Cancel all operations

[groue]

Can we add a cancelAllOperations() method?

Currently, this conflicts with the fact that the perform methods prefer running in the current task:

// AsyncQueues 0.3.0

let queue = AsyncQueue()
await queue.perform {
  // In the same task as the caller
}

For cancelAllOperations() to work, we'd need to run those operations in a distinct task:

// With hypothetic support for cancelling all operations

let queue = AsyncQueue()
await queue.perform {
  // Must be in a distinct task than the caller
  // so that we can cancel this operation.
}

This would be a breaking change:

let queue = AsyncQueue()

await queue.perform {
  // Would not cancel the same task
  withUnsafeCurrentTask { currentTask in
    currentTask?.cancel()
  }
}

cc @mattmassicotte - in case you'd have hindsights about the differences between running in the current task vs. a new top-level Task created from the current task, and why one could prefer one or the other.

[groue]

What are the observable differences between code executed in current task vs. a new top-level Task?