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# Copyright (C) 2006, 2007, 2009, 2010, 2011 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
"""Common code for generating file or revision ids."""
from __future__ import absolute_import
from bzrlib.lazy_import import lazy_import
lazy_import(globals(), """
import time
from bzrlib import (
config,
errors,
osutils,
)
""")
from bzrlib import (
lazy_regex,
)
# the regex removes any weird characters; we don't escape them
# but rather just pull them out
_file_id_chars_re = lazy_regex.lazy_compile(r'[^\w.]')
_rev_id_chars_re = lazy_regex.lazy_compile(r'[^-\w.+@]')
_gen_file_id_suffix = None
_gen_file_id_serial = 0
def _next_id_suffix():
"""Create a new file id suffix that is reasonably unique.
On the first call we combine the current time with 64 bits of randomness to
give a highly probably globally unique number. Then each call in the same
process adds 1 to a serial number we append to that unique value.
"""
# XXX TODO: change bzrlib.add.smart_add_tree to call workingtree.add() rather
# than having to move the id randomness out of the inner loop like this.
# XXX TODO: for the global randomness this uses we should add the thread-id
# before the serial #.
# XXX TODO: jam 20061102 I think it would be good to reset every 100 or
# 1000 calls, or perhaps if time.time() increases by a certain
# amount. time.time() shouldn't be terribly expensive to call,
# and it means that long-lived processes wouldn't use the same
# suffix forever.
global _gen_file_id_suffix, _gen_file_id_serial
if _gen_file_id_suffix is None:
_gen_file_id_suffix = "-%s-%s-" % (osutils.compact_date(time.time()),
osutils.rand_chars(16))
_gen_file_id_serial += 1
return _gen_file_id_suffix + str(_gen_file_id_serial)
def gen_file_id(name):
"""Return new file id for the basename 'name'.
The uniqueness is supplied from _next_id_suffix.
"""
# The real randomness is in the _next_id_suffix, the
# rest of the identifier is just to be nice.
# So we:
# 1) Remove non-ascii word characters to keep the ids portable
# 2) squash to lowercase, so the file id doesn't have to
# be escaped (case insensitive filesystems would bork for ids
# that only differ in case without escaping).
# 3) truncate the filename to 20 chars. Long filenames also bork on some
# filesystems
# 4) Removing starting '.' characters to prevent the file ids from
# being considered hidden.
ascii_word_only = str(_file_id_chars_re.sub('', name.lower()))
short_no_dots = ascii_word_only.lstrip('.')[:20]
return short_no_dots + _next_id_suffix()
def gen_root_id():
"""Return a new tree-root file id."""
return gen_file_id('tree_root')
def gen_revision_id(username, timestamp=None):
"""Return new revision-id.
:param username: The username of the committer, in the format returned by
config.username(). This is typically a real name, followed by an
email address. If found, we will use just the email address portion.
Otherwise we flatten the real name, and use that.
:return: A new revision id.
"""
try:
user_or_email = config.extract_email_address(username)
except errors.NoEmailInUsername:
user_or_email = username
user_or_email = user_or_email.lower()
user_or_email = user_or_email.replace(' ', '_')
user_or_email = _rev_id_chars_re.sub('', user_or_email)
# This gives 36^16 ~= 2^82.7 ~= 83 bits of entropy
unique_chunk = osutils.rand_chars(16)
if timestamp is None:
timestamp = time.time()
rev_id = u'-'.join((user_or_email,
osutils.compact_date(timestamp),
unique_chunk))
return rev_id.encode('utf8')
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