view mercurial/ @ 978:ea67e5b37043

hgweb: Changed file revision page to list format syntax
author Josef "Jeff" Sipek <>
date Wed, 17 Aug 2005 22:08:15 -0500
parents 0902ffece4b4
children 6d5a62a549fa
line wrap: on
line source

# - 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 <>
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import os
import util

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

        # abort here if the journal already exists
        if os.path.exists(journal):
            raise "journal already exists - run hg recover" = report
        self.opener = opener
        self.after = after
        self.entries = [] = {}
        self.journal = journal

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

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

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

    def close(self):
        self.entries = []
        if self.after:
        self.journal = None

    def abort(self):
        if not self.entries: return"transaction abort!\n")

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

        self.entries = []"rollback completed\n")

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