mercurial/admin/chainsaw.py

ci: shard the test run on mac os X

This should comes with some benefit:
- spread the load across more runner,
- reduce the real-time CI run,
- reduce the "retry" run when we need them.

We start with the Mac jobs, but that would be tremendously useful for Windows
too.

For linux, we need to reduce the startup overhead for this to be worth it.
Building smaller image and speeding up clone should help with that.

# chainsaw.py
#
# Copyright 2022 Georges Racinet <[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.
"""chainsaw is a collection of single-minded and dangerous tools. (EXPERIMENTAL)

  "Don't use a chainsaw to cut your food!"

The chainsaw is a collection of commands that are so much geared towards a
specific use case in a specific context or environment that they are totally
inappropriate and **really dangerous** in other contexts.

The help text of each command explicitly summarizes its context of application
and the wanted end result.

It is recommended to run these commands with the ``HGPLAIN`` environment
variable (see :hg:`help scripting`).
"""

from __future__ import annotations

import shutil

from ..i18n import _
from .. import (
    cmdutil,
    commands,
    error,
    localrepo,
    registrar,
)
from ..utils import (
    urlutil,
)

cmdtable = {}
command = registrar.command(cmdtable)


@command(
    b'admin::chainsaw-update',
    [
        (
            b'',
            b'purge-unknown',
            True,
            _(
                b'Remove unversioned files before update. Disabling this can '
                b'in some cases interfere with the update.'
                b'See also :hg:`purge`.'
            ),
        ),
        (
            b'',
            b'purge-ignored',
            True,
            _(
                b'Remove ignored files before update. Disable this for '
                b'instance to reuse previous compiler object files. '
                b'See also :hg:`purge`.'
            ),
        ),
        (
            b'',
            b'rev',
            b'',
            _(b'revision to update to'),
        ),
        (
            b'',
            b'source',
            b'',
            _(b'repository to clone from'),
        ),
        (
            b'',
            b'dest',
            b'',
            _(b'repository to update to REV (possibly cloning)'),
        ),
        (
            b'',
            b'initial-clone-minimal',
            False,
            _(
                b'Pull only the prescribed revision upon initial cloning. '
                b'This has the side effect of ignoring clone-bundles, '
                b'which if often slower on the client side and stressful '
                b'to the server than applying available clone bundles.'
            ),
        ),
    ],
    _(
        b'hg admin::chainsaw-update [OPTION] --rev REV --source SOURCE --dest DEST'
    ),
    helpbasic=True,
    norepo=True,
)
def update(ui, **opts):
    """pull and update to a given revision, no matter what, (EXPERIMENTAL)

    Context of application: *some* Continuous Integration (CI) systems,
    packaging or deployment tools.

    Wanted end result: local repository at the given REPO_PATH, having the
    latest changes to the given revision and with a clean working directory
    updated at the given revision.

    chainsaw-update pulls from one source, then updates the working directory
    to the given revision, overcoming anything that would stand in the way.

    By default, it will:

    - clone if the local repo does not exist yet, **removing any directory
      at the given path** that would not be a Mercurial repository.
      The initial clone is full by default, so that clonebundles can be
      applied. Use the --initial-clone-minimal flag to avoid this.
    - break locks if needed, leading to possible corruption if there
      is a concurrent write access.
    - perform recovery actions if needed
    - revert any local modification.
    - purge unknown and ignored files.
    - go as far as to reclone if everything else failed (not implemented yet).

    DO NOT use it for anything else than performing a series
    of unattended updates, with full exclusive repository access each time
    and without any other local work than running build scripts.
    In case the local repository is a share (see :hg:`help share`), exclusive
    write access to the share source is also mandatory.

    It is recommended to run these commands with the ``HGPLAIN`` environment
    variable (see :hg:`scripting`).

    Motivation: in Continuous Integration and Delivery systems (CI/CD), the
    occasional remnant or bogus lock are common sources of waste of time (both
    working time and calendar time). CI/CD scripts tend to grow with counter-
    measures, often done in urgency. Also, whilst it is neat to keep
    repositories from one job to the next (especially with large
    repositories), an exceptional recloning is better than missing a release
    deadline.
    """
    rev = opts['rev']
    source = opts['source']
    repo_path = opts['dest']
    if not rev:
        raise error.InputError(_(b'specify a target revision with --rev'))
    if not source:
        raise error.InputError(_(b'specify a pull path with --source'))
    if not repo_path:
        raise error.InputError(_(b'specify a repo path with --dest'))
    repo_path = urlutil.urllocalpath(repo_path)

    try:
        repo = localrepo.instance(ui, repo_path, create=False)
        repo_created = False
        ui.status(_(b'loaded repository at "%s"\n' % repo_path))
    except error.RepoError:
        try:
            shutil.rmtree(repo_path)
        except FileNotFoundError:
            ui.status(_(b'no such directory: "%s"\n' % repo_path))
        else:
            ui.status(
                _(
                    b'removed non-repository file or directory '
                    b'at "%s"' % repo_path
                )
            )

        ui.status(_(b'creating repository at "%s"\n' % repo_path))
        repo = localrepo.instance(ui, repo_path, create=True)
        repo_created = True

    if repo.svfs.tryunlink(b'lock'):
        ui.status(_(b'had to break store lock\n'))
    if repo.vfs.tryunlink(b'wlock'):
        ui.status(_(b'had to break working copy lock\n'))
    # If another process relock after the breacking above, the next locking
    # will have to wait.
    with repo.wlock(), repo.lock():
        ui.status(_(b'recovering after interrupted transaction, if any\n'))
        repo.recover()

        ui.status(_(b'pulling from %s\n') % source)
        if repo_created and not opts.get('initial_clone_minimal'):
            pull_revs = []
        else:
            pull_revs = [rev]
        overrides = {(b'ui', b'quiet'): True}
        with repo.ui.configoverride(overrides, b'chainsaw-update'):
            pull = cmdutil.findcmd(b'pull', commands.table)[1][0]
            ret = pull(
                repo.ui,
                repo,
                source,
                rev=pull_revs,
                remote_hidden=False,
            )
            if ret:
                return ret

        purge = cmdutil.findcmd(b'purge', commands.table)[1][0]
        ret = purge(
            ui,
            repo,
            dirs=True,
            all=opts.get('purge_ignored'),
            files=opts.get('purge_unknown'),
            confirm=False,
        )
        if ret:
            return ret

        ui.status(_(b'updating to revision \'%s\'\n') % rev)
        update = cmdutil.findcmd(b'update', commands.table)[1][0]
        ret = update(ui, repo, rev=rev, clean=True)
        if ret:
            return ret

        ui.status(
            _(
                b'chainsaw-update to revision \'%s\' '
                b'for repository at \'%s\' done\n'
            )
            % (rev, repo.root)
        )