Re: Re: How to create Persistent zval?
On Sat, Jan 18, 2014 at 9:01 PM, Lin Yo-An <[email protected]> wrote:
> By the way, Is this the reason of date ext always check the global
> HashTable and re-initialize the tzdata in every request?
>
> Lin Yo-An <[email protected]> 於 2014年1月19日星期日寫道：
>
>>
>>
>> Daniel Lowrey <[email protected] <javascript:_e({}, 'cvml',
>> '[email protected]');>> 於 2014年1月19日星期日寫道：
>>
>>> >> Hello,
>>> >>
>>> >> I am trying to store a zval object into the persistent list in zend VM.
>>> >> (Using EG(persistent_list) and zend_rscd_list_entry)
>>> >>
>>> >> Which works fine if I store/fetch the zval in the same request context.
>>> >>
>>> >> But it seems that zend engine cleans up the zval object after the
>>> request,
>>> >> when the next request comes, the fetched list entry points to a freed
>>> zval
>>> >> address and it makes php segmentationfault. I guess zval is allocated
>>> by
>>> >> emalloc, so I cant keep it cross requests?
>>>
>>> > For persistent alloc, you should use pemalloc() , which is just a
>>> > wrapper leading to libc's malloc.
>>> > If you use emalloc() , the Zend Memory Manager will free the storage
>>> > at the end of the request, thus leading to use-after-free crash if you
>>> > reuse your pointer on a next request.
>>>
>>> --- Disclaimer ---
>>> I'm passing this along; Joe is having technical difficulties and asked for
>>> help sending this to the list. I provide no warranties or refunds ;)
>>> ---
>>>
>>> All zvals passed into the engine must be allocated by the mm, you cannot
>>> pemalloc anything and pass it into the engine safely.
>>>
>>> You don't want to store a persistent zval, you want to store a persistent
>>> resource entry, which should be allocated with pemalloc(size, 1)
>>>
>>> The reason for this is when cleaning up, the engine has no means by which
>>> to tell if a zval has been pemalloc or emalloc'd, zval_ptr_dtor works the
>>> same for everything.
>>
>>
>>
>> Thank you so much! That is what i was guessing.. - ref cnt and pemalloc
>> does not work for persistent zval.
>>
>> And zend engine cleans up zvals at the end of request no matter the ref
>> cnt is?
>>
>> so zval is not persistent, then is HashTable persistent?
>>
>> It's because I need to store a zval object which has several properties.
>> Is there a way to do make the object persistent? Or do i need to serialize
>> it just like apc?
Read the shutdown sequence, and you will figure it out by yourself.
Non-persistent pointers are freed at request shutdown.
http://lxr.php.net/xref/PHP_5_5/Zend/zend_alloc.c#1601
Julien
Thread (14 messages)