ovsdb/file.c

   1 /* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15
  16 #include <config.h>
  17
  18 #include "file.h"
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <unistd.h>
  23
  24 #include "bitmap.h"
  25 #include "column.h"
  26 #include "log.h"
  27 #include "json.h"
  28 #include "lockfile.h"
  29 #include "ovsdb.h"
  30 #include "ovsdb-error.h"
  31 #include "row.h"
  32 #include "socket-util.h"
  33 #include "table.h"
  34 #include "timeval.h"
  35 #include "transaction.h"
  36 #include "uuid.h"
  37 #include "util.h"
  38 #include "vlog.h"
  39
  40 VLOG_DEFINE_THIS_MODULE(ovsdb_file);
  41
  42 /* Minimum number of milliseconds between database compactions. */
  43 #define COMPACT_MIN_MSEC        (10 * 60 * 1000) /* 10 minutes. */
  44
  45 /* Minimum number of milliseconds between trying to compact the database if
  46  * compacting fails. */
  47 #define COMPACT_RETRY_MSEC      (60 * 1000)      /* 1 minute. */
  48
  49 /* A transaction being converted to JSON for writing to a file. */
  50 struct ovsdb_file_txn {
  51     struct json *json;          /* JSON for the whole transaction. */
  52     struct json *table_json;    /* JSON for 'table''s transaction. */
  53     struct ovsdb_table *table;  /* Table described in 'table_json'.  */
  54 };
  55
  56 static void ovsdb_file_txn_init(struct ovsdb_file_txn *);
  57 static void ovsdb_file_txn_add_row(struct ovsdb_file_txn *,
  58                                    const struct ovsdb_row *old,
  59                                    const struct ovsdb_row *new,
  60                                    const unsigned long int *changed);
  61 static struct ovsdb_error *ovsdb_file_txn_commit(struct json *,
  62                                                  const char *comment,
  63                                                  bool durable,
  64                                                  struct ovsdb_log *);
  65
  66 static struct ovsdb_error *ovsdb_file_open__(const char *file_name,
  67                                              const struct ovsdb_schema *,
  68                                              bool read_only, struct ovsdb **,
  69                                              struct ovsdb_file **);
  70 static struct ovsdb_error *ovsdb_file_txn_from_json(
  71     struct ovsdb *, const struct json *, bool converting,
  72     long long int *date, struct ovsdb_txn **);
  73 static struct ovsdb_error *ovsdb_file_create(struct ovsdb *,
  74                                              struct ovsdb_log *,
  75                                              const char *file_name,
  76                                              long long int oldest_commit,
  77                                              unsigned int n_transactions,
  78                                              struct ovsdb_file **filep);
  79
  80 /* Opens database 'file_name' and stores a pointer to the new database in
  81  * '*dbp'.  If 'read_only' is false, then the database will be locked and
  82  * changes to the database will be written to disk.  If 'read_only' is true,
  83  * the database will not be locked and changes to the database will persist
  84  * only as long as the "struct ovsdb".
  85  *
  86  * If 'filep' is nonnull and 'read_only' is false, then on success sets
  87  * '*filep' to an ovsdb_file that represents the open file.  This ovsdb_file
  88  * persists until '*dbp' is destroyed.
  89  *
  90  * On success, returns NULL.  On failure, returns an ovsdb_error (which the
  91  * caller must destroy) and sets '*dbp' and '*filep' to NULL. */
  92 struct ovsdb_error *
  93 ovsdb_file_open(const char *file_name, bool read_only,
  94                 struct ovsdb **dbp, struct ovsdb_file **filep)
  95 {
  96     return ovsdb_file_open__(file_name, NULL, read_only, dbp, filep);
  97 }
  98
  99 /* Opens database 'file_name' with an alternate schema.  The specified 'schema'
 100  * is used to interpret the data in 'file_name', ignoring the schema actually
 101  * stored in the file.  Data in the file for tables or columns that do not
 102  * exist in 'schema' are ignored, but the ovsdb file format must otherwise be
 103  * observed, including column constraints.
 104  *
 105  * This function can be useful for upgrading or downgrading databases to
 106  * "almost-compatible" formats.
