Re: Octave Memory Management

[Kai Torben Ohlhus]

On 8/19/19 6:32 AM, Thomas D. Dean wrote:
> On 8/18/19 11:36 AM, Sebastian Schöps wrote:
>> Thomas D. Dean-2 wrote
>>> I have an .oct file that I want to open a device, return the pointer to
>>> the device structure.
>>>
>>> ...
>>>
>>> Does octave keep the allocation of dev_ptr between function calls?
>>>
>>> Is it possible to use a static variable in the .cc file?  Would I have
>>> to free it when the device is closed?
>>>
>>> I can post the full application if necessary.
>>>
>>> Tom Dean
>>
>> Maybe Carlo‘s old advice helps?
>> https://octave.1599824.n4.nabble.com/Persistent-dara-across-oct-files-tp4689039.html
>>
>>
>> Seb.
> 
> Carlo's answer is static variables.
> 
> That gets me mostly there.  I am opening a USB device.
> 
> A clear("all") most likely destroys the instance of the static variable.
> A subsequent call to the function results in
>    usb_claim_interface error -6
> 
> This most likely results in a memory leak of the size of a device
> structure.
> 
> Is there any way to implement a "call on clear" or
> "call on function removal" function.  Sort of like a device callback
> function?  Google is not much help.
> 
> Tom Dean
> 
> 

Your description reminds me of the "onCleanup" function [1].  If you
wrap your oct-files in some m-file code, you should be able to define
some onCleanup action in case your wrapper object is cleared.

HTH,
Kai

[1] https://octave.org/doc/v5.1.0/XREFonCleanup.html