view hgext/amend.py @ 49622:dcb2581e33be stable

memory-usage: fix `hg log --follow --rev R F` space complexity

When running `hg log --follow --rev REVS FILES`, the log code will walk the
history of all FILES starting from the file revisions that exists in each REVS.

Before doing so, it looks if the files actually exists in the target revisions.
To do so, it opens the manifest of each revision in REVS to look up if we find
the associated items in FILES.

Before this changeset this was done in a way that created a changectx for
each target revision, keeping them in memory while we look into each file.

If the set of REVS is large, this means keeping the manifest for each entry in
REVS in memory. That can be large… if REV is in the form `::X`, this can quickly
become huge and saturate the memory. We have seen usage allocating 2GB per
second until memory runs out.

So this changeset invert the two loop so that only one revision is kept in
memory during the operation. This solve the memory explosion issue.

# amend.py - provide the amend command
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""provide the amend command (EXPERIMENTAL)

This extension provides an ``amend`` command that is similar to
``commit --amend`` but does not prompt an editor.
"""


from mercurial.i18n import _
from mercurial import (
    cmdutil,
    commands,
    registrar,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'

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


@command(
    b'amend',
    [
        (
            b'A',
            b'addremove',
            None,
            _(b'mark new/missing files as added/removed before committing'),
        ),
        (b'e', b'edit', None, _(b'invoke editor on commit messages')),
        (b'i', b'interactive', None, _(b'use interactive mode')),
        (
            b'',
            b'close-branch',
            None,
            _(b'mark a branch as closed, hiding it from the branch list'),
        ),
        (b's', b'secret', None, _(b'use the secret phase for committing')),
        (b'n', b'note', b'', _(b'store a note on the amend')),
    ]
    + cmdutil.walkopts
    + cmdutil.commitopts
    + cmdutil.commitopts2
    + cmdutil.commitopts3,
    _(b'[OPTION]... [FILE]...'),
    helpcategory=command.CATEGORY_COMMITTING,
    inferrepo=True,
)
def amend(ui, repo, *pats, **opts):
    """amend the working copy parent with all or specified outstanding changes

    Similar to :hg:`commit --amend`, but reuse the commit message without
    invoking editor, unless ``--edit`` was set.

    See :hg:`help commit` for more details.
    """
    cmdutil.check_note_size(opts)

    with repo.wlock(), repo.lock():
        if not opts.get('logfile'):
            opts['message'] = opts.get('message') or repo[b'.'].description()
        opts['amend'] = True
        return commands._docommit(ui, repo, *pats, **opts)