_Jv_InitPrimClass?

Mon Mar 4 10:33:00 GMT 2002

"Boehm, Hans" <hans_boehm@hp.com> writes:
> I think there is a fairly easy workaround, provided we know that distinct
> objects used for locking are at least 8 bytes apart.

Yes, this was my hack (which is why I can confidently say "hash
locking works on Win32 modulo the PrimClasses") -- I just added a line
to clear the bottom three bits of the object address on entry to all
the hash-locking functions.
Since we know that all objects are always at least 8 bytes apart, this
won't cause problems. However, I figured it was too much of a hack, or
too dangerous to commit. If you all are okay with it, I'll submit a
patch.
Perhaps a sanity check is in order to counterbalance the risk -- if
any of the bottom three bits of the address are set, confirm that the
object being locked is one of the primclasses; if it is not, abort
with an error message. This would cause a slight slowdown when locking
on one of the primclasses (due to the sanity check), though I doubt it
happens often enough to make a big difference.
> Of course, I haven't actually tried this ...

I have. It works.
> makes it easier to detect any accidental alignment problems.

This is my biggest concern; what do you think about the sanity check?
 - a
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