grep: add test coverage of behavior on symlinks
Differential Revision: https://phab.mercurial-scm.org/D8580
# Copyright 2016-present Facebook. All Rights Reserved.
#
# context: context needed to annotate a file
#
# 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 collections
import contextlib
import os
from mercurial.i18n import _
from mercurial.pycompat import (
getattr,
open,
setattr,
)
from mercurial import (
error,
linelog as linelogmod,
lock as lockmod,
mdiff,
node,
pycompat,
scmutil,
util,
)
from mercurial.utils import (
hashutil,
stringutil,
)
from . import (
error as faerror,
revmap as revmapmod,
)
# given path, get filelog, cached
@util.lrucachefunc
def _getflog(repo, path):
return repo.file(path)
# extracted from mercurial.context.basefilectx.annotate
def _parents(f, follow=True):
# Cut _descendantrev here to mitigate the penalty of lazy linkrev
# adjustment. Otherwise, p._adjustlinkrev() would walk changelog
# from the topmost introrev (= srcrev) down to p.linkrev() if it
# isn't an ancestor of the srcrev.
f._changeid
pl = f.parents()
# Don't return renamed parents if we aren't following.
if not follow:
pl = [p for p in pl if p.path() == f.path()]
# renamed filectx won't have a filelog yet, so set it
# from the cache to save time
for p in pl:
if not '_filelog' in p.__dict__:
p._filelog = _getflog(f._repo, p.path())
return pl
# extracted from mercurial.context.basefilectx.annotate. slightly modified
# so it takes a fctx instead of a pair of text and fctx.
def _decorate(fctx):
text = fctx.data()
linecount = text.count(b'\n')
if text and not text.endswith(b'\n'):
linecount += 1
return ([(fctx, i) for i in pycompat.xrange(linecount)], text)
# extracted from mercurial.context.basefilectx.annotate. slightly modified
# so it takes an extra "blocks" parameter calculated elsewhere, instead of
# calculating diff here.
def _pair(parent, child, blocks):
for (a1, a2, b1, b2), t in blocks:
# Changed blocks ('!') or blocks made only of blank lines ('~')
# belong to the child.
if t == b'=':
child[0][b1:b2] = parent[0][a1:a2]
return child
# like scmutil.revsingle, but with lru cache, so their states (like manifests)
# could be reused
_revsingle = util.lrucachefunc(scmutil.revsingle)
def resolvefctx(repo, rev, path, resolverev=False, adjustctx=None):
"""(repo, str, str) -> fctx
get the filectx object from repo, rev, path, in an efficient way.
if resolverev is True, "rev" is a revision specified by the revset
language, otherwise "rev" is a nodeid, or a revision number that can
be consumed by repo.__getitem__.
if adjustctx is not None, the returned fctx will point to a changeset
that introduces the change (last modified the file). if adjustctx
is 'linkrev', trust the linkrev and do not adjust it. this is noticeably
faster for big repos but is incorrect for some cases.
"""
if resolverev and not isinstance(rev, int) and rev is not None:
ctx = _revsingle(repo, rev)
else:
ctx = repo[rev]
# If we don't need to adjust the linkrev, create the filectx using the
# changectx instead of using ctx[path]. This means it already has the
# changectx information, so blame -u will be able to look directly at the
# commitctx object instead of having to resolve it by going through the
# manifest. In a lazy-manifest world this can prevent us from downloading a
# lot of data.
if adjustctx is None:
