ovsdb/ovsdb.c

   1 /* Copyright (c) 2009, 2010, 2011 Nicira Networks
   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 "ovsdb.h"
  19
  20 #include "column.h"
  21 #include "json.h"
  22 #include "ovsdb-error.h"
  23 #include "ovsdb-parser.h"
  24 #include "ovsdb-types.h"
  25 #include "table.h"
  26 #include "transaction.h"
  27
  28 struct ovsdb_schema *
  29 ovsdb_schema_create(const char *name, const char *version, const char *cksum)
  30 {
  31     struct ovsdb_schema *schema;
  32
  33     schema = xzalloc(sizeof *schema);
  34     schema->name = xstrdup(name);
  35     schema->version = xstrdup(version);
  36     schema->cksum = xstrdup(cksum);
  37     shash_init(&schema->tables);
  38
  39     return schema;
  40 }
  41
  42 struct ovsdb_schema *
  43 ovsdb_schema_clone(const struct ovsdb_schema *old)
  44 {
  45     struct ovsdb_schema *new;
  46     struct shash_node *node;
  47
  48     new = ovsdb_schema_create(old->name, old->version, old->cksum);
  49     SHASH_FOR_EACH (node, &old->tables) {
  50         const struct ovsdb_table_schema *ts = node->data;
  51
  52         shash_add(&new->tables, node->name, ovsdb_table_schema_clone(ts));
  53     }
  54     return new;
  55 }
  56
  57 void
  58 ovsdb_schema_destroy(struct ovsdb_schema *schema)
  59 {
  60     struct shash_node *node;
  61
  62     if (!schema) {
  63         return;
  64     }
  65
  66     SHASH_FOR_EACH (node, &schema->tables) {
  67         ovsdb_table_schema_destroy(node->data);
  68     }
  69     shash_destroy(&schema->tables);
  70     free(schema->name);
  71     free(schema->version);
  72     free(schema->cksum);
  73     free(schema);
  74 }
  75
  76 struct ovsdb_error *
  77 ovsdb_schema_from_file(const char *file_name, struct ovsdb_schema **schemap)
  78 {
  79     struct ovsdb_schema *schema;
  80     struct ovsdb_error *error;
  81     struct json *json;
  82
  83     *schemap = NULL;
  84     json = json_from_file(file_name);
  85     if (json->type == JSON_STRING) {
  86         error = ovsdb_error("failed to read schema",
  87                            "\"%s\" could not be read as JSON (%s)",
  88                            file_name, json_string(json));
  89         json_destroy(json);
  90         return error;
  91     }
  92
  93     error = ovsdb_schema_from_json(json, &schema);
  94     json_destroy(json);
  95     if (error) {
  96         return ovsdb_wrap_error(error,
  97                                 "failed to parse \"%s\" as ovsdb schema",
  98                                 file_name);
  99     }
 100
 101     *schemap = schema;
 102     return NULL;
 103 }
 104
 105 static struct ovsdb_error * WARN_UNUSED_RESULT
 106 ovsdb_schema_check_ref_table(struct ovsdb_column *column,
 107                              const struct shash *tables,
 108                              const struct ovsdb_base_type *base,
 109                              const char *base_name)
 110 {
 111     struct ovsdb_table_schema *refTable;
 112
 113     if (base->type != OVSDB_TYPE_UUID || !base->u.uuid.refTableName) {
 114         return NULL;
 115     }
 116
 117     refTable = shash_find_data(tables, base->u.uuid.refTableName);
 118     if (!refTable) {
 119         return ovsdb_syntax_error(NULL, NULL,
 120                                   "column %s %s refers to undefined table %s",
 121                                   column->name, base_name,
 122                                   base->u.uuid.refTableName);
 123     }
 124
 125     if (ovsdb_base_type_is_strong_ref(base) && !refTable->is_root) {
 126         /* We cannot allow a strong reference to a non-root table to be
 127          * ephemeral: if it is the only reference to a row, then replaying the
 128          * database log from disk will cause the referenced row to be deleted,
 129          * even though it did exist in memory.  If there are references to that
 130          * row later in the log (to modify it, to delete it, or just to point
 131          * to it), then this will yield a transaction error. */
 132         column->persistent = true;
 133     }
 134
 135     return NULL;
 136 }
 137
 138 static bool
 139 is_valid_version(const char *s)
 140 {
 141     int n = -1;
 142     ignore(sscanf(s, "%*[0-9].%*[0-9].%*[0-9]%n", &n));
 143     return n != -1 && s[n] == '\0';
 144 }
 145
 146 /* Returns the number of tables in 'schema''s root set. */
 147 static size_t
 148 root_set_size(const struct ovsdb_schema *schema)
 149 {
 150     struct shash_node *node;
 151     size_t n_root = 0;
 152
 153     SHASH_FOR_EACH (node, &schema->tables) {
 154         struct ovsdb_table_schema *table = node->data;
