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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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unionrepo.py
259 lines | 9.0 KiB | text/x-python | PythonLexer
# unionrepo.py - repository class for viewing union of repository changesets
#
# Derived from bundlerepo.py
# Copyright 2006, 2007 Benoit Boissinot <bboissin@gmail.com>
# Copyright 2013 Unity Technologies, Mads Kiilerich <madski@unity3d.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Repository class for "in-memory pull" of one local repository to another,
allowing operations like diff and log with revsets.
"""
from __future__ import absolute_import
from .i18n import _
from .node import nullid
from . import (
changelog,
cmdutil,
error,
filelog,
localrepo,
manifest,
mdiff,
pathutil,
pycompat,
revlog,
util,
vfs as vfsmod,
)
class unionrevlog(revlog.revlog):
def __init__(self, opener, indexfile, revlog2, linkmapper):
# How it works:
# To retrieve a revision, we just need to know the node id so we can
# look it up in revlog2.
#
# To differentiate a rev in the second revlog from a rev in the revlog,
# we check revision against repotiprev.
opener = vfsmod.readonlyvfs(opener)
revlog.revlog.__init__(self, opener, indexfile)
self.revlog2 = revlog2
n = len(self)
self.repotiprev = n - 1
self.bundlerevs = set() # used by 'bundle()' revset expression
for rev2 in self.revlog2:
rev = self.revlog2.index[rev2]
# rev numbers - in revlog2, very different from self.rev
_start, _csize, _rsize, base, linkrev, p1rev, p2rev, node = rev
flags = _start & 0xFFFF
if linkmapper is None: # link is to same revlog
assert linkrev == rev2 # we never link back
link = n
else: # rev must be mapped from repo2 cl to unified cl by linkmapper
link = linkmapper(linkrev)
if linkmapper is not None: # link is to same revlog
base = linkmapper(base)
if node in self.nodemap:
# this happens for the common revlog revisions
self.bundlerevs.add(self.nodemap[node])
continue
p1node = self.revlog2.node(p1rev)
p2node = self.revlog2.node(p2rev)
e = (flags, None, None, base,
link, self.rev(p1node), self.rev(p2node), node)
self.index.insert(-1, e)
self.nodemap[node] = n
self.bundlerevs.add(n)
n += 1
def _chunk(self, rev):
if rev <= self.repotiprev:
return revlog.revlog._chunk(self, rev)
return self.revlog2._chunk(self.node(rev))
def revdiff(self, rev1, rev2):
"""return or calculate a delta between two revisions"""
if rev1 > self.repotiprev and rev2 > self.repotiprev:
return self.revlog2.revdiff(
self.revlog2.rev(self.node(rev1)),
self.revlog2.rev(self.node(rev2)))
elif rev1 <= self.repotiprev and rev2 <= self.repotiprev:
return self.baserevdiff(rev1, rev2)
return mdiff.textdiff(self.revision(rev1), self.revision(rev2))
def revision(self, nodeorrev, raw=False):
"""return an uncompressed revision of a given node or revision
number.
"""
if isinstance(nodeorrev, int):
rev = nodeorrev
node = self.node(rev)
else:
node = nodeorrev
rev = self.rev(node)
if node == nullid:
return ""
if rev > self.repotiprev:
text = self.revlog2.revision(node)
self._cache = (node, rev, text)
else:
text = self.baserevision(rev)
# already cached
return text
def baserevision(self, nodeorrev):
# Revlog subclasses may override 'revision' method to modify format of
# content retrieved from revlog. To use unionrevlog with such class one
# needs to override 'baserevision' and make more specific call here.
return revlog.revlog.revision(self, nodeorrev)
def baserevdiff(self, rev1, rev2):
