Need a method to close/unlock the database about py-leveldb HOT 5 OPEN

The implementation might be tricky. I release the Python GIL for all DB 
operations, so a naive implementation might close the database in the middle of 
an operation.

Not releasing it serializes DB operations, so you can add the necessary 
safeguards.

One idea I had to add a close() operation, was basically to set a flag, and 
then do a wait until all running DB operations are done. In the interim you 
would disallow all new DB operations.

If it helps I do keep track of objects referencing the main DB object (e.g. 
snapshots and iterators), which is easy to expose.

If it helps, my problem is that I want to have multiple processes accessing the 
same database. Obviously I need to serialize their access, but there's no way 
(I can see) to get the first process to give up the db and let other processes 
use it.

Ok, I think I understand.

The pattern I describe is the simplest approach I've found so far. You just 
need to keep track of the count all live objects and live operations. A number 
which, when zero, indicates that it is safe to close the DB.

close() would then block until that number reaches zero, and then close the DB. 
Perhaps a timeout would also be in order?

(I'm open to other ideas)

Hi, is there any further progress on the `close` feature?

Thanks.

Unfortunately, no. Because of the threading issues, I felt the implementation 
would be complicated, and was a bit reluctant to pursue it.

Note that there is a very good and active fork at 
https://github.com/rjpower/py-leveldb, and a not so active (mine) at 
https://github.com/arnimarj/py-leveldb