tests/test-obsolete-changeset-exchange.t

wireprotov2: move response handling out of httppeer

And fix some bugs while we're here.

The code for processing response data from the unified framing
protocol is mostly peer agnostic. The peer-specific bits are the
configuration of the client reactor and how I/O is performed. I
initially implemented things in httppeer for expediency.

This commit establishes a module for holding the peer API level
code for the framing based protocol. Inside this module we have
a class to help coordinate higher-level activities, such as managing
response object.

The client handler bits could be rolled into clientreactor. However,
I want clientreactor to be sans I/O and I want it to only be
concerned with protocol-level details, not higher-level concepts
like how protocol events are converted into peer API concepts. I
want clientreactor to receive a frame and then tell the caller what
should probably be done about it. If we start putting things like
future resolution into clientreactor, we'll constrain how the protocol
can be used (e.g. by requiring futures).

The new code is loosely based on what was in httppeer before. I
changed things a bit around response handling. We now buffer the
entire response "body" and then handle it as one atomic unit. This
fixed a bug around decoding CBOR data that spanned multiple frames.
I also fixed an off-by-one bug where we failed to read a single byte
CBOR value at the end of the stream. That's why tests have changed.

The new state of httppeer is much cleaner. It is largely agnostic
about framing protocol implementation details. That's how it should
be: the framing protocol is designed to be largely transport
agnostic. We want peers merely putting bytes on the wire and telling
the framing protocol where to read response data from.

There's still a bit of work to be done here, especially for
representing responses. But at least we're a step closer to having a
higher-level peer interface that can be plugged into the SSH peer
someday.

I initially added this class to wireprotoframing. However, we'll
eventually need version 2 specific functions to convert CBOR responses
into data structures expected by the code calling commands. This
needs to live somewhere. Since that code would be shared across peers,
we need a common module. We have wireprotov1peer for the equivalent
version 1 code. So I decided to establish wireprotov2peer.

Differential Revision: https://phab.mercurial-scm.org/D3379

Test changesets filtering during exchanges (some tests are still in
test-obsolete.t)

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > evolution.createmarkers=True
  > EOF

Push does not corrupt remote
----------------------------

Create a DAG where a changeset reuses a revision from a file first used in an
extinct changeset.

  $ hg init local
  $ cd local
  $ echo 'base' > base
  $ hg commit -Am base
  adding base
  $ echo 'A' > A
  $ hg commit -Am A
  adding A
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg revert -ar 1
  adding A
  $ hg commit -Am "A'"
  created new head
  $ hg log -G --template='{desc} {node}'
  @  A' f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
  |
  | o  A 9d73aac1b2ed7d53835eaeec212ed41ea47da53a
  |/
  o  base d20a80d4def38df63a4b330b7fb688f3d4cae1e3
  
  $ hg debugobsolete 9d73aac1b2ed7d53835eaeec212ed41ea47da53a f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
  obsoleted 1 changesets

Push it. The bundle should not refer to the extinct changeset.

  $ hg init ../other
  $ hg push ../other
  pushing to ../other
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  $ hg -R ../other verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  2 files, 2 changesets, 2 total revisions

Adding a changeset going extinct locally
------------------------------------------

Pull a changeset that will immediatly goes extinct (because you already have a
marker to obsolete him)
(test resolution of issue3788)

  $ hg phase --draft --force f89bcc95eba5
  $ hg phase -R ../other --draft --force f89bcc95eba5
  $ hg commit --amend -m "A''"
  $ hg --hidden --config extensions.mq= strip  --no-backup f89bcc95eba5
  $ hg pull ../other
  pulling from ../other
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 1 files (+1 heads)
  1 new phase-divergent changesets
  new changesets f89bcc95eba5
  (run 'hg heads' to see heads, 'hg merge' to merge)

check that bundle is not affected

  $ hg bundle --hidden --rev f89bcc95eba5 --base "f89bcc95eba5^" ../f89bcc95eba5.hg
  1 changesets found
  $ hg --hidden --config extensions.mq= strip --no-backup f89bcc95eba5
  $ hg unbundle ../f89bcc95eba5.hg
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads)

check-that bundle can contain markers:

  $ hg bundle --hidden --rev f89bcc95eba5 --base "f89bcc95eba5^" ../f89bcc95eba5-obs.hg --config experimental.evolution.bundle-obsmarker=1
  1 changesets found
  $ hg debugbundle ../f89bcc95eba5.hg
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 1, version: 02}
      f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
  cache:rev-branch-cache -- {}
  $ hg debugbundle ../f89bcc95eba5-obs.hg
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 1, version: 02}
      f89bcc95eba5174b1ccc3e33a82e84c96e8338ee
  cache:rev-branch-cache -- {}
  obsmarkers -- {}
      version: 1 (70 bytes)
      9d73aac1b2ed7d53835eaeec212ed41ea47da53a f89bcc95eba5174b1ccc3e33a82e84c96e8338ee 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}

  $ cd ..

pull does not fetch excessive changesets when common node is hidden (issue4982)
-------------------------------------------------------------------------------

initial repo with server and client matching

  $ hg init pull-hidden-common
  $ cd pull-hidden-common
  $ touch foo
  $ hg -q commit -A -m initial
  $ echo 1 > foo
  $ hg commit -m 1
  $ echo 2a > foo
  $ hg commit -m 2a
  $ cd ..
  $ hg clone --pull pull-hidden-common pull-hidden-common-client
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  new changesets 96ee1d7354c4:6a29ed9c68de
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

server obsoletes the old head

  $ cd pull-hidden-common
  $ hg -q up -r 1
  $ echo 2b > foo
  $ hg -q commit -m 2b
  $ hg debugobsolete 6a29ed9c68defff1a139e5c6fa9696fb1a75783d bec0734cd68e84477ba7fc1d13e6cff53ab70129
  obsoleted 1 changesets
  $ cd ..

client only pulls down 1 changeset

  $ cd pull-hidden-common-client
  $ hg pull --debug
  pulling from $TESTTMP/pull-hidden-common
  query 1; heads
  searching for changes
  taking quick initial sample
  query 2; still undecided: 2, sample size is: 2
  2 total queries in *.????s (glob)
  1 changesets found
  list of changesets:
  bec0734cd68e84477ba7fc1d13e6cff53ab70129
  listing keys for "bookmarks"
  bundle2-output-bundle: "HG20", 4 parts total
  bundle2-output-part: "changegroup" (params: 1 mandatory 1 advisory) streamed payload
  bundle2-output-part: "listkeys" (params: 1 mandatory) empty payload
  bundle2-output-part: "phase-heads" 24 bytes payload
  bundle2-output-part: "cache:rev-branch-cache" streamed payload
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "changegroup" (params: 1 mandatory 1 advisory) supported
  adding changesets
  add changeset bec0734cd68e
  adding manifests
  adding file changes
  adding foo revisions
  added 1 changesets with 1 changes to 1 files (+1 heads)
  bundle2-input-part: total payload size 476
  bundle2-input-part: "listkeys" (params: 1 mandatory) supported
  bundle2-input-part: "phase-heads" supported
  bundle2-input-part: total payload size 24
  bundle2-input-part: "cache:rev-branch-cache" supported
  bundle2-input-part: total payload size 39
  bundle2-input-bundle: 3 parts total
  checking for updated bookmarks
  updating the branch cache
  new changesets bec0734cd68e
  (run 'hg heads' to see heads, 'hg merge' to merge)