view tests/test-wireproto-command-filesdata.t @ 44118:f81c17ec303c

hgdemandimport: apply lazy module loading to sys.meta_path finders

Python's `sys.meta_path` finders are the primary objects whose job it
is to find a module at import time. When `import` is called, Python
iterates objects in this list and calls `o.find_spec(...)` to find
a `ModuleSpec` (or None if the module couldn't be found by that
finder). If no meta path finder can find a module, import fails.

One of the default meta path finders is `PathFinder`. Its job is to
import modules from the filesystem and is probably the most important
importer. This finder looks at `sys.path` and `sys.path_hooks` to do
its job.

The `ModuleSpec` returned by `MetaPathImporter.find_spec()` has a
`loader` attribute, which defines the concrete module loader to use.
`sys.path_hooks` is a hook point for teaching `PathFinder` to
instantiate custom loader types.

Previously, we injected a custom `sys.path_hook` that told `PathFinder`
to wrap the default loaders with a loader that creates a module object
that is lazy.

This approach worked. But its main limitation was that it only applied
to the `PathFinder` meta path importer. There are other meta path
importers that are registered. And in the case of PyOxidizer loading
modules from memory, `PathFinder` doesn't come into play since
PyOxidizer's own meta path importer was handling all imports.

This commit changes our approach to lazy module loading by proxying
all meta path importers. Specifically, we overload the `find_spec()`
method to swap in a wrapped loader on the `ModuleSpec` before it
is returned. The end result of this is all meta path importers should
be lazy.

As much as I would have loved to utilize .__class__ manipulation to
achieve this, some meta path importers are implemented in C/Rust
in such a way that they cannot be monkeypatched. This is why we
use __getattribute__ to define a proxy.

Also, this change could theoretically open us up to regressions in
meta path importers whose loader is creating module objects which
can't be monkeypatched. But I'm not aware of any of these in the
wild. So I think we'll be safe.

According to hyperfine, this change yields a decent startup time win of
5-6ms:

```
Benchmark #1: ~/.pyenv/versions/3.6.10/bin/python ./hg version
  Time (mean ± σ):      86.8 ms ±   0.5 ms    [User: 78.0 ms, System: 8.7 ms]
  Range (min … max):    86.0 ms …  89.1 ms    50 runs

  Time (mean ± σ):      81.1 ms ±   2.7 ms    [User: 74.5 ms, System: 6.5 ms]
  Range (min … max):    77.8 ms …  90.5 ms    50 runs

Benchmark #2: ~/.pyenv/versions/3.7.6/bin/python ./hg version
  Time (mean ± σ):      78.9 ms ±   0.6 ms    [User: 70.2 ms, System: 8.7 ms]
  Range (min … max):    78.1 ms …  81.2 ms    50 runs

  Time (mean ± σ):      73.4 ms ±   0.6 ms    [User: 65.3 ms, System: 8.0 ms]
  Range (min … max):    72.4 ms …  75.7 ms    50 runs

Benchmark #3: ~/.pyenv/versions/3.8.1/bin/python ./hg version
  Time (mean ± σ):      78.1 ms ±   0.6 ms    [User: 70.2 ms, System: 7.9 ms]
  Range (min … max):    77.4 ms …  80.9 ms    50 runs

  Time (mean ± σ):      72.1 ms ±   0.4 ms    [User: 64.4 ms, System: 7.6 ms]
  Range (min … max):    71.4 ms …  74.1 ms    50 runs
```

Differential Revision: https://phab.mercurial-scm.org/D7954

  $ . $TESTDIR/wireprotohelpers.sh

  $ hg init server
  $ enablehttpv2 server
  $ cd server
  $ cat > a << EOF
  > a0
  > 00000000000000000000000000000000000000
  > 11111111111111111111111111111111111111
  > EOF
  $ cat > b << EOF
  > b0
  > aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  > bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
  > EOF
  $ mkdir -p dir0/child0 dir0/child1 dir1
  $ echo c0 > dir0/c
  $ echo d0 > dir0/d
  $ echo e0 > dir0/child0/e
  $ echo f0 > dir0/child1/f
  $ hg -q commit -A -m 'commit 0'

  $ echo a1 >> a
  $ echo d1 > dir0/d
  $ echo g0 > g
  $ echo h0 > h
  $ hg -q commit -A -m 'commit 1'
  $ echo f1 > dir0/child1/f
  $ echo i0 > dir0/i
  $ hg -q commit -A -m 'commit 2'