# ctx.rev() is None means it's the working copy, which is a special
# case.
if ctx.rev() is None:
fctx = ctx[path]
else:
fctx = repo.filectx(path, changeid=ctx.rev())
else:
fctx = ctx[path]
if adjustctx == b'linkrev':
introrev = fctx.linkrev()
else:
introrev = fctx.introrev()
if introrev != ctx.rev():
fctx._changeid = introrev
fctx._changectx = repo[introrev]
return fctx
# like mercurial.store.encodedir, but use linelog suffixes: .m, .l, .lock
def encodedir(path):
return (
path.replace(b'.hg/', b'.hg.hg/')
.replace(b'.l/', b'.l.hg/')
.replace(b'.m/', b'.m.hg/')
.replace(b'.lock/', b'.lock.hg/')
)
def hashdiffopts(diffopts):
diffoptstr = stringutil.pprint(
sorted((k, getattr(diffopts, k)) for k in mdiff.diffopts.defaults)
)
return node.hex(hashutil.sha1(diffoptstr).digest())[:6]
_defaultdiffopthash = hashdiffopts(mdiff.defaultopts)
class annotateopts(object):
"""like mercurial.mdiff.diffopts, but is for annotate
followrename: follow renames, like "hg annotate -f"
followmerge: follow p2 of a merge changeset, otherwise p2 is ignored
"""
defaults = {
b'diffopts': None,
b'followrename': True,
b'followmerge': True,
}
def __init__(self, **opts):
opts = pycompat.byteskwargs(opts)
for k, v in pycompat.iteritems(self.defaults):
setattr(self, k, opts.get(k, v))
@util.propertycache
def shortstr(self):
"""represent opts in a short string, suitable for a directory name"""
result = b''
if not self.followrename:
result += b'r0'
if not self.followmerge:
result += b'm0'
if self.diffopts is not None:
assert isinstance(self.diffopts, mdiff.diffopts)
diffopthash = hashdiffopts(self.diffopts)
if diffopthash != _defaultdiffopthash:
result += b'i' + diffopthash
return result or b'default'
defaultopts = annotateopts()
class _annotatecontext(object):
"""do not use this class directly as it does not use lock to protect
writes. use "with annotatecontext(...)" instead.
"""
def __init__(self, repo, path, linelogpath, revmappath, opts):
self.repo = repo
self.ui = repo.ui
self.path = path
self.opts = opts
self.linelogpath = linelogpath
self.revmappath = revmappath
self._linelog = None
self._revmap = None
self._node2path = {} # {str: str}
@property
def linelog(self):
if self._linelog is None:
if os.path.exists(self.linelogpath):
with open(self.linelogpath, b'rb') as f:
try:
self._linelog = linelogmod.linelog.fromdata(f.read())
except linelogmod.LineLogError:
self._linelog = linelogmod.linelog()
else:
self._linelog = linelogmod.linelog()
return self._linelog
@property
def revmap(self):
if self._revmap is None:
self._revmap = revmapmod.revmap(self.revmappath)
return self._revmap
def close(self):
if self._revmap is not None:
self._revmap.flush()
self._revmap = None
if self._linelog is not None:
with open(self.linelogpath, b'wb') as f:
f.write(self._linelog.encode())
self._linelog = None
__del__ = close
def rebuild(self):
"""delete linelog and revmap, useful for rebuilding"""
self.close()
self._node2path.clear()
_unlinkpaths([self.revmappath, self.linelogpath])
@property
def lastnode(self):
"""return last node in revmap, or None if revmap is empty"""
if self._revmap is None:
# fast path, read revmap without loading its full content
return revmapmod.getlastnode(self.revmappath)
else:
return self._revmap.rev2hsh(self._revmap.maxrev)
def isuptodate(self, master, strict=True):
"""return True if the revmap / linelog is up-to-date, or the file
does not exist in the master revision. False otherwise.
it tries to be fast and could return false negatives, because of the
use of linkrev instead of introrev.
useful for both server and client to decide whether to update
fastannotate cache or not.
if strict is True, even if fctx exists in the revmap, but is not the
last node, isuptodate will return False. it's good for performance - no
expensive check was done.
if strict is False, if fctx exists in the revmap, this function may
return True. this is useful for the client to skip downloading the
cache if the client's master is behind the server's.
"""
lastnode = self.lastnode
try:
f = self._resolvefctx(master, resolverev=True)
# choose linkrev instead of introrev as the check is meant to be
# *fast*.
linknode = self.repo.changelog.node(f.linkrev())
if not strict and lastnode and linknode != lastnode:
# check if f.node() is in the revmap. note: this loads the
# revmap and can be slow.
return self.revmap.hsh2rev(linknode) is not None
# avoid resolving old manifest, or slow adjustlinkrev to be fast,
# false negatives are acceptable in this case.
return linknode == lastnode
except LookupError:
# master does not have the file, or the revmap is ahead
return True
def annotate(self, rev, master=None, showpath=False, showlines=False):
"""incrementally update the cache so it includes revisions in the main
branch till 'master'. and run annotate on 'rev', which may or may not be
included in the main branch.
if master is None, do not update linelog.
the first value returned is the annotate result, it is [(node, linenum)]
by default. [(node, linenum, path)] if showpath is True.
if showlines is True, a second value will be returned, it is a list of
corresponding line contents.
