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rust-discovery: using the children cache in add_missing
The DAG range computation often needs to get back to very old
revisions, and turns out to be disproportionately long, given
that the end goal is to remove the descendents of the given
missing revisons from the undecided set.
The fast iteration capabilities available in the Rust case make
it possible to avoid the DAG range entirely, at the cost of
precomputing the children cache, and to simply iterate on
children of the given missing revisions.
This is a case where staying on the same side of the interface
between the two languages has clear benefits.
On discoveries with initial undecided sets
small enough to bypass sampling entirely, the total cost of
computing the children cache and the subsequent iteration
becomes better than the Python + C counterpart, which relies on
reachableroots2.
For example, on a repo with more than one million revisions with
an initial undecided set of 11 elements, we get these figures:
Rust version with simple iteration
addcommons: 57.287us
first undecided computation: 184.278334ms
first children cache computation: 131.056us
addmissings iteration: 42.766us
first addinfo total: 185.24 ms
Python + C version
first addcommons: 0.29 ms
addcommons 0.21 ms
first undecided computation 191.35 ms
addmissings 45.75 ms
first addinfo total: 237.77 ms
On discoveries with large undecided sets, the initial price paid
makes the first addinfo slower than the Python + C version,
but that's more than compensated by the gain in sampling and
subsequent iterations.
Here's an extreme example with an undecided set of a million revisions:
Rust version:
first undecided computation: 293.842629ms
first children cache computation: 407.911297ms
addmissings iteration: 34.312869ms
first addinfo total: 776.02 ms
taking initial sample
query 2: sampling time: 1318.38 ms
query 2; still undecided: 1005013, sample size is: 200
addmissings: 143.062us
Python + C version:
first undecided computation 298.13 ms
addmissings 80.13 ms
first addinfo total: 399.62 ms
taking initial sample
query 2: sampling time: 3957.23 ms
query 2; still undecided: 1005013, sample size is: 200
addmissings 52.88 ms
Differential Revision: https://phab.mercurial-scm.org/D6428
author | Georges Racinet <georges.racinet@octobus.net> |
---|---|
date | Tue, 16 Apr 2019 01:16:39 +0200 |
parents | 666d90ace0bb |
children | 99e231afc29c |
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#!/usr/bin/env python # # Copyright 2005-2007 by Intevation GmbH <intevation@intevation.de> # # 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. """ hg-ssh - a wrapper for ssh access to a limited set of mercurial repos To be used in ~/.ssh/authorized_keys with the "command" option, see sshd(8): command="hg-ssh path/to/repo1 /path/to/repo2 ~/repo3 ~user/repo4" ssh-dss ... (probably together with these other useful options: no-port-forwarding,no-X11-forwarding,no-agent-forwarding) This allows pull/push over ssh from/to the repositories given as arguments. If all your repositories are subdirectories of a common directory, you can allow shorter paths with: command="cd path/to/my/repositories && hg-ssh repo1 subdir/repo2" You can use pattern matching of your normal shell, e.g.: command="cd repos && hg-ssh user/thomas/* projects/{mercurial,foo}" You can also add a --read-only flag to allow read-only access to a key, e.g.: command="hg-ssh --read-only repos/*" """ from __future__ import absolute_import import os import shlex import sys # enable importing on demand to reduce startup time import hgdemandimport ; hgdemandimport.enable() from mercurial import ( dispatch, pycompat, ui as uimod, ) def main(): # Prevent insertion/deletion of CRs dispatch.initstdio() cwd = os.getcwd() readonly = False args = sys.argv[1:] while len(args): if args[0] == '--read-only': readonly = True args.pop(0) else: break allowed_paths = [os.path.normpath(os.path.join(cwd, os.path.expanduser(path))) for path in args] orig_cmd = os.getenv('SSH_ORIGINAL_COMMAND', '?') try: cmdargv = shlex.split(orig_cmd) except ValueError as e: sys.stderr.write('Illegal command "%s": %s\n' % (orig_cmd, e)) sys.exit(255) if cmdargv[:2] == ['hg', '-R'] and cmdargv[3:] == ['serve', '--stdio']: path = cmdargv[2] repo = os.path.normpath(os.path.join(cwd, os.path.expanduser(path))) if repo in allowed_paths: cmd = [b'-R', pycompat.fsencode(repo), b'serve', b'--stdio'] req = dispatch.request(cmd) if readonly: if not req.ui: req.ui = uimod.ui.load() req.ui.setconfig(b'hooks', b'pretxnopen.hg-ssh', b'python:__main__.rejectpush', b'hg-ssh') req.ui.setconfig(b'hooks', b'prepushkey.hg-ssh', b'python:__main__.rejectpush', b'hg-ssh') dispatch.dispatch(req) else: sys.stderr.write('Illegal repository "%s"\n' % repo) sys.exit(255) else: sys.stderr.write('Illegal command "%s"\n' % orig_cmd) sys.exit(255) def rejectpush(ui, **kwargs): ui.warn((b"Permission denied\n")) # mercurial hooks use unix process conventions for hook return values # so a truthy return means failure return True if __name__ == '__main__': main()