On 2014-04-11 22:22:18 +0000, Nick Sabalausky
<seewebsitetocontac...@semitwist.com> said:
On 4/11/2014 3:54 PM, Michel Fortin wrote:
Can destructors be @safe at all? When called from the GC the destructor
1) likely runs in a different thread and 2) can potentially access other
destructed objects, those objects might contain pointers to deallocated
memory if their destructor manually freed a memory block.
If destructors can't be @safe, that would seem to create a fairly
sizable hole in the utility of @safe.
Well, they are safe as long as they're not called by the GC. I think
you could make them safe even with the GC by changing things this way:
1- make the GC call the destructor in the same thread the object was
created in (for non-shared objects), so any access to thread-local
stuff stays in the right thread, avoiding low-level races.
2- after the destructor is run on an object, wipe out the memory block
with zeros. This way if another to-be-destructed object has a pointer
to it, at worse it'll dereference a null pointer. With this you might
get a sporadic crash when it happens, but that's better than memory
corruption. You only need to do this when allocated on the GC heap, and
only pointers need to be zeroed, and only if another object being
destroyed is still pointing to this object, and perhaps only do it for
@safe destructors.
--
Michel Fortin
michel.for...@michelf.ca
http://michelf.ca