"""
# the fast path test requires commit hash, convert rev number to hash,
# so it may hit the fast path. note: in the "fctx" mode, the "annotate"
# command could give us a revision number even if the user passes a
# commit hash.
if isinstance(rev, int):
rev = node.hex(self.repo.changelog.node(rev))
# fast path: if rev is in the main branch already
directly, revfctx = self.canannotatedirectly(rev)
if directly:
if self.ui.debugflag:
self.ui.debug(
b'fastannotate: %s: using fast path '
b'(resolved fctx: %s)\n'
% (
self.path,
stringutil.pprint(util.safehasattr(revfctx, b'node')),
)
)
return self.annotatedirectly(revfctx, showpath, showlines)
# resolve master
masterfctx = None
if master:
try:
masterfctx = self._resolvefctx(
master, resolverev=True, adjustctx=True
)
except LookupError: # master does not have the file
pass
else:
if masterfctx in self.revmap: # no need to update linelog
masterfctx = None
# ... - @ <- rev (can be an arbitrary changeset,
# / not necessarily a descendant
# master -> o of master)
# |
# a merge -> o 'o': new changesets in the main branch
# |\ '#': revisions in the main branch that
# o * exist in linelog / revmap
# | . '*': changesets in side branches, or
# last master -> # . descendants of master
# | .
# # * joint: '#', and is a parent of a '*'
# |/
# a joint -> # ^^^^ --- side branches
# |
# ^ --- main branch (in linelog)
# these DFSes are similar to the traditional annotate algorithm.
# we cannot really reuse the code for perf reason.
# 1st DFS calculates merges, joint points, and needed.
# "needed" is a simple reference counting dict to free items in
# "hist", reducing its memory usage otherwise could be huge.
initvisit = [revfctx]
if masterfctx:
if masterfctx.rev() is None:
raise error.Abort(
_(b'cannot update linelog to wdir()'),
hint=_(b'set fastannotate.mainbranch'),
)
initvisit.append(masterfctx)
visit = initvisit[:]
pcache = {}
needed = {revfctx: 1}
hist = {} # {fctx: ([(llrev or fctx, linenum)], text)}
while visit:
f = visit.pop()
if f in pcache or f in hist:
continue
if f in self.revmap: # in the old main branch, it's a joint
llrev = self.revmap.hsh2rev(f.node())
self.linelog.annotate(llrev)
result = self.linelog.annotateresult
hist[f] = (result, f.data())
continue
pl = self._parentfunc(f)
pcache[f] = pl
for p in pl:
needed[p] = needed.get(p, 0) + 1
if p not in pcache:
visit.append(p)
# 2nd (simple) DFS calculates new changesets in the main branch
# ('o' nodes in # the above graph), so we know when to update linelog.
newmainbranch = set()
f = masterfctx
while f and f not in self.revmap:
newmainbranch.add(f)
pl = pcache[f]
if pl:
f = pl[0]
else:
f = None
break
# f, if present, is the position where the last build stopped at, and
# should be the "master" last time. check to see if we can continue
# building the linelog incrementally. (we cannot if diverged)
if masterfctx is not None:
self._checklastmasterhead(f)
if self.ui.debugflag:
if newmainbranch:
self.ui.debug(
b'fastannotate: %s: %d new changesets in the main'
b' branch\n' % (self.path, len(newmainbranch))
)
elif not hist: # no joints, no updates
self.ui.debug(
b'fastannotate: %s: linelog cannot help in '
b'annotating this revision\n' % self.path
)
# prepare annotateresult so we can update linelog incrementally
self.linelog.annotate(self.linelog.maxrev)
# 3rd DFS does the actual annotate
visit = initvisit[:]
progress = self.ui.makeprogress(
b'building cache', total=len(newmainbranch)
)
while visit:
f = visit[-1]
if f in hist:
visit.pop()
continue
ready = True
pl = pcache[f]
for p in pl:
if p not in hist:
ready = False
visit.append(p)
if not ready:
continue
visit.pop()
