Re: [PHP-DEV] destructors and output_buffering

On 31 Aug, 2014, at 9:33 am, Stas Malyshev <[email protected]> wrote:

> Hi!
> 
> I was looking at bug https://bugs.php.net/bug.php?id=67644 and it looks
> like we have a bit of a problem with output buffering and dtors on
> shutdown. Basically, right now our code looks like this:
> 
> 	/* 2. Call all possible __destruct() functions */
> 	zend_try {
> 		zend_call_destructors(TSRMLS_C);
> 	} zend_end_try();
> 
> 	/* 3. Flush all output buffers */
> 	zend_try {
> 	
> // And here we go flushing output buffers
> 
> Now, since ob functions can have userland handlers, these handlers can
> create new objects. And these objects will not benefit from orderly dtor
> round that zend_call_destructors(TSRMLS_C) is providing - instead their
> dtors will be called from zend_objects_store_free_object_storage() and
> by then their environment may already be ruined and their dtors can not
> run properly.
> 
> OTOH, moving __destruct after output buffers may not be good either, as
> dtors may output something.
> 
> The problem seems to be resolved if I either duplicate
> zend_call_destructors(TSRMLS_C); after the output buffers flushing or put
> zend_objects_store_mark_destructed(&EG(objects_store) TSRMLS_CC);
> there.
> 
> Of course, the second solution has the downside of not calling the dtors
> of objects that were created while flushing ob buffers. The
> zend_call_destructors would work but since output buffering is supposed
> to be shut down by then, I wonder if it won't also have bad consequences
> if these dtors do something with output buffering.
> 
> I'm leaning towards the second solution - if you create the objects so
> late on shutdown stage, you shouldn't really expect them to be destroyed
> normally, otherwise the cycle would never end. However, we could
> consider the first option too. Any thoughts?

This is just a thought; could we delay the call to `zend_call_destructors` ONLY IF there’s output buffering taking place (i.e. ob_get_level() > 0)?

> -- 
> Stanislav Malyshev, Software Architect
> SugarCRM: http://www.sugarcrm.com/
> 
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