tests/test-wireproto-command-changesetdata.t

wireprotov2: add phases to "changesetdata" command

This commit teaches the "changesetdata" wire protocol command
to emit the phase state for each changeset.

This is a different approach from existing phase transfer in a
few ways. Previously, if there are no new revisions (or we're
not using bundle2), we perform a "listkeys" request to retrieve
phase heads. And when revision data is being transferred
with bundle2, phases data is encoded in a standalone bundle2 part.
In both cases, phases data is logically decoupled from the changeset
data and is encountered/applied after changeset revision data
is received.

The new wire protocol purposefully tries to more tightly associate
changeset metadata (phases, bookmarks, obsolescence markers, etc)
with the changeset revision and index data itself, rather than
have it live as a separate entity that must be fetched and
processed separately. I reckon that one reason we didn't do this
before was it was difficult to add new data types/fields without
breaking existing consumers. By using CBOR maps to transfer
changeset data and putting clients in control of what fields are
requested / present in those maps, we can easily add additional
changeset data while maintaining backwards compatibility. I believe
this to be a superior approach to the problem.

That being said, for performance reasons, we may need to resort
to alternative mechanisms for transferring data like phases. But
for now, I think giving the wire protocol the ability to transfer
changeset metadata next to the changeset itself is a powerful feature
because it is a raw, changeset-centric data API. And if you build
simple APIs for accessing the fundamental units of repository data,
you enable client-side experimentation (partial clone, etc). If it
turns out that we need specialized APIs or mechanisms for transferring
data like phases, we can build in those APIs later. For now, I'd
like to see how far we can get on simple APIs.

It's worth noting that when phase data is being requested, the
server will also emit changeset records for nodes in the bases
specified by the "noderange" argument. This is to ensure that
phase-only updates for nodes the client has are available to the
client, even if no new changesets will be transferred.

Differential Revision: https://phab.mercurial-scm.org/D4483

  $ . $TESTDIR/wireprotohelpers.sh

  $ hg init server
  $ enablehttpv2 server
  $ cd server
  $ cat >> .hg/hgrc << EOF
  > [phases]
  > publish = false
  > EOF
  $ echo a0 > a
  $ echo b0 > b

  $ hg -q commit -A -m 'commit 0'

  $ echo a1 > a
  $ echo b1 > b
  $ hg commit -m 'commit 1'
  $ echo b2 > b
  $ hg commit -m 'commit 2'
  $ hg phase --public -r .

  $ hg -q up -r 0
  $ echo a2 > a
  $ hg commit -m 'commit 3'
  created new head

  $ hg log -G -T '{rev}:{node} {desc}\n'
  @  3:eae5f82c2e622368d27daecb76b7e393d0f24211 commit 3
  |
  | o  2:0bb8ad894a15b15380b2a2a5b183e20f2a4b28dd commit 2
  | |
  | o  1:7592917e1c3e82677cb0a4bc715ca25dd12d28c1 commit 1
  |/
  o  0:3390ef850073fbc2f0dfff2244342c8e9229013a commit 0
  

  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
  $ cat hg.pid > $DAEMON_PIDS

No arguments is an invalid request

  $ sendhttpv2peer << EOF
  > command changesetdata
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 28\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     \x14\x00\x00\x01\x00\x01\x01\x11\xa1DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     49\r\n
  s>     A\x00\x00\x01\x00\x02\x012
  s>     \xa2Eerror\xa1GmessageX"noderange or nodes must be definedFstatusEerror
  s>     \r\n
  received frame(size=65; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=eos)
  s>     0\r\n
  s>     \r\n
  abort: noderange or nodes must be defined!
  [255]

Empty noderange heads results in an error

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     noderange eval:[[],[]]
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 47\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     \'\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa1Inoderange\x82\x80\x80DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     51\r\n
  s>     I\x00\x00\x01\x00\x02\x012
  s>     \xa2Eerror\xa1GmessageX*heads in noderange request cannot be emptyFstatusEerror
  s>     \r\n
  received frame(size=73; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=eos)
  s>     0\r\n
  s>     \r\n
  abort: heads in noderange request cannot be empty!
  [255]

Sending just noderange heads sends all revisions

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     noderange eval:[[], [b'\x0b\xb8\xad\x89\x4a\x15\xb1\x53\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f\x2a\x4b\x28\xdd', b'\xea\xe5\xf8\x2c\x2e\x62\x23\x68\xd2\x7d\xae\xcb\x76\xb7\xe3\x93\xd0\xf2\x42\x11']]
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 89\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     Q\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa1Inoderange\x82\x80\x82T\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     81\r\n
  s>     y\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x04\xa1DnodeT3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:\xa1DnodeTu\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1\xa1DnodeT\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd\xa1DnodeT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11
  s>     \r\n
  received frame(size=121; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 4
    },
    {
      b'node': b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:'
    },
    {
      b'node': b'u\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1'
    },
    {
      b'node': b'\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd'
    },
    {
      b'node': b'\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11'
    }
  ]

