Blocking token request example

AsyncTokenProvider.kt

internal class AsyncTokenProvider : Runnable {
    val lock = ReentrantLock()
    val requestCondition = lock.newCondition()
    var done = false

    interface AsyncTokenListener {
        fun onEvent(foo: String)
    }

    var result: String = "Not Done"

    override fun run() {
        lock.lock()

        Log.d("AsyncTokenProvider", "Starting run")

        try {
            var sum = 1000000000
            while (sum > 0) {
                sum -= 1
                Log.d("AsyncTokenProvider", "Counting down...")
            }
            result = "Done"
            done = true
            requestCondition.signal()
        } finally {
            lock.unlock()
        }
    }

    fun getAccessToken(): String {
        lock.lock()
        try {
            while (!done) {
                Log.d("AsyncTokenProvider", "Waiting...")
                requestCondition.await()
            }

            Log.d("AsyncTokenProvider", "Done, result is $result")
            return result
        } finally {
            lock.unlock()
        }
    }
}

AuthManager.kt

object AuthManager {
    private val asyncTokenProvider = AsyncTokenProvider()

    var accessToken: String? = null
        get() = asyncTokenProvider.getAccessToken()

    fun getTokens() {
        Thread(asyncTokenProvider).start()
    }
}

MainActivity.kt

// in onCreate
Log.d("MainActivity", "onCreate")
AuthManager.getTokens()
val myToken = AuthManager.accessToken
Log.d("MainActivity", "$myToken")