 107  *
 108  * The database will not be locked.  Changes to the database will persist only
 109  * as long as the "struct ovsdb".
 110  *
 111  * On success, stores a pointer to the new database in '*dbp' and returns a
 112  * null pointer.  On failure, returns an ovsdb_error (which the caller must
 113  * destroy) and sets '*dbp' to NULL. */
 114 struct ovsdb_error *
 115 ovsdb_file_open_as_schema(const char *file_name,
 116                           const struct ovsdb_schema *schema,
 117                           struct ovsdb **dbp)
 118 {
 119     return ovsdb_file_open__(file_name, schema, true, dbp, NULL);
 120 }
 121
 122 static struct ovsdb_error *
 123 ovsdb_file_open_log(const char *file_name, enum ovsdb_log_open_mode open_mode,
 124                     struct ovsdb_log **logp, struct ovsdb_schema **schemap)
 125 {
 126     struct ovsdb_schema *schema = NULL;
 127     struct ovsdb_log *log = NULL;
 128     struct ovsdb_error *error;
 129     struct json *json = NULL;
 130
 131     ovs_assert(logp || schemap);
 132
 133     error = ovsdb_log_open(file_name, open_mode, -1, &log);
 134     if (error) {
 135         goto error;
 136     }
 137
 138     error = ovsdb_log_read(log, &json);
 139     if (error) {
 140         goto error;
 141     } else if (!json) {
 142         error = ovsdb_io_error(EOF, "%s: database file contains no schema",
 143                                file_name);
 144         goto error;
 145     }
 146
 147     if (schemap) {
 148         error = ovsdb_schema_from_json(json, &schema);
 149         if (error) {
 150             error = ovsdb_wrap_error(error,
 151                                      "failed to parse \"%s\" as ovsdb schema",
 152                                      file_name);
 153             goto error;
 154         }
 155     }
 156     json_destroy(json);
 157
 158     if (logp) {
 159         *logp = log;
 160     } else {
 161         ovsdb_log_close(log);
 162     }
 163     if (schemap) {
 164         *schemap = schema;
 165     }
 166     return NULL;
 167
 168 error:
 169     ovsdb_log_close(log);
 170     json_destroy(json);
 171     if (logp) {
 172         *logp = NULL;
 173     }
 174     if (schemap) {
 175         *schemap = NULL;
 176     }
 177     return error;
 178 }
 179
 180 static struct ovsdb_error *
 181 ovsdb_file_open__(const char *file_name,
 182                   const struct ovsdb_schema *alternate_schema,
 183                   bool read_only, struct ovsdb **dbp,
 184                   struct ovsdb_file **filep)
 185 {
 186     enum ovsdb_log_open_mode open_mode;
 187     long long int oldest_commit;
 188     unsigned int n_transactions;
 189     struct ovsdb_schema *schema = NULL;
 190     struct ovsdb_error *error;
 191     struct ovsdb_log *log;
 192     struct json *json;
 193     struct ovsdb *db = NULL;
 194
 195     /* In read-only mode there is no ovsdb_file so 'filep' must be null. */
 196     ovs_assert(!(read_only && filep));
 197
 198     open_mode = read_only ? OVSDB_LOG_READ_ONLY : OVSDB_LOG_READ_WRITE;
 199     error = ovsdb_file_open_log(file_name, open_mode, &log,
 200                                 alternate_schema ? NULL : &schema);
 201     if (error) {
 202         goto error;
 203     }
 204
 205     db = ovsdb_create(schema ? schema : ovsdb_schema_clone(alternate_schema));
 206
 207     oldest_commit = LLONG_MAX;
 208     n_transactions = 0;
 209     while ((error = ovsdb_log_read(log, &json)) == NULL && json) {
 210         struct ovsdb_txn *txn;
 211         long long int date;
 212
 213         error = ovsdb_file_txn_from_json(db, json, alternate_schema != NULL,
 214                                          &date, &txn);
 215         json_destroy(json);
 216         if (error) {
 217             ovsdb_log_unread(log);
 218             break;
 219         }
 220
 221         n_transactions++;
 222         if (date < oldest_commit) {
 223             oldest_commit = date;
 224         }
 225
 226         error = ovsdb_txn_commit(txn, false);
 227         if (error) {
 228             ovsdb_log_unread(log);
 229             break;
 230         }
 231     }
 232     if (error) {
 233         /* Log error but otherwise ignore it.  Probably the database just got
 234          * truncated due to power failure etc. and we should use its current
 235          * contents. */
 236         char *msg = ovsdb_error_to_string(error);
 237         VLOG_ERR("%s", msg);
 238         free(msg);
 239
 240         ovsdb_error_destroy(error);
 241     }
 242
 243     if (!read_only) {
 244         struct ovsdb_file *file;
 245