Sending root nodes limits what data is sent

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     noderange eval:[[b'\x33\x90\xef\x85\x00\x73\xfb\xc2\xf0\xdf\xff\x22\x44\x34\x2c\x8e\x92\x29\x01\x3a'], [b'\x0b\xb8\xad\x89\x4a\x15\xb1\x53\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f\x2a\x4b\x28\xdd']]
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 89\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     Q\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa1Inoderange\x82\x81T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:\x81T\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddDnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     4b\r\n
  s>     C\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x02\xa1DnodeTu\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1\xa1DnodeT\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd
  s>     \r\n
  received frame(size=67; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'node': b'u\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1'
    },
    {
      b'node': b'\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd'
    }
  ]

Requesting data on a single node by node works

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     nodes eval:[b'\x33\x90\xef\x85\x00\x73\xfb\xc2\xf0\xdf\xff\x22\x44\x34\x2c\x8e\x92\x29\x01\x3a']
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 62\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     6\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa1Enodes\x81T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     30\r\n
  s>     (\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x01\xa1DnodeT3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:
  s>     \r\n
  received frame(size=40; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:'
    }
  ]

Specifying a noderange and nodes takes union

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     noderange eval:[[b'\x75\x92\x91\x7e\x1c\x3e\x82\x67\x7c\xb0\xa4\xbc\x71\x5c\xa2\x5d\xd1\x2d\x28\xc1'], [b'\x0b\xb8\xad\x89\x4a\x15\xb1\x53\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f\x2a\x4b\x28\xdd']]
  >     nodes eval:[b'\xea\xe5\xf8\x2c\x2e\x62\x23\x68\xd2\x7d\xae\xcb\x76\xb7\xe3\x93\xd0\xf2\x42\x11']
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 117\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     m\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa2Inoderange\x82\x81Tu\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1\x81T\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddEnodes\x81T\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     4b\r\n
  s>     C\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x02\xa1DnodeT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11\xa1DnodeT\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd
  s>     \r\n
  received frame(size=67; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 2
    },
    {
      b'node': b'\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11'
    },
    {
      b'node': b'\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd'
    }
  ]

Parents data is transferred upon request

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     fields eval:[b'parents']
  >     nodes eval:[b'\xea\xe5\xf8\x2c\x2e\x62\x23\x68\xd2\x7d\xae\xcb\x76\xb7\xe3\x93\xd0\xf2\x42\x11']
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 78\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     F\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa2Ffields\x81GparentsEnodes\x81T\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     63\r\n
  s>     [\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x01\xa2DnodeT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11Gparents\x82T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
  s>     \r\n
  received frame(size=91; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11',
      b'parents': [
        b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

Phase data is transferred upon request

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     fields eval:[b'phase']
  >     nodes eval:[b'\x0b\xb8\xad\x89\x4a\x15\xb1\x53\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f\x2a\x4b\x28\xdd']
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 76\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     D\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa2Ffields\x81EphaseEnodes\x81T\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddDnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     3d\r\n
  s>     5\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x01\xa2DnodeT\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddEphaseFpublic
  s>     \r\n
  received frame(size=53; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd',
      b'phase': b'public'
    }
  ]

Revision data is transferred upon request

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     fields eval:[b'revision']
  >     nodes eval:[b'\xea\xe5\xf8\x2c\x2e\x62\x23\x68\xd2\x7d\xae\xcb\x76\xb7\xe3\x93\xd0\xf2\x42\x11']
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 79\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     G\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa2Ffields\x81HrevisionEnodes\x81T\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     7e\r\n
  s>     v\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x01\xa2DnodeT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11Lrevisionsize\x18=X=1b74476799ec8318045db759b1b4bcc9b839d0aa\n
  s>     test\n
  s>     0 0\n
  s>     a\n
  s>     \n
  s>     commit 3
  s>     \r\n
  received frame(size=118; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11',
      b'revisionsize': 61
    },
    b'1b74476799ec8318045db759b1b4bcc9b839d0aa\ntest\n0 0\na\n\ncommit 3'
  ]

Multiple fields can be transferred

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     fields eval:[b'parents', b'revision']
  >     nodes eval:[b'\xea\xe5\xf8\x2c\x2e\x62\x23\x68\xd2\x7d\xae\xcb\x76\xb7\xe3\x93\xd0\xf2\x42\x11']
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 87\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     O\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa2Ffields\x82GparentsHrevisionEnodes\x81T\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     b1\r\n
  s>     \xa9\x00\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x01\xa3DnodeT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11Gparents\x82T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00Lrevisionsize\x18=X=1b74476799ec8318045db759b1b4bcc9b839d0aa\n
  s>     test\n
  s>     0 0\n
  s>     a\n
  s>     \n
  s>     commit 3
  s>     \r\n
  received frame(size=169; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 1
    },
    {
      b'node': b'\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11',
      b'parents': [
        b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ],
      b'revisionsize': 61
    },
    b'1b74476799ec8318045db759b1b4bcc9b839d0aa\ntest\n0 0\na\n\ncommit 3'
  ]

