Hi Antonio,
The only exception are strings: getting a text attribute means to take a
slice of the buffer. However, if the returned value is short-lived, the JIT
might be able to optimize the slicing away.
(note: there is no automatic conversion to unicode, although I might add an
option for that in the future).
Are you aware of
https://github.com/alex/zero_buffer
?
This emulates Python strings using zero-copy read-only buffer views.
I think zero_buffer only supports byte strings not unicode.
But for that, maybe it would be cool to have capnpy return zero_buffers
upon byte string attribute access, because that should finally provide
zero copy ..
Caveat: this is a hypothesis I haven't really explored / thought through ..
--
Holy grail for me (use case being IPC) would be:
Python process 1 mmap's a file shared with Python process 2.
Python process 1 puts a string into mmap'ed file, pointer to that is
"somehow transferred" to process 2 (eg pushing the index into the
mmap'ed file over Unix domain socket .. a single uint64), and Python
code in process 2 can do stuff with this string _without_ copying -
probably via zero_buffer.
I don't understand what you mean by dicts are there are no dictionaries in
capnproto.
Right. Structs.
Note also that capnpy is serialization only: there is no support for RPC
stuff.
That's fine .. I don't need RPC (we have WAMP for that in
Autobahn/Crossbar.io).
Note: I am purely interested in performance on PyPy ..
In general: I thought it would be a good idea to use capnproto C++
generator, and then cppyy to get the best performance (on pypy). Given
there is "antocuni/capnpy", do you think this is a pointless endeavour?
The original goal of capnpy was to be as fast as possible on PyPy. However,
if you find that C++ + cppyy is faster, I'd be very interested to know :).
Sure .. right now I cannot progress on cppyy as I can't get the basic
example running..
Cheers,
/Tobias
ciao,
Anto
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