Overview

1. Ilias quiz
2. Summary:
   • Futures
   • Promises
3. Exercises

Summary

Futures:

• Computation runs without blocking rest of the program
• Completion invokes callback functions

Promises:

• Generalization of futures
• Placeholder for a value that can be set at any time
• Setting invokes callback functions
• Instantiate futures as promises: completion of computation sets promise’s value

Exercise: Promises without locks: concurrency bugs?

• In the implementation of promises, we use locks to prevent concurrency bugs
• Your task: assuming we don’t use locks, find and describe such a concurrency bug scenario

Exercise: Events

• Promises can be further generalized to events
• An event can be fired, invoking any “listening” callback functions
• Firing an event can happen multiple times
• Your tasks:
  • Implement events in Go
  • Modify the promise implementation from the lecture as a specialization of your event implementation