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

Create multiple heads introducing the same file nodefile node

  $ hg -q up -r 0
  $ echo foo > dupe-file
  $ hg commit -Am 'dupe 1'
  adding dupe-file
  created new head
  $ hg -q up -r 0
  $ echo foo > dupe-file
  $ hg commit -Am 'dupe 2'
  adding dupe-file
  created new head

  $ hg log -G -T '{rev}:{node} {desc}\n'
  @  5:47fc30580911232cb264675b402819deddf6c6f0 dupe 2
  |
  | o  4:b16cce2967c1749ef4f4e3086a806cfbad8a3af7 dupe 1
  |/
  | o  3:476fbf122cd82f6726f0191ff146f67140946abc commit 3
  |/
  | o  2:b91c03cbba3519ab149b6cd0a0afbdb5cf1b5c8a commit 2
  | |
  | o  1:5b0b1a23577e205ea240e39c9704e28d7697cbd8 commit 1
  |/
  o  0:6e875ff18c227659ad6143bb3580c65700734884 commit 0
  

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

Missing arguments is an error

  $ sendhttpv2peer << EOF
  > command filesdata
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  abort: missing required arguments: revisions!
  [255]

Bad pattern to pathfilter is rejected

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >          b'type': b'changesetexplicit',
  >          b'nodes': [
  >              b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >          ]}]
  >     pathfilter eval:{b'include': [b'bad:foo']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  abort: include pattern must begin with `path:` or `rootfilesin:`; got bad:foo!
  [255]

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     pathfilter eval:{b'exclude': [b'glob:foo']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  abort: exclude pattern must begin with `path:` or `rootfilesin:`; got glob:foo!
  [255]

Fetching a single changeset without parents fetches all files

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 8,
      b'totalpaths': 8
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2'
    },
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01'
    },
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4'
    },
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 1
    },
    {
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4'
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    }
  ]

Fetching a single changeset saying parents data is available fetches just new files

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     haveparents eval:True
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 4,
      b'totalpaths': 4
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    }
  ]

A path filter for a sub-directory is honored

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     haveparents eval:True
  >     pathfilter eval:{b'include': [b'path:dir0']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 1,
      b'totalpaths': 1
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    }
  ]

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     haveparents eval:True
  >     pathfilter eval:{b'exclude': [b'path:a', b'path:g']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 2,
      b'totalpaths': 2
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    }
  ]

Requesting multiple changeset nodes without haveparents sends all data for both

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >             b'\xb9\x1c\x03\xcb\xba\x35\x19\xab\x14\x9b\x6c\xd0\xa0\xaf\xbd\xb5\xcf\x1b\x5c\x8a',
  >         ]}]
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 10,
      b'totalpaths': 9
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2'
    },
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01'
    },
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4'
    },
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 2
    },
    {
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4'
    },
    {
      b'node': b'(\xc7v\xae\x08\xd0\xd5^\xb4\x06H\xb4\x01\xb9\x0f\xf5DH4\x8e'
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    {
      b'path': b'dir0/i',
      b'totalitems': 1
    },
    {
      b'node': b'\xd7t\xb5\x80Jq\xfd1\xe1\xae\x05\xea\x8e2\xdd\x9b\xa3\xd8S\xd7'
    },
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    }
  ]

Requesting multiple changeset nodes with haveparents sends incremental data for both

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >             b'\xb9\x1c\x03\xcb\xba\x35\x19\xab\x14\x9b\x6c\xd0\xa0\xaf\xbd\xb5\xcf\x1b\x5c\x8a',
  >         ]}]
  >     haveparents eval:True
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 6,
      b'totalpaths': 6
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 1
    },
    {
      b'node': b'(\xc7v\xae\x08\xd0\xd5^\xb4\x06H\xb4\x01\xb9\x0f\xf5DH4\x8e'
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    {
      b'path': b'dir0/i',
      b'totalitems': 1
    },
    {
      b'node': b'\xd7t\xb5\x80Jq\xfd1\xe1\xae\x05\xea\x8e2\xdd\x9b\xa3\xd8S\xd7'
    },
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    }
  ]

Requesting parents works

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     fields eval:[b'parents']
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 8,
      b'totalpaths': 8
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11',
      b'parents': [
        b'd\x9d\x14\x9d\xf4=\x83\x88%#\xb7\xfb\x1ej:\xf6\xf1\x90{9',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 1
    },
    {
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G',
      b'parents': [
        b'S\x82\x06\xdc\x97\x1eR\x15@\xd6\x84:\xbf\xe6\xd1`2\xf6\xd4&',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K',
      b'parents': [
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
      ]
    }
  ]

Requesting revision data works
(haveparents defaults to False, so fulltext is emitted)