 246         error = ovsdb_file_create(db, log, file_name, oldest_commit,
 247                                   n_transactions, &file);
 248         if (error) {
 249             goto error;
 250         }
 251         if (filep) {
 252             *filep = file;
 253         }
 254     } else {
 255         ovsdb_log_close(log);
 256     }
 257
 258     *dbp = db;
 259     return NULL;
 260
 261 error:
 262     *dbp = NULL;
 263     if (filep) {
 264         *filep = NULL;
 265     }
 266     ovsdb_destroy(db);
 267     ovsdb_log_close(log);
 268     return error;
 269 }
 270
 271 static struct ovsdb_error *
 272 ovsdb_file_update_row_from_json(struct ovsdb_row *row, bool converting,
 273                                 const struct json *json)
 274 {
 275     struct ovsdb_table_schema *schema = row->table->schema;
 276     struct ovsdb_error *error;
 277     struct shash_node *node;
 278
 279     if (json->type != JSON_OBJECT) {
 280         return ovsdb_syntax_error(json, NULL, "row must be JSON object");
 281     }
 282
 283     SHASH_FOR_EACH (node, json_object(json)) {
 284         const char *column_name = node->name;
 285         const struct ovsdb_column *column;
 286         struct ovsdb_datum datum;
 287
 288         column = ovsdb_table_schema_get_column(schema, column_name);
 289         if (!column) {
 290             if (converting) {
 291                 continue;
 292             }
 293             return ovsdb_syntax_error(json, "unknown column",
 294                                       "No column %s in table %s.",
 295                                       column_name, schema->name);
 296         }
 297
 298         error = ovsdb_datum_from_json(&datum, &column->type, node->data, NULL);
 299         if (error) {
 300             return error;
 301         }
 302         ovsdb_datum_swap(&row->fields[column->index], &datum);
 303         ovsdb_datum_destroy(&datum, &column->type);
 304     }
 305
 306     return NULL;
 307 }
 308
 309 static struct ovsdb_error *
 310 ovsdb_file_txn_row_from_json(struct ovsdb_txn *txn, struct ovsdb_table *table,
 311                              bool converting,
 312                              const struct uuid *row_uuid, struct json *json)
 313 {
 314     const struct ovsdb_row *row = ovsdb_table_get_row(table, row_uuid);
 315     if (json->type == JSON_NULL) {
 316         if (!row) {
 317             return ovsdb_syntax_error(NULL, NULL, "transaction deletes "
 318                                       "row "UUID_FMT" that does not exist",
 319                                       UUID_ARGS(row_uuid));
 320         }
 321         ovsdb_txn_row_delete(txn, row);
 322         return NULL;
 323     } else if (row) {
 324         return ovsdb_file_update_row_from_json(ovsdb_txn_row_modify(txn, row),
 325                                                converting, json);
 326     } else {
 327         struct ovsdb_error *error;
 328         struct ovsdb_row *new;
 329
 330         new = ovsdb_row_create(table);
 331         *ovsdb_row_get_uuid_rw(new) = *row_uuid;
 332         error = ovsdb_file_update_row_from_json(new, converting, json);
 333         if (error) {
 334             ovsdb_row_destroy(new);
 335         } else {
 336             ovsdb_txn_row_insert(txn, new);
 337         }
 338         return error;
 339     }
 340 }
 341
 342 static struct ovsdb_error *
 343 ovsdb_file_txn_table_from_json(struct ovsdb_txn *txn,
 344                                struct ovsdb_table *table,
 345                                bool converting, struct json *json)
 346 {
 347     struct shash_node *node;
 348
 349     if (json->type != JSON_OBJECT) {
 350         return ovsdb_syntax_error(json, NULL, "object expected");
 351     }
 352
 353     SHASH_FOR_EACH (node, json->u.object) {
 354         const char *uuid_string = node->name;
 355         struct json *txn_row_json = node->data;
 356         struct ovsdb_error *error;
 357         struct uuid row_uuid;
 358
 359         if (!uuid_from_string(&row_uuid, uuid_string)) {
 360             return ovsdb_syntax_error(json, NULL, "\"%s\" is not a valid UUID",
 361                                       uuid_string);
 362         }
 363
 364         error = ovsdb_file_txn_row_from_json(txn, table, converting,
 365                                              &row_uuid, txn_row_json);
 366         if (error) {
 367             return error;
 368         }
 369     }
 370
 371     return NULL;
 372 }
 373
 374 /* Converts 'json' to an ovsdb_txn for 'db', storing the new transaction in
 375  * '*txnp'.  Returns NULL if successful, otherwise an error.
