In order to be able to use the tree in multi-threading mode (more than one user parallel),
we had to treat the BST itself and is nodes as a resource.
Each operation on the BST will cause lock and release operations.

For this job we used object called “ReaderWriterLockSlim”
more information here – Microsoft documentation

This object, allow us to manage accesses to the resource in a way that Read key is allowed to multiply threads, but Write key is exclusive.
Following the above method, combined with code structure that will shortly describe, we achieved managed synchronization access to the tree resources.

Example of code structure:
The tree has a single “ReaderWriterLockSlim” instance named “CaheLockSlim”.
Each time some function is trying to access tree resource,
we will try to enter the relevant key (remember multiple readers and exclusive write).
After that we will use Try-Finally blocks, which will be used first (try) to make operations on resource and last (finally) release the lock.
We use the Try-Finally approach because finally block runs at any case. This allows us to release lock no matter if some user (thread) fails.

Code examples: