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openvswitch/ovsdb/file.c
2010-02-15 12:54:52 -08:00

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/* Copyright (c) 2009, 2010 Nicira Networks
*
* 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 "file.h"
#include <assert.h>
#include <fcntl.h>
#include "column.h"
#include "log.h"
#include "json.h"
#include "ovsdb.h"
#include "ovsdb-error.h"
#include "row.h"
#include "table.h"
#include "timeval.h"
#include "transaction.h"
#include "uuid.h"
#include "util.h"
#define THIS_MODULE VLM_ovsdb_file
#include "vlog.h"
/* A transaction being converted to JSON for writing to a file. */
struct ovsdb_file_txn {
struct json *json; /* JSON for the whole transaction. */
struct json *table_json; /* JSON for 'table''s transaction. */
struct ovsdb_table *table; /* Table described in 'table_json'. */
};
static void ovsdb_file_txn_init(struct ovsdb_file_txn *);
static void ovsdb_file_txn_add_row(struct ovsdb_file_txn *,
const struct ovsdb_row *old,
const struct ovsdb_row *new);
static struct ovsdb_error *ovsdb_file_txn_commit(struct json *,
const char *comment,
bool durable,
struct ovsdb_log *);
static struct ovsdb_error *ovsdb_file_open__(const char *file_name,
const struct ovsdb_schema *,
bool read_only, struct ovsdb **);
static struct ovsdb_error *ovsdb_file_txn_from_json(struct ovsdb *,
const struct json *,
bool converting,
struct ovsdb_txn **);
static void ovsdb_file_replica_create(struct ovsdb *, struct ovsdb_log *);
/* Opens database 'file_name' and stores a pointer to the new database in
* '*dbp'. If 'read_only' is false, then the database will be locked and
* changes to the database will be written to disk. If 'read_only' is true,
* the database will not be locked and changes to the database will persist
* only as long as the "struct ovsdb".
*
* On success, returns NULL. On failure, returns an ovsdb_error (which the
* caller must destroy) and sets '*dbp' to NULL. */
struct ovsdb_error *
ovsdb_file_open(const char *file_name, bool read_only, struct ovsdb **dbp)
{
return ovsdb_file_open__(file_name, NULL, read_only, dbp);
}
/* Opens database 'file_name' with an alternate schema. The specified 'schema'
* is used to interpret the data in 'file_name', ignoring the schema actually
* stored in the file. Data in the file for tables or columns that do not
* exist in 'schema' are ignored, but the ovsdb file format must otherwise be
* observed, including column constraints.
*
* This function can be useful for upgrading or downgrading databases to
* "almost-compatible" formats.
*
* The database will not be locked. Changes to the database will persist only
* as long as the "struct ovsdb".
*
* On success, stores a pointer to the new database in '*dbp' and returns a
* null pointer. On failure, returns an ovsdb_error (which the caller must
* destroy) and sets '*dbp' to NULL. */
struct ovsdb_error *
ovsdb_file_open_as_schema(const char *file_name,
const struct ovsdb_schema *schema,
struct ovsdb **dbp)
{
return ovsdb_file_open__(file_name, schema, true, dbp);
}
static struct ovsdb_error *
ovsdb_file_open__(const char *file_name,
const struct ovsdb_schema *alternate_schema,
bool read_only, struct ovsdb **dbp)
{
enum ovsdb_log_open_mode open_mode;
struct ovsdb_schema *schema;
struct ovsdb_error *error;
struct ovsdb_log *log;
struct json *json;
struct ovsdb *db;
open_mode = read_only ? OVSDB_LOG_READ_ONLY : OVSDB_LOG_READ_WRITE;
error = ovsdb_log_open(file_name, open_mode, -1, &log);
if (error) {
return error;
}
error = ovsdb_log_read(log, &json);
if (error) {
return error;
} else if (!json) {
return ovsdb_io_error(EOF, "%s: database file contains no schema",
file_name);
}
if (alternate_schema) {
schema = ovsdb_schema_clone(alternate_schema);
} else {
error = ovsdb_schema_from_json(json, &schema);
if (error) {
json_destroy(json);
return ovsdb_wrap_error(error,
"failed to parse \"%s\" as ovsdb schema",
file_name);
}
}
json_destroy(json);
db = ovsdb_create(schema);
while ((error = ovsdb_log_read(log, &json)) == NULL && json) {
