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httppeer: remove support for connecting to <0.9.1 servers (BC)...
httppeer: remove support for connecting to <0.9.1 servers (BC) Previously, HTTP wire protocol clients would attempt a "capabilities" wire protocol command. If that failed, they would fall back to issuing a "between" command. The "capabilities" command was added in Mercurial 0.9.1 (released July 2006). The "between" command has been present for as long as the wire protocol has existed. So if the "between" command failed, it was safe to assume that the remote could not speak any version of the Mercurial wire protocol. The "between" fallback was added in 395a84f78736 in 2011. Before that changeset, Mercurial would *always* issue the "between" command and would issue "capabilities" if capabilities were requested. At that time, many connections would issue "capabilities" eventually, so it was decided to issue "capabilities" by default and fall back to "between" if that failed. This saved a round trip when connecting to modern servers while still preserving compatibility with legacy servers. Fast forward ~7 years. Mercurial servers supporting "capabilities" have been around for over a decade. If modern clients are connecting to <0.9.1 servers, they are getting a bad experience. They may even be getting bad data (an old server is vulnerable to numerous security issues and could have been p0wned, leading to a Mercurial repository serving backdoors or other badness). In addition, the fallback can harm experience for modern servers. If a client experiences an intermittent HTTP request failure (due to bad network, etc) and falls back to a "between" that works, it would assume an empty capability set and would attempt to communicate with the repository using a very ancient wire protocol. Auditing HTTP logs for hg.mozilla.org, I did find a handful of requests for the null range of the "between" command. However, requests can be days apart. And when I do see requests, they come in batches. Those batches seem to correlate to spikes of HTTP 500 or other server/network events. So I think these requests are fallbacks from failed "capabilities" requests and not from old clients. If you need even more evidence to discontinue support, apparently we have no test coverage for communicating with servers not supporting "capabilities." I know this because all tests pass with the "between" fallback removed. Finally, server-side support for <0.9.1 pushing (the "addchangegroup" wire protocol command along with locking-related commands) was dropped from the HTTP client in fda0867cfe03 in 2017 and the SSH client in 9f6e0e7ef828 in 2015. I think this all adds up to enough justification for removing client support for communicating with servers not supporting "capabilities." So this commit removes that fallback. Differential Revision: https://phab.mercurial-scm.org/D2001

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destutil.py
414 lines | 15.4 KiB | text/x-python | PythonLexer
# destutil.py - Mercurial utility function for command destination
#
# Copyright Matt Mackall <mpm@selenic.com> and other
#
# 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 .i18n import _
from . import (
bookmarks,
error,
obsutil,
scmutil,
)
def _destupdateobs(repo, clean):
"""decide of an update destination from obsolescence markers"""
node = None
wc = repo[None]
p1 = wc.p1()
movemark = None
if p1.obsolete() and not p1.children():
# allow updating to successors
successors = obsutil.successorssets(repo, p1.node())
# behavior of certain cases is as follows,
#
# divergent changesets: update to highest rev, similar to what
# is currently done when there are more than one head
# (i.e. 'tip')
#
# replaced changesets: same as divergent except we know there
# is no conflict
#
# pruned changeset: no update is done; though, we could
# consider updating to the first non-obsolete parent,
# similar to what is current done for 'hg prune'
if successors:
# flatten the list here handles both divergent (len > 1)
# and the usual case (len = 1)
successors = [n for sub in successors for n in sub]
# get the max revision for the given successors set,
# i.e. the 'tip' of a set
node = repo.revs('max(%ln)', successors).first()
if bookmarks.isactivewdirparent(repo):
movemark = repo['.'].node()
return node, movemark, None
def _destupdatebook(repo, clean):
"""decide on an update destination from active bookmark"""
# we also move the active bookmark, if any
activemark = None
node, movemark = bookmarks.calculateupdate(repo.ui, repo, None)
if node is not None:
activemark = node
return node, movemark, activemark
def _destupdatebranch(repo, clean):
"""decide on an update destination from current branch
This ignores closed branch heads.
