Concurrency primitives

• concurrent composition of futures
  • c.f., sequential composition with await, composition of tasks with spawn
  • concurrent/task behaviour
  • behaviour on error
• streams as alternative, forward ref
• different versions in different runtimes/other crates
  • focus on the Tokio versions

From comment: A framing I've started using is that tasks are not the async/await form of threads; it's more accurate to think of them as parallelizable futures. This framing does not match Tokio and async-std's current task design; but both also have trouble propagating cancellation. See parallel_future and tasks are the wrong abstraction for more.

Join

• Tokio/futures-rs join macro
• c.f., joining tasks
• join in futures-concurrency
• FuturesUnordered
  • like a dynamic version of join
  • forward ref to stream

Race/select

• Tokio select macro
• cancellation issues
• different behaviour of futures-rs version
• race in futures-concurrency