Files
GoogleDriveManagement/src/controlflow.py
2020-01-28 07:06:42 -06:00

66 lines
2.3 KiB
Python

"""Methods related to the central control flow of an application."""
import random
import sys
import time
import display # TODO: Change to relative import when gam is setup as a package
from var import MESSAGE_HEADER_NOT_FOUND_IN_CSV_HEADERS
from var import MESSAGE_INVALID_JSON
def system_error_exit(return_code, message):
"""Raises a system exit with the given return code and message.
Args:
return_code: Int, the return code to yield when the system exits.
message: An error message to print before the system exits.
"""
if message:
display.print_error(message)
sys.exit(return_code)
def csv_field_error_exit(field_name, field_names):
"""Raises a system exit when a CSV field is malformed.
Args:
field_name: The CSV field name for which a header does not exist in the
existing CSV headers.
field_names: The known list of CSV headers.
"""
system_error_exit(
2,
MESSAGE_HEADER_NOT_FOUND_IN_CSV_HEADERS.format(field_name,
','.join(field_names)))
def invalid_json_exit(file_name):
"""Raises a sysyem exit when invalid JSON content is encountered."""
system_error_exit(17, MESSAGE_INVALID_JSON.format(file_name))
def wait_on_failure(current_attempt_num,
total_num_retries,
error_message,
error_print_threshold=3):
"""Executes an exponential backoff-style system sleep.
Args:
current_attempt_num: Int, the current number of retries.
total_num_retries: Int, the total number of times the current action will be
retried.
error_message: String, a message to be displayed that will give more context
around why the action is being retried.
error_print_threshold: Int, the number of attempts which will have their
error messages suppressed. Any current_attempt_num greater than
error_print_threshold will print the prescribed error.
"""
wait_on_fail = min(2**current_attempt_num,
60) + float(random.randint(1, 1000)) / 1000
if current_attempt_num > error_print_threshold:
sys.stderr.write((f'Temporary error: {error_message}, Backing off: '
f'{int(wait_on_fail)} seconds, Retry: '
f'{current_attempt_num}/{total_num_retries}\n'))
sys.stderr.flush()
time.sleep(wait_on_fail)