view mercurial/transaction.py @ 6174:434139080ed4

Permit XML entities to be escaped in template output.

Useful for creating XML documents directly from Hg logging. Can also be used for
HTML. For use in content, will escape '&', '<', and for completeness '>'
(although it is not strictly necessary). For use in attributes, will also escape
' and ". Will also replace nonprinting (ASCII) control characters with spaces,
since these are illegal in XML.

# 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, 2006 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

from i18n import _
import os

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

        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")
        if createmode is not None:
            os.chmod(self.journal, createmode & 0666)

    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, data=None):
        if file in self.map: return
        self.entries.append((file, offset, data))
        self.map[file] = len(self.entries) - 1
        # add enough data to the journal to do the truncate
        self.file.write("%s\0%d\n" % (file, offset))
        self.file.flush()

    def find(self, file):
        if file in self.map:
            return self.entries[self.map[file]]
        return None

    def replace(self, file, offset, data=None):
        if file not in self.map:
            raise KeyError(file)
        index = self.map[file]
        self.entries[index] = (file, offset, data)
        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, ignore 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):
    files = {}
    for l in open(file).readlines():
        f, o = l.split('\0')
        files[f] = o
    for f in files:
        o = files[f]
        opener(f, "a").truncate(int(o))
    os.unlink(file)