Cancel Quick Access compute on dispose to stop orphaned jobs

doDispose() left computeProposalsJob running, so a closed dialog kept
querying providers and lingered in COMPUTE_JOB_FAMILY. The setUp warmup
made this visible: it set "t", waited only for the first results, then
closed the dialog while the lazy providers were still cold-initializing
on the worker. That orphaned job stayed in the family and, on a loaded
macOS runner, could outlive a test's 30 s waitForQuickAccessResults wait,
which waits for the whole family to drain (issue #4009,
testPreviousChoicesAvailableForExtension).

Cancel the compute job in doDispose so a closed dialog stops computing
and leaves the family promptly. Make the warmup wait for results and for
the compute job to drain, so the providers' slow first query finishes in
setUp rather than leaking into a test's timed wait.

Author: vogella

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/quickaccess/QuickAccessContents.java

@@ -644,6 +644,12 @@ protected Pattern getCategoryPattern() {
 	}
 
 	private void doDispose() {
+		// Stop any in-flight compute so a closed dialog neither keeps querying providers
+		// nor leaves a job lingering in COMPUTE_JOB_FAMILY.
+		if (computeProposalsJob != null) {
+			computeProposalsJob.cancel();
+			computeProposalsJob = null;
+		}
 		if (textLayout != null && !textLayout.isDisposed()) {
 			textLayout.dispose();
 		}

tests/org.eclipse.ui.tests/Eclipse UI Tests/org/eclipse/ui/tests/quickaccess/QuickAccessDialogTest.java

@@ -124,7 +124,11 @@ public void setUp() throws Exception {
 			Text warmupText = warmupDialog.getQuickAccessContents().getFilterText();
 			Table warmupTable = warmupDialog.getQuickAccessContents().getTable();
 			warmupText.setText("t");
-			DisplayHelper.waitForCondition(warmupText.getDisplay(), WARMUP_TIMEOUT, () -> warmupTable.getItemCount() > 0);
+			// Wait for results AND for the compute job to drain, so the lazy providers'
+			// slow first query completes here rather than leaking into a test's timed wait.
+			DisplayHelper.waitForCondition(warmupText.getDisplay(), WARMUP_TIMEOUT,
+					() -> warmupTable.getItemCount() > 0
+							&& Job.getJobManager().find(QuickAccessContents.COMPUTE_JOB_FAMILY).length == 0);
 			providersWarmedUp = true;
 		}
 		warmupDialog.close();