Modes

Depending on your application, you might want ScalaCache to wrap its operations in a Try, a Future, a Scalaz Task, or some other effect container.

Or maybe you want to keep it simple and just return plain old values, performing the operations on the current thread and throwing exceptions in case of failure.

In order to control ScalaCache’s behaviour in this way, you need to choose a “mode”.

ScalaCache comes with a few built-in modes.

Synchronous mode

import scalacache.modes.sync._
  • Blocks the current thread until the operation completes
  • Returns a plain value, not wrapped in any container
  • Throws exceptions in case of failure

Note: If you’re using an in-memory cache (e.g. Guava or Caffeine) then it makes sense to use the synchronous mode. But if you’re communicating with a cache over a network (e.g. Redis, Memcached) then this mode is not recommended. If the network goes down, your app could hang forever!

Try mode

import scalacache.modes.try_._
  • Blocks the current thread until the operation completes
  • Wraps failures in scala.util.Failure

Future mode

import scalacache.modes.scalaFuture._
  • Executes the operation on a separate thread and returns a scala.concurrent.Future

You will also need an ExecutionContext in implicit scope:

import scala.concurrent.ExecutionContext.Implicits.global

cats-effect IO mode

You will need a dependency on the scalacache-cats-effect module:

libraryDependencies += "com.github.cb372" %% "scalacache-cats-effect" % "0.28.0"

import scalacache.Mode
import cats.effect.IO
implicit val mode: Mode[IO] = scalacache.CatsEffect.modes.async
  • Wraps the operation in IO, deferring execution until it is explicitly run

Monix Task (Monix 3.x)

You will need a dependency on the scalacache-cats-effect module:

libraryDependencies += "com.github.cb372" %% "scalacache-cats-effect" % "0.28.0"

import monix.eval.Task
implicit val mode: Mode[Task] = scalacache.CatsEffect.modes.async
  • Wraps the operation in Monix Task, deferring execution until it is explicitly run

Note: There used to a scalacache-monix module but it was removed because it didn’t do very much.

Scalaz Task

You will need a dependency on the scalacache-scalaz72 module:

libraryDependencies += "com.github.cb372" %% "scalacache-scalaz72" % "0.28.0"

import scalacache.Scalaz72.modes._
  • Wraps the operation in Task, deferring execution until it is explicitly run