##// END OF EJS Templates
revlog: add a mechanism to verify expected file position before appending...
revlog: add a mechanism to verify expected file position before appending If someone uses `hg debuglocks`, or some non-hg process writes to the .hg directory without respecting the locks, or if the repo's on a networked filesystem, it's possible for the revlog code to write out corrupted data. The form of this corruption can vary depending on what data was written and how that happened. We are in the "networked filesystem" case (though I've had users also do this to themselves with the "`hg debuglocks`" scenario), and most often see this with the changelog. What ends up happening is we produce two items (let's call them rev1 and rev2) in the .i file that have the same linkrev, baserev, and offset into the .d file, while the data in the .d file is appended properly. rev2's compressed_size is accurate for rev2, but when we go to decompress the data in the .d file, we use the offset that's recorded in the index file, which is the same as rev1, and attempt to decompress rev2.compressed_size bytes of rev1's data. This usually does not succeed. :) When using inline data, this also fails, though I haven't investigated why too closely. This shows up as a "patch decode" error. I believe what's happening there is that we're basically ignoring the offset field, getting the data properly, but since baserev != rev, it thinks this is a delta based on rev (instead of a full text) and can't actually apply it as such. For now, I'm going to make this an optional component and default it to entirely off. I may increase the default severity of this in the future, once I've enabled it for my users and we gain more experience with it. Luckily, most of my users have a versioned filesystem and can roll back to before the corruption has been written, it's just a hassle to do so and not everyone knows how (so it's a support burden). Users on other filesystems will not have that luxury, and this can cause them to have a corrupted repository that they are unlikely to know how to resolve, and they'll see this as a data-loss event. Refusing to create the corruption is a much better user experience. This mechanism is not perfect. There may be false-negatives (racy writes that are not detected). There should not be any false-positives (non-racy writes that are detected as such). This is not a mechanism that makes putting a repo on a networked filesystem "safe" or "supported", just *less* likely to cause corruption. Differential Revision: https://phab.mercurial-scm.org/D9952

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formatter.py
177 lines | 5.8 KiB | text/x-python | PythonLexer
# Copyright 2016-present Facebook. All Rights Reserved.
#
# format: defines the format used to output annotate result
#
# 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
from mercurial.node import (
hex,
short,
)
from mercurial import (
encoding,
pycompat,
templatefilters,
util,
)
from mercurial.utils import dateutil
# imitating mercurial.commands.annotate, not using the vanilla formatter since
# the data structures are a bit different, and we have some fast paths.
class defaultformatter(object):
"""the default formatter that does leftpad and support some common flags"""
def __init__(self, ui, repo, opts):
self.ui = ui
self.opts = opts
if ui.quiet:
datefunc = dateutil.shortdate
else:
datefunc = dateutil.datestr
datefunc = util.cachefunc(datefunc)
getctx = util.cachefunc(lambda x: repo[x[0]])
hexfunc = self._hexfunc
# special handling working copy "changeset" and "rev" functions
if self.opts.get(b'rev') == b'wdir()':
orig = hexfunc
hexfunc = lambda x: None if x is None else orig(x)
wnode = hexfunc(repo[b'.'].node()) + b'+'
wrev = b'%d' % repo[b'.'].rev()
wrevpad = b''
if not opts.get(b'changeset'): # only show + if changeset is hidden
wrev += b'+'
wrevpad = b' '
revenc = lambda x: wrev if x is None else (b'%d' % x) + wrevpad
def csetenc(x):
if x is None:
return wnode
return pycompat.bytestr(x) + b' '
else:
revenc = csetenc = pycompat.bytestr
# opt name, separator, raw value (for json/plain), encoder (for plain)
opmap = [
(b'user', b' ', lambda x: getctx(x).user(), ui.shortuser),
(b'number', b' ', lambda x: getctx(x).rev(), revenc),
(b'changeset', b' ', lambda x: hexfunc(x[0]), csetenc),
(b'date', b' ', lambda x: getctx(x).date(), datefunc),
(b'file', b' ', lambda x: x[2], pycompat.bytestr),
(b'line_number', b':', lambda x: x[1] + 1, pycompat.bytestr),
]
fieldnamemap = {b'number': b'rev', b'changeset': b'node'}
funcmap = [
(get, sep, fieldnamemap.get(op, op), enc)
for op, sep, get, enc in opmap
if opts.get(op)
]
# no separator for first column
funcmap[0] = list(funcmap[0])
funcmap[0][1] = b''
self.funcmap = funcmap
def write(self, annotatedresult, lines=None, existinglines=None):
"""(annotateresult, [str], set([rev, linenum])) -> None. write output.
annotateresult can be [(node, linenum, path)], or [(node, linenum)]
"""
pieces = [] # [[str]]
maxwidths = [] # [int]
# calculate padding
for f, sep, name, enc in self.funcmap:
l = [enc(f(x)) for x in annotatedresult]
pieces.append(l)
if name in [b'node', b'date']: # node and date has fixed size
l = l[:1]
widths = pycompat.maplist(encoding.colwidth, set(l))
maxwidth = max(widths) if widths else 0
maxwidths.append(maxwidth)
# buffered output
result = b''
for i in pycompat.xrange(len(annotatedresult)):
for j, p in enumerate(pieces):
sep = self.funcmap[j][1]
padding = b' ' * (maxwidths[j] - len(p[i]))
result += sep + padding + p[i]
if lines:
if existinglines is None:
result += b': ' + lines[i]
else: # extra formatting showing whether a line exists
key = (annotatedresult[i][0], annotatedresult[i][1])
if key in existinglines:
result += b': ' + lines[i]
else:
result += b': ' + self.ui.label(
b'-' + lines[i], b'diff.deleted'
)
if result[-1:] != b'\n':
result += b'\n'
self.ui.write(result)
@util.propertycache
def _hexfunc(self):
if self.ui.debugflag or self.opts.get(b'long_hash'):
return hex
else:
return short
def end(self):
pass
class jsonformatter(defaultformatter):
def __init__(self, ui, repo, opts):
super(jsonformatter, self).__init__(ui, repo, opts)
self.ui.write(b'[')
self.needcomma = False
def write(self, annotatedresult, lines=None, existinglines=None):
if annotatedresult:
self._writecomma()
pieces = [
(name, pycompat.maplist(f, annotatedresult))
for f, sep, name, enc in self.funcmap
]
if lines is not None:
pieces.append((b'line', lines))
pieces.sort()
seps = [b','] * len(pieces[:-1]) + [b'']
result = b''
lasti = len(annotatedresult) - 1
for i in pycompat.xrange(len(annotatedresult)):
result += b'\n {\n'
for j, p in enumerate(pieces):
k, vs = p
result += b' "%s": %s%s\n' % (
k,
templatefilters.json(vs[i], paranoid=False),
seps[j],
)
result += b' }%s' % (b'' if i == lasti else b',')
if lasti >= 0:
self.needcomma = True
self.ui.write(result)
def _writecomma(self):
if self.needcomma:
self.ui.write(b',')
self.needcomma = False
@util.propertycache
def _hexfunc(self):
return hex
def end(self):
self.ui.write(b'\n]\n')