Get the full path to the pid file for the given process type and name.

def get_pidpath(rundir, process_type, name=None):
    """
    Get the full path to the pid file for the given process type and name.
    """
    assert rundir, "rundir is not configured"
    path = os.path.join(rundir, '%s.pid' % process_type)
    if name:
        path = os.path.join(rundir, '%s.%s.pid' % (process_type, name))
    log.log('common', 'get_pidpath for type %s, name %r: %s'
            % (process_type, name, path))
    return path