Robert Roessler wrote:
This could still potentially be handled by a C-style interface, if we
could optionally associate a C "finalize" function with a volatile -
this function could be called by the Poly memory reclamation when the
volatile is truly unreachable; upon its return, Poly can go ahead and
complete the free operation.
This issue comes up both in the general case of talking to extra-Poly
code (where we may have some control of the interface presented), but
also in the case of talking to an existing library that is C++ rather
than C based... in this case, we really need to allow the foreign code
base to perform its own lifetime-management related operations.
Like I said, this functionality may be available already... but if
isn't, what are others' thoughts on the subject? Is this facility needed?
It seems like it could be useful. It isn't possible to run ML code
while actually doing the garbage-collection so it would be necessary to
record that a vol was due to be deleted and then call the finaliser at
some point later on. That, of course, raises the question of which
thread runs the finaliser. From a bit of searching it appears that in
Java finalisers can be run on any thread which doesn't seem a good idea.
It may be possible to get the effect by using a weak reference
(structure Weak). That requires a thread to monitor Weak.weakSignal and
use that to then check which values have been deleted.
David
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