text: /* Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at:
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <config.h>
  
  #include "ovsdb.h"
  
  #include "column.h"
  #include "json.h"
  #include "ovsdb-error.h"
  #include "ovsdb-parser.h"
  #include "ovsdb-types.h"
  #include "simap.h"
  #include "table.h"
  #include "transaction.h"
  
  struct ovsdb_schema *
  ovsdb_schema_create(const char *name, const char *version, const char *cksum)
  {
      struct ovsdb_schema *schema;
  
      schema = xzalloc(sizeof *schema);
      schema->name = xstrdup(name);
      schema->version = xstrdup(version);
      schema->cksum = xstrdup(cksum);
      shash_init(&schema->tables);
  
      return schema;
  }
  
  struct ovsdb_schema *
  ovsdb_schema_clone(const struct ovsdb_schema *old)
  {
      struct ovsdb_schema *new;
      struct shash_node *node;
  
      new = ovsdb_schema_create(old->name, old->version, old->cksum);
      SHASH_FOR_EACH (node, &old->tables) {
          const struct ovsdb_table_schema *ts = node->data;
  
          shash_add(&new->tables, node->name, ovsdb_table_schema_clone(ts));
      }
      return new;
  }
  
  void
  ovsdb_schema_destroy(struct ovsdb_schema *schema)
  {
      struct shash_node *node;
  
      if (!schema) {
          return;
      }
  
      SHASH_FOR_EACH (node, &schema->tables) {
          ovsdb_table_schema_destroy(node->data);
      }
      shash_destroy(&schema->tables);
      free(schema->name);
      free(schema->version);
      free(schema->cksum);
      free(schema);
  }
  
  struct ovsdb_error *
  ovsdb_schema_from_file(const char *file_name, struct ovsdb_schema **schemap)
  {
      struct ovsdb_schema *schema;
      struct ovsdb_error *error;
      struct json *json;
  
      *schemap = NULL;
      json = json_from_file(file_name);
      if (json->type == JSON_STRING) {
          error = ovsdb_error("failed to read schema",
                             "\"%s\" could not be read as JSON (%s)",
                             file_name, json_string(json));
          json_destroy(json);
          return error;
      }
  
      error = ovsdb_schema_from_json(json, &schema);
      json_destroy(json);
      if (error) {
          return ovsdb_wrap_error(error,
                                  "failed to parse \"%s\" as ovsdb schema",
                                  file_name);
      }
  
      *schemap = schema;
      return NULL;
  }
  
  static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
  ovsdb_schema_check_ref_table(struct ovsdb_column *column,
                               const struct shash *tables,
                               const struct ovsdb_base_type *base,
                               const char *base_name)
  {
      struct ovsdb_table_schema *refTable;
  
      if (base->type != OVSDB_TYPE_UUID || !base->u.uuid.refTableName) {
          return NULL;
      }
  
      refTable = shash_find_data(tables, base->u.uuid.refTableName);
      if (!refTable) {
          return ovsdb_syntax_error(NULL, NULL,
                                    "column %s %s refers to undefined table %s",
                                    column->name, base_name,
                                    base->u.uuid.refTableName);
      }
  
      if (ovsdb_base_type_is_strong_ref(base) && !refTable->is_root) {
          /* We cannot allow a strong reference to a non-root table to be
           * ephemeral: if it is the only reference to a row, then replaying the
           * database log from disk will cause the referenced row to be deleted,
           * even though it did exist in memory.  If there are references to that
           * row later in the log (to modify it, to delete it, or just to point
           * to it), then this will yield a transaction error. */
          column->persistent = true;
      }
  
      return NULL;
  }
  
  static bool
  is_valid_version(const char *s)
  {
      int n = -1;
      ignore(ovs_scan(s, "%*[0-9].%*[0-9].%*[0-9]%n", &n));
      return n != -1 && s[n] == '\0';
  }
  
  /* Returns the number of tables in 'schema''s root set. */
  static size_t
  root_set_size(const struct ovsdb_schema *schema)
  {
      struct shash_node *node;
      size_t n_root = 0;
  
      SHASH_FOR_EACH (node, &schema->tables) {
          struct ovsdb_table_schema *table = node->data;
  
          n_root += table->is_root;
      }
      return n_root;
  }
  
  struct ovsdb_error *
  ovsdb_schema_from_json(struct json *json, struct ovsdb_schema **schemap)
  {
      struct ovsdb_schema *schema;
      const struct json *name, *tables, *version_json, *cksum;
      struct ovsdb_error *error;
      struct shash_node *node;
      struct ovsdb_parser parser;
      const char *version;
  