blocks = None # mdiff blocks, used for appending linelog
ismainbranch = f in newmainbranch
# curr is the same as the traditional annotate algorithm,
# if we only care about linear history (do not follow merge),
# then curr is not actually used.
assert f not in hist
curr = _decorate(f)
for i, p in enumerate(pl):
bs = list(self._diffblocks(hist[p][1], curr[1]))
if i == 0 and ismainbranch:
blocks = bs
curr = _pair(hist[p], curr, bs)
if needed[p] == 1:
del hist[p]
del needed[p]
else:
needed[p] -= 1
hist[f] = curr
del pcache[f]
if ismainbranch: # need to write to linelog
progress.increment()
bannotated = None
if len(pl) == 2 and self.opts.followmerge: # merge
bannotated = curr[0]
if blocks is None: # no parents, add an empty one
blocks = list(self._diffblocks(b'', curr[1]))
self._appendrev(f, blocks, bannotated)
elif showpath: # not append linelog, but we need to record path
self._node2path[f.node()] = f.path()
progress.complete()
result = [
((self.revmap.rev2hsh(fr) if isinstance(fr, int) else fr.node()), l)
for fr, l in hist[revfctx][0]
] # [(node, linenumber)]
return self._refineannotateresult(result, revfctx, showpath, showlines)
def canannotatedirectly(self, rev):
"""(str) -> bool, fctx or node.
return (True, f) if we can annotate without updating the linelog, pass
f to annotatedirectly.
return (False, f) if we need extra calculation. f is the fctx resolved
from rev.
"""
result = True
f = None
if not isinstance(rev, int) and rev is not None:
hsh = {20: bytes, 40: node.bin}.get(len(rev), lambda x: None)(rev)
if hsh is not None and (hsh, self.path) in self.revmap:
f = hsh
if f is None:
adjustctx = b'linkrev' if self._perfhack else True
f = self._resolvefctx(rev, adjustctx=adjustctx, resolverev=True)
result = f in self.revmap
if not result and self._perfhack:
# redo the resolution without perfhack - as we are going to
# do write operations, we need a correct fctx.
f = self._resolvefctx(rev, adjustctx=True, resolverev=True)
return result, f
def annotatealllines(self, rev, showpath=False, showlines=False):
"""(rev : str) -> [(node : str, linenum : int, path : str)]
the result has the same format with annotate, but include all (including
deleted) lines up to rev. call this after calling annotate(rev, ...) for
better performance and accuracy.
"""
revfctx = self._resolvefctx(rev, resolverev=True, adjustctx=True)
# find a chain from rev to anything in the mainbranch
if revfctx not in self.revmap:
chain = [revfctx]
a = b''
while True:
f = chain[-1]
pl = self._parentfunc(f)
if not pl:
break
if pl[0] in self.revmap:
a = pl[0].data()
break
chain.append(pl[0])
# both self.linelog and self.revmap is backed by filesystem. now
# we want to modify them but do not want to write changes back to
# files. so we create in-memory objects and copy them. it's like
# a "fork".
linelog = linelogmod.linelog()
linelog.copyfrom(self.linelog)
linelog.annotate(linelog.maxrev)
revmap = revmapmod.revmap()
revmap.copyfrom(self.revmap)
for f in reversed(chain):
b = f.data()
blocks = list(self._diffblocks(a, b))
self._doappendrev(linelog, revmap, f, blocks)
a = b
else:
# fastpath: use existing linelog, revmap as we don't write to them
linelog = self.linelog
revmap = self.revmap
lines = linelog.getalllines()
hsh = revfctx.node()
llrev = revmap.hsh2rev(hsh)
result = [(revmap.rev2hsh(r), l) for r, l in lines if r <= llrev]
# cannot use _refineannotateresult since we need custom logic for
# resolving line contents
if showpath:
result = self._addpathtoresult(result, revmap)
if showlines:
linecontents = self._resolvelines(result, revmap, linelog)
result = (result, linecontents)
return result
def _resolvelines(self, annotateresult, revmap, linelog):
"""(annotateresult) -> [line]. designed for annotatealllines.
this is probably the most inefficient code in the whole fastannotate
directory. but we have made a decision that the linelog does not
store line contents. so getting them requires random accesses to
the revlog data, since they can be many, it can be very slow.