Base nodes have just their metadata (e.g. phase) transferred

  $ sendhttpv2peer << EOF
  > command changesetdata
  >     fields eval:[b'phase', b'parents', b'revision']
  >     noderange eval:[[b'\x33\x90\xef\x85\x00\x73\xfb\xc2\xf0\xdf\xff\x22\x44\x34\x2c\x8e\x92\x29\x01\x3a'], [b'\x0b\xb8\xad\x89\x4a\x15\xb1\x53\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f\x2a\x4b\x28\xdd', b'\xea\xe5\xf8\x2c\x2e\x62\x23\x68\xd2\x7d\xae\xcb\x76\xb7\xe3\x93\xd0\xf2\x42\x11']]
  > EOF
  creating http peer for wire protocol version 2
  sending changesetdata command
  s>     POST /api/exp-http-v2-0001/ro/changesetdata HTTP/1.1\r\n
  s>     Accept-Encoding: identity\r\n
  s>     accept: application/mercurial-exp-framing-0005\r\n
  s>     content-type: application/mercurial-exp-framing-0005\r\n
  s>     content-length: 141\r\n
  s>     host: $LOCALIP:$HGPORT\r\n (glob)
  s>     user-agent: Mercurial debugwireproto\r\n
  s>     \r\n
  s>     \x85\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa2Ffields\x83EphaseGparentsHrevisionInoderange\x82\x81T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:\x82T\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11DnameMchangesetdata
  s> makefile('rb', None)
  s>     HTTP/1.1 200 OK\r\n
  s>     Server: testing stub value\r\n
  s>     Date: $HTTP_DATE$\r\n
  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
  s>     Transfer-Encoding: chunked\r\n
  s>     \r\n
  s>     13\r\n
  s>     \x0b\x00\x00\x01\x00\x02\x011
  s>     \xa1FstatusBok
  s>     \r\n
  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
  s>     239\r\n
  s>     1\x02\x00\x01\x00\x02\x001
  s>     \xa1Jtotalitems\x03\xa2DnodeT3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:EphaseFpublic\xa4DnodeTu\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1Gparents\x82T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00EphaseFpublicLrevisionsize\x18?X?7f144aea0ba742713887b564d57e9d12f12ff382\n
  s>     test\n
  s>     0 0\n
  s>     a\n
  s>     b\n
  s>     \n
  s>     commit 1\xa4DnodeT\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xddGparents\x82Tu\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00EphaseFpublicLrevisionsize\x18=X=37f0a2d1c28ffe4b879109a7d1bbf8f07b3c763b\n
  s>     test\n
  s>     0 0\n
  s>     b\n
  s>     \n
  s>     commit 2\xa4DnodeT\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11Gparents\x82T3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00EphaseEdraftLrevisionsize\x18=X=1b74476799ec8318045db759b1b4bcc9b839d0aa\n
  s>     test\n
  s>     0 0\n
  s>     a\n
  s>     \n
  s>     commit 3
  s>     \r\n
  received frame(size=561; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
  s>     8\r\n
  s>     \x00\x00\x00\x01\x00\x02\x002
  s>     \r\n
  s>     0\r\n
  s>     \r\n
  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
  response: gen[
    {
      b'totalitems': 3
    },
    {
      b'node': b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:',
      b'phase': b'public'
    },
    {
      b'node': b'u\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1',
      b'parents': [
        b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ],
      b'phase': b'public',
      b'revisionsize': 63
    },
    b'7f144aea0ba742713887b564d57e9d12f12ff382\ntest\n0 0\na\nb\n\ncommit 1',
    {
      b'node': b'\x0b\xb8\xad\x89J\x15\xb1S\x80\xb2\xa2\xa5\xb1\x83\xe2\x0f*K(\xdd',
      b'parents': [
        b'u\x92\x91~\x1c>\x82g|\xb0\xa4\xbcq\\\xa2]\xd1-(\xc1',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ],
      b'phase': b'public',
      b'revisionsize': 61
    },
    b'37f0a2d1c28ffe4b879109a7d1bbf8f07b3c763b\ntest\n0 0\nb\n\ncommit 2',
    {
      b'node': b'\xea\xe5\xf8,.b#h\xd2}\xae\xcbv\xb7\xe3\x93\xd0\xf2B\x11',
      b'parents': [
        b'3\x90\xef\x85\x00s\xfb\xc2\xf0\xdf\xff"D4,\x8e\x92)\x01:',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ],
      b'phase': b'draft',
      b'revisionsize': 61
    },
    b'1b74476799ec8318045db759b1b4bcc9b839d0aa\ntest\n0 0\na\n\ncommit 3'
  ]

  $ cat error.log