gnu-social/lib/schemaupdater.php

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<?php
/**
* StatusNet, the distributed open-source microblogging tool
*
* Database schema utilities
*
* PHP version 5
*
* LICENCE: This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* @category Database
* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @copyright 2009 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
* @link http://status.net/
*/
if (!defined('STATUSNET')) {
exit(1);
}
class SchemaUpdater
{
public function __construct($schema)
{
$this->schema = $schema;
$this->conn = $conn;
$this->checksums = $this->getChecksums();
}
/**
* @param array $tableDefs
* @fixme handle tables that belong on different database servers...?
*/
public function checkTables(array $tableDefs)
{
$checksums = $this->checksums;
foreach ($tableDefs as $table => $def) {
$checksum = $this->tableChecksum($def);
if (empty($checksums[$table])) {
common_log(LOG_DEBUG, "No previous schema_version for $table: updating to $checksum");
} else if ($checksums[$table] == $checksum) {
common_log(LOG_DEBUG, "Last schema_version for $table up to date: $checksum");
continue;
} else {
common_log(LOG_DEBUG, "Last schema_version for $table is {$checksums[$table]}: updating to $checksum");
}
$this->conn->query('BEGIN');
$this->schema->ensureTable($table, $def);
$this->saveChecksum($table, $checksum);
$this->conn->commit();
}
}
/**
* Calculate a checksum for this table definition array.
*
* @param array $def
* @return string
*/
public function checksum(array $def)
{
$flat = serialize($def);
return sha1($flat);
}
/**
* Pull all known table checksums into an array for easy lookup.
*
* @return array: associative array of table names to checksum strings
*/
protected function getChecksums()
{
$checksums = array();
$sv = new Schema_version();
$sv->find();
while ($sv->fetch()) {
$checksums[$sv->table_name] = $sv->checksum;
}
return $checksums;
}
/**
* Save or update current available checksums.
*
* @param string $table
* @param string $checksum
*/
protected function saveChecksum($table, $checksum)
{
$sv = new Schema_version();
$sv->table_name = $table;
$sv->checksum = $checksum;
$sv->modified = common_sql_now();
if (isset($this->checksums[$table])) {
$sv->update();
} else {
$sv->insert();
}
$this->checksums[$table] = $checksum;
}
}