annotate mercurial/testing/__init__.py @ 47804:5ad37164a8fe stable

testing: make sure write_file is "atomic"

This make sure viewer cannot see the new file with partial content.

This was likely the cause of some flakiness in `test-nointerrupt.t`

Differential Revision: https://phab.mercurial-scm.org/D11250

from __future__ import (
    absolute_import,
    division,
)

import os
import time


# work around check-code complains
#
# This is a simple log level module doing simple test related work, we can't
# import more things, and we do not need it.
environ = getattr(os, 'environ')


def _timeout_factor():
    """return the current modification to timeout"""
    default = int(environ.get('HGTEST_TIMEOUT_DEFAULT', 360))
    current = int(environ.get('HGTEST_TIMEOUT', default))
    if current == 0:
        return 1
    return current / float(default)


def wait_file(path, timeout=10):
    timeout *= _timeout_factor()
    start = time.time()
    while not os.path.exists(path):
        if timeout and time.time() - start > timeout:
            raise RuntimeError(b"timed out waiting for file: %s" % path)
        time.sleep(0.01)


def write_file(path, content=b''):
    if content:
        write_path = b'%s.tmp' % path
    else:
        write_path = path
    with open(write_path, 'wb') as f:
        f.write(content)
    if path != write_path:
        os.rename(write_path, path)