def find_highest_oeis_id():
"""Find the highest entry ID in the remote OEIS database by performing HTTP queries and doing a binary search."""
SLEEP_AFTER_FAILURE = 5.0
success_id = 263000 # We know a-priori that this entry exists.
failure_id = 1000000 # We know a-priori that this entry does not exist.
# Do a binary search, looking for the success/failure boundary.
while success_id + 1 != failure_id:
fetch_id = (success_id + failure_id) // 2
logger.info("OEIS search range is ({}, {}), attempting to fetch entry {} ...".format(success_id, failure_id, fetch_id))
try:
fetch_remote_oeis_entry(fetch_id, fetch_bfile_flag = False)
except BadOeisResponse:
# This exception happens when trying to read beyond the last entry in the database.
# We mark the failure and continue the binary search.
logging.info("OEIS entry {} does not exist.".format(fetch_id))
failure_id = fetch_id
except BaseException as exception:
# Some other error occurred. We have to retry.
logger.error("Unexpected fetch result ({}), retrying in {} seconds.".format(exception, SLEEP_AFTER_FAILURE))
time.sleep(SLEEP_AFTER_FAILURE)
else:
# We mark the success and continue the binary search.
logging.info("OEIS entry {} exists.".format(fetch_id))
success_id = fetch_id
logger.info("Last valid OEIS entry is A{:06}.".format(success_id))
return success_id
def find_highest_oeis_id():
"""Find the highest entry ID in the remote OEIS database by performing HTTP queries and doing a binary search."""
SLEEP_AFTER_FAILURE = 5.0
success_id = 263000 # We know a-priori that this entry exists.
failure_id = 1000000 # We know a-priori that this entry does not exist.
# Do a binary search, looking for the success/failure boundary.
while success_id + 1 != failure_id:
fetch_id = (success_id + failure_id) // 2
logger.info(
"OEIS search range is ({}, {}), attempting to fetch entry {} ...".
format(success_id, failure_id, fetch_id))
try:
fetch_remote_oeis_entry(fetch_id, fetch_bfile_flag=False)
except BadOeisResponse:
# This exception happens when trying to read beyond the last entry in the database.
# We mark the failure and continue the binary search.
logging.info("OEIS entry {} does not exist.".format(fetch_id))
failure_id = fetch_id
except BaseException as exception:
# Some other error occurred. We have to retry.
logger.error(
"Unexpected fetch result ({}), retrying in {} seconds.".format(
exception, SLEEP_AFTER_FAILURE))
time.sleep(SLEEP_AFTER_FAILURE)
else:
# We mark the success and continue the binary search.
logging.info("OEIS entry {} exists.".format(fetch_id))
success_id = fetch_id
logger.info("Last valid OEIS entry is A{:06}.".format(success_id))
return success_id
def safe_fetch_remote_oeis_entry(entry):
"""Fetch a single OEIS entry from the remote OEIS database, and swallow any exceptions.
If no issues are encountered, this function is identical to the 'fetch_remote_oeis_entry' function.
In case of an exception, a log message is generated and 'None' is returned.
The purpose of this function in to be used in a "map", where we want to inhibit exceptions.
"""
# Intercepts and reports any exceptions.
# In case of an exception, a log message is generated, and None is returned.
try:
result = fetch_remote_oeis_entry(entry, True)
except BaseException as exception:
logger.error("Unable to fetch entry {}: '{}'.".format(entry, exception))
result = None
return result
def safe_fetch_remote_oeis_entry(entry):
"""Fetch a single OEIS entry from the remote OEIS database, and swallow any exceptions.
If no issues are encountered, this function is identical to the 'fetch_remote_oeis_entry' function.
In case of an exception, a log message is generated and 'None' is returned.
The purpose of this function in to be used in a "map", where we want to inhibit exceptions.
"""
# Intercepts and reports any exceptions.
# In case of an exception, a log message is generated, and None is returned.
try:
result = fetch_remote_oeis_entry(entry, True)
except BaseException as exception:
logger.error("Unable to fetch entry {}: '{}'.".format(
entry, exception))
result = None
return result