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     fields eval:[b'revision']
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 8,
      b'totalpaths': 8
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          84
        ]
      ],
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    b'a0\n00000000000000000000000000000000000000\n11111111111111111111111111111111111111\na1\n',
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          81
        ]
      ],
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2'
    },
    b'b0\naaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\nbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\n',
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01'
    },
    b'c0\n',
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4'
    },
    b'e0\n',
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4'
    },
    b'f0\n',
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    b'd1\n',
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    b'g0\n',
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    },
    b'h0\n'
  ]

haveparents=False should be same as above

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     fields eval:[b'revision']
  >     haveparents eval:False
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 8,
      b'totalpaths': 8
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          84
        ]
      ],
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    b'a0\n00000000000000000000000000000000000000\n11111111111111111111111111111111111111\na1\n',
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          81
        ]
      ],
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2'
    },
    b'b0\naaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\nbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\n',
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01'
    },
    b'c0\n',
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4'
    },
    b'e0\n',
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4'
    },
    b'f0\n',
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    b'd1\n',
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    b'g0\n',
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    },
    b'h0\n'
  ]

haveparents=True should emit a delta

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >         ]}]
  >     fields eval:[b'revision']
  >     haveparents eval:True
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 4,
      b'totalpaths': 4
    },
    {
      b'path': b'a',
      b'totalitems': 1
    },
    {
      b'deltabasenode': b'd\x9d\x14\x9d\xf4=\x83\x88%#\xb7\xfb\x1ej:\xf6\xf1\x90{9',
      b'fieldsfollowing': [
        [
          b'delta',
          15
        ]
      ],
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    b'\x00\x00\x00Q\x00\x00\x00Q\x00\x00\x00\x03a1\n',
    {
      b'path': b'dir0/d',
      b'totalitems': 1
    },
    {
      b'deltabasenode': b'S\x82\x06\xdc\x97\x1eR\x15@\xd6\x84:\xbf\xe6\xd1`2\xf6\xd4&',
      b'fieldsfollowing': [
        [
          b'delta',
          15
        ]
      ],
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    b'\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x03d1\n',
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    b'g0\n',
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    },
    b'h0\n'
  ]

Requesting multiple revisions works
(first revision is a fulltext since haveparents=False by default)

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x6e\x87\x5f\xf1\x8c\x22\x76\x59\xad\x61\x43\xbb\x35\x80\xc6\x57\x00\x73\x48\x84',
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >             b'\xb9\x1c\x03\xcb\xba\x35\x19\xab\x14\x9b\x6c\xd0\xa0\xaf\xbd\xb5\xcf\x1b\x5c\x8a',
  >         ]}]
  >     fields eval:[b'revision']
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 12,
      b'totalpaths': 9
    },
    {
      b'path': b'a',
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          81
        ]
      ],
      b'node': b'd\x9d\x14\x9d\xf4=\x83\x88%#\xb7\xfb\x1ej:\xf6\xf1\x90{9'
    },
    b'a0\n00000000000000000000000000000000000000\n11111111111111111111111111111111111111\n',
    {
      b'deltabasenode': b'd\x9d\x14\x9d\xf4=\x83\x88%#\xb7\xfb\x1ej:\xf6\xf1\x90{9',
      b'fieldsfollowing': [
        [
          b'delta',
          15
        ]
      ],
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    b'\x00\x00\x00Q\x00\x00\x00Q\x00\x00\x00\x03a1\n',
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          81
        ]
      ],
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2'
    },
    b'b0\naaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\nbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\n',
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01'
    },
    b'c0\n',
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4'
    },
    b'e0\n',
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4'
    },
    b'f0\n',
    {
      b'deltabasenode': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4',
      b'fieldsfollowing': [
        [
          b'delta',
          15
        ]
      ],
      b'node': b'(\xc7v\xae\x08\xd0\xd5^\xb4\x06H\xb4\x01\xb9\x0f\xf5DH4\x8e'
    },
    b'\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x03f1\n',
    {
      b'path': b'dir0/d',
      b'totalitems': 2
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'S\x82\x06\xdc\x97\x1eR\x15@\xd6\x84:\xbf\xe6\xd1`2\xf6\xd4&'
    },
    b'd0\n',
    {
      b'deltabasenode': b'S\x82\x06\xdc\x97\x1eR\x15@\xd6\x84:\xbf\xe6\xd1`2\xf6\xd4&',
      b'fieldsfollowing': [
        [
          b'delta',
          15
        ]
      ],
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    b'\x00\x00\x00\x00\x00\x00\x00\x03\x00\x00\x00\x03d1\n',
    {
      b'path': b'dir0/i',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xd7t\xb5\x80Jq\xfd1\xe1\xae\x05\xea\x8e2\xdd\x9b\xa3\xd8S\xd7'
    },
    b'i0\n',
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    b'g0\n',
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'fieldsfollowing': [
        [
          b'revision',
          3
        ]
      ],
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    },
    b'h0\n'
  ]