 376  *
 377  * If 'converting' is true, then unknown table and column names are ignored
 378  * (which can ease upgrading and downgrading schemas); otherwise, they are
 379  * treated as errors.
 380  *
 381  * If successful, the date associated with the transaction, as the number of
 382  * milliseconds since the epoch, is stored in '*date'.  If the transaction does
 383  * not include a date, LLONG_MAX is stored. */
 384 static struct ovsdb_error *
 385 ovsdb_file_txn_from_json(struct ovsdb *db, const struct json *json,
 386                          bool converting, long long int *date,
 387                          struct ovsdb_txn **txnp)
 388 {
 389     struct ovsdb_error *error;
 390     struct shash_node *node;
 391     struct ovsdb_txn *txn;
 392
 393     *txnp = NULL;
 394     *date = LLONG_MAX;
 395
 396     if (json->type != JSON_OBJECT) {
 397         return ovsdb_syntax_error(json, NULL, "object expected");
 398     }
 399
 400     txn = ovsdb_txn_create(db);
 401     SHASH_FOR_EACH (node, json->u.object) {
 402         const char *table_name = node->name;
 403         struct json *node_json = node->data;
 404         struct ovsdb_table *table;
 405
 406         table = shash_find_data(&db->tables, table_name);
 407         if (!table) {
 408             if (!strcmp(table_name, "_date")
 409                 && node_json->type == JSON_INTEGER) {
 410                 *date = json_integer(node_json);
 411                 continue;
 412             } else if (!strcmp(table_name, "_comment") || converting) {
 413                 continue;
 414             }
 415
 416             error = ovsdb_syntax_error(json, "unknown table",
 417                                        "No table named %s.", table_name);
 418             goto error;
 419         }
 420
 421         error = ovsdb_file_txn_table_from_json(txn, table, converting,
 422                                                node_json);
 423         if (error) {
 424             goto error;
 425         }
 426     }
 427     *txnp = txn;
 428     return NULL;
 429
 430 error:
 431     ovsdb_txn_abort(txn);
 432     return error;
 433 }
 434
 435 static struct ovsdb_error *
 436 ovsdb_file_save_copy__(const char *file_name, int locking,
 437                        const char *comment, const struct ovsdb *db,
 438                        struct ovsdb_log **logp)
 439 {
 440     const struct shash_node *node;
 441     struct ovsdb_file_txn ftxn;
 442     struct ovsdb_error *error;
 443     struct ovsdb_log *log;
 444     struct json *json;
 445
 446     error = ovsdb_log_open(file_name, OVSDB_LOG_CREATE, locking, &log);
 447     if (error) {
 448         return error;
 449     }
 450
 451     /* Write schema. */
 452     json = ovsdb_schema_to_json(db->schema);
 453     error = ovsdb_log_write(log, json);
 454     json_destroy(json);
 455     if (error) {
 456         goto exit;
 457     }
 458
 459     /* Write data. */
 460     ovsdb_file_txn_init(&ftxn);
 461     SHASH_FOR_EACH (node, &db->tables) {
 462         const struct ovsdb_table *table = node->data;
 463         const struct ovsdb_row *row;
 464
 465         HMAP_FOR_EACH (row, hmap_node, &table->rows) {
 466             ovsdb_file_txn_add_row(&ftxn, NULL, row, NULL);
 467         }
 468     }
 469     error = ovsdb_file_txn_commit(ftxn.json, comment, true, log);
 470
 471 exit:
 472     if (logp) {
 473         if (!error) {
 474             *logp = log;
 475             log = NULL;
 476         } else {
 477             *logp = NULL;
 478         }
 479     }
 480     ovsdb_log_close(log);
 481     if (error) {
 482         remove(file_name);
 483     }
 484     return error;
 485 }
 486
 487 /* Saves a snapshot of 'db''s current contents as 'file_name'.  If 'comment' is
 488  * nonnull, then it is added along with the data contents and can be viewed
 489  * with "ovsdb-tool show-log".
