Is scalacache thread-safe?

[soloman817]

I am using CaffeineCache for local in-memory cache, and I want to achieve this:

• TTL is 10 seconds
• To get a new value, it is a long process, say cost 5 seconds
• Provide a REST service, to retrieve the value, if it is older than 10 seconds, I just want to trigger the refreshing of the new value, but I don't want to wait for the new value, in the mean time, I want to just return the old value instead
• Once the new value is retrieved, I should update the old value

So roughly it is like code here:

    import scalacache._
    import scalacache.caffeine._
    import scalacache.memoization._

    implicit val ec: ExecutionContext = scala.concurrent.ExecutionContext.global
    val l1Cache: Cache[Future[Cat]] = CaffeineCache[Future[Cat]]
    val l2Cache: Cache[Cat] = CaffeineCache[Cat]
    val flags: Flags = Flags.defaultFlags

    def getCat(id: Int) = {
      // to trigger refreshing if necessary
      val l1CacheResult: Future[Cat] = memoizeSync[Future[Cat]](Some(10 seconds)){
        Future {
          Thread.sleep(5000)
          val newCat = Cat(id, s"cat $id", s"${Timestamp.now()}")
          // update l2Cache
          put(id)(newCat)(l2Cache, modes.scalaFuture.mode, flags)
          newCat
        }
      }(l1Cache, modes.sync.mode, flags)

      // get the result from l2Cache
      val l2CacheResult: Try[Option[Cat]] = get(id)(l2Cache, modes.try_.mode, flags)

      l2CacheResult.toString
    }

    while (true) {
      println(s"  ${Timestamp.now()} ${getCat(1)}")
      Thread.sleep(1000)
    }
  }

The point is in the l1Cache future, when the new value is retrieved, I want update the l2Cache, that would be in a background thread, but I read them from another thread, would that be thread-safe?