"""
wc = repo[None]
movemark = node = None
currentbranch = wc.branch()
if clean:
currentbranch = repo['.'].branch()
if currentbranch in repo.branchmap():
heads = repo.branchheads(currentbranch)
if heads:
node = repo.revs('max(.::(%ln))', heads).first()
if bookmarks.isactivewdirparent(repo):
movemark = repo['.'].node()
elif currentbranch == 'default' and not wc.p1():
# "null" parent belongs to "default" branch, but it doesn't exist, so
# update to the tipmost non-closed branch head
node = repo.revs('max(head() and not closed())').first()
else:
node = repo['.'].node()
return node, movemark, None
def _destupdatebranchfallback(repo, clean):
"""decide on an update destination from closed heads in current branch"""
wc = repo[None]
currentbranch = wc.branch()
movemark = None
if currentbranch in repo.branchmap():
# here, all descendant branch heads are closed
heads = repo.branchheads(currentbranch, closed=True)
assert heads, "any branch has at least one head"
node = repo.revs('max(.::(%ln))', heads).first()
assert node is not None, ("any revision has at least "
"one descendant branch head")
if bookmarks.isactivewdirparent(repo):
movemark = repo['.'].node()
else:
# here, no "default" branch, and all branches are closed
node = repo.lookup('tip')
assert node is not None, "'tip' exists even in empty repository"
return node, movemark, None
# order in which each step should be evaluated
# steps are run until one finds a destination
destupdatesteps = ['evolution', 'bookmark', 'branch', 'branchfallback']
# mapping to ease extension overriding steps.
destupdatestepmap = {'evolution': _destupdateobs,
'bookmark': _destupdatebook,
'branch': _destupdatebranch,
'branchfallback': _destupdatebranchfallback,
}
def destupdate(repo, clean=False):
"""destination for bare update operation
return (rev, movemark, activemark)
- rev: the revision to update to,
- movemark: node to move the active bookmark from
(cf bookmark.calculate update),
- activemark: a bookmark to activate at the end of the update.
"""
node = movemark = activemark = None
for step in destupdatesteps:
node, movemark, activemark = destupdatestepmap[step](repo, clean)
if node is not None:
break
rev = repo[node].rev()
return rev, movemark, activemark
msgdestmerge = {
# too many matching divergent bookmark
'toomanybookmarks':
{'merge':
(_("multiple matching bookmarks to merge -"
" please merge with an explicit rev or bookmark"),
_("run 'hg heads' to see all heads")),
'rebase':
(_("multiple matching bookmarks to rebase -"
" please rebase to an explicit rev or bookmark"),
_("run 'hg heads' to see all heads")),
},
# no other matching divergent bookmark
'nootherbookmarks':
{'merge':
(_("no matching bookmark to merge - "
"please merge with an explicit rev or bookmark"),
_("run 'hg heads' to see all heads")),
'rebase':
(_("no matching bookmark to rebase - "
"please rebase to an explicit rev or bookmark"),
_("run 'hg heads' to see all heads")),
},
# branch have too many unbookmarked heads, no obvious destination
'toomanyheads':
{'merge':
(_("branch '%s' has %d heads - please merge with an explicit rev"),
_("run 'hg heads .' to see heads")),
'rebase':
(_("branch '%s' has %d heads - please rebase to an explicit rev"),
_("run 'hg heads .' to see heads")),
},
# branch have no other unbookmarked heads
'bookmarkedheads':
{'merge':
(_("heads are bookmarked - please merge with an explicit rev"),
_("run 'hg heads' to see all heads")),
'rebase':
(_("heads are bookmarked - please rebase to an explicit rev"),
_("run 'hg heads' to see all heads")),
},
# branch have just a single heads, but there is other branches
'nootherbranchheads':
