localrepo: restore dirstate to one before rollbacking if not parent-gone
'localrepository.rollback()' explicilty restores dirstate, only if at
least one of current parents of the working directory is removed at
rollbacking (a.k.a "parent-gone").
After DirstateTransactionPlan, 'dirstate.write()' will cause marking
'.hg/dirstate' as a file to be restored at rollbacking.
https://mercurial.selenic.com/wiki/DirstateTransactionPlan
Then, 'transaction.rollback()' restores '.hg/dirstate' regardless of
parents of the working directory at that time, and this causes
unexpected dirstate changes if not "parent-gone" (e.g. "hg update" to
another branch after "hg commit" or so, then "hg rollback").
To avoid such situation, this patch restores dirstate to one before
rollbacking if not "parent-gone".
before:
b1. restore dirstate explicitly, if "parent-gone"
after:
a1. save dirstate before actual rollbacking via dirstateguard
a2. restore dirstate via 'transaction.rollback()'
a3. if "parent-gone"
- discard backup (a1)
- restore dirstate from 'undo.dirstate'
a4. otherwise, restore dirstate from backup (a1)
Even though restoring dirstate at (a3) after (a2) seems redundant,
this patch keeps this existing code path, because:
- it isn't ensured that 'dirstate.write()' was invoked at least once
while transaction running
If not, '.hg/dirstate' isn't restored at (a2).
In addition to it, rude 3rd party extension invoking
'dirstate.write()' without 'repo' while transaction running (see
subsequent patches for detail) may break consistency of a file
backup-ed by transaction.
- this patch mainly focuses on changes for DirstateTransactionPlan
Restoring dirstate at (a3) itself should be cheaper enough than
rollbacking itself. Redundancy will be removed in next step.
Newly added test is almost meaningless at this point. It will be used
to detect regression while implementing delayed dirstate write out.
# filelog.py - file history class for mercurial
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import re
import struct
from . import (
error,
mdiff,
revlog,
)
_mdre = re.compile('\1\n')
def parsemeta(text):
"""return (metadatadict, keylist, metadatasize)"""
# text can be buffer, so we can't use .startswith or .index
if text[:2] != '\1\n':
return None, None
s = _mdre.search(text, 2).start()
mtext = text[2:s]
meta = {}
for l in mtext.splitlines():
k, v = l.split(": ", 1)
meta[k] = v
return meta, (s + 2)
def packmeta(meta, text):
keys = sorted(meta.iterkeys())
metatext = "".join("%s: %s\n" % (k, meta[k]) for k in keys)
return "\1\n%s\1\n%s" % (metatext, text)
def _censoredtext(text):
m, offs = parsemeta(text)
return m and "censored" in m
class filelog(revlog.revlog):
def __init__(self, opener, path):
super(filelog, self).__init__(opener,
"/".join(("data", path + ".i")))
def read(self, node):
t = self.revision(node)
if not t.startswith('\1\n'):
return t
s = t.index('\1\n', 2)
return t[s + 2:]
def add(self, text, meta, transaction, link, p1=None, p2=None):
if meta or text.startswith('\1\n'):
text = packmeta(meta, text)
return self.addrevision(text, transaction, link, p1, p2)
def renamed(self, node):
if self.parents(node)[0] != revlog.nullid:
return False
t = self.revision(node)
m = parsemeta(t)[0]
if m and "copy" in m:
return (m["copy"], revlog.bin(m["copyrev"]))
return False
def size(self, rev):
"""return the size of a given revision"""
# for revisions with renames, we have to go the slow way
node = self.node(rev)
if self.renamed(node):
return len(self.read(node))
if self.iscensored(rev):
return 0
# XXX if self.read(node).startswith("\1\n"), this returns (size+4)
return super(filelog, self).size(rev)
def cmp(self, node, text):
"""compare text with a given file revision
returns True if text is different than what is stored.
"""
t = text
if text.startswith('\1\n'):
t = '\1\n\1\n' + text
samehashes = not super(filelog, self).cmp(node, t)
if samehashes:
return False
# censored files compare against the empty file
if self.iscensored(self.rev(node)):
return text != ''
# renaming a file produces a different hash, even if the data
# remains unchanged. Check if it's the case (slow):
if self.renamed(node):
t2 = self.read(node)
return t2 != text
return True
def checkhash(self, text, p1, p2, node, rev=None):
try:
super(filelog, self).checkhash(text, p1, p2, node, rev=rev)
except error.RevlogError:
if _censoredtext(text):
raise error.CensoredNodeError(self.indexfile, node, text)
raise
def iscensored(self, rev):
"""Check if a file revision is censored."""
return self.flags(rev) & revlog.REVIDX_ISCENSORED
def _peek_iscensored(self, baserev, delta, flush):
"""Quickly check if a delta produces a censored revision."""
# Fragile heuristic: unless new file meta keys are added alphabetically
# preceding "censored", all censored revisions are prefixed by
# "\1\ncensored:". A delta producing such a censored revision must be a
# full-replacement delta, so we inspect the first and only patch in the
# delta for this prefix.
hlen = struct.calcsize(">lll")
if len(delta) <= hlen:
return False
oldlen = self.rawsize(baserev)
newlen = len(delta) - hlen
if delta[:hlen] != mdiff.replacediffheader(oldlen, newlen):
return False
add = "\1\ncensored:"
addlen = len(add)
return newlen >= addlen and delta[hlen:hlen + addlen] == add