Requesting linknode field works

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x6e\x87\x5f\xf1\x8c\x22\x76\x59\xad\x61\x43\xbb\x35\x80\xc6\x57\x00\x73\x48\x84',
  >             b'\x5b\x0b\x1a\x23\x57\x7e\x20\x5e\xa2\x40\xe3\x9c\x97\x04\xe2\x8d\x76\x97\xcb\xd8',
  >             b'\xb9\x1c\x03\xcb\xba\x35\x19\xab\x14\x9b\x6c\xd0\xa0\xaf\xbd\xb5\xcf\x1b\x5c\x8a',
  >         ]}]
  >     fields eval:[b'linknode']
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 12,
      b'totalpaths': 9
    },
    {
      b'path': b'a',
      b'totalitems': 2
    },
    {
      b'linknode': b'n\x87_\xf1\x8c"vY\xadaC\xbb5\x80\xc6W\x00sH\x84',
      b'node': b'd\x9d\x14\x9d\xf4=\x83\x88%#\xb7\xfb\x1ej:\xf6\xf1\x90{9'
    },
    {
      b'linknode': b'[\x0b\x1a#W~ ^\xa2@\xe3\x9c\x97\x04\xe2\x8dv\x97\xcb\xd8',
      b'node': b'\n\x862\x1f\x13y\xd1\xa9\xec\xd0W\x9a"\x97z\xf7\xa5\xac\xaf\x11'
    },
    {
      b'path': b'b',
      b'totalitems': 1
    },
    {
      b'linknode': b'n\x87_\xf1\x8c"vY\xadaC\xbb5\x80\xc6W\x00sH\x84',
      b'node': b'\x88\xbac\xb8\xd8\xc6 :\xc6z\xc9\x98\xac\xd9\x17K\xf7\x05!\xb2'
    },
    {
      b'path': b'dir0/c',
      b'totalitems': 1
    },
    {
      b'linknode': b'n\x87_\xf1\x8c"vY\xadaC\xbb5\x80\xc6W\x00sH\x84',
      b'node': b'\x91DE4j\x0c\xa0b\x9b\xd4|\xeb]\xfe\x07\xe4\xd4\xcf%\x01'
    },
    {
      b'path': b'dir0/child0/e',
      b'totalitems': 1
    },
    {
      b'linknode': b'n\x87_\xf1\x8c"vY\xadaC\xbb5\x80\xc6W\x00sH\x84',
      b'node': b'\xbb\xbal\x06\xb3\x0fD=4\xff\x84\x1b\xc9\x85\xc4\xd0\x82|k\xe4'
    },
    {
      b'path': b'dir0/child1/f',
      b'totalitems': 2
    },
    {
      b'linknode': b'n\x87_\xf1\x8c"vY\xadaC\xbb5\x80\xc6W\x00sH\x84',
      b'node': b'\x12\xfc}\xcdw;Z\n\x92\x9c\xe1\x95"\x80\x83\xc6\xdd\xc9\xce\xc4'
    },
    {
      b'linknode': b'\xb9\x1c\x03\xcb\xba5\x19\xab\x14\x9bl\xd0\xa0\xaf\xbd\xb5\xcf\x1b\\\x8a',
      b'node': b'(\xc7v\xae\x08\xd0\xd5^\xb4\x06H\xb4\x01\xb9\x0f\xf5DH4\x8e'
    },
    {
      b'path': b'dir0/d',
      b'totalitems': 2
    },
    {
      b'linknode': b'n\x87_\xf1\x8c"vY\xadaC\xbb5\x80\xc6W\x00sH\x84',
      b'node': b'S\x82\x06\xdc\x97\x1eR\x15@\xd6\x84:\xbf\xe6\xd1`2\xf6\xd4&'
    },
    {
      b'linknode': b'[\x0b\x1a#W~ ^\xa2@\xe3\x9c\x97\x04\xe2\x8dv\x97\xcb\xd8',
      b'node': b'\x93\x88)\xad\x01R}2\xba\x06_\x81#6\xfe\xc7\x9d\xdd9G'
    },
    {
      b'path': b'dir0/i',
      b'totalitems': 1
    },
    {
      b'linknode': b'\xb9\x1c\x03\xcb\xba5\x19\xab\x14\x9bl\xd0\xa0\xaf\xbd\xb5\xcf\x1b\\\x8a',
      b'node': b'\xd7t\xb5\x80Jq\xfd1\xe1\xae\x05\xea\x8e2\xdd\x9b\xa3\xd8S\xd7'
    },
    {
      b'path': b'g',
      b'totalitems': 1
    },
    {
      b'linknode': b'[\x0b\x1a#W~ ^\xa2@\xe3\x9c\x97\x04\xe2\x8dv\x97\xcb\xd8',
      b'node': b'\xde\xca\xba5DFjI\x95r\xe9\x0f\xac\xe6\xfa\x0c!k\xba\x8c'
    },
    {
      b'path': b'h',
      b'totalitems': 1
    },
    {
      b'linknode': b'[\x0b\x1a#W~ ^\xa2@\xe3\x9c\x97\x04\xe2\x8dv\x97\xcb\xd8',
      b'node': b'\x03A\xfc\x84\x1b\xb5\xb4\xba\x93\xb2mM\xdaa\xf7y6]\xb3K'
    }
  ]

