MongoDB doing find_and_modify, allowing for possible operation failure and auto reconnections. This example shows using find_and_modify to run a counter on a document that may not initially exist.

MongoSafeModify.py

import time
import pymongo
from pymongo import Connection

def safe_modify(col, query, update):
  for attempt in range(5):
		try:
			result = col.find_and_modify(query={'name': 'Andrew'}, 
										 update={"$inc": {"count": 1}}, 
										 upsert=True,		# If document for 'name':'Andrew' not in there, make one. 
										 new=True)			# Return the updated result.
			return result
		except pymongo.errors.OperationFailure:
			return False
		except pymongo.errors.AutoReconnect as _e:
			wait_t = 0.5 * pow(2, attempt)
			time.sleep(wait_t)
	return False

countercol = Connection().counterdb.countercol
#countercol.drop()	# Uncomment once to see it go back to empty and start from count=0
result = safe_modify(countercol, {'name': 'Andrew'}, {"$inc": {"count": 1}})
print(result['count'])