Workaround for "SAS Message Log" dialog

close_sas_message_log.py

#
# Purpose:
# Close the "SAS Message Log" dialog caused by the logging message 
# "ODBC: COMMIT performed on connection #" because this hangs the SAS process,
# so control is not turned back over to SJS.
#
# Requirement:
# Python version 3
#
# By:
# Andrew Ziem, January 2019
#
#
# See article https://heuristicandrew.blogspot.com/2019/01/sas-message-log-with-odbc-commit.html
#
# Some code thanks to https://gist.github.com/inaz2/6f72f18af15c47ab7432
#


import os
import ctypes
import logging
import time
from ctypes import CFUNCTYPE, POINTER, c_bool, c_int, cdll, create_unicode_buffer

# ctypes functions
EnumWindows = cdll.user32.EnumWindows
EnumWindowsProc = CFUNCTYPE(c_bool, POINTER(c_int), POINTER(c_int))
GetWindowText = cdll.user32.GetWindowTextW
GetWindowTextLength = cdll.user32.GetWindowTextLengthW
IsWindowVisible = cdll.user32.IsWindowVisible
SendMessage = ctypes.windll.user32.SendMessageW

# constant
WM_CLOSE = 0x0010
TARGET_WINDOW_NAME = 'SAS Message Log'
POLLING_FREQUENCY_IN_SECONDS = 30

# environment setup
logging.basicConfig(format='%(asctime)s %(message)s', level=logging.DEBUG)


def get_mutex_fn():
    """Return the filename of them mutex"""
    import tempfile
    return os.path.join(tempfile.gettempdir(), 'close_sas_message_log_mutex')


def is_other_process_running():
    """Is there another process like this?"""
    if not os.path.exists(get_mutex_fn()):
        return False
    file_mtime = os.stat(get_mutex_fn()).st_mtime
    file_age_seconds = time.time() - file_mtime


def update_mutex():
    """Let other processes know this process is alive"""
    logging.debug('Touching mutex: %s', get_mutex_fn())
    from pathlib import Path
    Path(get_mutex_fn()).touch()


def print_last_error(rc, ctx):
    """Print last Windows error, if there was an error"""
    if not rc == 0:
        return
    last_error_code = ctypes.GetLastError()
    last_err_msg = ctypes.FormatError(last_error_code)
    print('error %s in %s: %s' % (last_error_code, ctx, last_err_msg))


def enum_func(hwnd, lParam):
    """Callback function for enumerating windows"""
    if IsWindowVisible(hwnd):
        length = GetWindowTextLength(hwnd)
        buff = create_unicode_buffer(length + 1)
        GetWindowText(hwnd, buff, length + 1)
        if buff.value:
            if buff.value == TARGET_WINDOW_NAME:
                logging.warning('Closing window with title "%s"', buff.value)
                SendMessage(hwnd, WM_CLOSE, 0, 0)
    # True means to keep enumerating
    return True


def loop():
    """The main loop to keep checking for the window to close"""
    if is_other_process_running():
        logger.error('Another detected because of mutex: %s', get_mutex_fn())
        return
    while True:
        logging.debug('Enumerating titles of active windows')
        rc = EnumWindows(EnumWindowsProc(enum_func), 0)
        print_last_error(rc, 'EnumWindows')
        update_mutex()
        logging.info('Sleeping for %s seconds' % POLLING_FREQUENCY_IN_SECONDS)
        time.sleep(POLLING_FREQUENCY_IN_SECONDS)

try:
    loop()
except KeyboardInterrupt:
    logging.warning('Keyboard interrupt detected, so deleting mutex')
    os.remove(get_mutex_fn())