Callbacks
Result callbacks
Result callbacks are invoked by
Memcached::getDelayed or
Memcached::getDelayedBykey methods for each item in
the result set. The callback is passed the Memcached object and the array
with the item information. The callback does not have to return anything.
Result callback example
addServer('localhost', 11211);
$items = array(
'key1' => 'value1',
'key2' => 'value2',
'key3' => 'value3'
);
$m->setMulti($items);
$m->getDelayed(array('key1', 'key3'), true, 'result_cb');
function result_cb($memc, $item)
{
var_dump($item);
}
?>
]]>
&example.outputs.similar;
string(4) "key1"
["value"]=>
string(6) "value1"
["cas"]=>
float(49)
}
array(3) {
["key"]=>
string(4) "key3"
["value"]=>
string(6) "value3"
["cas"]=>
float(50)
}
]]>
Read-through cache callbacks
Read-through cache callbacks are invoked when an item cannot be retrieved
from the server. The callback is passed the Memcached object, the requested
key, and the by-reference value variable. The callback is responsible for
setting the value and returning true or false. If the callback returns true,
Memcached will store the populated value on the server and return it to the
original calling function. Only Memcached::get and
Memcached::getByKey support these callbacks,
because the memcache protocol does not provide information on which keys
were not found in the multi-key request.
Read-through callback example
addServer('localhost', 11211);
$profile_info = $m->get('user:'.$user_id, 'user_info_cb');
function user_info_cb($memc, $key, &$value)
{
$user_id = substr($key, 5);
/* lookup profile info in the DB */
/* ... */
$value = $profile_info;
return true;
}
?>
]]>