/brz/remove-bazaar

# Copyright (C) 2004, 2005 by 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

import codecs

import errno

import os

import socket

import sys

from warnings import warn

from bzrlib.osutils import rename

# not forksafe - but we dont fork.

_pid = os.getpid()

class AtomicFile(object):

    """A file that does an atomic-rename to move into place.

    This also causes hardlinks to break when it's written out.

    Open this as for a regular file, then use commit() to move into

    place or abort() to cancel.

    An encoding can be specified; otherwise the default is ascii.

    """

    __slots__ = ['f', 'tmpfilename', 'realfilename', 'write']

    def __init__(self, filename, mode='wb', new_mode=0666):

        self.f = None

        assert mode in ('wb', 'wt'), \

            "invalid AtomicFile mode %r" % mode

        # old version:

        #self.tmpfilename = '%s.%d.%s.tmp' % (filename, os.getpid(),

        #                                     socket.gethostname())

        # new version:

        # This is 'broken' on NFS: it wmay collide with another NFS client.

        # however, we use this to write files within a directory that we have

        # locked, so it being racy on NFS is not a concern. The only other

        # files we use this for are .bzr.ignore, which can race anyhow.

        self.tmpfilename = '%s.%d.tmp' % (filename, _pid)

        self.realfilename = filename

        # Use a low level fd operation to avoid chmodding later.

        fd = os.open(self.tmpfilename, os.O_EXCL | os.O_CREAT | os.O_WRONLY,

            new_mode)

        # open a normal python file to get the text vs binary support needed

        # for windows.

        try:

            self.f = os.fdopen(fd, mode)

        except:

            os.close(fd)

            raise

        self.write = self.f.write

    def __repr__(self):

        return '%s(%r)' % (self.__class__.__name__,

                           self.realfilename)

    def commit(self):

        """Close the file and move to final name."""

        if self.f is None:

            raise Exception('%r is already closed' % self)

        f = self.f

        self.f = None

        f.close()

        rename(self.tmpfilename, self.realfilename)

    def abort(self):

        """Discard temporary file without committing changes."""

        if self.f is None:

            raise Exception('%r is already closed' % self)

        f = self.f

        self.f = None

        f.close()

        os.remove(self.tmpfilename)

    def close(self):

        """Discard the file unless already committed."""

        if self.f is not None:

            self.abort()

    def __del__(self):

        if self.f is not None:

            warn("%r leaked" % self)