New project modal: Display logs + Cancel task by ThierryBerger · Pull Request #257 · jbuehler23/jackdaw

ThierryBerger · 2026-05-21T08:14:33Z

based on Add scroll for new project modal #256

wip attempt on improving the new project modal:

makes error enums more specific
have a automatically scrolling log (be able to see if something goes wrong (libssl)
- reusing existing scroll could be made but we'd need to pin it to bottom, I'll consider this out of scope because the component may be reworked to use feathers.
be able to cancel tasks (when cargo generate / when building the project)
- I considered a timeout but coming up with a default is not really possible, a cancel makes more sense (low internet may make that longer, and a long timeout defeats the purpose)
the back button now shows "back" to close the modal, and "Cancel" to cancel the scaffolding/building.

possible follow ups

Consider using the cancelation logic for the modal opening an existing project
Check if the scrolling component is needed / usable elsewhere.

ThierryBerger · 2026-05-21T11:40:22Z

+            // Cooperative cancel: flip the flag the worker polls and
+            // keep the modal open showing "Cancelling…". The poller's
+            // Err(Cancelled) arm will switch the status to
+            // "Cancelled." once the worker unwinds (the worker kills
+            // the child + drainer threads join + final Err returns),
+            // leaving the user free to tweak inputs and retry.


while interesting, not sure implementation details are well served in comments, as it is it's describing the code..

NicoZweifel · 2026-05-21T12:04:32Z

+    let mut cancelled = false;
+    let status = loop {
+        // Don't busy wait (try_wait is non-blocking).
+        std::thread::sleep(Duration::from_millis(50));


https://doc.rust-lang.org/std/hint/fn.spin_loop.html might be a better fit or another way of awaiting/polling without any blocking but I dont think it's a big deal if it works and doesn't potentially deadlock.

I don't think spin_loop is particularly better than a sleep here as we expect the wait to take some time anyway.

That being said, I can see sleep being a problem if we target web ? Any insight about that ?

I dont think it will deadlock on web currently but it might lag. I'm not sure how realistic targeting web is at this stage so not sure we can try it out at this time.

I don't think spin_loop is particularly better than a sleep here as we expect the wait to take some time anyway.

Fair enough, I agree if it doesn't cause issues its fine.

You actually convinced me:

sleep is probably blocking in single thread environment, where tasks have to run on the same thread

not really an issue, but web wouldn't like us using sleep 😅

i don't have plans to support jackdaw on web.....yet

NicoZweifel · 2026-05-21T12:05:21Z

+                        .unwrap_or_default();
+                    return Err(BuildError::Cancelled { stderr_tail: tail });
+                }
+                std::thread::sleep(Duration::from_millis(50));


Same here I guess

let's keep the discussion on #257 (comment) then.

NicoZweifel · 2026-05-21T12:09:40Z


-    // Scaffold.
-    if let Some(task) = state.scaffold_task.as_mut()
-        && let Some(result) = future::block_on(future::poll_once(task))


Might be fine but block_on could also potentially cause deadlocks down the line if called from the main UI thread on Windows/MacOS while requiring the main thread inside the child somewhere (e.g. a popup file dialog)

Here we use poll_once, so we're not really blocking here 🎉

ThierryBerger commented May 21, 2026

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Comment thread src/project_select.rs Outdated

ThierryBerger commented May 21, 2026

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Comment thread src/lib.rs

ThierryBerger commented May 21, 2026

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Comment thread src/scrolling_log.rs

ThierryBerger force-pushed the cancelling_tasks branch 3 times, most recently from a051cf8 to 9a754bd Compare May 21, 2026 09:51

ThierryBerger commented May 21, 2026

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NicoZweifel reviewed May 21, 2026

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ThierryBerger force-pushed the cancelling_tasks branch from 9a754bd to a866fa0 Compare May 21, 2026 12:30

NicoZweifel approved these changes May 22, 2026

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ThierryBerger force-pushed the cancelling_tasks branch from 2bff2a3 to a5ee4a4 Compare May 22, 2026 14:51

ThierryBerger added 7 commits May 22, 2026 16:56

better error enums

c256ced

cancellable tasks + scrolling log

dfdaf00

cancel building

13bbc67

use enum for new project scaffold state

d86de7b

use spin loop

f16b41a

change button label depending on intent

5648abc

remove obvious comments

fa9960b

ThierryBerger force-pushed the cancelling_tasks branch from 0bb2aaa to fa9960b Compare May 22, 2026 14:58

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ThierryBerger commented May 21, 2026 •

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ThierryBerger May 21, 2026 •

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