Best Practices for RemoteDatabase in Kotlin (specifically thread-safety)

[tristanradams]

I am currently in the process of trying to convert my Spring Kotlin project to using ArcadeDB for its graph database. In the process of setting things up, I noticed that the RemoteDatabase is not thread safe and that I should produce one per thread.

Here is my rough draft so far of a possible wrapper class (which my application would only have one instance of the wrapper class) I could use to keep things safe:

import com.arcadedb.remote.RemoteDatabase

class RemoteDatabaseThreadProxy(
    private val host: String,
    private val port: Int,
    private val databaseName: String,
    private val username: String,
    private val password: String
) {
    private val remoteDatabaseByThreadName = mutableMapOf<String, RemoteDatabase>()

    fun get(): RemoteDatabase {
        val currentThread = Thread.currentThread()
        return remoteDatabaseByThreadName.getOrPut(currentThread.name) {
            RemoteDatabase(host, port, databaseName, username, password)
        }
    }
}

My main questions are:

• Would this wrapper class be appropriate for getting an instance of RemoteDatabase?
• Is it an "expensive" transaction to fully initialize a RemoteDatabase if many threads are being created?
• Would the approach above cause any memory leaks since I am not expressly closing the RemoteDatabase instances when Threads are closed?

Please let me know if any more context is needed or if I am shooting in the completely wrong direction!

[jstuyts]

You should take a look at ThreadLocal. Using withInitial(...) you can ensure that a remote database is available the first time it is used.