struct ovsdb_txn *txn;
error = ovsdb_file_txn_from_json(db, json, alternate_schema != NULL,
&txn);
json_destroy(json);
if (error) {
break;
}
ovsdb_txn_commit(txn, false);
}
if (error) {
char *msg = ovsdb_error_to_string(error);
VLOG_WARN("%s", msg);
free(msg);
ovsdb_error_destroy(error);
}
if (!read_only) {
ovsdb_file_replica_create(db, log);
} else {
ovsdb_log_close(log);
}
*dbp = db;
return NULL;
}
static struct ovsdb_error *
ovsdb_file_update_row_from_json(struct ovsdb_row *row, bool converting,
const struct json *json)
{
struct ovsdb_table_schema *schema = row->table->schema;
struct ovsdb_error *error;
struct shash_node *node;
if (json->type != JSON_OBJECT) {
return ovsdb_syntax_error(json, NULL, "row must be JSON object");
}
SHASH_FOR_EACH (node, json_object(json)) {
const char *column_name = node->name;
const struct ovsdb_column *column;
struct ovsdb_datum datum;
column = ovsdb_table_schema_get_column(schema, column_name);
if (!column) {
if (converting) {
continue;
}
return ovsdb_syntax_error(json, "unknown column",
"No column %s in table %s.",
column_name, schema->name);
}
error = ovsdb_datum_from_json(&datum, &column->type, node->data, NULL);
if (error) {
return error;
}
ovsdb_datum_swap(&row->fields[column->index], &datum);
ovsdb_datum_destroy(&datum, &column->type);
}
return NULL;
}
static struct ovsdb_error *
ovsdb_file_txn_row_from_json(struct ovsdb_txn *txn, struct ovsdb_table *table,
bool converting,
const struct uuid *row_uuid, struct json *json)
{
const struct ovsdb_row *row = ovsdb_table_get_row(table, row_uuid);
if (json->type == JSON_NULL) {
if (!row) {
return ovsdb_syntax_error(NULL, NULL, "transaction deletes "
"row "UUID_FMT" that does not exist",
UUID_ARGS(row_uuid));
}
ovsdb_txn_row_delete(txn, row);
return NULL;
} else if (row) {
return ovsdb_file_update_row_from_json(ovsdb_txn_row_modify(txn, row),
converting, json);
} else {
struct ovsdb_error *error;
struct ovsdb_row *new;
new = ovsdb_row_create(table);
*ovsdb_row_get_uuid_rw(new) = *row_uuid;
error = ovsdb_file_update_row_from_json(new, converting, json);
if (error) {
ovsdb_row_destroy(new);
}
ovsdb_txn_row_insert(txn, new);
return error;
}
}
static struct ovsdb_error *
ovsdb_file_txn_table_from_json(struct ovsdb_txn *txn,
struct ovsdb_table *table,
bool converting, struct json *json)
{
struct shash_node *node;
if (json->type != JSON_OBJECT) {
return ovsdb_syntax_error(json, NULL, "object expected");
}
SHASH_FOR_EACH (node, json->u.object) {
const char *uuid_string = node->name;
struct json *txn_row_json = node->data;
struct ovsdb_error *error;
struct uuid row_uuid;
if (!uuid_from_string(&row_uuid, uuid_string)) {
return ovsdb_syntax_error(json, NULL, "\"%s\" is not a valid UUID",
uuid_string);
}
error = ovsdb_file_txn_row_from_json(txn, table, converting,
&row_uuid, txn_row_json);
if (error) {
return error;
}
}
return NULL;
}
static struct ovsdb_error *
ovsdb_file_txn_from_json(struct ovsdb *db, const struct json *json,
bool converting, struct ovsdb_txn **txnp)
{
struct ovsdb_error *error;
struct shash_node *node;
struct ovsdb_txn *txn;
*txnp = NULL;
if (json->type != JSON_OBJECT) {
return ovsdb_syntax_error(json, NULL, "object expected");
}
txn = ovsdb_txn_create(db);
SHASH_FOR_EACH (node, json->u.object) {
const char *table_name = node->name;
struct json *txn_table_json = node->data;
struct ovsdb_table *table;
table = shash_find_data(&db->tables, table_name);
if (!table) {
if (!strcmp(table_name, "_date")
|| !strcmp(table_name, "_comment")
|| converting) {
continue;
}
error = ovsdb_syntax_error(json, "unknown table",
"No table named %s.", table_name);
goto error;
}
error = ovsdb_file_txn_table_from_json(txn, table, converting,
txn_table_json);
if (error) {
goto error;
}
}
*txnp = txn;
return NULL;
error:
ovsdb_txn_abort(txn);
return error;
}
/* Saves a snapshot of 'db''s current contents as 'file_name'. If 'comment' is
* nonnull, then it is added along with the data contents and can be viewed
* with "ovsdb-tool show-log".
