Summary

We have now seen an end-to-end example of how asynchronous Rust works. Rust’s async/await feature is backed by traits. This allows third-party crates, like Tokio, to provide the execution details.

• Asynchronous Rust operation are lazy and require a caller to poll them.
• Wakers are passed to futures to link a future to the task calling it.
• When a resource is not ready to complete an operation, Poll::Pending is returned and the task’s waker is recorded.
• When the resource becomes ready, the task’s waker is notified.
• The executor receives the notification and schedules the task to execute.
• The task is polled again, this time the resource is ready and the task makes progress.