ovsdb/file.c

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