view mercurial/node.py @ 52167:7346f93be7a4

revlog: add the glue to use the Rust `InnerRevlog` from Python

The performance of this has been looked at for quite some time, and some
workflows are actually quite a bit faster than with the Python + C code.

However, we are still (up to 20%) slower in some crucial places like cloning
certain repos, log, cat, which makes this an incomplete rewrite. This is
mostly due to the high amount of overhead in Python <-> Rust FFI, especially
around the VFS code. A future patch series will rewrite the VFS code in
pure Rust, which should hopefully get us up to par with current perfomance,
if not better in all important cases.

This is a "save state" of sorts, as this is a ton of code, and I don't want
to pile up even more things in a single review.

Continuing to try to match the current performance will take an extremely
long time, if it's not impossible, without the aforementioned VFS work.

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Olivia Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import annotations

import binascii

# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
bin = binascii.unhexlify


def short(node):
    return hex(node[:6])


nullrev = -1

# pseudo identifier for working directory
# (experimental, so don't add too many dependencies on it)
wdirrev = 0x7FFFFFFF


class sha1nodeconstants:
    nodelen = 20

    # In hex, this is '0000000000000000000000000000000000000000'
    nullid = b"\0" * nodelen
    nullhex = hex(nullid)

    # Phony node value to stand-in for new files in some uses of
    # manifests.
    # In hex, this is '2121212121212121212121212121212121212121'
    newnodeid = b'!!!!!!!!!!!!!!!!!!!!'
    # In hex, this is '3030303030303030303030303030306164646564'
    addednodeid = b'000000000000000added'
    # In hex, this is '3030303030303030303030306d6f646966696564'
    modifiednodeid = b'000000000000modified'

    wdirfilenodeids = {newnodeid, addednodeid, modifiednodeid}

    # pseudo identifier for working directory
    # (experimental, so don't add too many dependencies on it)
    # In hex, this is 'ffffffffffffffffffffffffffffffffffffffff'
    wdirid = b"\xff" * nodelen
    wdirhex = hex(wdirid)


# legacy starting point for porting modules
nullid = sha1nodeconstants.nullid
nullhex = sha1nodeconstants.nullhex
newnodeid = sha1nodeconstants.newnodeid
addednodeid = sha1nodeconstants.addednodeid
modifiednodeid = sha1nodeconstants.modifiednodeid
wdirfilenodeids = sha1nodeconstants.wdirfilenodeids
wdirid = sha1nodeconstants.wdirid
wdirhex = sha1nodeconstants.wdirhex