[PATCH 3/5] jscript: Implement script persistence.

[Jacek Caban]

On 11/7/19 1:19 PM, Gabriel Ivăncescu wrote:
> On 11/6/19 6:57 PM, Jacek Caban wrote:
>> On 11/6/19 5:50 PM, Jacek Caban wrote:
>>> Hi Gabriel,
>>>
>>> On 11/6/19 4:28 PM, Gabriel Ivăncescu wrote:
>>>> --- a/dlls/jscript/jscript.c
>>>> +++ b/dlls/jscript/jscript.c
>>>> @@ -62,6 +62,8 @@ typedef struct {
>>>>         bytecode_t *queue_head;
>>>>       bytecode_t *queue_tail;
>>>> +    bytecode_t *persistent_head;
>>>> +    bytecode_t *persistent_tail;
>>>
>>>
>>> I think it would be cleaner to use struct list from wine/list.h 
>>> instead. 
>>
>>
>> I replied too soon. It would be generally preferable, more 
>> importantly, it's the same question as I had for vbscript: why do we 
>> need a separated list? Can we just store a flag?
>>
>>
>> Thanks,
>>
>> Jacek
>>
>
> We can use a flag, but then we have to also use a flag for queued 
> code, just like vbscript (where it has both pending_exec and 
> is_persistent). Meaning we have to revamp the current implementation 
> with queue list.
>
> That's because without a pending_exec flag, we'll lose the code list 
> when the queue gets cleared -- and thus, access to the persistent code 
> list, too. Unless, of course, we store two lists but that's what the 
> patch had already.
>
> The reason is that persistent and non-persistent code can be mixed in 
> ordering, for example (P = persistent, N = non-persistent):
>
> P->P->N->P->N
>
> So the queue now looks like the above. Then the script is started and 
> they get executed.
>
> When it is uninitialized, and then re-initialized, the queue is now:
>
> P->P->P
>
> because the persistent code has to be re-executed. Adding more code 
> before starting the script will add to the end, of course.
>
>
> But currently, we keep a queue of pending code *only*. So, if the 
> script gets started, the queue gets cleared. That means we lose access 
> to the persistent code list without a second list, and thus can't 
> re-queue it back when it is uninitialized.
>
>
> So, should I proceed with two flags like in vbscript and a single list? 


I can see your point. I'm not against separated lists, but I don't 
really like the way your patch makes it more complicated than it needs 
to be, eg. by adding additional fields to bytecode_t. I think that if 
you'd have the bytecode in only one list at a time (so pending 
persistent code would be only on pending list and it would be moved to 
persistent list when it's executed), it could be a bit cleaner. Of 
course then you'd need to store persistent flags to know which pending 
code should be removed when changing the state to SCRIPTSTATE_UNINITIALIZED.


In any case, to be able to easily remove entries from a queue, a double 
linked list would be nicer, so changing bytecode_t to use standard list 
first seems like a good idea.


Thanks,

Jacek