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<?php
/**
* Elgg metastrngs
* Functions to manage object metastrings.
*
* @package Elgg
* @subpackage Core
* @author Curverider Ltd <info@elgg.com>
* @link http://elgg.org/
*/
/** Cache metastrings for a page */
$METASTRINGS_CACHE = array();
/** Keep a record of strings we know don't exist */
$METASTRINGS_DEADNAME_CACHE = array();
/**
* Return the meta string id for a given tag, or false.
*
* @param string $string The value (whatever that is) to be stored
* @param bool $case_sensitive Do we want to make the query case sensitive?
* @return mixed Integer tag or false.
*/
function get_metastring_id($string, $case_sensitive = true)
{
global $CONFIG, $METASTRINGS_CACHE, $METASTRINGS_DEADNAME_CACHE;
$string = sanitise_string($string);
$result = array_search($string, $METASTRINGS_CACHE);
if ($result!==false) {
if (isset($CONFIG->debug) && $CONFIG->debug)
error_log("** Returning id for string:$string from cache.");
return $result;
}
// See if we have previously looked for this and found nothing
if (in_array($string, $METASTRINGS_DEADNAME_CACHE))
return false;
// Experimental memcache
$msfc = null;
static $metastrings_memcache;
if ((!$metastrings_memcache) && (is_memcache_available()))
$metastrings_memcache = new ElggMemcache('metastrings_memcache');
if ($metastrings_memcache) $msfc = $metastrings_memcache->load($string);
if ($msfc) return $msfc;
// Case sensitive
$cs = "";
if ($case_sensitive) $cs = " BINARY ";
$row = get_data_row("SELECT * from {$CONFIG->dbprefix}metastrings where string=$cs'$string' limit 1");
if ($row) {
$METASTRINGS_CACHE[$row->id] = $row->string; // Cache it
// Attempt to memcache it if memcache is available
if ($metastrings_memcache) $metastrings_memcache->save($row->string, $row->id);
if (isset($CONFIG->debug) && $CONFIG->debug)
error_log("** Cacheing string '{$row->string}'");
return $row->id;
}
else
$METASTRINGS_DEADNAME_CACHE[$string] = $string;
return false;
}
/**
* When given an ID, returns the corresponding metastring
*
* @param int $id Metastring ID
* @return string Metastring
*/
function get_metastring($id) {
global $CONFIG, $METASTRINGS_CACHE;
$id = (int) $id;
if (isset($METASTRINGS_CACHE[$id])) {
if ($CONFIG->debug)
error_log("** Returning string for id:$id from cache.");
return $METASTRINGS_CACHE[$id];
}
$row = get_data_row("SELECT * from {$CONFIG->dbprefix}metastrings where id='$id' limit 1");
if ($row) {
$METASTRINGS_CACHE[$id] = $row->string; // Cache it
if ($CONFIG->debug)
error_log("** Cacheing string '{$row->string}'");
return $row->string;
}
return false;
}
/**
* Add a metastring.
* It returns the id of the tag, whether by creating it or updating it.
*
* @param string $string The value (whatever that is) to be stored
* @param bool $case_sensitive Do we want to make the query case sensitive?
* @return mixed Integer tag or false.
*/
function add_metastring($string, $case_sensitive = true)
{
global $CONFIG, $METASTRINGS_CACHE, $METASTRINGS_DEADNAME_CACHE;
$sanstring = sanitise_string($string);
$id = get_metastring_id($string, $case_sensitive);
if ($id) return $id;
$result = insert_data("INSERT into {$CONFIG->dbprefix}metastrings (string) values ('$sanstring')");
if ($result) {
$METASTRINGS_CACHE[$result] = $string;
if (isset($METASTRINGS_DEADNAME_CACHE[$string])) unset($METASTRINGS_DEADNAME_CACHE[$string]);
}
return $result;
}
/**
* Delete any orphaned entries in metastrings. This is run by the garbage collector.
*
*/
function delete_orphaned_metastrings()
{
global $CONFIG;
// If memcache is enabled then we need to flush it of deleted values
if (is_memcache_available())
{
$select_query = "
SELECT *
from {$CONFIG->dbprefix}metastrings where
(
(id not in (select name_id from {$CONFIG->dbprefix}metadata)) AND
(id not in (select value_id from {$CONFIG->dbprefix}metadata)) AND
(id not in (select name_id from {$CONFIG->dbprefix}annotations)) AND
(id not in (select value_id from {$CONFIG->dbprefix}annotations))
)";
$dead = get_data($select_query);
if ($dead)
{
static $metastrings_memcache;
if (!$metastrings_memcache)
$metastrings_memcache = new ElggMemcache('metastrings_memcache');
foreach ($dead as $d)
$metastrings_memcache->delete($d->string);
}
}
$query = "
DELETE
from {$CONFIG->dbprefix}metastrings where
(
(id not in (select name_id from {$CONFIG->dbprefix}metadata)) AND
(id not in (select value_id from {$CONFIG->dbprefix}metadata)) AND
(id not in (select name_id from {$CONFIG->dbprefix}annotations)) AND
(id not in (select value_id from {$CONFIG->dbprefix}annotations))
)";
return delete_data($query);
}
?>
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