tests/fsmonitor-run-tests.py

localrepo: stop doing special dirstate backup at transaction open

Since the dirstate writes are already managed by the transaction, we already do
a backup of the dirstate when necessary (and even trigger one to keep `hg
rollback` happy).

We needs some special code to deal with the initial empty checkout, but it is
not too complicated.

Managing variable filename (as dirstate-v2 uses) at the "journalfile" level, is
complex and fragile (which is consistent with the fact these files are not
journal…). If we no longer do it, our life is significantly simpler.

In some sense, we apply the xkcd-1134¹ solution to our savebackup/restorebackup
problem.

[1] https://xkcd.com/1134/

(the change to test-hardlink are expect as decreasing the number of duplicated
backup drive the hardlink count down)

#!/usr/bin/env python3

# 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.


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

    def _sys2bytes(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 _sys2bytes(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'] = _sys2bytes(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'] = _sys2bytes(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=',
                # specify fsmonitor.mode=paranoid always in order to force
                # fsmonitor extension execute "paranoid" code path
                #
                # TODO: make fsmonitor-run-tests.py accept specific options
                '--extra-config',
                'fsmonitor.mode=paranoid',
                '--blacklist',
                blacklist,
            ]
        )

        return subprocess.call(runtestsargv)


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