Hi! Mathieu Othacehe <othac...@gnu.org> skribis:
>> ‘pointer->device!’ attempts to do that but I think it’s bogus: it >> uses a weak-value hash table, where the value is the wrapper. So >> if the wrapper disappears before the underlying C object, then the >> pointer is called and bad things ensue. > > I'm not sure to understand how could the wrapper disappear before the > underlying C object? We are only exposing <device> records to the > Guile-Parted users so my assumption is that when <device> goes out of > scope, the pointer it wraps can be freed, but I'm maybe missing > something? Hmm you’re right (and yes it’s the same as ‘define-wrapped-pointer-type’ does). So that should be fine. > Regarding object lifetime, I wrote a small memo in 2019 here: > https://issues.guix.gnu.org/36402#11. Nice, though it does feel like we’re running in circles. :-) > We have three weak hash tables in Guile-Parted: > > %devices: To make sure that we do not set multiple finalizers on the > same pointers. > > %disk-devices: So that a device always outlives its disks. > > %partition-disks: So that a disk always outlives its partitions. > > This means that as far as I can tell we are OK regarding your second > point about "aggregation relations". OK. Another thing to keep in mind: finalizers run in a separate thread, so finalization can happen concurrently. That can be problematic is there is shared global state in the library that’s being access when an benign-looking free function is called. Could you show the backtrace of the other threads as well, preferably with debugging info? Thanks, Ludo’.