 490  *
 491  * 'locking' is passed along to ovsdb_log_open() untouched. */
 492 struct ovsdb_error *
 493 ovsdb_file_save_copy(const char *file_name, int locking,
 494                      const char *comment, const struct ovsdb *db)
 495 {
 496     return ovsdb_file_save_copy__(file_name, locking, comment, db, NULL);
 497 }
 498
 499 /* Opens database 'file_name', reads its schema, and closes it.  On success,
 500  * stores the schema into '*schemap' and returns NULL; the caller then owns the
 501  * schema.  On failure, returns an ovsdb_error (which the caller must destroy)
 502  * and sets '*dbp' to NULL. */
 503 struct ovsdb_error *
 504 ovsdb_file_read_schema(const char *file_name, struct ovsdb_schema **schemap)
 505 {
 506     ovs_assert(schemap != NULL);
 507     return ovsdb_file_open_log(file_name, OVSDB_LOG_READ_ONLY, NULL, schemap);
 508 }
 509 \f
 510 /* Replica implementation. */
 511
 512 struct ovsdb_file {
 513     struct ovsdb_replica replica;
 514     struct ovsdb *db;
 515     struct ovsdb_log *log;
 516     char *file_name;
 517     long long int oldest_commit;
 518     long long int next_compact;
 519     unsigned int n_transactions;
 520 };
 521
 522 static const struct ovsdb_replica_class ovsdb_file_class;
 523
 524 static struct ovsdb_error *
 525 ovsdb_file_create(struct ovsdb *db, struct ovsdb_log *log,
 526                   const char *file_name,
 527                   long long int oldest_commit,
 528                   unsigned int n_transactions,
 529                   struct ovsdb_file **filep)
 530 {
 531     long long int now = time_msec();
 532     struct ovsdb_file *file;
 533     char *deref_name;
 534     char *abs_name;
 535
 536     /* Use the absolute name of the file because ovsdb-server opens its
 537      * database before daemonize() chdirs to "/". */
 538     deref_name = follow_symlinks(file_name);
 539     abs_name = abs_file_name(NULL, deref_name);
 540     free(deref_name);
 541     if (!abs_name) {
 542         *filep = NULL;
 543         return ovsdb_io_error(0, "could not determine current "
 544                               "working directory");
 545     }
 546
 547     file = xmalloc(sizeof *file);
 548     ovsdb_replica_init(&file->replica, &ovsdb_file_class);
 549     file->db = db;
 550     file->log = log;
 551     file->file_name = abs_name;
 552     file->oldest_commit = MIN(oldest_commit, now);
 553     file->next_compact = file->oldest_commit + COMPACT_MIN_MSEC;
 554     file->n_transactions = n_transactions;
 555     ovsdb_add_replica(db, &file->replica);
 556
 557     *filep = file;
 558     return NULL;
 559 }
 560
 561 static struct ovsdb_file *
 562 ovsdb_file_cast(struct ovsdb_replica *replica)
 563 {
 564     ovs_assert(replica->class == &ovsdb_file_class);
 565     return CONTAINER_OF(replica, struct ovsdb_file, replica);
 566 }
 567
 568 static bool
 569 ovsdb_file_change_cb(const struct ovsdb_row *old,
 570                      const struct ovsdb_row *new,
 571                      const unsigned long int *changed,
 572                      void *ftxn_)
 573 {
 574     struct ovsdb_file_txn *ftxn = ftxn_;
 575     ovsdb_file_txn_add_row(ftxn, old, new, changed);
 576     return true;
 577 }
 578
 579 static struct ovsdb_error *
 580 ovsdb_file_commit(struct ovsdb_replica *replica,
 581                   const struct ovsdb_txn *txn, bool durable)
 582 {
 583     struct ovsdb_file *file = ovsdb_file_cast(replica);
 584     struct ovsdb_file_txn ftxn;
 585     struct ovsdb_error *error;
 586
 587     ovsdb_file_txn_init(&ftxn);
 588     ovsdb_txn_for_each_change(txn, ovsdb_file_change_cb, &ftxn);
 589     if (!ftxn.json) {
 590         /* Nothing to commit. */
 591         return NULL;