      *schemap = NULL;
  
      ovsdb_parser_init(&parser, json, "database schema");
      name = ovsdb_parser_member(&parser, "name", OP_ID);
      version_json = ovsdb_parser_member(&parser, "version",
                                         OP_STRING | OP_OPTIONAL);
      cksum = ovsdb_parser_member(&parser, "cksum", OP_STRING | OP_OPTIONAL);
      tables = ovsdb_parser_member(&parser, "tables", OP_OBJECT);
      error = ovsdb_parser_finish(&parser);
      if (error) {
          return error;
      }
  
      if (version_json) {
          version = json_string(version_json);
          if (!is_valid_version(version)) {
              return ovsdb_syntax_error(json, NULL, "schema version \"%s\" not "
                                        "in format x.y.z", version);
          }
      } else {
          /* Backward compatibility with old databases. */
          version = "";
      }
  
      schema = ovsdb_schema_create(json_string(name), version,
                                   cksum ? json_string(cksum) : "");
      SHASH_FOR_EACH (node, json_object(tables)) {
          struct ovsdb_table_schema *table;
  
          if (node->name[0] == '_') {
              error = ovsdb_syntax_error(json, NULL, "names beginning with "
                                         "\"_\" are reserved");
          } else if (!ovsdb_parser_is_id(node->name)) {
              error = ovsdb_syntax_error(json, NULL, "name must be a valid id");
          } else {
              error = ovsdb_table_schema_from_json(node->data, node->name,
                                                   &table);
          }
          if (error) {
              ovsdb_schema_destroy(schema);
              return error;
          }
  
          shash_add(&schema->tables, table->name, table);
      }
  
      /* "isRoot" was not part of the original schema definition.  Before it was
       * added, there was no support for garbage collection.  So, for backward
       * compatibility, if the root set is empty then assume that every table is
       * in the root set. */
      if (root_set_size(schema) == 0) {
          SHASH_FOR_EACH (node, &schema->tables) {
              struct ovsdb_table_schema *table = node->data;
  
              table->is_root = true;
          }
      }
  
      /* Validate that all refTables refer to the names of tables that exist.
       *
       * Also force certain columns to be persistent, as explained in
       * ovsdb_schema_check_ref_table().  This requires 'is_root' to be known, so
       * this must follow the loop updating 'is_root' above. */
      SHASH_FOR_EACH (node, &schema->tables) {
          struct ovsdb_table_schema *table = node->data;
          struct shash_node *node2;
  
          SHASH_FOR_EACH (node2, &table->columns) {
              struct ovsdb_column *column = node2->data;
  
              error = ovsdb_schema_check_ref_table(column, &schema->tables,
                                                   &column->type.key, "key");
              if (!error) {
                  error = ovsdb_schema_check_ref_table(column, &schema->tables,
                                                       &column->type.value,
                                                       "value");
              }
              if (error) {
                  ovsdb_schema_destroy(schema);
                  return error;
              }
          }
      }
  
      *schemap = schema;
      return NULL;
  }
  
  struct json *
  ovsdb_schema_to_json(const struct ovsdb_schema *schema)
  {
      struct json *json, *tables;
      struct shash_node *node;
      bool default_is_root;
  
      json = json_object_create();
      json_object_put_string(json, "name", schema->name);
      if (schema->version[0]) {
          json_object_put_string(json, "version", schema->version);
      }
      if (schema->cksum[0]) {
          json_object_put_string(json, "cksum", schema->cksum);
      }
  
      /* "isRoot" was not part of the original schema definition.  Before it was
       * added, there was no support for garbage collection.  So, for backward
       * compatibility, if every table is in the root set then do not output
       * "isRoot" in table schemas. */
      default_is_root = root_set_size(schema) == shash_count(&schema->tables);
  
      tables = json_object_create();
  
