mercurial/version.py

Avoid extra filelogs entries.

Right now, there are some situations in which localrepo.filecommit can
create filelog entries even though they're not needed.  For example:

- permissions for a file have changed;

- qrefresh can create a filelog entry identical to its parent (see the
  added test);

- convert-repo creates extra filelog entries in every merge where the
  first parent has added files (for example, changeset ebebe9577a1a of
  the kernel repo added extra filelog entries to files in the
  arch/blackfin directory, even though the merge should only touch the
  drivers/ata directory).  This makes "hg log file" in a converted repo
  less useful than it could be, since it may mention many merges that
  don't actually touch that specific file.

They all come from the same basic problem:  localrepo.commit (through
filecommit) creates new filelog entries for all files passed to it
(except for some cases during a merge).

Patch and test case provided by Benoit.

This should fix issue351.

# Copyright (C) 2005, 2006 by Intevation GmbH
# Author(s):
# Thomas Arendsen Hein <[e-mail]>
#
# This program is free software under the GNU GPL (>=v2)
# Read the file COPYING coming with the software for details.

"""
Mercurial version
"""

import os
import os.path
import re
import time
import util

unknown_version = 'unknown'
remembered_version = False

def get_version(doreload=False):
    """Return version information if available."""
    try:
        import mercurial.__version__
        if doreload:
            reload(mercurial.__version__)
        version = mercurial.__version__.version
    except ImportError:
        version = unknown_version
    return version

def write_version(version):
    """Overwrite version file."""
    if version == get_version():
        return
    directory = os.path.dirname(__file__)
    for suffix in ['py', 'pyc', 'pyo']:
        try:
            os.unlink(os.path.join(directory, '__version__.%s' % suffix))
        except OSError:
            pass
    f = open(os.path.join(directory, '__version__.py'), 'w')
    f.write("# This file is auto-generated.\n")
    f.write("version = %r\n" % version)
    f.close()
    # reload the file we've just written
    get_version(True)

def remember_version(version=None):
    """Store version information."""
    global remembered_version
    if not version and os.path.isdir(".hg"):
        f = os.popen("hg identify 2> %s" % util.nulldev)  # use real hg installation
        ident = f.read()[:-1]
        if not f.close() and ident:
            ids = ident.split(' ', 1)
            version = ids.pop(0)
            if version[-1] == '+':
                version = version[:-1]
                modified = True
            else:
                modified = False
            if version.isalnum() and ids:
                for tag in ids[0].split('/'):
                    # is a tag is suitable as a version number?
                    if re.match(r'^(\d+\.)+[\w.-]+$', tag):
                        version = tag
                        break
            if modified:
                version += time.strftime('+%Y%m%d')
    if version:
        remembered_version = True
        write_version(version)

def forget_version():
    """Remove version information."""
    if remembered_version:
        write_version(unknown_version)