tests/dumbhttp.py

changelog: specify checkambig=True to revlog.__init__, to avoid ambiguity

If steps below occurs at "the same time in sec", all of mtime, ctime
and size are same between (1) and (3).

  1. append data to 00changelog.i (and close transaction)
  2. discard appended data by truncation (strip or rollback)
  3. append same size but different data to 00changelog.i again

Therefore, cache validation doesn't work after (3) as expected.

To avoid such file stat ambiguity around truncation, this patch
specifies checkambig=True to revlog.__init__(). This makes revlog
write changes out with checkambig=True.

Even though changes of 00changelog.i themselves are written out at
changelog._finalize(), this checkambig=True is needed, because
revlog.checkinlinesize(), which is invoked at the end of
changelog._finalize(), might replace already changed 00changelog.i by
converted one.

Even after this patch, avoiding file stat ambiguity of 00changelog.i
around truncation isn't yet completed, because truncation side isn't
aware of this issue.

This is a part of ExactCacheValidationPlan.

    https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan

#!/usr/bin/env python

from __future__ import absolute_import

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

import optparse
import signal
import sys

from mercurial import (
    cmdutil,
    util,
)

httpserver = util.httpserver
OptionParser = optparse.OptionParser

class simplehttpservice(object):
    def __init__(self, host, port):
        self.address = (host, port)
    def init(self):
        self.httpd = httpserver.httpserver(
            self.address, httpserver.simplehttprequesthandler)
    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('--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.pid:
        parser.error("options --pid and --foreground are mutually exclusive")

    opts = {'pid_file': options.pid,
            'daemon': not options.foreground,
            'daemon_postexec': options.daemon_postexec}
    service = simplehttpservice(options.host, options.port)
    cmdutil.service(opts, initfn=service.init, runfn=service.run,
                    runargs=[sys.executable, __file__] + sys.argv[1:])