Distributed
← Reliable asynchronous processing

Lesson 03.7

Progress tracking & cancellation

Cancellation lets a user stop a long-running job; the worker must check for the request, stop at a safe point, and undo or report what it had already done.

Pressing Cancel

Mia orders a photo book. Ava makes it in five steps; printing all 40 pages takes the longest. The computer shows Mia how far along it is.

Then Mia presses Cancel. Pressing it only changes a note on the computer. Does Ava ever look?

In this lesson you'll

  1. 1Watch Ava check for a cancel between steps.
  2. 2Guess what happens if Mia cancels during printing.
  3. 3Make Ava stop quickly, wherever the cancel lands.