      SHASH_FOR_EACH (node, &schema->tables) {
          struct ovsdb_table_schema *table = node->data;
          json_object_put(tables, table->name,
                          ovsdb_table_schema_to_json(table, default_is_root));
      }
      json_object_put(json, "tables", tables);
  
      return json;
  }
  
  /* Returns true if 'a' and 'b' specify equivalent schemas, false if they
   * differ. */
  bool
  ovsdb_schema_equal(const struct ovsdb_schema *a,
                     const struct ovsdb_schema *b)
  {
      /* This implementation is simple, stupid, and slow, but I doubt that it
       * will ever require much maintenance. */
      struct json *ja = ovsdb_schema_to_json(a);
      struct json *jb = ovsdb_schema_to_json(b);
      bool equals = json_equal(ja, jb);
      json_destroy(ja);
      json_destroy(jb);
  
      return equals;
  }
  
  static void
  ovsdb_set_ref_table(const struct shash *tables,
                      struct ovsdb_base_type *base)
  {
      if (base->type == OVSDB_TYPE_UUID && base->u.uuid.refTableName) {
          struct ovsdb_table *table;
  
          table = shash_find_data(tables, base->u.uuid.refTableName);
          base->u.uuid.refTable = table;
      }
  }
  
  struct ovsdb *
  ovsdb_create(struct ovsdb_schema *schema)
  {
      struct shash_node *node;
      struct ovsdb *db;
  
      db = xmalloc(sizeof *db);
      db->schema = schema;
      ovs_list_init(&db->replicas);
      ovs_list_init(&db->triggers);
      db->run_triggers = false;
  
      shash_init(&db->tables);
      SHASH_FOR_EACH (node, &schema->tables) {
          struct ovsdb_table_schema *ts = node->data;
          shash_add(&db->tables, node->name, ovsdb_table_create(ts));
      }
  
      /* Set all the refTables. */
      SHASH_FOR_EACH (node, &schema->tables) {
          struct ovsdb_table_schema *table = node->data;
          struct shash_node *node2;
  
          SHASH_FOR_EACH (node2, &table->columns) {
              struct ovsdb_column *column = node2->data;
  
              ovsdb_set_ref_table(&db->tables, &column->type.key);
              ovsdb_set_ref_table(&db->tables, &column->type.value);
          }
      }
  
      return db;
  }
  
  void
  ovsdb_destroy(struct ovsdb *db)
  {
      if (db) {
          struct shash_node *node;
  
          /* Remove all the replicas. */
          while (!ovs_list_is_empty(&db->replicas)) {
              struct ovsdb_replica *r
                  = CONTAINER_OF(ovs_list_pop_back(&db->replicas),
                                 struct ovsdb_replica, node);
              ovsdb_remove_replica(db, r);
          }
  
          /* Delete all the tables.  This also deletes their schemas. */
          SHASH_FOR_EACH (node, &db->tables) {
              struct ovsdb_table *table = node->data;
              ovsdb_table_destroy(table);
          }
          shash_destroy(&db->tables);
  
          /* The schemas, but not the table that points to them, were deleted in
           * the previous step, so we need to clear out the table.  We can't
           * destroy the table, because ovsdb_schema_destroy() will do that. */
          shash_clear(&db->schema->tables);
  
          ovsdb_schema_destroy(db->schema);
          free(db);
      }
  }
  
  /* Adds some memory usage statistics for 'db' into 'usage', for use with
   * memory_report(). */
  void
  ovsdb_get_memory_usage(const struct ovsdb *db, struct simap *usage)
  {
      const struct shash_node *node;
      unsigned int cells = 0;
  
      SHASH_FOR_EACH (node, &db->tables) {
          const struct ovsdb_table *table = node->data;
          unsigned int n_columns = shash_count(&table->schema->columns);
          unsigned int n_rows = hmap_count(&table->rows);
  
          cells += n_rows * n_columns;
      }
  
      simap_increase(usage, "cells", cells);
  }
  
  struct ovsdb_table *
  ovsdb_get_table(const struct ovsdb *db, const char *name)
  {
      return shash_find_data(&db->tables, name);
  }
  
  void
  ovsdb_replica_init(struct ovsdb_replica *r,
                     const struct ovsdb_replica_class *class)
  {
      r->class = class;
  }
  
  void
  ovsdb_add_replica(struct ovsdb *db, struct ovsdb_replica *r)
  {
      ovs_list_push_back(&db->replicas, &r->node);
  }
  
  void
  ovsdb_remove_replica(struct ovsdb *db OVS_UNUSED, struct ovsdb_replica *r)
  {
      ovs_list_remove(&r->node);
      (r->class->destroy)(r);
  }
  