gnu-social/classes/Safe_DataObject.php
Brion Vibber 9ec24f59ca Drop result ID from data objects on clone(). This keeps the original object working if it was in the middle of a query loop, even if the cloned object falls out of scope and triggers its destructor.
This bug was hitting a number of places where we had the pattern:

$db->find();
while($dbo->fetch()) {
  $x = clone($dbo);
  // do anything with $x other than storing it in an array
}

The cloned object's destructor would trigger on the second run through the loop, freeing the database result set -- not really what we wanted.
(Loops that stored the clones into an array were fine, since the clones stay in scope in the array longer than the original does.)

Detaching the database result from the clone lets us work with its data without interfering with the rest of the query.
In the unlikely even that somebody is making clones in the middle of a query, then trying to continue the query with the clone instead of the original object, well they're gonna be broken now.
2010-03-15 15:58:55 -07:00

270 lines
9.9 KiB
PHP

<?php
/*
* StatusNet - the distributed open-source microblogging tool
* Copyright (C) 2010, StatusNet, Inc.
*
* 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/>.
*/
if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
/**
* Extended DB_DataObject to improve a few things:
* - free global resources from destructor
* - remove bogus global references from serialized objects
* - don't leak memory when loading already-used .ini files
* (eg when using the same schema on thousands of databases)
*/
class Safe_DataObject extends DB_DataObject
{
/**
* Destructor to free global memory resources associated with
* this data object when it's unset or goes out of scope.
* DB_DataObject doesn't do this yet by itself.
*/
function __destruct()
{
$this->free();
if (method_exists('DB_DataObject', '__destruct')) {
parent::__destruct();
}
}
/**
* Magic function called at clone() time.
*
* We use this to drop connection with some global resources.
* This supports the fairly common pattern where individual
* items being read in a loop via a single object are cloned
* for individual processing, then fall out of scope when the
* loop comes around again.
*
* As that triggers the destructor, we want to make sure that
* the original object doesn't have its database result killed.
* It will still be freed properly when the original object
* gets destroyed.
*/
function __clone()
{
$this->_DB_resultid = false;
}
/**
* Magic function called at serialize() time.
*
* We use this to drop a couple process-specific references
* from DB_DataObject which can cause trouble in future
* processes.
*
* @return array of variable names to include in serialization.
*/
function __sleep()
{
$vars = array_keys(get_object_vars($this));
$skip = array('_DB_resultid', '_link_loaded');
return array_diff($vars, $skip);
}
/**
* Magic function called at unserialize() time.
*
* Clean out some process-specific variables which might
* be floating around from a previous process's cached
* objects.
*
* Old cached objects may still have them.
*/
function __wakeup()
{
// Refers to global state info from a previous process.
// Clear this out so we don't accidentally break global
// state in *this* process.
$this->_DB_resultid = null;
// We don't have any local DBO refs, so clear these out.
$this->_link_loaded = false;
}
/**
* Work around memory-leak bugs...
* Had to copy-paste the whole function in order to patch a couple lines of it.
* Would be nice if this code was better factored.
*
* @param optional string name of database to assign / read
* @param optional array structure of database, and keys
* @param optional array table links
*
* @access public
* @return true or PEAR:error on wrong paramenters.. or false if no file exists..
* or the array(tablename => array(column_name=>type)) if called with 1 argument.. (databasename)
*/
function databaseStructure()
{
global $_DB_DATAOBJECT;
// Assignment code
if ($args = func_get_args()) {
if (count($args) == 1) {
// this returns all the tables and their structure..