*
* 'locking' is passed along to ovsdb_log_open() untouched. */
struct ovsdb_error *
ovsdb_file_save_copy(const char *file_name, int locking,
const char *comment, const struct ovsdb *db)
{
const struct shash_node *node;
struct ovsdb_file_txn ftxn;
struct ovsdb_error *error;
struct ovsdb_log *log;
struct json *json;
error = ovsdb_log_open(file_name, OVSDB_LOG_CREATE, locking, &log);
if (error) {
return error;
}
/* Write schema. */
json = ovsdb_schema_to_json(db->schema);
error = ovsdb_log_write(log, json);
json_destroy(json);
if (error) {
goto exit;
}
/* Write data. */
ovsdb_file_txn_init(&ftxn);
SHASH_FOR_EACH (node, &db->tables) {
const struct ovsdb_table *table = node->data;
const struct ovsdb_row *row;
HMAP_FOR_EACH (row, struct ovsdb_row, hmap_node, &table->rows) {
ovsdb_file_txn_add_row(&ftxn, NULL, row);
}
}
error = ovsdb_file_txn_commit(ftxn.json, comment, true, log);
exit:
ovsdb_log_close(log);
if (error) {
remove(file_name);
}
return error;
}
/* Replica implementation. */
struct ovsdb_file_replica {
struct ovsdb_replica replica;
struct ovsdb_log *log;
};
static const struct ovsdb_replica_class ovsdb_file_replica_class;
static void
ovsdb_file_replica_create(struct ovsdb *db, struct ovsdb_log *log)
{
struct ovsdb_file_replica *r = xmalloc(sizeof *r);
ovsdb_replica_init(&r->replica, &ovsdb_file_replica_class);
r->log = log;
ovsdb_add_replica(db, &r->replica);
}
static struct ovsdb_file_replica *
ovsdb_file_replica_cast(struct ovsdb_replica *replica)
{
assert(replica->class == &ovsdb_file_replica_class);
return CONTAINER_OF(replica, struct ovsdb_file_replica, replica);
}
static bool
ovsdb_file_replica_change_cb(const struct ovsdb_row *old,
const struct ovsdb_row *new,
void *ftxn_)
{
struct ovsdb_file_txn *ftxn = ftxn_;
ovsdb_file_txn_add_row(ftxn, old, new);
return true;
}
static struct ovsdb_error *
ovsdb_file_replica_commit(struct ovsdb_replica *r_,
const struct ovsdb_txn *txn, bool durable)
{
struct ovsdb_file_replica *r = ovsdb_file_replica_cast(r_);
struct ovsdb_file_txn ftxn;
ovsdb_file_txn_init(&ftxn);
ovsdb_txn_for_each_change(txn, ovsdb_file_replica_change_cb, &ftxn);
if (!ftxn.json) {
/* Nothing to commit. */
return NULL;
}
return ovsdb_file_txn_commit(ftxn.json, ovsdb_txn_get_comment(txn),
durable, r->log);
}
static void
ovsdb_file_replica_destroy(struct ovsdb_replica *r_)
{
struct ovsdb_file_replica *r = ovsdb_file_replica_cast(r_);
ovsdb_log_close(r->log);
free(r);
}
static const struct ovsdb_replica_class ovsdb_file_replica_class = {
ovsdb_file_replica_commit,
ovsdb_file_replica_destroy
};
static void
ovsdb_file_txn_init(struct ovsdb_file_txn *ftxn)
{
ftxn->json = NULL;
ftxn->table_json = NULL;
ftxn->table = NULL;
}
static void
ovsdb_file_txn_add_row(struct ovsdb_file_txn *ftxn,
const struct ovsdb_row *old,
const struct ovsdb_row *new)
{
struct json *row;
if (!new) {
row = json_null_create();
} else {
struct shash_node *node;
row = old ? NULL : json_object_create();
SHASH_FOR_EACH (node, &new->table->schema->columns) {
const struct ovsdb_column *column = node->data;
const struct ovsdb_type *type = &column->type;
unsigned int idx = column->index;
if (idx != OVSDB_COL_UUID && column->persistent
&& (old
? !ovsdb_datum_equals(&old->fields[idx], &new->fields[idx],
type)
: !ovsdb_datum_is_default(&new->fields[idx], type)))
{
if (!row) {
row = json_object_create();
}
json_object_put(row, column->name,
ovsdb_datum_to_json(&new->fields[idx], type));
}
}
}
if (row) {
struct ovsdb_table *table = new ? new->table : old->table;
char uuid[UUID_LEN + 1];
if (table != ftxn->table) {
/* Create JSON object for transaction overall. */
if (!ftxn->json) {
ftxn->json = json_object_create();
}
/* Create JSON object for transaction on this table. */
ftxn->table_json = json_object_create();
ftxn->table = table;
json_object_put(ftxn->json, table->schema->name, ftxn->table_json);
}
/* Add row to transaction for this table. */
snprintf(uuid, sizeof uuid,
UUID_FMT, UUID_ARGS(ovsdb_row_get_uuid(new ? new : old)));
json_object_put(ftxn->table_json, uuid, row);
}
}
static struct ovsdb_error *
ovsdb_file_txn_commit(struct json *json, const char *comment,
bool durable, struct ovsdb_log *log)
{
struct ovsdb_error *error;
if (!json) {
json = json_object_create();
}
if (comment) {
json_object_put_string(json, "_comment", comment);
}
json_object_put(json, "_date", json_integer_create(time_now()));
error = ovsdb_log_write(log, json);
json_destroy(json);
if (error) {
return ovsdb_wrap_error(error, "writing transaction failed");
}
if (durable) {
error = ovsdb_log_commit(log);
if (error) {
return ovsdb_wrap_error(error, "committing transaction failed");
}
}
return NULL;
}