 592     }
 593
 594     error = ovsdb_file_txn_commit(ftxn.json, ovsdb_txn_get_comment(txn),
 595                                   durable, file->log);
 596     if (error) {
 597         return error;
 598     }
 599     file->n_transactions++;
 600
 601     /* If it has been at least COMPACT_MIN_MSEC ms since the last time we
 602      * compacted (or at least COMPACT_RETRY_MSEC ms since the last time we
 603      * tried), and if there are at least 100 transactions in the database, and
 604      * if the database is at least 10 MB, then compact the database. */
 605     if (time_msec() >= file->next_compact
 606         && file->n_transactions >= 100
 607         && ovsdb_log_get_offset(file->log) >= 10 * 1024 * 1024)
 608     {
 609         error = ovsdb_file_compact(file);
 610         if (error) {
 611             char *s = ovsdb_error_to_string(error);
 612             ovsdb_error_destroy(error);
 613             VLOG_WARN("%s: compacting database failed (%s), retrying in "
 614                       "%d seconds",
 615                       file->file_name, s, COMPACT_RETRY_MSEC / 1000);
 616             free(s);
 617
 618             file->next_compact = time_msec() + COMPACT_RETRY_MSEC;
 619         }
 620     }
 621
 622     return NULL;
 623 }
 624
 625 struct ovsdb_error *
 626 ovsdb_file_compact(struct ovsdb_file *file)
 627 {
 628     struct ovsdb_log *new_log = NULL;
 629     struct lockfile *tmp_lock = NULL;
 630     struct ovsdb_error *error;
 631     char *tmp_name = NULL;
 632     char *comment = NULL;
 633     int retval;
 634
 635     comment = xasprintf("compacting database online "
 636                         "(%.3f seconds old, %u transactions, %llu bytes)",
 637                         (time_msec() - file->oldest_commit) / 1000.0,
 638                         file->n_transactions,
 639                         (unsigned long long) ovsdb_log_get_offset(file->log));
 640     VLOG_INFO("%s: %s", file->file_name, comment);
 641
 642     /* Commit the old version, so that we can be assured that we'll eventually
 643      * have either the old or the new version. */
 644     error = ovsdb_log_commit(file->log);
 645     if (error) {
 646         goto exit;
 647     }
 648
 649     /* Lock temporary file. */
 650     tmp_name = xasprintf("%s.tmp", file->file_name);
 651     retval = lockfile_lock(tmp_name, &tmp_lock);
 652     if (retval) {
 653         error = ovsdb_io_error(retval, "could not get lock on %s", tmp_name);
 654         goto exit;
 655     }
 656
 657     /* Remove temporary file.  (It might not exist.) */
 658     if (unlink(tmp_name) < 0 && errno != ENOENT) {
 659         error = ovsdb_io_error(errno, "failed to remove %s", tmp_name);
 660         goto exit;
 661     }
 662
 663     /* Save a copy. */
 664     error = ovsdb_file_save_copy__(tmp_name, false, comment, file->db,
 665                                    &new_log);
 666     if (error) {
 667         goto exit;
 668     }
 669
 670     /* Replace original by temporary. */
 671     if (rename(tmp_name, file->file_name)) {
 672         error = ovsdb_io_error(errno, "failed to rename \"%s\" to \"%s\"",
 673                                tmp_name, file->file_name);
 674         goto exit;
 675     }
 676     fsync_parent_dir(file->file_name);
 677
 678 exit:
 679     if (!error) {
 680         ovsdb_log_close(file->log);
 681         file->log = new_log;
 682         file->oldest_commit = time_msec();
 683         file->next_compact = file->oldest_commit + COMPACT_MIN_MSEC;
 684         file->n_transactions = 1;
 685     } else {
 686         ovsdb_log_close(new_log);
 687         if (tmp_lock) {
 688             unlink(tmp_name);
 689         }
 690     }
 691
