Current Non-Blocking Behavior

• Promise
  • Blocks on read
  • Uses CountDownLatch
  • Calls .await on deref, no timeout
• Delay
  • Blocks on read if value is not cached
  • Read with force or deref
• Future
  • Blocks on read if computation not finished
  • future-done?
  • deref calls .get
  • Implements java.util.concurrent.Future
    • .get
    • .get with timeout
    • .isCancelled
    • .isDone
    • .cancel
• Agents
  • Reads never block
  • await (no timeout) and await-for (timeout)
    • Uses CountDownLatch
• Vars, Atoms, and Refs
  • Reads never block

Summary of Current Behavior

Which types have blocking reads?

What are the APIs?

Proposed New API

• await
  • block until all args are done, don't care about return value
• await-for
  • same with timeout
• deref
  • generic read, may block depending on type
• deref-for
  • same with timeout
• done?
  • true if deref/await on this object will NOT block
• cancel
  • on a Future
    • calls cancel
  • on an Agent
    • abort current action
    • clear action queue
    • further action sends throw an Exception
  • on a Promise
    • causes deliver to throw an Exception
  • on a Delay
    • clears cached value, future reads will throw an Exception
• cancelled?
  • true if this object has been cancelled

Deprecated Type-Specific Functions

• force
• future-done?
• future-cancel