Mercurial > hg
view mercurial/pvec.py @ 25759:ff11c1565c04
cmdutil: apply dirstate.normallookup on (maybe partially) committed files
To detect change of a file without redundant comparison of file
content, dirstate recognizes a file as certainly clean, if:
(1) it is already known as "normal",
(2) dirstate entry for it has valid (= not "-1") timestamp, and
(3) mode, size and timestamp of it on the filesystem are as same as
ones expected in dirstate
This works as expected in many cases, but doesn't in the corner case
that changing a file keeps mode, size and timestamp of it on the
filesystem.
The timetable below shows steps in one of typical such situations:
---- ----------------------------------- ----------------
timestamp of "f"
----------------
dirstate file-
time action mem file system
---- ----------------------------------- ---- ----- -----
N *** ***
- change "f" N
- execute 'hg commit -i'
- backup "f" with timestamp N
- revert "f" by 'merge.update()' N
with 'partially'
- apply selected hunks N
by 'patch.patch()'
- 'repo.commit()'
- 'dirstate.normal("f")' N
N+1
- 'dirstate.write()' N N
- restore "f" N+1
- restore timestamp of "f" N
- 'hg status' shows "f" as "clean" N N N
---- ----------------------------------- ---- ----- -----
The most important point is that 'dirstate.write()' is executed at N+1
or later. This causes writing dirstate timestamp N of "f" out
successfully. If it is executed at N, 'parsers.pack_dirstate()'
replaces timestamp N with "-1" before actual writing dirstate out.
This issue can occur when 'hg commit -i' satisfies conditions below:
- the file is committed partially, and
- mode and size of the file aren't changed before and after committing
The root cause of this issue is that (maybe partially changed) files
are restored with original timestamp but dirstate isn't updated for
them.
To detect changes of files correctly, this patch applies
'dirstate.normallookup()' on restored files. Status check is needed
before 'dirstate.normallookup()', because status other than "n(ormal)"
should be kept at failure of committing.
This patch doesn't examine whether each files are committed fully or
partially, because interactive hunk selection makes it difficult.
After this change, timetable is changed as below:
---- ----------------------------------- ----------------
timestamp of "f"
----------------
dirstate file-
time action mem file system
---- ----------------------------------- ---- ----- -----
N *** ***
- change "f" N
- execute 'hg commit -i'
- backup "f" with timestamp N
- revert "f" by 'merge.update()' N
with 'partially'
- apply selected hunks N
by 'patch.internalpatch()'
- 'repo.commit()'
- 'dirstate.normal("f")' N
N+1
- 'dirstate.write()' N N
- restore "f" N+1
- restore timestamp of "f" N
----------------------------------- ---- ----- -----
- normallookup("f") -1
- release wlock
- 'dirstate.write()' -1 -1 N
----------------------------------- ---- ----- -----
- 'hg status' shows "f" as "clean" -1 -1 N
---- ----------------------------------- ---- ----- -----
To reproduce this issue in tests certainly, this patch emulates some
timing critical actions as below:
- change "f" at N
'touch -t 200001010000' before command invocation changes mtime of
"f" to "2000-01-01 00:00" (= N).
- apply selected hunks at N
'patch.internalpatch()' with 'fakepatchtime.py' explicitly changes
mtime of patched files to "2000-01-01 00:00" (= N).
- 'dirstate.write()' at N+1 (or "not at N")
'pack_dirstate()' uses actual timestamp at runtime as "now", and
it should be different from the "2000-01-01 00:00" of "f".
BTW, in 'test-commit-interactive.t', files are sometimes treated as
modified , even though they are just committed fully via 'hg commit
-i' and 'hg diff' shows nothing for them.
Enabling win32text causes EOL style mismatching below:
- files are changed in LF style EOL
=> files restored after committing uses LF style EOL (1)
- 'merge.update()' reverts files in CRLF style EOL
- 'patch.internalpatch()' changes files in CRLF style EOL
=> 'dirstate.normal()' via 'repo.commit()' uses the size of files
in CRLF style EOL (2)
Therefore, fully committed files are treated as "modified", because
'lstat()' returns size of (1) restored files in LF style EOL, but
dirstate expects size of (2) committed files in CRLF style EOL.
After this patch, 'dirstate.normallookup()' on committed files forces
subsequent 'hg status' to examine changes exactly, and fully committed
files are treated as clean as expected.