 155
 156         n_root += table->is_root;
 157     }
 158     return n_root;
 159 }
 160
 161 struct ovsdb_error *
 162 ovsdb_schema_from_json(struct json *json, struct ovsdb_schema **schemap)
 163 {
 164     struct ovsdb_schema *schema;
 165     const struct json *name, *tables, *version_json, *cksum;
 166     struct ovsdb_error *error;
 167     struct shash_node *node;
 168     struct ovsdb_parser parser;
 169     const char *version;
 170
 171     *schemap = NULL;
 172
 173     ovsdb_parser_init(&parser, json, "database schema");
 174     name = ovsdb_parser_member(&parser, "name", OP_ID);
 175     version_json = ovsdb_parser_member(&parser, "version",
 176                                        OP_STRING | OP_OPTIONAL);
 177     cksum = ovsdb_parser_member(&parser, "cksum", OP_STRING | OP_OPTIONAL);
 178     tables = ovsdb_parser_member(&parser, "tables", OP_OBJECT);
 179     error = ovsdb_parser_finish(&parser);
 180     if (error) {
 181         return error;
 182     }
 183
 184     if (version_json) {
 185         version = json_string(version_json);
 186         if (!is_valid_version(version)) {
 187             return ovsdb_syntax_error(json, NULL, "schema version \"%s\" not "
 188                                       "in format x.y.z", version);
 189         }
 190     } else {
 191         /* Backward compatibility with old databases. */
 192         version = "";
 193     }
 194
 195     schema = ovsdb_schema_create(json_string(name), version,
 196                                  cksum ? json_string(cksum) : "");
 197     SHASH_FOR_EACH (node, json_object(tables)) {
 198         struct ovsdb_table_schema *table;
 199
 200         if (node->name[0] == '_') {
 201             error = ovsdb_syntax_error(json, NULL, "names beginning with "
 202                                        "\"_\" are reserved");
 203         } else if (!ovsdb_parser_is_id(node->name)) {
 204             error = ovsdb_syntax_error(json, NULL, "name must be a valid id");
 205         } else {
 206             error = ovsdb_table_schema_from_json(node->data, node->name,
 207                                                  &table);
 208         }
 209         if (error) {
 210             ovsdb_schema_destroy(schema);
 211             return error;
 212         }
 213
 214         shash_add(&schema->tables, table->name, table);
 215     }
 216
 217     /* "isRoot" was not part of the original schema definition.  Before it was
 218      * added, there was no support for garbage collection.  So, for backward
 219      * compatibility, if the root set is empty then assume that every table is
 220      * in the root set. */
 221     if (root_set_size(schema) == 0) {
 222         SHASH_FOR_EACH (node, &schema->tables) {
 223             struct ovsdb_table_schema *table = node->data;
 224
 225             table->is_root = true;
 226         }
 227     }
 228
 229     /* Validate that all refTables refer to the names of tables that exist.
 230      *
 231      * Also force certain columns to be persistent, as explained in
 232      * ovsdb_schema_check_ref_table().  This requires 'is_root' to be known, so
 233      * this must follow the loop updating 'is_root' above. */
 234     SHASH_FOR_EACH (node, &schema->tables) {
 235         struct ovsdb_table_schema *table = node->data;
 236         struct shash_node *node2;
 237
 238         SHASH_FOR_EACH (node2, &table->columns) {
 239             struct ovsdb_column *column = node2->data;
 240
 241             error = ovsdb_schema_check_ref_table(column, &schema->tables,
 242                                                  &column->type.key, "key");
 243             if (!error) {
 244                 error = ovsdb_schema_check_ref_table(column, &schema->tables,
 245                                                      &column->type.value,
 246                                                      "value");
 247             }
 248             if (error) {
 249                 ovsdb_schema_destroy(schema);
 250                 return error;
 251             }
 252         }
 253     }
 254
 255     *schemap = schema;
 256     return NULL;
 257 }
 258
 259 struct json *
 260 ovsdb_schema_to_json(const struct ovsdb_schema *schema)
 261 {
 262     struct json *json, *tables;
 263     struct shash_node *node;
 264     bool default_is_root;
 265
 266     json = json_object_create();
 267     json_object_put_string(json, "name", schema->name);
 268     if (schema->version[0]) {
 269         json_object_put_string(json, "version", schema->version);
 270     }
 271     if (schema->cksum[0]) {
