT(ctdb, locks.num_pending);
 783         if (ctdb_db) {
 784                 CTDB_INCREMENT_DB_STAT(ctdb_db, locks.num_pending);
 785         }
 786
 787         /* Start the timer when we activate the context */
 788         lock_ctx->start_time = timeval_current();
 789
 790         request->lctx = lock_ctx;
 791         request->callback = callback;
 792         request->private_data = private_data;
 793
 794         talloc_set_destructor(request, ctdb_lock_request_destructor);
 795         talloc_set_destructor(lock_ctx, ctdb_lock_context_destructor);
 796
 797         ctdb_lock_schedule(ctdb);
 798
 799         return request;
 800 }
 801
 802
 803 /*
 804  * obtain a lock on a record in a database
 805  */
 806 struct lock_request *ctdb_lock_record(TALLOC_CTX *mem_ctx,
 807                                       struct ctdb_db_context *ctdb_db,
 808                                       TDB_DATA key,
 809                                       bool auto_mark,
 810                                       void (*callback)(void *, bool),
 811                                       void *private_data)
 812 {
 813         return ctdb_lock_internal(mem_ctx,
 814                                   ctdb_db->ctdb,
 815                                   ctdb_db,
 816                                   key,
 817                                   0,
 818                                   callback,
 819                                   private_data,
 820                                   LOCK_RECORD,
 821                                   auto_mark);
 822 }
 823
 824
 825 /*
 826  * obtain a lock on a database
 827  */
 828 struct lock_request *ctdb_lock_db(TALLOC_CTX *mem_ctx,
 829                                   struct ctdb_db_context *ctdb_db,
 830                                   bool auto_mark,
 831                                   void (*callback)(void *, bool),
 832                                   void *private_data)
 833 {
 834         return ctdb_lock_internal(mem_ctx,
 835                                   ctdb_db->ctdb,
 836                                   ctdb_db,
 837                                   tdb_null,
 838                                   0,
 839                                   callback,
 840                                   private_data,
 841                                   LOCK_DB,
 842                                   auto_mark);
 843 }