SafeLaunch.kt

42 lines · 1.9 KB

Changed in: 0.5.0

1	package dev.stave.ui
2
3	import androidx.lifecycle.ViewModel
4	import androidx.lifecycle.viewModelScope
5	import kotlinx.coroutines.CoroutineExceptionHandler
6	import kotlinx.coroutines.CoroutineScope
7	import kotlinx.coroutines.Job
8	import kotlinx.coroutines.launch
9
10	/**
11	* Coroutine exception handler shared by every ViewModel.launch site.
12	*
13	* Without this, uncaught exceptions from viewModelScope.launch bubble up to the JVM
14	* default handler, which Compose Desktop / Swing surfaces as an opaque "Error"
15	* dialog showing only the exception message — e.g. `index: 57, size: 57` after a
16	* right-click → Play Next, with no stack trace and no way to recover gracefully.
17	*
18	* Logging here means the same exception becomes a stderr stack trace
19	* (recoverable from `./gradlew :desktop:run` output or a shell-launched packaged
20	* install) and the user keeps playing music. The app remains responsive.
21	*
22	* Note: This swallows the exception by handling it — viewModelScope's
23	* SupervisorJob doesn't cancel siblings, so other launches continue normally.
24	*/
25	private val viewModelExceptionHandler = CoroutineExceptionHandler { _, throwable ->
26	System.err.println(
27	"[Earhorn] ViewModel coroutine threw (${throwable.javaClass.simpleName}):"
28	)
29	throwable.printStackTrace(System.err)
30	}
31
32	/**
33	* Like viewModelScope.launch, but installs [viewModelExceptionHandler] so an
34	* unexpected throw becomes a logged stack trace rather than an error dialog.
35	*
36	* Use for any coroutine triggered by a user action (right-click handlers,
37	* button clicks, menu items, drag callbacks, etc). Long-running collection
38	* jobs (state flows, lifecycle observers) can also use this; the handler
39	* only fires on actually-uncaught exceptions.
40	*/
41	fun ViewModel.safeLaunch(block: suspend CoroutineScope.() -> Unit): Job =
42	viewModelScope.launch(viewModelExceptionHandler, block = block)