Python pip.compat 模块，total_seconds() 实例源码

def datetime2timestamp(dt, convert_to_utc=False):
    """ Converts a datetime object to UNIX timestamp in milliseconds. """
    if isinstance(dt, datetime.datetime):
        if convert_to_utc:  # ?????UTC??
            dt = dt + datetime.timedelta(hours=-8)  # ??????
        timestamp = total_seconds(dt - EPOCH)
        return long(timestamp)
    return dt

def pip_version_check(session):
    """Check for an update for pip.

    Limit the frequency of checks to once per week. State is stored either in
    the active virtualenv or in the user's USER_CACHE_DIR keyed off the prefix
    of the pip script path.
    """
    import pip  # imported here to prevent circular imports
    pypi_version = None

    try:
        state = load_selfcheck_statefile()

        current_time = datetime.datetime.utcnow()
        # Determine if we need to refresh the state
        if "last_check" in state.state and "pypi_version" in state.state:
            last_check = datetime.datetime.strptime(
                state.state["last_check"],
                SELFCHECK_DATE_FMT
            )
            if total_seconds(current_time - last_check) < 7 * 24 * 60 * 60:
                pypi_version = state.state["pypi_version"]

        # Refresh the version if we need to or just see if we need to warn
        if pypi_version is None:
            resp = session.get(
                PyPI.pip_json_url,
                headers={"Accept": "application/json"},
            )
            resp.raise_for_status()
            pypi_version = resp.json()["info"]["version"]

            # save that we've performed a check
            state.save(pypi_version, current_time)

        pip_version = pkg_resources.parse_version(pip.__version__)

        # Determine if our pypi_version is older
        if pip_version < pkg_resources.parse_version(pypi_version):
            logger.warning(
                "You are using pip version %s, however version %s is "
                "available.\nYou should consider upgrading via the "
                "'pip install --upgrade pip' command." % (pip.__version__,
                                                          pypi_version)
            )

    except Exception:
        logger.debug(
            "There was an error checking the latest version of pip",
            exc_info=True,
        )