# Exists for the same purpose as baserevision.
return revlog.revlog.revdiff(self, rev1, rev2)
def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):
raise NotImplementedError
def addgroup(self, deltas, transaction, addrevisioncb=None):
raise NotImplementedError
def strip(self, rev, minlink):
raise NotImplementedError
def checksize(self):
raise NotImplementedError
class unionchangelog(unionrevlog, changelog.changelog):
def __init__(self, opener, opener2):
changelog.changelog.__init__(self, opener)
linkmapper = None
changelog2 = changelog.changelog(opener2)
unionrevlog.__init__(self, opener, self.indexfile, changelog2,
linkmapper)
def baserevision(self, nodeorrev):
# Although changelog doesn't override 'revision' method, some extensions
# may replace this class with another that does. Same story with
# manifest and filelog classes.
return changelog.changelog.revision(self, nodeorrev)
def baserevdiff(self, rev1, rev2):
return changelog.changelog.revdiff(self, rev1, rev2)
class unionmanifest(unionrevlog, manifest.manifestrevlog):
def __init__(self, opener, opener2, linkmapper):
manifest.manifestrevlog.__init__(self, opener)
manifest2 = manifest.manifestrevlog(opener2)
unionrevlog.__init__(self, opener, self.indexfile, manifest2,
linkmapper)
def baserevision(self, nodeorrev):
return manifest.manifestrevlog.revision(self, nodeorrev)
def baserevdiff(self, rev1, rev2):
return manifest.manifestrevlog.revdiff(self, rev1, rev2)
class unionfilelog(unionrevlog, filelog.filelog):
def __init__(self, opener, path, opener2, linkmapper, repo):
filelog.filelog.__init__(self, opener, path)
filelog2 = filelog.filelog(opener2, path)
unionrevlog.__init__(self, opener, self.indexfile, filelog2,
linkmapper)
self._repo = repo
def baserevision(self, nodeorrev):
return filelog.filelog.revision(self, nodeorrev)
def baserevdiff(self, rev1, rev2):
return filelog.filelog.revdiff(self, rev1, rev2)
def iscensored(self, rev):
"""Check if a revision is censored."""
if rev <= self.repotiprev:
return filelog.filelog.iscensored(self, rev)
node = self.node(rev)
return self.revlog2.iscensored(self.revlog2.rev(node))
class unionpeer(localrepo.localpeer):
def canpush(self):
return False
class unionrepository(localrepo.localrepository):
def __init__(self, ui, path, path2):
localrepo.localrepository.__init__(self, ui, path)
self.ui.setconfig('phases', 'publish', False, 'unionrepo')
self._url = 'union:%s+%s' % (util.expandpath(path),
util.expandpath(path2))
self.repo2 = localrepo.localrepository(ui, path2)
@localrepo.unfilteredpropertycache
def changelog(self):
return unionchangelog(self.svfs, self.repo2.svfs)
def _clrev(self, rev2):
"""map from repo2 changelog rev to temporary rev in self.changelog"""
node = self.repo2.changelog.node(rev2)
return self.changelog.rev(node)
def _constructmanifest(self):
return unionmanifest(self.svfs, self.repo2.svfs,
self.unfiltered()._clrev)
def url(self):
return self._url
def file(self, f):
return unionfilelog(self.svfs, f, self.repo2.svfs,
self.unfiltered()._clrev, self)
def close(self):
self.repo2.close()
def cancopy(self):
return False
def peer(self):
return unionpeer(self)
def getcwd(self):
return pycompat.getcwd() # always outside the repo
def instance(ui, path, create):
if create:
raise error.Abort(_('cannot create new union repository'))
parentpath = ui.config("bundle", "mainreporoot")
if not parentpath:
# try to find the correct path to the working directory repo
parentpath = cmdutil.findrepo(pycompat.getcwd())
if parentpath is None:
parentpath = ''
if parentpath:
# Try to make the full path relative so we get a nice, short URL.
# In particular, we don't want temp dir names in test outputs.
cwd = pycompat.getcwd()
if parentpath == cwd:
parentpath = ''
else:
cwd = pathutil.normasprefix(cwd)
if parentpath.startswith(cwd):
parentpath = parentpath[len(cwd):]
if path.startswith('union:'):
s = path.split(":", 1)[1].split("+", 1)
if len(s) == 1:
repopath, repopath2 = parentpath, s[0]
else:
repopath, repopath2 = s
else:
repopath, repopath2 = parentpath, path
return unionrepository(ui, repopath, repopath2)