 272         json_object_put_string(json, "cksum", schema->cksum);
 273     }
 274
 275     /* "isRoot" was not part of the original schema definition.  Before it was
 276      * added, there was no support for garbage collection.  So, for backward
 277      * compatibility, if every table is in the root set then do not output
 278      * "isRoot" in table schemas. */
 279     default_is_root = root_set_size(schema) == shash_count(&schema->tables);
 280
 281     tables = json_object_create();
 282
 283     SHASH_FOR_EACH (node, &schema->tables) {
 284         struct ovsdb_table_schema *table = node->data;
 285         json_object_put(tables, table->name,
 286                         ovsdb_table_schema_to_json(table, default_is_root));
 287     }
 288     json_object_put(json, "tables", tables);
 289
 290     return json;
 291 }
 292
 293 /* Returns true if 'a' and 'b' specify equivalent schemas, false if they
 294  * differ. */
 295 bool
 296 ovsdb_schema_equal(const struct ovsdb_schema *a,
 297                    const struct ovsdb_schema *b)
 298 {
 299     /* This implementation is simple, stupid, and slow, but I doubt that it
 300      * will ever require much maintenance. */
 301     struct json *ja = ovsdb_schema_to_json(a);
 302     struct json *jb = ovsdb_schema_to_json(b);
 303     bool equals = json_equal(ja, jb);
 304     json_destroy(ja);
 305     json_destroy(jb);
 306
 307     return equals;
 308 }
 309 \f
 310 static void
 311 ovsdb_set_ref_table(const struct shash *tables,
 312                     struct ovsdb_base_type *base)
 313 {
 314     if (base->type == OVSDB_TYPE_UUID && base->u.uuid.refTableName) {
 315         struct ovsdb_table *table;
 316
 317         table = shash_find_data(tables, base->u.uuid.refTableName);
 318         base->u.uuid.refTable = table;
 319     }
 320 }
 321
 322 struct ovsdb *
 323 ovsdb_create(struct ovsdb_schema *schema)
 324 {
 325     struct shash_node *node;
 326     struct ovsdb *db;
 327
 328     db = xmalloc(sizeof *db);
 329     db->schema = schema;
 330     list_init(&db->replicas);
 331     list_init(&db->triggers);
 332     db->run_triggers = false;
 333
 334     shash_init(&db->tables);
 335     SHASH_FOR_EACH (node, &schema->tables) {
 336         struct ovsdb_table_schema *ts = node->data;
 337         shash_add(&db->tables, node->name, ovsdb_table_create(ts));
 338     }
 339
 340     /* Set all the refTables. */
 341     SHASH_FOR_EACH (node, &schema->tables) {
 342         struct ovsdb_table_schema *table = node->data;
 343         struct shash_node *node2;
 344
 345         SHASH_FOR_EACH (node2, &table->columns) {
 346             struct ovsdb_column *column = node2->data;
 347
 348             ovsdb_set_ref_table(&db->tables, &column->type.key);
 349             ovsdb_set_ref_table(&db->tables, &column->type.value);
 350         }
 351     }
 352
 353     return db;
 354 }
 355
 356 void
 357 ovsdb_destroy(struct ovsdb *db)
 358 {
 359     if (db) {
 360         struct shash_node *node;
 361
 362         /* Remove all the replicas. */
 363         while (!list_is_empty(&db->replicas)) {
 364             struct ovsdb_replica *r
 365                 = CONTAINER_OF(list_pop_back(&db->replicas),
 366                                struct ovsdb_replica, node);
 367             ovsdb_remove_replica(db, r);
 368         }
 369
 370         /* Delete all the tables.  This also deletes their schemas. */
 371         SHASH_FOR_EACH (node, &db->tables) {
 372             struct ovsdb_table *table = node->data;
 373             ovsdb_table_destroy(table);
 374         }
 375         shash_destroy(&db->tables);
 376
 377         /* The schemas, but not the table that points to them, were deleted in
 378          * the previous step, so we need to clear out the table.  We can't
 379          * destroy the table, because ovsdb_schema_destroy() will do that. */
 380         shash_clear(&db->schema->tables);
 381
 382         ovsdb_schema_destroy(db->schema);
 383         free(db);
 384     }
 385 }
 386
 387 struct ovsdb_table *
 388 ovsdb_get_table(const struct ovsdb *db, const char *name)
 389 {
 390     return shash_find_data(&db->tables, name);
 391 }
 392 \f
 393 void
 394 ovsdb_replica_init(struct ovsdb_replica *r,
 395                    const struct ovsdb_replica_class *class)
 396 {
 397     r->class = class;
 398 }
 399
 400 void
 401 ovsdb_add_replica(struct ovsdb *db, struct ovsdb_replica *r)
 402 {
 403     list_push_back(&db->replicas, &r->node);
 404 }
 405
 406 void
 407 ovsdb_remove_replica(struct ovsdb *db OVS_UNUSED, struct ovsdb_replica *r)
 408 {
 409     list_remove(&r->node);
 410     (r->class->destroy)(r);
 411 }