 692     lockfile_unlock(tmp_lock);
 693     free(tmp_name);
 694     free(comment);
 695
 696     return error;
 697 }
 698
 699 static void
 700 ovsdb_file_destroy(struct ovsdb_replica *replica)
 701 {
 702     struct ovsdb_file *file = ovsdb_file_cast(replica);
 703
 704     ovsdb_log_close(file->log);
 705     free(file->file_name);
 706     free(file);
 707 }
 708
 709 static const struct ovsdb_replica_class ovsdb_file_class = {
 710     ovsdb_file_commit,
 711     ovsdb_file_destroy
 712 };
 713 \f
 714 static void
 715 ovsdb_file_txn_init(struct ovsdb_file_txn *ftxn)
 716 {
 717     ftxn->json = NULL;
 718     ftxn->table_json = NULL;
 719     ftxn->table = NULL;
 720 }
 721
 722 static void
 723 ovsdb_file_txn_add_row(struct ovsdb_file_txn *ftxn,
 724                        const struct ovsdb_row *old,
 725                        const struct ovsdb_row *new,
 726                        const unsigned long int *changed)
 727 {
 728     struct json *row;
 729
 730     if (!new) {
 731         row = json_null_create();
 732     } else {
 733         struct shash_node *node;
 734
 735         row = old ? NULL : json_object_create();
 736         SHASH_FOR_EACH (node, &new->table->schema->columns) {
 737             const struct ovsdb_column *column = node->data;
 738             const struct ovsdb_type *type = &column->type;
 739             unsigned int idx = column->index;
 740
 741             if (idx != OVSDB_COL_UUID && column->persistent
 742                 && (old
 743                     ? bitmap_is_set(changed, idx)
 744                     : !ovsdb_datum_is_default(&new->fields[idx], type)))
 745             {
 746                 if (!row) {
 747                     row = json_object_create();
 748                 }
 749                 json_object_put(row, column->name,
 750                                 ovsdb_datum_to_json(&new->fields[idx], type));
 751             }
 752         }
 753     }
 754
 755     if (row) {
 756         struct ovsdb_table *table = new ? new->table : old->table;
 757         char uuid[UUID_LEN + 1];
 758
 759         if (table != ftxn->table) {
 760             /* Create JSON object for transaction overall. */
 761             if (!ftxn->json) {
 762                 ftxn->json = json_object_create();
 763             }
 764
 765             /* Create JSON object for transaction on this table. */
 766             ftxn->table_json = json_object_create();
 767             ftxn->table = table;
 768             json_object_put(ftxn->json, table->schema->name, ftxn->table_json);
 769         }
 770
 771         /* Add row to transaction for this table. */
 772         snprintf(uuid, sizeof uuid,
 773                  UUID_FMT, UUID_ARGS(ovsdb_row_get_uuid(new ? new : old)));
 774         json_object_put(ftxn->table_json, uuid, row);
 775     }
 776 }
 777
 778 static struct ovsdb_error *
 779 ovsdb_file_txn_commit(struct json *json, const char *comment,
 780                       bool durable, struct ovsdb_log *log)
 781 {
 782     struct ovsdb_error *error;
 783
 784     if (!json) {
 785         json = json_object_create();
 786     }
 787     if (comment) {
 788         json_object_put_string(json, "_comment", comment);
 789     }
 790     json_object_put(json, "_date", json_integer_create(time_wall()));
 791
 792     error = ovsdb_log_write(log, json);
 793     json_destroy(json);
 794     if (error) {
 795         return ovsdb_wrap_error(error, "writing transaction failed");
 796     }
 797
 798     if (durable) {
 799         error = ovsdb_log_commit(log);
 800         if (error) {
 801             return ovsdb_wrap_error(error, "committing transaction failed");
 802         }
 803     }
 804
 805     return NULL;
 806 }