view tests/test-py3-commands.t @ 35884:197d10e157ce

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

#require py3exe

This test helps in keeping a track on which commands we can run on
Python 3 and see what kind of errors are coming up.
The full traceback is hidden to have a stable output.
  $ HGBIN=`which hg`

  $ for cmd in version debuginstall ; do
  >   echo $cmd
  >   $PYTHON3 $HGBIN $cmd 2>&1 2>&1 | tail -1
  > done
  version
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  debuginstall
  no problems detected

#if test-repo
Make a clone so that any features in the developer's .hg/hgrc that
might confuse Python 3 don't break this test. When we can do commit in
Python 3, we'll stop doing this. We use e76ed1e480ef for the clone
because it has different files than 273ce12ad8f1, so we can test both
`files` from dirstate and `files` loaded from a specific revision.

  $ hg clone -r e76ed1e480ef "`dirname "$TESTDIR"`" testrepo 2>&1 | tail -1
  15 files updated, 0 files merged, 0 files removed, 0 files unresolved

Test using -R, which exercises some URL code:
  $ $PYTHON3 $HGBIN -R testrepo files -r 273ce12ad8f1 | tail -1
  testrepo/tkmerge

Now prove `hg files` is reading the whole manifest. We have to grep
out some potential warnings that come from hgrc as yet.
  $ cd testrepo
  $ $PYTHON3 $HGBIN files -r 273ce12ad8f1
  .hgignore
  PKG-INFO
  README
  hg
  mercurial/__init__.py
  mercurial/byterange.py
  mercurial/fancyopts.py
  mercurial/hg.py
  mercurial/mdiff.py
  mercurial/revlog.py
  mercurial/transaction.py
  notes.txt
  setup.py
  tkmerge

  $ $PYTHON3 $HGBIN files -r 273ce12ad8f1 | wc -l
  \s*14 (re)
  $ $PYTHON3 $HGBIN files | wc -l
  \s*15 (re)

Test if log-like commands work:

  $ $PYTHON3 $HGBIN tip
  changeset:   10:e76ed1e480ef
  tag:         tip
  user:        [e-mail]
  date:        Tue May 03 23:37:43 2005 -0800
  summary:     Fix linking of changeset revs when merging
  

  $ $PYTHON3 $HGBIN log -r0
  changeset:   0:9117c6561b0b
  user:        [e-mail]
  date:        Tue May 03 13:16:10 2005 -0800
  summary:     Add back links from file revisions to changeset revisions
  

  $ cd ..
#endif

Test if `hg config` works:

  $ $PYTHON3 $HGBIN config
  devel.all-warnings=true
  devel.default-date=0 0
  largefiles.usercache=$TESTTMP/.cache/largefiles
  ui.slash=True
  ui.interactive=False
  ui.mergemarkers=detailed
  ui.promptecho=True
  web.address=localhost
  web.ipv6=False

  $ cat > included-hgrc <<EOF
  > [extensions]
  > babar = imaginary_elephant
  > EOF
  $ cat >> $HGRCPATH <<EOF
  > %include $TESTTMP/included-hgrc
  > EOF
  $ $PYTHON3 $HGBIN version | tail -1
  *** failed to import extension babar from imaginary_elephant: *: 'imaginary_elephant' (glob)
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

  $ rm included-hgrc
  $ touch included-hgrc

Test bytes-ness of policy.policy with HGMODULEPOLICY

  $ HGMODULEPOLICY=py
  $ export HGMODULEPOLICY
  $ $PYTHON3 `which hg` debuginstall 2>&1 2>&1 | tail -1
  no problems detected

`hg init` can create empty repos
`hg status works fine`
`hg summary` also works!

  $ $PYTHON3 `which hg` init py3repo
  $ cd py3repo
  $ echo "This is the file 'iota'." > iota
  $ $PYTHON3 $HGBIN status
  ? iota
  $ $PYTHON3 $HGBIN add iota
  $ $PYTHON3 $HGBIN status
  A iota
  $ hg diff --nodates --git
  diff --git a/iota b/iota
  new file mode 100644
  --- /dev/null
  +++ b/iota
  @@ -0,0 +1,1 @@
  +This is the file 'iota'.
  $ $PYTHON3 $HGBIN commit --message 'commit performed in Python 3'
  $ $PYTHON3 $HGBIN status

  $ mkdir A
  $ echo "This is the file 'mu'." > A/mu
  $ $PYTHON3 $HGBIN addremove
  adding A/mu
  $ $PYTHON3 $HGBIN status
  A A/mu
  $ HGEDITOR='echo message > ' $PYTHON3 $HGBIN commit
  $ $PYTHON3 $HGBIN status
  $ $PYHON3 $HGBIN summary
  parent: 1:e1e9167203d4 tip
   message
  branch: default
  commit: (clean)
  update: (current)
  phases: 2 draft

Test weird unicode-vs-bytes stuff

  $ $PYTHON3 $HGBIN help | egrep -v '^ |^$'
  Mercurial Distributed SCM
  list of commands:
  additional help topics:
  (use 'hg help -v' to show built-in aliases and global options)

  $ $PYTHON3 $HGBIN help help | egrep -v '^ |^$'
  hg help [-ecks] [TOPIC]
  show help for a given topic or a help overview
  options ([+] can be repeated):
  (some details hidden, use --verbose to show complete help)

  $ $PYTHON3 $HGBIN help -k notopic
  abort: no matches
  (try 'hg help' for a list of topics)
  [255]

Prove the repo is valid using the Python 2 `hg`:
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  2 files, 2 changesets, 2 total revisions
  $ hg log
  changeset:   1:e1e9167203d4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     message
  
  changeset:   0:71c96e924262
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit performed in Python 3
  

  $ $PYTHON3 $HGBIN log -G
  @  changeset:   1:e1e9167203d4
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     message
  |
  o  changeset:   0:71c96e924262
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     commit performed in Python 3
  
  $ $PYTHON3 $HGBIN log -Tjson
  [
   {
    "rev": 1,
    "node": "e1e9167203d450ca2f558af628955b5f5afd4489",
    "branch": "default",
    "phase": "draft",
    "user": "test",
    "date": [0, 0],
    "desc": "message",
    "bookmarks": [],
    "tags": ["tip"],
    "parents": ["71c96e924262969ff0d8d3d695b0f75412ccc3d8"]
   },
   {
    "rev": 0,
    "node": "71c96e924262969ff0d8d3d695b0f75412ccc3d8",
    "branch": "default",
    "phase": "draft",
    "user": "test",
    "date": [0, 0],
    "desc": "commit performed in Python 3",
    "bookmarks": [],
    "tags": [],
    "parents": ["0000000000000000000000000000000000000000"]
   }
  ]

Show that update works now!

  $ $PYTHON3 $HGBIN up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ $PYTHON3 $HGBIN identify
  71c96e924262

branches and bookmarks also works!

  $ $PYTHON3 $HGBIN branches
  default                        1:e1e9167203d4
  $ $PYTHON3 $HGBIN bookmark book
  $ $PYTHON3 $HGBIN bookmarks
   * book                      0:71c96e924262