Fix flaky ResourceInitialSelectionTest via pipeline scheduling rule

FilteredItemsSelectionDialog's background pipeline has three jobs that
read and write the same ContentProvider state: FilterHistoryJob mutates
it via contentProvider.reset() and contentProvider.addHistoryItems(),
FilterJob populates it via contentProvider.add() (inside
fillContentProvider), and RefreshCacheJob reads it in
contentProvider.reloadCache(). Without a shared scheduling rule they can
run concurrently on different worker threads.

Under the right timing, FilterHistoryJob.contentProvider.reset() clears
the items set on one worker while FilterJob is iterating members() and
adding items on another - wiping some or all of the populated items
before the table is rendered. This manifested as the long-standing
ResourceInitialSelectionTest flake (issue #294): sometimes the table was
empty, sometimes a random subset of items survived in the wrong order.

The race is reliably triggered by the ModifyListener on the pattern Text
firing applyFilter() twice in quick succession during createDialogArea
on slow runners, which schedules two FilterHistoryJobs that overlap with
the FilterJob.

Fix: share a per-dialog ISchedulingRule across filterHistoryJob,
filterJob and refreshCacheJob. They now serialize; the race cannot
occur. Separate dialogs still run in parallel.

Also expose JOB_FAMILY (@noreference) and tag all four pipeline jobs
with it, so tests can deterministically wait for the pipeline via
Job.getJobManager().find(JOB_FAMILY). The item-count stability probe in
ResourceInitialSelectionTest.waitForDialogRefresh() is replaced with
that family-based wait - this also gets rid of the unreliable 5 s
timeout that was the visible symptom.

Fixes #294

Author: vogella

bundles/org.eclipse.ui.workbench/.settings/.api_filters

@@ -1,5 +1,13 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <component id="org.eclipse.ui.workbench" version="2">
+    <resource path="eclipseui/org/eclipse/ui/dialogs/FilteredItemsSelectionDialog.java" type="org.eclipse.ui.dialogs.FilteredItemsSelectionDialog">
+        <filter id="336658481">
+            <message_arguments>
+                <message_argument value="org.eclipse.ui.dialogs.FilteredItemsSelectionDialog"/>
+                <message_argument value="JOB_FAMILY"/>
+            </message_arguments>
+        </filter>
+    </resource>
     <resource path="eclipseui/org/eclipse/ui/dialogs/YesNoCancelListSelectionDialog.java" type="org.eclipse.ui.dialogs.YesNoCancelListSelectionDialog">
         <filter id="576778288">
             <message_arguments>

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/dialogs/FilteredItemsSelectionDialog.java

@@ -50,6 +50,7 @@
 import org.eclipse.core.runtime.ProgressMonitorWrapper;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.SubMonitor;
+import org.eclipse.core.runtime.jobs.ISchedulingRule;
 import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.jface.action.Action;
 import org.eclipse.jface.action.ActionContributionItem;
@@ -236,6 +237,17 @@ public abstract class FilteredItemsSelectionDialog extends SelectionStatusDialog
 	 */
 	private boolean isShownForTheFirstTime = true;
 
+	/**
+	 * Job family under which all background filtering and refresh jobs of this
+	 * dialog are grouped. Tests may use this with
+	 * {@link org.eclipse.core.runtime.jobs.IJobManager#join(Object, org.eclipse.core.runtime.IProgressMonitor)}
+	 * to deterministically wait for the filter/refresh pipeline to settle.
+	 *
+	 * @noreference This field is not intended to be referenced by clients.
+	 * @since 3.138
+	 */
+	public static final Object JOB_FAMILY = new Object();
+
 	/**
 	 * Creates a new instance of the class.
 	 *
@@ -250,10 +262,36 @@ public FilteredItemsSelectionDialog(Shell shell, boolean multi) {
 		filterJob = new FilterJob();
 		contentProvider = new ContentProvider();
 		refreshCacheJob = new RefreshCacheJob();
+		// All three jobs mutate / read the same ContentProvider state (items,
+		// duplicates, lastFilteredItems, ...). Without a common scheduling rule
+		// they can run concurrently on different worker threads, racing
+		// FilterHistoryJob.contentProvider.reset() against FilterJob's
+		// fillContentProvider() and silently emptying or corrupting the visible
+		// items. The rule is per-dialog, so separate dialogs still run in
+		// parallel.
+		ISchedulingRule pipelineRule = new ContentProviderSerialRule();
+		filterHistoryJob.setRule(pipelineRule);
+		filterJob.setRule(pipelineRule);
+		refreshCacheJob.setRule(pipelineRule);
 		itemsListSeparator = new ItemsListSeparator(WorkbenchMessages.FilteredItemsSelectionDialog_separatorLabel);
 		selectionMode = NONE;
 	}
 
+	/**
+	 * Per-dialog mutex rule used to serialize the filter/refresh pipeline jobs.
+	 */
+	private static final class ContentProviderSerialRule implements ISchedulingRule {
+		@Override
+		public boolean contains(ISchedulingRule rule) {
+			return rule == this;
+		}
+
+		@Override
+		public boolean isConflicting(ISchedulingRule rule) {
+			return rule == this;
+		}
+	}
+
 	/**
 	 * Creates a new instance of the class. Created dialog won't allow to select
 	 * more than one item.
@@ -1315,6 +1353,11 @@ public IStatus runInUIThread(IProgressMonitor monitor) {
 			return new Status(IStatus.OK, PlatformUI.PLUGIN_ID, IStatus.OK, EMPTY_STRING, null);
 		}
 
+		@Override
+		public boolean belongsTo(Object family) {
+			return family == JOB_FAMILY;
+		}
+
 	}
 
