outgoing: rework the handling of the `missingroots` case to be faster
The previous implementation was slow, to the point it was taking a significant
amount of `hg bundle --type none-streamv2` call. We rework the code to compute
the same value much faster, making the operation disappear from the `hg bundle
--type none-streamv2` profile. Someone would remark that producing a streamclone
does not requires an `outgoing` object. However that is a matter for another
day. There is other user of `missingroots` (non stream `hg bundle` call for
example), and they will also benefit from this rework.
We implement an old TODO in the process, directly computing the missing and
common attribute as we have most element at hand already.
### benchmark.name = hg.command.bundle
# bin-env-vars.hg.flavor = default
# bin-env-vars.hg.py-re2-module = default
# benchmark.variants.revs = all
# benchmark.variants.type = none-streamv2
## data-env-vars.name = heptapod-public-2024-03-25-zstd-sparse-revlog
before: 7.750458
after: 6.665565 (-14.00%, -1.08)
## data-env-vars.name = mercurial-public-2024-03-22-zstd-sparse-revlog
before: 0.700229
after: 0.496050 (-29.16%, -0.20)
## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog
before: 346.508952
after: 316.749699 (-8.59%, -29.76)
## data-env-vars.name = pypy-2024-03-22-zstd-sparse-revlog
before: 3.401700
after: 2.915810 (-14.28%, -0.49)
## data-env-vars.name = tryton-public-2024-03-22-zstd-sparse-revlog
before: 1.870798
after: 1.461583 (-21.87%, -0.41)
note: this whole `missingroots` of outgoing has a limited number of callers and
could likely be replace by something simpler (like taking an explicit
"missing_revs" set for example). However this is a wider change and we focus on
a small impact, quick rework that does not change the API for now.
Tests if hgweb can run without touching sys.stdin, as is required
by the WSGI standard and strictly implemented by mod_wsgi.
$ hg init repo
$ cd repo
$ echo foo > bar
$ hg add bar
$ hg commit -m "test"
$ cat > request.py <<EOF
> import os
> import sys
> from mercurial import (
> dispatch,
> encoding,
> hg,
> ui as uimod,
> util,
> )
> from mercurial.utils import (
> procutil,
> )
> ui = uimod.ui
> from mercurial.hgweb import hgweb_mod
> stringio = util.stringio
>
> class FileLike(object):
> def __init__(self, real):
> self.real = real
> def fileno(self):
> print >> sys.__stdout__, 'FILENO'
> return self.real.fileno()
> def read(self):
> print >> sys.__stdout__, 'READ'
> return self.real.read()
> def readline(self):
> print >> sys.__stdout__, 'READLINE'
> return self.real.readline()
>
> sys.stdin = FileLike(sys.stdin)
> errors = stringio()
> input = stringio()
> output = stringio()
>
> def startrsp(status, headers):
> print('---- STATUS')
> print(status)
> print('---- HEADERS')
> print([i for i in headers if i[0] != 'ETag'])
> print('---- DATA')
> return output.write
>
> env = {
> 'wsgi.version': (1, 0),
> 'wsgi.url_scheme': 'http',
> 'wsgi.errors': errors,
> 'wsgi.input': input,
> 'wsgi.multithread': False,
> 'wsgi.multiprocess': False,
> 'wsgi.run_once': False,
> 'REQUEST_METHOD': 'GET',
> 'SCRIPT_NAME': '',
> 'PATH_INFO': '',
> 'QUERY_STRING': '',
> 'SERVER_NAME': '$LOCALIP',
> 'SERVER_PORT': os.environ['HGPORT'],
> 'SERVER_PROTOCOL': 'HTTP/1.0'
> }
>
> i = hgweb_mod.hgweb(b'.')
> for c in i(env, startrsp):
> pass
> sys.stdout.flush()
> procutil.stdout.write(b'---- ERRORS\n')
> procutil.stdout.write(b'%s\n' % errors.getvalue())
> print('---- OS.ENVIRON wsgi variables')
> print(sorted([x for x in os.environ if x.startswith('wsgi')]))
> print('---- request.ENVIRON wsgi variables')
> with i._obtainrepo() as repo:
> print(sorted([encoding.strfromlocal(x) for x in repo.ui.environ
> if x.startswith(b'wsgi')]))
> EOF
$ "$PYTHON" request.py
---- STATUS
200 Script output follows
---- HEADERS
[('Content-Type', 'text/html; charset=ascii')]
---- DATA
---- ERRORS
---- OS.ENVIRON wsgi variables
[]
---- request.ENVIRON wsgi variables
['wsgi.errors', 'wsgi.input', 'wsgi.multiprocess', 'wsgi.multithread', 'wsgi.run_once', 'wsgi.url_scheme', 'wsgi.version']
$ cd ..