[rd debugger] fix showing breakpoint dialog, IJPL-213298

1. Fix data race when collection breakpoints to show and adding a new one.
2. Make the dialog showing only when the initial breakpoint is ready to be shown.

^IJPL-213298 fixed

GitOrigin-RevId: 1508b08883fab72dc96de0e5d14ecba95f153801

Author: cypok

platform/xdebugger-impl/frontend/src/com/intellij/platform/debugger/impl/frontend/FrontendXBreakpointManager.kt

@@ -128,6 +128,7 @@ class FrontendXBreakpointManager(private val project: Project, private val cs: C
 
   /**
    * Waits for breakpoint creation from [XBreakpointEvent.BreakpointAdded] event from backend.
+   * Returns `null` in case of timeout.
    *
    * [addBreakpoint] is not called in parallel, to have only one source of truth and avoid races.
    */
@@ -385,9 +386,10 @@ class FrontendXBreakpointManager(private val project: Project, private val cs: C
 }
 
 /**
- * Searches element with [search] or suspends until the element appears.
+ * Searches an element with [search] or suspends until the element appears.
  * Uses [updateFlow] as a trigger for updates.
- * [updateFlow] must be a flow with replay
+ * [updateFlow] must be a flow with replay.
+ * Returns `null` in case of timeout.
  */
 internal suspend fun <T> findOrAwaitElement(
   updateFlow: Flow<*>,

platform/xdebugger-impl/src/com/intellij/xdebugger/impl/breakpoints/ui/BreakpointsDialog.java

@@ -102,6 +102,11 @@ protected BreakpointsDialog(@NotNull Project project,
 
     collectGroupingRules();
 
+    // First subscribe, then collect — we shouldn't skip any changes.
+    myBreakpointManager.subscribeOnBreakpointsChanges(myListenerDisposable, () -> {
+      myRebuildAlarm.cancelAndRequest();
+      return Unit.INSTANCE;
+    });
     collectItems();
 
     setTitle(XDebuggerBundle.message("xbreakpoints.dialog.title"));
@@ -355,11 +360,6 @@ public void actionPerformed(@NotNull AnActionEvent e) {
 
     initSelection(myBreakpointItems);
 
-    myBreakpointManager.subscribeOnBreakpointsChanges(myListenerDisposable, () -> {
-      myRebuildAlarm.cancelAndRequest();
-      return Unit.INSTANCE;
-    });
-
     return decoratorPanel;
   }
 

platform/xdebugger-impl/src/com/intellij/xdebugger/impl/breakpoints/ui/BreakpointsDialogFactory.kt

@@ -3,6 +3,7 @@ package com.intellij.xdebugger.impl.breakpoints.ui
 
 
 import com.intellij.idea.AppMode
+import com.intellij.openapi.application.EDT
 import com.intellij.openapi.components.Service
 import com.intellij.openapi.components.service
 import com.intellij.openapi.project.Project
@@ -17,13 +18,17 @@ import com.intellij.xdebugger.impl.breakpoints.XBreakpointBase
 import com.intellij.xdebugger.impl.breakpoints.XBreakpointProxy
 import com.intellij.xdebugger.impl.frame.XDebugManagerProxy
 import com.intellij.xdebugger.impl.rpc.XBreakpointId
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import org.jetbrains.annotations.ApiStatus
 import org.jetbrains.annotations.VisibleForTesting
 
 
 @Service(Service.Level.PROJECT)
 @ApiStatus.Internal
-class BreakpointsDialogFactory(private val project: Project) {
+class BreakpointsDialogFactory(private val project: Project, private val scope: CoroutineScope) {
   private var balloonToHide: Balloon? = null
   private var breakpointFromBalloon: Any? = null
 
@@ -64,6 +69,22 @@ class BreakpointsDialogFactory(private val project: Project) {
 
   @ApiStatus.Internal
   fun showDialogImpl(initialBreakpoint: XBreakpointId?) {
+    if (initialBreakpoint == null) {
+      showDialogImplImmediately(initialBreakpoint)
+      return
+    }
+
+    scope.launch {
+      XDebugManagerProxy.getInstance()
+        .getBreakpointManagerProxy(project)
+        .awaitBreakpointCreation(initialBreakpoint)
+      withContext(Dispatchers.EDT) {
+        showDialogImplImmediately(initialBreakpoint)
+      }
+    }
+  }
+
+  private fun showDialogImplImmediately(initialBreakpoint: XBreakpointId?) {
     if (selectInDialogShowing(initialBreakpoint)) return
 
     val breakpointManager = XDebugManagerProxy.getInstance().getBreakpointManagerProxy(project)