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Date: Wed, 9 Nov 2005 19:38:00 -0800
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Subject: Good memory management
From: me@bobsilva.com ("Bob Silva")

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Hi,

 

Got a question on proper memory management within the engine.

 

I have an object that stores an Array (IS_ARRAY) as a property. Inside this
property array are other objects.

 

So heres my memory layout for an initialized object:

 

Object

    Property => Array (refcount = 1)

        Array[0] = Object (refcount=1 if created inside Object constructor)

        Array[1] = Object (refcount= >1 if passed into Object from userland)

 

I have a set handler so that I can set the internal array value with an
assignment.

 

$Object = array(1, 'string');

 

Results in:

Object

    Property => Array (refcount = 1)

        Array[0] = Object (represents an the integer 0 in this case)

        Array[1] = Object (represents the string "string")

 

My question is, inside my set handler, I simply call zend_update_property,
during which refcount on the old Array property gets decremented to 0 and
has zval_dtor called on it.

Now the objects that were inside that array are dangling.

 

So here is the question. 

 

Do I just rely on the engine itself to destroy the dangling objects in the
first array at the end of the script (which works),

or do I destruct the objects myself before replacing the property (Array)
with the new one?

 

Depending on the answer, what is the process to destruct an object? Just
ZVAL_DEL_REF it and let the engine GC do the rest?

 

Thanks

 

Bob Silva


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