On 2016-09-04 00:03, Yury Selivanov wrote: > > > On 2016-09-03 12:27 PM, Brett Cannon wrote: >> Below is the `co_extra` section of PEP 523 with the update saying that >> users are expected to put a tuple in the field for easier simultaneous >> use of the field. >> >> Since the `co_extra` discussions do not affect CPython itself I'm >> planning on landing the changes stemming from the PEP probably on Monday. > > Tuples are immutable. If you have multiple co_extra users then they > will have to either mutate tuple (which isn't always possible, for > instance, you can't increase size), or to replace it with another tuple. > > Creating lists is a bit more expensive, but item access speed should be > in the same ballpark. > > Another question -- sorry if this was discussed before -- why do we want > a PyObject* there at all? I.e. why don't we create a dedicated struct > CoExtraContainer to manage the stuff in co_extra? My understanding is > that the users of co_extra are C-level python optimizers and profilers, > which don't need the overhead of CPython API. > > This way my work to add an extra caching layer (which I'm very much > willing to continue to work on) wouldn't require another set of extra > fields for code objects.
Quick idea before I go to bed: You could adopt a similar API to OpenSSL's CRYPTO_get_ex_new_index() API, https://www.openssl.org/docs/manmaster/crypto/CRYPTO_get_ex_new_index.html static int code_index = 0; int PyCodeObject_NewIndex() { return code_index++; } A library like Pyjion has to acquire an index first. In further calls it uses the index as offset into the new co_extra field. Libraries don't have to hard-code their offset and two libraries will never conflict. PyCode_New() can pre-populate co_extra with a PyTuple of size code_index. This avoids most resizes if you load Pyjion early. For code_index == 0 leaf the field NULL. Christian _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