"""
# [llrev]
revs = [revmap.hsh2rev(l[0]) for l in annotateresult]
result = [None] * len(annotateresult)
# {(rev, linenum): [lineindex]}
key2idxs = collections.defaultdict(list)
for i in pycompat.xrange(len(result)):
key2idxs[(revs[i], annotateresult[i][1])].append(i)
while key2idxs:
# find an unresolved line and its linelog rev to annotate
hsh = None
try:
for (rev, _linenum), idxs in pycompat.iteritems(key2idxs):
if revmap.rev2flag(rev) & revmapmod.sidebranchflag:
continue
hsh = annotateresult[idxs[0]][0]
break
except StopIteration: # no more unresolved lines
return result
if hsh is None:
# the remaining key2idxs are not in main branch, resolving them
# using the hard way...
revlines = {}
for (rev, linenum), idxs in pycompat.iteritems(key2idxs):
if rev not in revlines:
hsh = annotateresult[idxs[0]][0]
if self.ui.debugflag:
self.ui.debug(
b'fastannotate: reading %s line #%d '
b'to resolve lines %r\n'
% (node.short(hsh), linenum, idxs)
)
fctx = self._resolvefctx(hsh, revmap.rev2path(rev))
lines = mdiff.splitnewlines(fctx.data())
revlines[rev] = lines
for idx in idxs:
result[idx] = revlines[rev][linenum]
assert all(x is not None for x in result)
return result
# run the annotate and the lines should match to the file content
self.ui.debug(
b'fastannotate: annotate %s to resolve lines\n'
% node.short(hsh)
)
linelog.annotate(rev)
fctx = self._resolvefctx(hsh, revmap.rev2path(rev))
annotated = linelog.annotateresult
lines = mdiff.splitnewlines(fctx.data())
if len(lines) != len(annotated):
raise faerror.CorruptedFileError(b'unexpected annotated lines')
# resolve lines from the annotate result
for i, line in enumerate(lines):
k = annotated[i]
if k in key2idxs:
for idx in key2idxs[k]:
result[idx] = line
del key2idxs[k]
return result
def annotatedirectly(self, f, showpath, showlines):
"""like annotate, but when we know that f is in linelog.
f can be either a 20-char str (node) or a fctx. this is for perf - in
the best case, the user provides a node and we don't need to read the
filelog or construct any filecontext.
"""
if isinstance(f, bytes):
hsh = f
else:
hsh = f.node()
llrev = self.revmap.hsh2rev(hsh)
if not llrev:
raise faerror.CorruptedFileError(
b'%s is not in revmap' % node.hex(hsh)
)
if (self.revmap.rev2flag(llrev) & revmapmod.sidebranchflag) != 0:
raise faerror.CorruptedFileError(
b'%s is not in revmap mainbranch' % node.hex(hsh)
)
self.linelog.annotate(llrev)
result = [
(self.revmap.rev2hsh(r), l) for r, l in self.linelog.annotateresult
]
return self._refineannotateresult(result, f, showpath, showlines)
def _refineannotateresult(self, result, f, showpath, showlines):
"""add the missing path or line contents, they can be expensive.
f could be either node or fctx.
"""
if showpath:
result = self._addpathtoresult(result)
if showlines:
if isinstance(f, bytes): # f: node or fctx
llrev = self.revmap.hsh2rev(f)
fctx = self._resolvefctx(f, self.revmap.rev2path(llrev))
else:
fctx = f
lines = mdiff.splitnewlines(fctx.data())
if len(lines) != len(result): # linelog is probably corrupted
raise faerror.CorruptedFileError()
result = (result, lines)
return result
def _appendrev(self, fctx, blocks, bannotated=None):
self._doappendrev(self.linelog, self.revmap, fctx, blocks, bannotated)
def _diffblocks(self, a, b):
return mdiff.allblocks(a, b, self.opts.diffopts)
@staticmethod
def _doappendrev(linelog, revmap, fctx, blocks, bannotated=None):
"""append a revision to linelog and revmap"""
def getllrev(f):
"""(fctx) -> int"""
# f should not be a linelog revision
if isinstance(f, int):
raise error.ProgrammingError(b'f should not be an int')
# f is a fctx, allocate linelog rev on demand
hsh = f.node()
rev = revmap.hsh2rev(hsh)
if rev is None:
rev = revmap.append(hsh, sidebranch=True, path=f.path())
return rev
# append sidebranch revisions to revmap
siderevs = []
siderevmap = {} # node: int
if bannotated is not None:
for (a1, a2, b1, b2), op in blocks:
if op != b'=':