This is reason why this patch also does:
- add some 'hg status' checking status of fully committed files
- clear win32text configuration before size/timestamp sensitive examination
author | FUJIWARA Katsunori <foozy@lares.dti.ne.jp> |
---|---|
date | Wed, 08 Jul 2015 17:07:45 +0900 |
parents | bcc319d936a3 |
children | 983e93d88193 |
line wrap: on
line source
# pvec.py - probabilistic vector clocks for Mercurial # # Copyright 2012 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. ''' A "pvec" is a changeset property based on the theory of vector clocks that can be compared to discover relatedness without consulting a graph. This can be useful for tasks like determining how a disconnected patch relates to a repository. Currently a pvec consist of 448 bits, of which 24 are 'depth' and the remainder are a bit vector. It is represented as a 70-character base85 string. Construction: - a root changeset has a depth of 0 and a bit vector based on its hash - a normal commit has a changeset where depth is increased by one and one bit vector bit is flipped based on its hash - a merge changeset pvec is constructed by copying changes from one pvec into the other to balance its depth Properties: - for linear changes, difference in depth is always <= hamming distance - otherwise, changes are probably divergent - when hamming distance is < 200, we can reliably detect when pvecs are near Issues: - hamming distance ceases to work over distances of ~ 200 - detecting divergence is less accurate when the common ancestor is very close to either revision or total distance is high - this could probably be improved by modeling the relation between delta and hdist Uses: - a patch pvec can be used to locate the nearest available common ancestor for resolving conflicts - ordering of patches can be established without a DAG - two head pvecs can be compared to determine whether push/pull/merge is needed and approximately how many changesets are involved - can be used to find a heuristic divergence measure between changesets on different branches ''' import base85, util from node import nullrev _size = 448 # 70 chars b85-encoded _bytes = _size / 8 _depthbits = 24 _depthbytes = _depthbits / 8 _vecbytes = _bytes - _depthbytes _vecbits = _vecbytes * 8 _radius = (_vecbits - 30) / 2 # high probability vectors are related def _bin(bs): '''convert a bytestring to a long''' v = 0 for b in bs: v = v * 256 + ord(b) return v def _str(v, l): bs = "" for p in xrange(l): bs = chr(v & 255) + bs v >>= 8 return bs def _split(b): '''depth and bitvec''' return _bin(b[:_depthbytes]), _bin(b[_depthbytes:]) def _join(depth, bitvec): return _str(depth, _depthbytes) + _str(bitvec, _vecbytes) def _hweight(x): c = 0 while x: if x & 1: c += 1 x >>= 1 return c _htab = [_hweight(x) for x in xrange(256)] def _hamming(a, b): '''find the hamming distance between two longs''' d = a ^ b c = 0 while d: c += _htab[d & 0xff] d >>= 8 return c def _mergevec(x, y, c): # Ideally, this function would be x ^ y ^ ancestor, but finding # ancestors is a nuisance. So instead we find the minimal number # of changes to balance the depth and hamming distance d1, v1 = x d2, v2 = y if d1 < d2: d1, d2, v1, v2 = d2, d1, v2, v1 hdist = _hamming(v1, v2) ddist = d1 - d2 v = v1 m = v1 ^ v2 # mask of different bits i = 1 if hdist > ddist: # if delta = 10 and hdist = 100, then we need to go up 55 steps # to the ancestor and down 45 changes = (hdist - ddist + 1) / 2 else: # must make at least one change changes = 1 depth = d1 + changes # copy changes from v2 if m: while changes: if m & i: v ^= i changes -= 1 i <<= 1 else: v = _flipbit(v, c) return depth, v def _flipbit(v, node): # converting bit strings to longs is slow bit = (hash(node) & 0xffffffff) % _vecbits return v ^ (1<<bit) def ctxpvec(ctx): '''construct a pvec for ctx while filling in the cache''' r = ctx.repo() if not util.safehasattr(r, "_pveccache"): r._pveccache = {} pvc = r._pveccache if ctx.rev() not in pvc: cl = r.changelog for n in xrange(ctx.rev() + 1): if n not in pvc: node = cl.node(n) p1, p2 = cl.parentrevs(n) if p1 == nullrev: # start with a 'random' vector at root pvc[n] = (0, _bin((node * 3)[:_vecbytes])) elif p2 == nullrev: d, v = pvc[p1] pvc[n] = (d + 1, _flipbit(v, node)) else: pvc[n] = _mergevec(pvc[p1], pvc[p2], node) bs = _join(*pvc[ctx.rev()]) return pvec(base85.b85encode(bs)) class pvec(object): def __init__(self, hashorctx): if isinstance(hashorctx, str): self._bs = hashorctx self._depth, self._vec = _split(base85.b85decode(hashorctx)) else: self._vec = ctxpvec(hashorctx) def __str__(self): return self._bs def __eq__(self, b): return self._vec == b._vec and self._depth == b._depth def __lt__(self, b): delta = b._depth - self._depth if delta < 0: return False # always correct if _hamming(self._vec, b._vec) > delta: return False return True def __gt__(self, b): return b < self def __or__(self, b): delta = abs(b._depth - self._depth) if _hamming(self._vec, b._vec) <= delta: return False return True def __sub__(self, b): if self | b: raise ValueError("concurrent pvecs") return self._depth - b._depth def distance(self, b): d = abs(b._depth - self._depth) h = _hamming(self._vec, b._vec) return max(d, h) def near(self, b): dist = abs(b.depth - self._depth) if dist > _radius or _hamming(self._vec, b._vec) > _radius: return False