rebase: exclude descendants of obsoletes w/o a successor in dest (
issue5300)
.. feature::
Let 'hg rebase' avoid content-divergence by skipping obsolete
changesets (and their descendants) when they are present in the rebase
set along with one of their successors but none of their successors is
in destination.
In the following example, when trying to rebase 3:: onto 2, the rebase
will abort with "this rebase will cause divergence from: 4":
o 7 f
|
| o 6 e
| |
| o 5 d'
| |
x | 4 d (rewritten as 5)
|/
o 3 c
|
| o 2 x
| |
o | 1 b
|/
o 0 a
By excluding obsolete changesets without a successor in destination (4
in the example above) and their descendants, we make rebase work in this
case, thus giving:
o 11 e
|
o 10 d'
|
o 9 c
|
o 8 b
|
| o 7 f
| |
| | x 6 e (rewritten using rebase as 11)
| | |
| | x 5 d' (rewritten using rebase as 10)
| | |
| x | 4 d
| |/
| x 3 c (rewritten using rebase as 9)
| |
o | 2 x
| |
| x 1 b (rewritten using rebase as 8)
|/
o 0 a
where branch 4:: is left behind while branch 5:: is rebased as expected.
The rationale is that users may not be interested in rebasing orphan
changesets when specifying a rebase set that include them but would
still want "stable" ones to be rebased. Currently, the user is suggested
to allow divergence (but probably does not want it) or they must specify
a rebase set excluding problematic changesets (which might be a bit
cumbersome). The approach proposed here corresponds to "Option 2" in
https://www.mercurial-scm.org/wiki/CEDRebase.
We extend _computeobsoletenotrebased() so that it also return a set of
obsolete changesets in rebase set without a successor in destination but
with at least one successor in rebase set. This
'obsoletewithoutsuccessorindestination' is then stored as an attribute
of rebaseruntime and used in _performrebasesubset() to:
* filter out descendants of these changesets from the revisions to
rebase;
* issue a message about these revisions being skipped.
This only occurs if 'evolution.allowdivergence' option is off and
'rebaseskipobsolete' is on.
# 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, 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)
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, node, p1=None, p2=None, rev=None):
try:
super(filelog, self).checkhash(text, node, p1=p1, p2=p2, 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