here's an idea. it's very very very very simple
create an eina_freeq(). instead of calling free() or whatever free function on
something immediately, call:
fq = eina_freeq_main_get();
eina_freeq_ptr_add(fq, pointer, size, free);
or
fq = eina_freeq_global_get();
eina_freeq_ptr_add(fq, l, sizeof(Eina_List), _eina_list_mempool_list_free);
etc.
and the free queue will "add this to the end" to be freed some time later. the
idea of size is so it could make intelligent choice like to free very large
chunks earlier than smaller allocations. the mainloop would drive this actual
freeing. or more specifically your LOCAL loop would. need to add some kind of
loop method that returns the "free queue" FOR your loop/thread. or wherever you
want it actually freed. probably have a main free queue driven by the mainloop
(and cleared up on eina_shutdown) etc.
why?
1. move overhead of doing actual frees out of critical code into idle time
2. improve stability by keeping memory eg for eo objects or eina list nodes in
a "free queue purgatory" for a while so if someone does bad things like "use
after free" the IMPACT is far smaller as they mess with memory in the free
queue not being used.
4. be able to fill memory about to be freed with patterns (eg 0x55 or 0xaa) so
after free the memory is guaranteed to have a pattern to know it was freed
(optional debug only for mem regions of size > 0 and maybe less than some max
size).
5. optional - checksum the memory when added to free queue then check checksum
on actual free to warn of some code "being bad" and scribbling over freed
memory. at least we get warnings of lurking bugs if we turn this on...
this doesn't solve everything, but it is an improvement and it's easy to slide
in and begin using very quickly - eg eo object data, eina lists and a few other
things. the free queue itself would be a very very very low overhead buffer -
not a linked list. maybe a mmaped or malloced buffer/array (ring buffer) with a
start and end point so we dont do anything but write the above ptr, free ptr
and maybe size to the next array slot and move the ring buffer next slot one
down.
adding the freeq code in eina is a cakewalk. i'd spend more time writing docs
and tests than the code itself. :( adding usage of it should be trivial.
any comments?
--
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler) ras...@rasterman.com
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