Dynamolock is a a distributed lock client on top of dynamo written in python. As long as clients use the library and respect the protocol, it provides gurantees that a lock will not be taken unless:
- the lock is explicity unlocked by its owner
- the lock is delete by its owner
- the lock has timed out locally
Furthermore, if any operation interleaves when we determine that we are okay to perform a lock operation and when we actually make that operation, it is prevented by using check-and-set(CAS) on the owner and version number of the lock.
To test if a lock is timed out, the lock in question stores a duration field in dynamo. When a client tries to acquire the lock, it must first wait at least that amount of time locally (now() + duration) before it is allowed to take over the lock. This protocol ensures that work can progress even in the face of failed clients without having to distribute up-status between clients.
For more information, please read the documentation at: https://readthedocs.org/projects/dynamolock/