view tests/dumbhttp.py @ 48507:58a3be48ddd2

simplemerge: stop merging file flags

As 384df4db6520 (merge: merge file flags together with file content,
2013-01-09) explains, we shouldn't do a 3-way merge of the
symlink. However, since 84614212ae39 (flags: actually merge flags in
simplemerge, 2020-05-16), we do that in
`simplemerge.simplemerge()`. What's more, the merging of the
executable flag there isn't actually necessary; it was made a no-op by
the very next commit, i.e. 4234c9af515d (flags: read flag from
dirstate/disk for workingcopyctx (issue5743), 2020-05-16).

I found the overall flag-merging code (not the bit in
`simplemerge.py`) very hard to follow, but I think I now finally
understand how it works. `mergestate.resolve()` calculates the merged
file flags and sets them on the local side of the merge (confusingly
by calling `_restore_backup()`). Then it calls
`filemerge.filemerge()`, which in turn calls
`simplemerge.simplemerge()` (if premerge is enabled). That means that
the flags on the local side `fcs.flags()` are already correct when the
flag-merging code in `simplemerge.simplemerge()` runs. Interestingly,
that code still works when the local side already has the merged
value, it just doesn't change the value. Here's a truth table to
explain why:

```
BLOMCAR
0000000
0011111
0101011
0111111
1000000
1010000
1100000
1111101
```

B: Base
L: Local
O: Other
M: Merged flags from `mergestate.resolve()`, i.e. what's called "local"
   when we get to `simplemerge.simplemerge()`
C: `commonflags` in `simplemerge.simplemerge()`, i.e. `M & O`
A: `addedflags` in `simplemerge.simplemerge()`, i.e. `(M ^ O) - B`
R: Re-merged flags `simplemerge.simplemerge()`, i.e. `C | A`

As you can see, the re-merged flags are always unchanged compared to
the initial merged flags (R equals M).

Therefore, this patch effectively backs out 84614212ae39. (I might
later refactor this code to have the flags explicitly passed in.)

`simplemerge.simplemerge()` is also called from
`contrib/simplemerge.py`, but that code never passes any flags.

Differential Revision: https://phab.mercurial-scm.org/D11879

#!/usr/bin/env python

from __future__ import absolute_import

"""
Small and dumb HTTP server for use in tests.
"""

import optparse
import os
import signal
import socket
import sys

from mercurial import (
    encoding,
    pycompat,
    server,
    util,
)

httpserver = util.httpserver
OptionParser = optparse.OptionParser

if os.environ.get('HGIPV6', '0') == '1':

    class simplehttpserver(httpserver.httpserver):
        address_family = socket.AF_INET6


else:
    simplehttpserver = httpserver.httpserver


class _httprequesthandler(httpserver.simplehttprequesthandler):
    def log_message(self, format, *args):
        httpserver.simplehttprequesthandler.log_message(self, format, *args)
        sys.stderr.flush()


class simplehttpservice(object):
    def __init__(self, host, port):
        self.address = (host, port)

    def init(self):
        self.httpd = simplehttpserver(self.address, _httprequesthandler)

    def run(self):
        self.httpd.serve_forever()


if __name__ == '__main__':
    parser = OptionParser()
    parser.add_option(
        '-p',
        '--port',
        dest='port',
        type='int',
        default=8000,
        help='TCP port to listen on',
        metavar='PORT',
    )
    parser.add_option(
        '-H',
        '--host',
        dest='host',
        default='localhost',
        help='hostname or IP to listen on',
        metavar='HOST',
    )
    parser.add_option('--logfile', help='file name of access/error log')
    parser.add_option(
        '--pid',
        dest='pid',
        help='file name where the PID of the server is stored',
    )
    parser.add_option(
        '-f',
        '--foreground',
        dest='foreground',
        action='store_true',
        help='do not start the HTTP server in the background',
    )
    parser.add_option('--daemon-postexec', action='append')

    (options, args) = parser.parse_args()

    signal.signal(signal.SIGTERM, lambda x, y: sys.exit(0))

    if options.foreground and options.logfile:
        parser.error(
            "options --logfile and --foreground are mutually " "exclusive"
        )
    if options.foreground and options.pid:
        parser.error("options --pid and --foreground are mutually exclusive")

    opts = {
        b'pid_file': options.pid,
        b'daemon': not options.foreground,
        b'daemon_postexec': pycompat.rapply(
            encoding.strtolocal, options.daemon_postexec
        ),
    }
    service = simplehttpservice(options.host, options.port)
    runargs = [sys.executable, __file__] + sys.argv[1:]
    runargs = [pycompat.fsencode(a) for a in runargs]
    server.runservice(
        opts,
        initfn=service.init,
        runfn=service.run,
        logfile=options.logfile,
        runargs=runargs,
    )