if (!empty($_DB_DATAOBJECT['CONFIG']['debug'])) {
$this->debug("Loading Generator as databaseStructure called with args",1);
}
$x = new DB_DataObject;
$x->_database = $args[0];
$this->_connect();
$DB = &$_DB_DATAOBJECT['CONNECTIONS'][$this->_database_dsn_md5];
$tables = $DB->getListOf('tables');
class_exists('DB_DataObject_Generator') ? '' :
require_once 'DB/DataObject/Generator.php';
foreach($tables as $table) {
$y = new DB_DataObject_Generator;
$y->fillTableSchema($x->_database,$table);
}
return $_DB_DATAOBJECT['INI'][$x->_database];
} else {
$_DB_DATAOBJECT['INI'][$args[0]] = isset($_DB_DATAOBJECT['INI'][$args[0]]) ?
$_DB_DATAOBJECT['INI'][$args[0]] + $args[1] : $args[1];
if (isset($args[1])) {
$_DB_DATAOBJECT['LINKS'][$args[0]] = isset($_DB_DATAOBJECT['LINKS'][$args[0]]) ?
$_DB_DATAOBJECT['LINKS'][$args[0]] + $args[2] : $args[2];
}
return true;
}
}
if (!$this->_database) {
$this->_connect();
}
// loaded already?
if (!empty($_DB_DATAOBJECT['INI'][$this->_database])) {
// database loaded - but this is table is not available..
if (
empty($_DB_DATAOBJECT['INI'][$this->_database][$this->__table])
&& !empty($_DB_DATAOBJECT['CONFIG']['proxy'])
) {
if (!empty($_DB_DATAOBJECT['CONFIG']['debug'])) {
$this->debug("Loading Generator to fetch Schema",1);
}
class_exists('DB_DataObject_Generator') ? '' :
require_once 'DB/DataObject/Generator.php';
$x = new DB_DataObject_Generator;
$x->fillTableSchema($this->_database,$this->__table);
}
return true;
}
if (empty($_DB_DATAOBJECT['CONFIG'])) {
DB_DataObject::_loadConfig();
}
// if you supply this with arguments, then it will take those
// as the database and links array...
$schemas = isset($_DB_DATAOBJECT['CONFIG']['schema_location']) ?
array("{$_DB_DATAOBJECT['CONFIG']['schema_location']}/{$this->_database}.ini") :
array() ;
if (isset($_DB_DATAOBJECT['CONFIG']["ini_{$this->_database}"])) {
$schemas = is_array($_DB_DATAOBJECT['CONFIG']["ini_{$this->_database}"]) ?
$_DB_DATAOBJECT['CONFIG']["ini_{$this->_database}"] :
explode(PATH_SEPARATOR,$_DB_DATAOBJECT['CONFIG']["ini_{$this->_database}"]);
}
/* BEGIN CHANGED FROM UPSTREAM */
$_DB_DATAOBJECT['INI'][$this->_database] = $this->parseIniFiles($schemas);
/* END CHANGED FROM UPSTREAM */
// now have we loaded the structure..
if (!empty($_DB_DATAOBJECT['INI'][$this->_database][$this->__table])) {
return true;
}
// - if not try building it..
if (!empty($_DB_DATAOBJECT['CONFIG']['proxy'])) {
class_exists('DB_DataObject_Generator') ? '' :
require_once 'DB/DataObject/Generator.php';
$x = new DB_DataObject_Generator;
$x->fillTableSchema($this->_database,$this->__table);
// should this fail!!!???
return true;
}
$this->debug("Cant find database schema: {$this->_database}/{$this->__table} \n".
"in links file data: " . print_r($_DB_DATAOBJECT['INI'],true),"databaseStructure",5);
// we have to die here!! - it causes chaos if we dont (including looping forever!)
$this->raiseError( "Unable to load schema for database and table (turn debugging up to 5 for full error message)", DB_DATAOBJECT_ERROR_INVALIDARGS, PEAR_ERROR_DIE);
return false;
}
/** For parseIniFiles */
protected static $iniCache = array();
/**
* When switching site configurations, DB_DataObject was loading its
* .ini files over and over, leaking gobs of memory.
* This refactored helper function uses a local cache of .ini files
* to minimize the leaks.
*
* @param array of .ini file names $schemas
* @return array
*/
protected function parseIniFiles($schemas)
{
$key = implode("|", $schemas);
if (!isset(Safe_DataObject::$iniCache[$key])) {
$data = array();
foreach ($schemas as $ini) {
if (file_exists($ini) && is_file($ini)) {
$data = array_merge($data, parse_ini_file($ini, true));
if (!empty($_DB_DATAOBJECT['CONFIG']['debug'])) {
if (!is_readable ($ini)) {
$this->debug("ini file is not readable: $ini","databaseStructure",1);
} else {
$this->debug("Loaded ini file: $ini","databaseStructure",1);
}
}
} else {
if (!empty($_DB_DATAOBJECT['CONFIG']['debug'])) {
$this->debug("Missing ini file: $ini","databaseStructure",1);
}
}
}
Safe_DataObject::$iniCache[$key] = $data;
}
return Safe_DataObject::$iniCache[$key];
}
}