 	/**
@@ -1420,6 +1463,11 @@ protected void canceling() {
 			contentProvider.stopReloadingCache();
 		}
 
+		@Override
+		public boolean belongsTo(Object family) {
+			return family == JOB_FAMILY;
+		}
+
 	}
 
 	private class RemoveHistoryItemAction extends Action {
@@ -1854,6 +1902,11 @@ protected IStatus run(IProgressMonitor monitor) {
 			return Status.OK_STATUS;
 		}
 
+		@Override
+		public boolean belongsTo(Object family) {
+			return family == JOB_FAMILY;
+		}
+
 	}
 
 	/**
@@ -1977,6 +2030,11 @@ protected void filterContent(GranualProgressMonitor monitor) throws CoreExceptio
 
 		}
 
+		@Override
+		public boolean belongsTo(Object family) {
+			return family == JOB_FAMILY;
+		}
+
 	}
 
 	/**

tests/org.eclipse.ui.tests/Eclipse UI Tests/org/eclipse/ui/tests/dialogs/ResourceInitialSelectionTest.java

@@ -38,6 +38,7 @@
 import org.eclipse.swt.widgets.Table;
 import org.eclipse.swt.widgets.TableItem;
 import org.eclipse.ui.PlatformUI;
+import org.eclipse.ui.dialogs.FilteredItemsSelectionDialog;
 import org.eclipse.ui.dialogs.FilteredResourcesSelectionDialog;
 import org.eclipse.ui.internal.decorators.DecoratorManager;
 import org.eclipse.ui.tests.harness.util.DisplayHelper;
@@ -125,8 +126,11 @@ public void testSingleSelectionAndOneInitialNonExistingSelectionWithInitialPatte
 		dialog.open();
 		dialog.refresh();
 
-		// Don't wait for full refresh - this test checks that invalid initial
-		// selections don't cause a selection before dialog is fully loaded
+		// Intentionally no waitForDialogRefresh: this asserts that during
+		// initial load, the dialog does not pre-select anything for an
+		// invalid initial element. After the refresh pipeline drains the
+		// dialog falls back to selecting row 0, which is a separate
+		// behavior not under test here.
 
 		List<Object> selected = getSelectedItems(dialog);
 
@@ -167,8 +171,10 @@ public void testSingleSelectionAndOneFilteredSelection() {
 		dialog.open();
 		dialog.refresh();
 
-		// Don't wait for full refresh - this test checks that filtered initial
-		// selections don't cause a selection before dialog is fully loaded
+		// Intentionally no waitForDialogRefresh: foofoo is filtered out by
+		// the *.txt pattern, so during initial load nothing is selected.
+		// After the refresh pipeline drains the dialog falls back to row 0,
+		// which is a separate behavior not under test here.
 
 		List<Object> selected = getSelectedItems(dialog);
 
@@ -274,8 +280,11 @@ public void testMultiSelectionAndTwoInitialNonExistingSelectionWithInitialPatter
 		dialog.open();
 		dialog.refresh();
 
-		// Don't wait for full refresh - this test checks that invalid initial
-		// selections don't cause a selection before dialog is fully loaded
+		// Intentionally no waitForDialogRefresh: this asserts that during
+		// initial load, the dialog does not pre-select anything for invalid
+		// initial elements. After the refresh pipeline drains the dialog
+		// falls back to selecting row 0, which is a separate behavior not
+		// under test here.
 
 		List<Object> selected = getSelectedItems(dialog);
 
@@ -448,37 +457,21 @@ private void processUIEvents() {
 	}
 
 	/**
-	 * Wait for dialog refresh jobs to complete and process UI events.
-	 * This ensures background jobs finish before assertions are made.
+	 * Wait for the dialog's background filter/refresh jobs to complete.
+	 * <p>
+	 * The dialog schedules a chain of jobs on open/refresh:
+	 * {@code FilterHistoryJob → FilterJob → RefreshCacheJob → RefreshJob}. All
+	 * four are tagged with {@link FilteredItemsSelectionDialog#JOB_FAMILY}, so
+	 * we wait for that family to drain. The 30 s ceiling is a deadlock guard;
+	 * the pipeline usually completes within a few hundred milliseconds.
 	 */
 	private void waitForDialogRefresh() {
 		Display display = PlatformUI.getWorkbench().getDisplay();
-
-		// The dialog performs async operations (FilterHistoryJob → FilterJob →
-		// RefreshCacheJob → RefreshJob) to filter and populate the table after refresh()
-		// We need to wait for the table item count to stabilize before checking
-		// selection state. The count can temporarily be non-zero after the history
-		// refresh, then change again when FilterJob populates actual results.
-		// Selection is applied only in the final refresh, so we must wait for
-		// stability rather than just for any non-zero count.
-		int[] lastCount = { -1 };
-		DisplayHelper.waitForCondition(display, 5000, () -> {
+		DisplayHelper.waitForCondition(display, 30_000L, () -> {
 			processUIEvents();
-			try {
-				Table table = (Table) ((Composite) ((Composite) ((Composite) dialog.getShell().getChildren()[0])
-						.getChildren()[0]).getChildren()[0]).getChildren()[3];
-				int count = table.getItemCount();
-				if (count > 0 && count == lastCount[0]) {
-					return true; // stable non-zero count: all refreshes have completed
-				}
-				lastCount[0] = count;
-				return false;
-			} catch (Exception e) {
-				return false;
-			}
+			return Job.getJobManager().find(FilteredItemsSelectionDialog.JOB_FAMILY).length == 0;
 		});
-
-		// Final event loop processing to pick up any trailing async tasks
+		// Final event loop processing to pick up any trailing asyncExecs.
 		processUIEvents();
 	}