# f could be either linelong rev, or fctx.
siderevs += [
f
for f, l in bannotated[b1:b2]
if not isinstance(f, int)
]
siderevs = set(siderevs)
if fctx in siderevs: # mainnode must be appended seperately
siderevs.remove(fctx)
for f in siderevs:
siderevmap[f] = getllrev(f)
# the changeset in the main branch, could be a merge
llrev = revmap.append(fctx.node(), path=fctx.path())
siderevmap[fctx] = llrev
for (a1, a2, b1, b2), op in reversed(blocks):
if op == b'=':
continue
if bannotated is None:
linelog.replacelines(llrev, a1, a2, b1, b2)
else:
blines = [
((r if isinstance(r, int) else siderevmap[r]), l)
for r, l in bannotated[b1:b2]
]
linelog.replacelines_vec(llrev, a1, a2, blines)
def _addpathtoresult(self, annotateresult, revmap=None):
"""(revmap, [(node, linenum)]) -> [(node, linenum, path)]"""
if revmap is None:
revmap = self.revmap
def _getpath(nodeid):
path = self._node2path.get(nodeid)
if path is None:
path = revmap.rev2path(revmap.hsh2rev(nodeid))
self._node2path[nodeid] = path
return path
return [(n, l, _getpath(n)) for n, l in annotateresult]
def _checklastmasterhead(self, fctx):
"""check if fctx is the master's head last time, raise if not"""
if fctx is None:
llrev = 0
else:
llrev = self.revmap.hsh2rev(fctx.node())
if not llrev:
raise faerror.CannotReuseError()
if self.linelog.maxrev != llrev:
raise faerror.CannotReuseError()
@util.propertycache
def _parentfunc(self):
"""-> (fctx) -> [fctx]"""
followrename = self.opts.followrename
followmerge = self.opts.followmerge
def parents(f):
pl = _parents(f, follow=followrename)
if not followmerge:
pl = pl[:1]
return pl
return parents
@util.propertycache
def _perfhack(self):
return self.ui.configbool(b'fastannotate', b'perfhack')
def _resolvefctx(self, rev, path=None, **kwds):
return resolvefctx(self.repo, rev, (path or self.path), **kwds)
def _unlinkpaths(paths):
"""silent, best-effort unlink"""
for path in paths:
try:
util.unlink(path)
except OSError:
pass
class pathhelper(object):
"""helper for getting paths for lockfile, linelog and revmap"""
def __init__(self, repo, path, opts=defaultopts):
# different options use different directories
self._vfspath = os.path.join(
b'fastannotate', opts.shortstr, encodedir(path)
)
self._repo = repo
@property
def dirname(self):
return os.path.dirname(self._repo.vfs.join(self._vfspath))
@property
def linelogpath(self):
return self._repo.vfs.join(self._vfspath + b'.l')
def lock(self):
return lockmod.lock(self._repo.vfs, self._vfspath + b'.lock')
@property
def revmappath(self):
return self._repo.vfs.join(self._vfspath + b'.m')
@contextlib.contextmanager
def annotatecontext(repo, path, opts=defaultopts, rebuild=False):
"""context needed to perform (fast) annotate on a file
an annotatecontext of a single file consists of two structures: the
linelog and the revmap. this function takes care of locking. only 1
process is allowed to write that file's linelog and revmap at a time.
when something goes wrong, this function will assume the linelog and the
revmap are in a bad state, and remove them from disk.
use this function in the following way:
with annotatecontext(...) as actx:
actx. ....
"""
helper = pathhelper(repo, path, opts)
util.makedirs(helper.dirname)
revmappath = helper.revmappath
linelogpath = helper.linelogpath
actx = None
try:
with helper.lock():
actx = _annotatecontext(repo, path, linelogpath, revmappath, opts)
if rebuild:
actx.rebuild()
yield actx
except Exception:
if actx is not None:
actx.rebuild()
repo.ui.debug(b'fastannotate: %s: cache broken and deleted\n' % path)
raise
finally:
if actx is not None:
actx.close()
def fctxannotatecontext(fctx, follow=True, diffopts=None, rebuild=False):
"""like annotatecontext but get the context from a fctx. convenient when
used in fctx.annotate
"""
repo = fctx._repo
path = fctx._path
if repo.ui.configbool(b'fastannotate', b'forcefollow', True):
follow = True
aopts = annotateopts(diffopts=diffopts, followrename=follow)
return annotatecontext(repo, path, aopts, rebuild)