You can create new a memory manager
(Zend_Memory_Manager object) using the
Zend_Memory::factory($backendName [, $backendOprions])
method.
The first argument $backendName is a string that
names one of the backend implementations supported by Zend_Cache.
The second argument $backendOptions is an optional
backend options array.
<?php
$backendOptions = array(
'cache_dir' => './tmp/' // Directory where to put the swapped memory blocks
);
$memoryManager = Zend_Memory::factory('File', $backendOptions);
Zend_Memory uses Zend_Cache backends as storage providers.
You may use the special name 'None' as a backend name,
in addition to standard Zend_Cache backends.
<?php
$memoryManager = Zend_Memory::factory('None');
If you use 'None' as the backend name, then the memory
manager never swaps memory blocks. This is useful if you know that
memory is not limited or the overall size of objects never reaches
the memory limit.
The 'None' backend doesn't need any option specified.
This section describes creating and destroying objects in the managed memory, and settings to control memory manager behavior.
Create movable objects (objects, which may be swapped) using
the Zend_Memory_Manager::create([$data]) method:
<?php
$memObject = $memoryManager->create($data);
The $data argument is optional and used to
initialize the object value. If the $data
argument is omitted, the value is an empty string.
Create locked objects (objects, which are not swapped) using
the Zend_Memory_Manager::createLocked([$data]) method:
<?php
$memObject = $memoryManager->createLocked($data);
The $data argument is optional and used to
initialize the object value. If the $data
argument is omitted, the value is an empty string.
Memory objects are automatically destroyed and removed from memory when they go out of scope:
<?php
function foo()
{
global $memoryManager, $memList;
...
$memObject1 = $memoryManager->create($data1);
$memObject2 = $memoryManager->create($data2);
$memObject3 = $memoryManager->create($data3);
...
$memList[] = $memObject3;
...
unset($memObject2); // $memObject2 is destroyed here
...
// $memObject1 is destroyed here
// but $memObject2 object is still referenced by $memList and is not destroyed
}
This applies to both movable and locked objects.
Memory limit is a number of bytes allowed to be used by loaded movable objects.
If loading or creation of an object causes memory usage to exceed of this limit, then the memory manager swaps some other objects.
You can retrieve or set the memory limit setting using the
getMemoryLimit() and setMemoryLimit($newLimit)
methods:
<?php
$oldLimit = $memoryManager->getMemoryLimit(); // Get memory limit in bytes
$memoryManager->setMemoryLimit($newLimit); // Set memory limit in bytes
A negative value for memory limit means 'no limit'.
The default vaule is two-thirds of the value of
'memory_limit' in php.ini or 'no limit' (-1)
if 'memory_limit' is not set in php.ini.
MinSize is a minimal size of memory objects, which may be swapped by memory manager. The memory manager does not swap objects that are smaller than this value. This reduces the number of swap/load operations.
You can retrieve or set the minimum size using the
getMinSize() and setMinSize($newSize)
methods:
<?php
$oldMinSize = $memoryManager->getMinSize(); // Get MinSize in bytes
$memoryManager->setMinSize($newSize); // Set MinSize limit in bytes
The default minimum size value is 16KB (16384 bytes).