Test behavior where a file node is introduced in 2 DAG heads

Request for changeset introducing filenode returns linknode as self

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\xb1\x6c\xce\x29\x67\xc1\x74\x9e\xf4\xf4\xe3\x08\x6a\x80\x6c\xfb\xad\x8a\x3a\xf7',
  >         ]}]
  >     fields eval:[b'linknode']
  >     pathfilter eval:{b'include': [b'path:dupe-file']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 1,
      b'totalpaths': 1
    },
    {
      b'path': b'dupe-file',
      b'totalitems': 1
    },
    {
      b'linknode': b'\xb1l\xce)g\xc1t\x9e\xf4\xf4\xe3\x08j\x80l\xfb\xad\x8a:\xf7',
      b'node': b'.\xd2\xa3\x91*\x0b$P C\xea\xe8N\xe4\xb2y\xc1\x8b\x90\xdd'
    }
  ]

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\xb1\x6c\xce\x29\x67\xc1\x74\x9e\xf4\xf4\xe3\x08\x6a\x80\x6c\xfb\xad\x8a\x3a\xf7',
  >         ]}]
  >     fields eval:[b'linknode']
  >     haveparents eval:True
  >     pathfilter eval:{b'include': [b'path:dupe-file']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 1,
      b'totalpaths': 1
    },
    {
      b'path': b'dupe-file',
      b'totalitems': 1
    },
    {
      b'linknode': b'\xb1l\xce)g\xc1t\x9e\xf4\xf4\xe3\x08j\x80l\xfb\xad\x8a:\xf7',
      b'node': b'.\xd2\xa3\x91*\x0b$P C\xea\xe8N\xe4\xb2y\xc1\x8b\x90\xdd'
    }
  ]

Request for changeset where recorded linknode isn't in DAG ancestry will get
rewritten accordingly

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x47\xfc\x30\x58\x09\x11\x23\x2c\xb2\x64\x67\x5b\x40\x28\x19\xde\xdd\xf6\xc6\xf0',
  >         ]}]
  >     fields eval:[b'linknode']
  >     pathfilter eval:{b'include': [b'path:dupe-file']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 1,
      b'totalpaths': 1
    },
    {
      b'path': b'dupe-file',
      b'totalitems': 1
    },
    {
      b'linknode': b'G\xfc0X\t\x11#,\xb2dg[@(\x19\xde\xdd\xf6\xc6\xf0',
      b'node': b'.\xd2\xa3\x91*\x0b$P C\xea\xe8N\xe4\xb2y\xc1\x8b\x90\xdd'
    }
  ]

  $ sendhttpv2peer << EOF
  > command filesdata
  >     revisions eval:[{
  >         b'type': b'changesetexplicit',
  >         b'nodes': [
  >             b'\x47\xfc\x30\x58\x09\x11\x23\x2c\xb2\x64\x67\x5b\x40\x28\x19\xde\xdd\xf6\xc6\xf0',
  >         ]}]
  >     fields eval:[b'linknode']
  >     haveparents eval:True
  >     pathfilter eval:{b'include': [b'path:dupe-file']}
  > EOF
  creating http peer for wire protocol version 2
  sending filesdata command
  response: gen[
    {
      b'totalitems': 1,
      b'totalpaths': 1
    },
    {
      b'path': b'dupe-file',
      b'totalitems': 1
    },
    {
      b'linknode': b'G\xfc0X\t\x11#,\xb2dg[@(\x19\xde\xdd\xf6\xc6\xf0',
      b'node': b'.\xd2\xa3\x91*\x0b$P C\xea\xe8N\xe4\xb2y\xc1\x8b\x90\xdd'
    }
  ]

  $ cat error.log