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[feature/migrations] Basic migrations with schema and data changes

The migrator takes care of applying migrations as necessary.

RFC: http://area51.phpbb.com/phpBB/viewtopic.php?f=84&t=41337

PHPBB3-9737
This commit is contained in:
Nils Adermann
2011-07-15 11:57:53 -04:00
committed by Nathan Guse
parent 0e9b7bcae9
commit f817e20f28
15 changed files with 574 additions and 0 deletions

View File

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<?php
/**
*
* @package db
* @copyright (c) 2011 phpBB Group
* @license http://opensource.org/licenses/gpl-license.php GNU Public License
*
*/
/**
* @ignore
*/
if (!defined('IN_PHPBB'))
{
exit;
}
/**
* The migrator is responsible for applying new migrations in the correct order.
*
* @package db
*/
class phpbb_db_migrator
{
var $db;
var $db_tools;
var $migrations_table;
var $migration_state;
var $migrations;
/**
* Constructor of the database migrator
*
* @param dbal $db Connected database abstraction instance
* @param phpbb_db_tools $db_tools Instance of db schema manipulation tools
* @param string $migrations_table The name of the db table storing
* information on applied migrations
*/
function phpbb_db_migrator(&$db, &$db_tools, $migrations_table)
{
$this->db = &$db;
$this->db_tools = &$db_tools;
$this->migrations_table = $migrations_table;
$this->migrations = array();
$this->load_migration_state();
}
/**
* Loads all migrations and their application state from the database.
*
* @return null
*/
function load_migration_state()
{
$sql = "SELECT *
FROM " . $this->migrations_table;
$result = $this->db->sql_query($sql);
$this->migration_state = array();
while ($migration = $this->db->sql_fetchrow($result))
{
$this->migration_state[$migration['migration_name']] = $migration;
}
$this->db->sql_freeresult($result);
}
/**
* Sets the list of available migration class names to the given array.
*
* @param array $class_names An array of migration class names
* @return null
*/
function set_migrations($class_names)
{
$this->migrations = $class_names;
}
/**
* Runs a single update step from the next migration to be applied.
*
* The update step can either be a schema or a (partial) data update. To
* check if update() needs to be called again use the finished() method.
*
* @return null
*/
function update()
{
foreach ($this->migrations as $name)
{
if (!isset($this->migration_state[$name]) ||
!$this->migration_state[$name]['migration_schema_done'] ||
!$this->migration_state[$name]['migration_data_done'])
{
if (!$this->try_apply($name))
{
continue;
}
else
{
return;
}
}
}
}
/**
* Attempts to apply a step of the given migration or one of its dependencies
*
* @param string The class name of the migration
* @return bool Whether any update step was successfully run
*/
function try_apply($name)
{
if (!class_exists($name))
{
return false;
}
$migration =& new $name($this->db, $this->db_tools);
$state = (isset($this->migration_state[$name])) ?
$this->migration_state[$name] :
array(
'migration_schema_done' => false,
'migration_data_done' => false,
'migration_data_state' => '',
);
$depends = $migration->depends_on();
foreach ($depends as $depend)
{
if (!isset($this->migration_state[$depend]) ||
!$this->migration_state[$depend]['migration_schema_done'] ||
!$this->migration_state[$depend]['migration_data_done'])
{
return $this->try_apply($depend);
}
}
if (!$state['migration_schema_done'])
{
$migration->update_schema();
$state['migration_schema_done'] = true;
}
else
{
$migration->update_data();
$state['migration_data_done'] = true;
}
$sql = 'UPDATE ' . $this->migrations_table . '
SET ' . $this->db->sql_build_array('UPDATE', $state) . "
WHERE migration_name = '" . $this->db->sql_escape($name) . "'";
$this->db->sql_query($sql);
$this->migration_state[$name] = $state;
return true;
}
/**
* Checks if a migration's dependencies can even theoretically be satisfied.
*
* @param string $name The class name of the migration
* @return bool Whether the migration cannot be fulfilled
*/
function unfulfillable($name)
{
if (isset($this->migration_state[$name]))
{
return false;
}
if (!class_exists($name))
{
return true;
}
$migration =& new $name($this->db, $this->db_tools);
$depends = $migration->depends_on();
foreach ($depends as $depend)
{
if ($this->unfulfillable($depend))
{
return true;
}
}
return false;
}
/**
* Checks whether all available, fulfillable migrations have been applied.
*
* @return bool Whether the migrations have been applied
*/
function finished()
{
foreach ($this->migrations as $name)
{
if (!isset($this->migration_state[$name]))
{
// skip unfulfillable migrations, but fulfillables mean we
// are not finished yet
if ($this->unfulfillable($name))
{
continue;
}
return false;
}
$migration = $this->migration_state[$name];
if (!$migration['migration_schema_done'] || !$migration['migration_data_done'])
{
return false;
}
}
return true;
}
}