Call SkiaLayerComponent.onComposeInvalidation() only from the event dispatch thread

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/Utils.desktop.kt

@@ -20,6 +20,7 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.IntRect
 import java.awt.Component
+import java.awt.EventQueue
 import java.awt.Rectangle
 import javax.swing.JComponent
 import kotlin.math.ceil
@@ -88,3 +89,16 @@ internal fun JComponent.setTransparent(transparent: Boolean) {
         isOpaque = false
     }
 }
+
+/**
+ * Calls [block] synchronously on the event dispatching thread. If the calling thread is already the
+ * event dispatch thread, simply executes [block]; otherwise schedules [block] to run on event
+ * dispatching thread and waits for it to return.
+ */
+internal fun runOnEDTThread(block: () -> Unit) {
+    if (EventQueue.isDispatchThread()) {
+        block()
+    } else {
+        EventQueue.invokeAndWait(block)
+    }
+}

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.desktop.kt

@@ -24,6 +24,7 @@ import androidx.compose.ui.awt.AwtEventListener
 import androidx.compose.ui.awt.AwtEventListeners
 import androidx.compose.ui.awt.OnlyValidPrimaryMouseButtonFilter
 import androidx.compose.ui.awt.SwingInteropContainer
+import androidx.compose.ui.awt.runOnEDTThread
 import androidx.compose.ui.focus.FocusDirection
 import androidx.compose.ui.focus.FocusManager
 import androidx.compose.ui.geometry.Offset
@@ -492,9 +493,11 @@ internal class ComposeSceneMediator(
         }
     }
 
-    fun onComposeInvalidation() = catchExceptions {
-        if (isDisposed) return
-        skiaLayerComponent.onComposeInvalidation()
+    fun onComposeInvalidation() = runOnEDTThread {
+        catchExceptions {
+            if (isDisposed) return@catchExceptions
+            skiaLayerComponent.onComposeInvalidation()
+        }
     }
 
     fun onChangeComponentPosition() = catchExceptions {

compose/ui/ui/src/desktopTest/kotlin/androidx/compose/ui/ComposeSceneTest.kt

@@ -48,6 +48,7 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.neverEqualPolicy
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.Snapshot
 import androidx.compose.ui.draw.clipToBounds
 import androidx.compose.ui.draw.drawBehind
 import androidx.compose.ui.focus.FocusRequester
@@ -79,11 +80,17 @@ import androidx.compose.ui.test.junit4.createComposeRule
 import androidx.compose.ui.test.onRoot
 import androidx.compose.ui.test.performKeyPress
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.runApplicationTest
 import com.google.common.truth.Truth.assertThat
 import kotlin.test.assertEquals
+import kotlin.test.assertNull
 import kotlin.test.assertTrue
+import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.withContext
 import org.junit.Assert.assertFalse
 import org.junit.Ignore
 import org.junit.Rule
@@ -638,6 +645,40 @@ class ComposeSceneTest {
         }
     }
 
+    @Test
+    fun stateChangeFromNonUiThreadDoesntCrash() = runApplicationTest {
+        // https://github.com/JetBrains/compose-multiplatform/issues/4546
+        var value by mutableStateOf(0)
+        val done = CompletableDeferred<Unit>()
+        var exceptionThrown: Throwable? = null
+
+        launchTestApplication {
+            Window(onCloseRequest = {}) {
+                Canvas(Modifier.size(100.dp)) {
+                    @Suppress("UNUSED_EXPRESSION")
+                    value
+                }
+                LaunchedEffect(Unit) {
+                    withContext(Dispatchers.IO) {
+                        try {
+                            for (i in 1..50) {
+                                value = i
+                                Snapshot.sendApplyNotifications()
+                                delay(1)
+                            }
+                        } catch (e: Throwable) {
+                            exceptionThrown = e
+                        }
+                        done.complete(Unit)
+                    }
+                }
+            }
+        }
+
+        done.await()
+        assertNull(exceptionThrown, "Exception thrown setting snapshot state from non-UI thread")
+    }
+
     private class TestException : RuntimeException()
 
     @ExperimentalComposeUiApi