status: prefer relative paths in Rust code
… when the repository root is under the current directory,
so the kernel needs to traverse fewer directory in every call
to `read_dir` or `symlink_metadata`.
Better yet would be to use libc functions like `openat` and `fstatat`
to remove such repeated traversals entirely, but the standard library
does not provide APIs based on those.
Maybe with a crate like https://crates.io/crates/openat instead?
Benchmarks of `rhg status` show that this patch is neutral in some configurations,
and makes the command up to ~20% faster in others.
Below is semi-arbitrary subset of results. The four numeric columns are:
time (in seconds) with this changeset’s parent, time with this changeset,
time difference (negative is better), time ratio (less than 1 is better).
```
mercurial-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.0061 -> 0.0059: -0.0002 (0.97)
mercurial-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0029 -> 0.0028: -0.0001 (0.97)
mozilla-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.2110 -> 0.2102: -0.0007 (1.00)
mozilla-dirstate-v2 | default-copies-clean.ignored.pbr | 0.0489 -> 0.0401: -0.0088 (0.82)
mozilla-dirstate-v2 | default-copies-clean.no-iu.pbr | 0.0479 -> 0.0393: -0.0085 (0.82)
mozilla-dirstate-v2 | default-copies-large.all.pbr | 0.1262 -> 0.1210: -0.0051 (0.96)
mozilla-dirstate-v2 | default-copies-small.ignored-unknown.pbr | 0.1262 -> 0.1200: -0.0062 (0.95)
mozilla-dirstate-v2 | default-copies-small.ignored.pbr | 0.0536 -> 0.0417: -0.0119 (0.78)
mozilla-dirstate-v2 | default-copies-small.no-iu.pbr | 0.0482 -> 0.0393: -0.0089 (0.81)
mozilla-dirstate-v2 | default-plain-clean.ignored.pbr | 0.0518 -> 0.0402: -0.0116 (0.78)
mozilla-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0481 -> 0.0392: -0.0088 (0.82)
mozilla-dirstate-v2 | default-plain-large.all.pbr | 0.1271 -> 0.1218: -0.0052 (0.96)
mozilla-dirstate-v2 | default-plain-small.ignored-unknown.pbr | 0.1225 -> 0.1202: -0.0022 (0.98)
mozilla-dirstate-v2 | default-plain-small.ignored.pbr | 0.0510 -> 0.0418: -0.0092 (0.82)
mozilla-dirstate-v2 | default-plain-small.no-iu.pbr | 0.0480 -> 0.0394: -0.0086 (0.82)
netbeans-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.1442 -> 0.1422: -0.0020 (0.99)
netbeans-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0325 -> 0.0282: -0.0043 (0.87)
```
Differential Revision: https://phab.mercurial-scm.org/D12175
#!/usr/bin/env python3
# Copyright 2010 Intevation GmbH
# Author(s):
# Thomas Arendsen Hein <thomas@intevation.de>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Create a Mercurial repository in revlog format 0
changeset: 0:a1ef0b125355
tag: tip
user: user
date: Thu Jan 01 00:00:00 1970 +0000
files: empty
description:
empty file
"""
from __future__ import absolute_import
import binascii
import os
import sys
files = [
(
b'formatv0/.hg/00changelog.i',
b'000000000000004400000000000000000000000000000000000000'
b'000000000000000000000000000000000000000000000000000000'
b'0000a1ef0b125355d27765928be600cfe85784284ab3',
),
(
b'formatv0/.hg/00changelog.d',
b'756163613935613961356635353036303562366138343738336237'
b'61623536363738616436356635380a757365720a3020300a656d70'
b'74790a0a656d7074792066696c65',
),
(
b'formatv0/.hg/00manifest.i',
b'000000000000003000000000000000000000000000000000000000'
b'000000000000000000000000000000000000000000000000000000'
b'0000aca95a9a5f550605b6a84783b7ab56678ad65f58',
),
(
b'formatv0/.hg/00manifest.d',
b'75656d707479006238306465356431333837353835343163356630'
b'35323635616431343461623966613836643164620a',
),
(
b'formatv0/.hg/data/empty.i',
b'000000000000000000000000000000000000000000000000000000'
b'000000000000000000000000000000000000000000000000000000'
b'0000b80de5d138758541c5f05265ad144ab9fa86d1db',
),
(b'formatv0/.hg/data/empty.d', b''),
]
def makedirs(name):
"""recursive directory creation"""
parent = os.path.dirname(name)
if parent:
makedirs(parent)
os.mkdir(name)
makedirs(os.path.join(*'formatv0/.hg/data'.split('/')))
for name, data in files:
f = open(name, 'wb')
f.write(binascii.unhexlify(data))
f.close()
sys.exit(0)