Bug 574519: Always collect WSL entries in a Job

Change-Id: I35abec7ca075bf525e972e4cbc03af4361d1d490

terminal/plugins/org.eclipse.tm.terminal.view.ui/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.tm.terminal.view.ui;singleton:=true
-Bundle-Version: 4.9.0.qualifier
+Bundle-Version: 4.9.1.qualifier
 Bundle-Activator: org.eclipse.tm.terminal.view.ui.activator.UIPlugin
 Bundle-Vendor: %providerName
 Require-Bundle: org.eclipse.core.expressions;bundle-version="3.4.400",

terminal/plugins/org.eclipse.tm.terminal.view.ui/src/org/eclipse/tm/terminal/view/ui/local/showin/detectors/DetectWSL.java

@@ -24,16 +24,19 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.Predicate;
 
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.OperationCanceledException;
 import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.Status;
+import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.tm.terminal.view.ui.interfaces.IExternalExecutablesProperties;
 import org.eclipse.tm.terminal.view.ui.local.showin.IDetectExternalExecutable;
 
 public class DetectWSL implements IDetectExternalExecutable {
 
-	/**
+	private List<Map<String, String>> result = null;
-	 * Don't access directly, use {@link #getEntries()}
+	private WslDetectJob detectJob = null;
-	 */
-	List<Map<String, String>> result = null;
 
 	@Override
 	public boolean hasEntries() {
@@ -55,16 +58,51 @@ public class DetectWSL implements IDetectExternalExecutable {
 	}
 
 	private synchronized List<Map<String, String>> getEntries() {
+		// getEntries can be called in many contexts, even from within
+		// menu creation (see Bug 574519). Therefore we spawn a job to
+		// get the real entries, which means until the job is done, this
+		// method will return no entries.
+		if (result != null) {
+			return result;
+		}
+		if (detectJob == null) {
+			detectJob = new WslDetectJob();
+			detectJob.schedule();
+		}
+		try {
+			if (detectJob.join(10, null)) {
+				result = detectJob.result;
+				detectJob = null;
+			} else {
+				return Collections.emptyList();
+			}
+		} catch (OperationCanceledException | InterruptedException e) {
+			result = Collections.emptyList();
+			detectJob = null;
+		}
+		return result;
+	}
+
+	private static class WslDetectJob extends Job {
+		private List<Map<String, String>> result = null;
+
+		public WslDetectJob() {
+			super("Detect WSL Instances"); //$NON-NLS-1$
+			setSystem(true);
+		}
+
+		@Override
+		protected IStatus run(IProgressMonitor monitor) {
 			if (result == null) {
 				result = Collections.emptyList();
 				if (Platform.OS_WIN32.equals(Platform.getOS())) {
 					String windir = System.getenv("windir"); //$NON-NLS-1$
 					if (windir == null) {
-					return result;
+						return Status.OK_STATUS;
 					}
 					String wsl = windir + "\\System32\\wsl.exe"; //$NON-NLS-1$
 					if (!Files.isExecutable(Paths.get(wsl))) {
-					return result;
+						return Status.OK_STATUS;
 					}
 
 					ProcessBuilder pb = new ProcessBuilder(wsl, "--list", "--quiet"); //$NON-NLS-1$ //$NON-NLS-2$
@@ -73,7 +111,7 @@ public class DetectWSL implements IDetectExternalExecutable {
 						try (InputStream is = process.getErrorStream()) {
 							// drain the error stream
 							if (is.readAllBytes().length != 0) {
-							return result;
+								return Status.OK_STATUS;
 							}
 						}
 
@@ -105,7 +143,9 @@ public class DetectWSL implements IDetectExternalExecutable {
 					}
 				}
 			}
-		return result;
+			return Status.OK_STATUS;
+		}
+
 	}
 
 }