tests/fsmonitor-run-tests.py

localrepo: create new function for instantiating a local repo object

Today, there is a single local repository class - localrepository. Its
__init__ is responsible for loading the .hg/requires file and taking
different actions depending on what is present.

In addition, extensions may define a "reposetup" function that
monkeypatches constructed repository instances, often by implementing
a derived type and changing the __class__ of the repo instance.

Work around alternate storage backends and partial clone has made it
clear to me that shoehorning all this logic into __init__ and operating
on an existing instance is too convoluted. For example, localrepository
assumes revlog storage and swapping in non-revlog storage requires
overriding e.g. file() to return something that isn't a revlog. I've
authored various patches that either:

a) teach various methods (like file()) about different states and
   taking the appropriate code path at run-time
b) create methods/attributes/callables used for instantiating things
   and populating these in __init__

"a" incurs run-time performance penalties and makes code more
complicated since various functions have a bunch of "if storage is X"
branches.

"b" makes localrepository quickly explode in complexity.

My plan for tackling this problem is to make the local repository type
more dynamic. Instead of a static localrepository class/type that
supports all of the local repository configurations (revlogs vs other,
revlogs with ellipsis, revlog v1 versus revlog v2, etc), we'll
dynamically construct a type providing the implementations that are
needed for the repository on disk, derived from the .hg/requires file
and configuration options. The constructed repository type will be
specialized and methods won't need to be taught about different
implementations nor overloaded.

We may also leverage this functionality for building types that don't
implement all attributes. For example, the "intents" feature allows
commands to declare that they are read only. By dynamically
constructing a repository type, we could return a repository instance
with no attributes related to mutating the repository. This could
include things like a "changelog" property implementation that doesn't
check whether it needs to invalidate the hidden revisions set on every
access.

This commit establishes a function for building a local repository
instance. Future commits will start moving functionality from
localrepository.__init__ to this function. Then we'll start dynamically
changing the returned type depending on options that are present.

This change may seem radical. But it should be fully compatible with
the reposetup() model - at least for now.

Differential Revision: https://phab.mercurial-scm.org/D4563

#!/usr/bin/env python

# fsmonitor-run-tests.py - Run Mercurial tests with fsmonitor enabled
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
#
# This is a wrapper around run-tests.py that spins up an isolated instance of
# Watchman and runs the Mercurial tests against it. This ensures that the global
# version of Watchman isn't affected by anything this test does.

from __future__ import absolute_import
from __future__ import print_function

import argparse
import contextlib
import json
import os
import shutil
import subprocess
import sys
import tempfile
import uuid

osenvironb = getattr(os, 'environb', os.environ)

if sys.version_info > (3, 5, 0):
    PYTHON3 = True
    xrange = range # we use xrange in one place, and we'd rather not use range
    def _bytespath(p):
        return p.encode('utf-8')

elif sys.version_info >= (3, 0, 0):
    print('%s is only supported on Python 3.5+ and 2.7, not %s' %
          (sys.argv[0], '.'.join(str(v) for v in sys.version_info[:3])))
    sys.exit(70) # EX_SOFTWARE from `man 3 sysexit`
else:
    PYTHON3 = False

    # In python 2.x, path operations are generally done using
    # bytestrings by default, so we don't have to do any extra
    # fiddling there. We define the wrapper functions anyway just to
    # help keep code consistent between platforms.
    def _bytespath(p):
        return p

def getparser():
    """Obtain the argument parser used by the CLI."""
    parser = argparse.ArgumentParser(
        description='Run tests with fsmonitor enabled.',
        epilog='Unrecognized options are passed to run-tests.py.')
    # - keep these sorted
    # - none of these options should conflict with any in run-tests.py
    parser.add_argument('--keep-fsmonitor-tmpdir', action='store_true',
        help='keep temporary directory with fsmonitor state')
    parser.add_argument('--watchman',
        help='location of watchman binary (default: watchman in PATH)',
        default='watchman')

    return parser

@contextlib.contextmanager
def watchman(args):
    basedir = tempfile.mkdtemp(prefix='hg-fsmonitor')
    try:
        # Much of this configuration is borrowed from Watchman's test harness.
        cfgfile = os.path.join(basedir, 'config.json')
        # TODO: allow setting a config
        with open(cfgfile, 'w') as f:
            f.write(json.dumps({}))

        logfile = os.path.join(basedir, 'log')
        clilogfile = os.path.join(basedir, 'cli-log')
        if os.name == 'nt':
            sockfile = '\\\\.\\pipe\\watchman-test-%s' % uuid.uuid4().hex
        else:
            sockfile = os.path.join(basedir, 'sock')
        pidfile = os.path.join(basedir, 'pid')
        statefile = os.path.join(basedir, 'state')

        argv = [
            args.watchman,
            '--sockname', sockfile,
            '--logfile', logfile,
            '--pidfile', pidfile,
            '--statefile', statefile,
            '--foreground',
            '--log-level=2', # debug logging for watchman
        ]

        envb = osenvironb.copy()
        envb[b'WATCHMAN_CONFIG_FILE'] = _bytespath(cfgfile)
        with open(clilogfile, 'wb') as f:
            proc = subprocess.Popen(
                argv, env=envb, stdin=None, stdout=f, stderr=f)
            try:
                yield sockfile
            finally:
                proc.terminate()
                proc.kill()
    finally:
        if args.keep_fsmonitor_tmpdir:
            print('fsmonitor dir available at %s' % basedir)
        else:
            shutil.rmtree(basedir, ignore_errors=True)

def run():
    parser = getparser()
    args, runtestsargv = parser.parse_known_args()

    with watchman(args) as sockfile:
        osenvironb[b'WATCHMAN_SOCK'] = _bytespath(sockfile)
        # Indicate to hghave that we're running with fsmonitor enabled.
        osenvironb[b'HGFSMONITOR_TESTS'] = b'1'

        runtestdir = os.path.dirname(__file__)
        runtests = os.path.join(runtestdir, 'run-tests.py')
        blacklist = os.path.join(runtestdir, 'blacklists', 'fsmonitor')

        runtestsargv.insert(0, runtests)
        runtestsargv.extend([
            '--extra-config',
            'extensions.fsmonitor=',
            '--blacklist',
            blacklist,
        ])

        return subprocess.call(runtestsargv)

if __name__ == '__main__':
    sys.exit(run())