{'merge':
(_("branch '%s' has one head - please merge with an explicit rev"),
_("run 'hg heads' to see all heads")),
'rebase':
(_("branch '%s' has one head - please rebase to an explicit rev"),
_("run 'hg heads' to see all heads")),
},
# repository have a single head
'nootherheads':
{'merge':
(_('nothing to merge'),
None),
'rebase':
(_('nothing to rebase'),
None),
},
# repository have a single head and we are not on it
'nootherheadsbehind':
{'merge':
(_('nothing to merge'),
_("use 'hg update' instead")),
'rebase':
(_('nothing to rebase'),
_("use 'hg update' instead")),
},
# We are not on a head
'notatheads':
{'merge':
(_('working directory not at a head revision'),
_("use 'hg update' or merge with an explicit revision")),
'rebase':
(_('working directory not at a head revision'),
_("use 'hg update' or rebase to an explicit revision"))
},
'emptysourceset':
{'merge':
(_('source set is empty'),
None),
'rebase':
(_('source set is empty'),
None),
},
'multiplebranchessourceset':
{'merge':
(_('source set is rooted in multiple branches'),
None),
'rebase':
(_('rebaseset is rooted in multiple named branches'),
_('specify an explicit destination with --dest')),
},
}
def _destmergebook(repo, action='merge', sourceset=None, destspace=None):
"""find merge destination in the active bookmark case"""
node = None
bmheads = bookmarks.headsforactive(repo)
curhead = repo[repo._activebookmark].node()
if len(bmheads) == 2:
if curhead == bmheads[0]:
node = bmheads[1]
else:
node = bmheads[0]
elif len(bmheads) > 2:
msg, hint = msgdestmerge['toomanybookmarks'][action]
raise error.ManyMergeDestAbort(msg, hint=hint)
elif len(bmheads) <= 1:
msg, hint = msgdestmerge['nootherbookmarks'][action]
raise error.NoMergeDestAbort(msg, hint=hint)
assert node is not None
return node
def _destmergebranch(repo, action='merge', sourceset=None, onheadcheck=True,
destspace=None):
"""find merge destination based on branch heads"""
node = None
if sourceset is None:
sourceset = [repo[repo.dirstate.p1()].rev()]
branch = repo.dirstate.branch()
elif not sourceset:
msg, hint = msgdestmerge['emptysourceset'][action]
raise error.NoMergeDestAbort(msg, hint=hint)
else:
branch = None
for ctx in repo.set('roots(%ld::%ld)', sourceset, sourceset):
if branch is not None and ctx.branch() != branch:
msg, hint = msgdestmerge['multiplebranchessourceset'][action]
raise error.ManyMergeDestAbort(msg, hint=hint)
branch = ctx.branch()
bheads = repo.branchheads(branch)
onhead = repo.revs('%ld and %ln', sourceset, bheads)
if onheadcheck and not onhead:
# Case A: working copy if not on a head. (merge only)
#
# This is probably a user mistake We bailout pointing at 'hg update'
if len(repo.heads()) <= 1:
msg, hint = msgdestmerge['nootherheadsbehind'][action]
else:
msg, hint = msgdestmerge['notatheads'][action]
raise error.Abort(msg, hint=hint)
# remove heads descendants of source from the set
bheads = list(repo.revs('%ln - (%ld::)', bheads, sourceset))
# filters out bookmarked heads
nbhs = list(repo.revs('%ld - bookmark()', bheads))
if destspace is not None:
# restrict search space
# used in the 'hg pull --rebase' case, see issue 5214.
nbhs = list(repo.revs('%ld and %ld', destspace, nbhs))
if len(nbhs) > 1:
# Case B: There is more than 1 other anonymous heads
#
# This means that there will be more than 1 candidate. This is
# ambiguous. We abort asking the user to pick as explicit destination
# instead.
msg, hint = msgdestmerge['toomanyheads'][action]
msg %= (branch, len(bheads) + 1)
raise error.ManyMergeDestAbort(msg, hint=hint)
elif not nbhs:
# Case B: There is no other anonymous heads
#
# This means that there is no natural candidate to merge with.
# We abort, with various messages for various cases.
if bheads:
msg, hint = msgdestmerge['bookmarkedheads'][action]
elif len(repo.heads()) > 1:
msg, hint = msgdestmerge['nootherbranchheads'][action]
msg %= branch
elif not onhead:
# if 'onheadcheck == False' (rebase case),
# this was not caught in Case A.
msg, hint = msgdestmerge['nootherheadsbehind'][action]
else:
msg, hint = msgdestmerge['nootherheads'][action]
raise error.NoMergeDestAbort(msg, hint=hint)
else:
node = nbhs[0]
assert node is not None
return node
def destmerge(repo, action='merge', sourceset=None, onheadcheck=True,
destspace=None):
"""return the default destination for a merge
(or raise exception about why it can't pick one)
:action: the action being performed, controls emitted error message
"""
# destspace is here to work around issues with `hg pull --rebase` see
# issue5214 for details
if repo._activebookmark:
node = _destmergebook(repo, action=action, sourceset=sourceset,
destspace=destspace)
else:
node = _destmergebranch(repo, action=action, sourceset=sourceset,
onheadcheck=onheadcheck, destspace=destspace)
return repo[node].rev()
histeditdefaultrevset = 'reverse(only(.) and not public() and not ::merge())'
def desthistedit(ui, repo):
"""Default base revision to edit for `hg histedit`."""
default = ui.config('histedit', 'defaultrev', histeditdefaultrevset)
if default:
revs = scmutil.revrange(repo, [default])
if revs:
# The revset supplied by the user may not be in ascending order nor
# take the first revision. So do this manually.
revs.sort()
return revs.first()
return None
def stackbase(ui, repo):
# The histedit default base stops at public changesets, branchpoints,
# and merges, which is exactly what we want for a stack.
revs = scmutil.revrange(repo, [histeditdefaultrevset])
return revs.last() if revs else None
def _statusotherbook(ui, repo):
bmheads = bookmarks.headsforactive(repo)
curhead = repo[repo._activebookmark].node()
if repo.revs('%n and parents()', curhead):
# we are on the active bookmark
bmheads = [b for b in bmheads if curhead != b]
if bmheads:
msg = _('%i other divergent bookmarks for "%s"\n')
ui.status(msg % (len(bmheads), repo._activebookmark))
def _statusotherbranchheads(ui, repo):
currentbranch = repo.dirstate.branch()
allheads = repo.branchheads(currentbranch, closed=True)
heads = repo.branchheads(currentbranch)
if repo.revs('%ln and parents()', allheads):
# we are on a head, even though it might be closed
#
# on closed otherheads
# ========= ==========
# o 0 all heads for current branch are closed
# N only descendant branch heads are closed
# x 0 there is only one non-closed branch head
# N there are some non-closed branch heads
# ========= ==========
otherheads = repo.revs('%ln - parents()', heads)
if repo['.'].closesbranch():
ui.warn(_('no open descendant heads on branch "%s", '
'updating to a closed head\n') %
(currentbranch))
if otherheads:
ui.warn(_("(committing will reopen the head, "
"use 'hg heads .' to see %i other heads)\n") %
(len(otherheads)))
else:
ui.warn(_('(committing will reopen branch "%s")\n') %
(currentbranch))
elif otherheads:
curhead = repo['.']
ui.status(_('updated to "%s: %s"\n') % (curhead,
curhead.description().split('\n')[0]))
ui.status(_('%i other heads for branch "%s"\n') %
(len(otherheads), currentbranch))
def statusotherdests(ui, repo):
"""Print message about other head"""
# XXX we should probably include a hint:
# - about what to do
# - how to see such heads
if repo._activebookmark:
_statusotherbook(ui, repo)
else:
_statusotherbranchheads(ui, repo)