Race condition in DefaultLockManager

[MarkCiliaVincenti]

Hi,

There is a race condition in the DefaultLockManager.

Scenario:

• thread A tries to lock on "123". It does not exist so it is created in the dictionary
• thread B tries to lock on "123". It exists and is currently locked by A, so it waits for A to finish.
• thread A finishes and removes the lock from the dictionary. Thread B enters the lock.
• thread C tries to lock on "123". It does not exist in the dictionary since thread A removed it, therefore it will start processing concurrently to thread B for the same key "123".

I am the author of https://github.com/MarkCiliaVincenti/AsyncKeyedLock and can help you implement the necessary changes. The library would also help you reduce memory allocations by pooling instances of SemaphoreSlim.

[vposd]

Thank you for noticing.
In the upcoming versions, I have removed the lock manager abstraction to simplify the library. If locking is necessary, it can easily be implemented using ICacheStore or strategy abstractions.