mercurial/transaction.py
author Thomas Arendsen Hein <thomas@intevation.de>
Mon, 03 Apr 2006 21:38:59 +0200
changeset 2044 b343e7d454b4
parent 1806 a2c69737e65e
child 2084 d66278012853
permissions -rw-r--r--
Don't allow --style and --template for hg update and hg merge. The only way that changesets will be shown with these command is in an error message when trying to update to an ambiguous branch name.

# transaction.py - simple journalling scheme for mercurial
#
# This transaction scheme is intended to gracefully handle program
# errors and interruptions. More serious failures like system crashes
# can be recovered with an fsck-like tool. As the whole repository is
# effectively log-structured, this should amount to simply truncating
# anything that isn't referenced in the changelog.
#
# Copyright 2005 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import os
from i18n import gettext as _

class transaction(object):
    def __init__(self, report, opener, journal, after=None):
        self.journal = None

        # abort here if the journal already exists
        if os.path.exists(journal):
            raise AssertionError(_("journal already exists - run hg recover"))

        self.count = 1
        self.report = report
        self.opener = opener
        self.after = after
        self.entries = []
        self.map = {}
        self.journal = journal

        self.file = open(self.journal, "w")

    def __del__(self):
        if self.journal:
            if self.entries: self.abort()
            self.file.close()
            try: os.unlink(self.journal)
            except: pass

    def add(self, file, offset):
        if file in self.map: return
        self.entries.append((file, offset))
        self.map[file] = 1
        # add enough data to the journal to do the truncate
        self.file.write("%s\0%d\n" % (file, offset))
        self.file.flush()

    def nest(self):
        self.count += 1
        return self

    def running(self):
        return self.count > 0

    def close(self):
        self.count -= 1
        if self.count != 0:
            return
        self.file.close()
        self.entries = []
        if self.after:
            self.after()
        else:
            os.unlink(self.journal)
        self.journal = None

    def abort(self):
        if not self.entries: return

        self.report(_("transaction abort!\n"))

        for f, o in self.entries:
            try:
                self.opener(f, "a").truncate(o)
            except:
                self.report(_("failed to truncate %s\n") % f)

        self.entries = []

        self.report(_("rollback completed\n"))

def rollback(opener, file):
    for l in open(file).readlines():
        f, o = l.split('\0')
        opener(f, "a").truncate(int(o))
    os.unlink(file)