[Python-Dev] Accepting PEP 3154 for 3.4? (original) (raw)

Tim Peters tim.peters at gmail.com
Tue Nov 19 01:50:01 CET 2013

[Antoine]

Yet another possibility: keep framing but use a variable-length encoding for the frame size:

- first byte: bits 7-5: N (= frame size bytes length - 1) - first byte: bits 4-0: first 5 bits of frame size - remaning N bytes: remaining bits of frame size With this scheme, very small pickles have a one byte overhead; small ones a two byte overhead; and the max frame size is 2**61 rather than 2**64, which should still be sufficient. And the frame size is read using either one or two read() calls, which is efficient.

That would be a happy compromise :-)

I'm unclear on how that would work for, e.g., encoding 40 = 0b000101000. That has 6 significant bits. Would you store 0 in the leading byte and 40 in the second byte? That would work.

2**61 = 2,305,843,009,213,693,952 is a lot of bytes, especially for a pickle ;-)

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