Key-based mutex

[jcornaz]

Draft:

class KeyBasedMutex<in K>(size: Int) {

  private val mutexes = List(size) { Mutex() }

  init {
    require(size > 0)
  }

  suspend fun lock(key: K) {
    mutexes[key.hashCode() % mutexes.size].lock()
  }

  fun unlock(key: K) {
    mutexes[key.hashCode() % mutexes.size].unlock()
  }
}

suspend inline fun <K, R> KeyBasedMutex<K>.withLock(key: K, block: () -> R): R {
  lock(key)
  return try {
    block()
  } finally {
    unlock(key)
  }
}