Improve workspace lock error dialog.

bundles/org.eclipse.ui.ide.application/src/org/eclipse/ui/internal/ide/application/IDEApplication.java

@@ -25,8 +25,10 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.net.InetAddress;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.net.UnknownHostException;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Properties;
@@ -49,7 +51,11 @@
 import org.eclipse.osgi.service.datalocation.Location;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.ui.IWorkbench;
 import org.eclipse.ui.PlatformUI;
@@ -79,6 +85,20 @@ public class IDEApplication implements IApplication, IExecutableExtension {
 
 	private static final String VERSION_FILENAME = "version.ini"; //$NON-NLS-1$
 
+	private static final String LOCK_FILENAME = ".lock"; //$NON-NLS-1$
+
+	private static final String DISPLAY_VAR = "DISPLAY"; //$NON-NLS-1$
+
+	private static final String PROCESS_ID = "process-id"; //$NON-NLS-1$
+
+	private static final String DISPLAY = "display"; //$NON-NLS-1$
+
+	private static final String HOST = "host"; //$NON-NLS-1$
+
+	private static final String USER = "user"; //$NON-NLS-1$
+
+	private static final String USER_NAME = "user.name"; //$NON-NLS-1$
+
 	// Use the branding plug-in of the platform feature since this is most likely
 	// to change on an update of the IDE.
 	private static final String WORKSPACE_CHECK_REFERENCE_BUNDLE_NAME = "org.eclipse.platform"; //$NON-NLS-1$
@@ -225,6 +245,7 @@ protected Object checkInstanceLocation(Shell shell, Map applicationArguments) {
 				try {
 					if (instanceLoc.lock()) {
 						writeWorkspaceVersion();
+						writeWsLockInfo();
 						return null;
 					}
 
@@ -313,6 +334,7 @@ protected Object checkInstanceLocation(Shell shell, Map applicationArguments) {
 				if (instanceLoc.set(workspaceUrl, true)) {
 					launchData.writePersistedData();
 					writeWorkspaceVersion();
+					writeWsLockInfo();
 					return null;
 				}
 			} catch (IllegalStateException e) {
@@ -332,17 +354,164 @@ protected Object checkInstanceLocation(Shell shell, Map applicationArguments) {
 
 			// by this point it has been determined that the workspace is
 			// already in use -- force the user to choose again
+
+			String lockInfo = getWorkspaceLockInfo(workspaceUrl);
+
 			MessageDialog dialog = new MessageDialog(null, IDEWorkbenchMessages.IDEApplication_workspaceInUseTitle,
 					null, NLS.bind(IDEWorkbenchMessages.IDEApplication_workspaceInUseMessage, workspaceUrl.getFile()),
 					MessageDialog.ERROR, 1, IDEWorkbenchMessages.IDEApplication_workspaceInUse_Retry,
-					IDEWorkbenchMessages.IDEApplication_workspaceInUse_Choose);
+					IDEWorkbenchMessages.IDEApplication_workspaceInUse_Choose) {
+				@Override
+				protected Control createCustomArea(Composite parent) {
+					if (lockInfo == null || lockInfo.isBlank()) {
+						return null;
+					}
+
+					String displayText = "Workspace lock is held by the following owner:\n".concat(lockInfo); //$NON-NLS-1$
+
+					Composite container = new Composite(parent, SWT.NONE);
+					container.setLayout(new FillLayout());
+
+					Label multiLineText = new Label(container, SWT.NONE);
+					multiLineText.setText(displayText);
+
+					return container;
+				}
+			};
 			// the return value influences the next loop's iteration
 			returnValue = dialog.open();
 			// Remember the locked workspace as recent workspace
 			launchData.writePersistedData();
 		}
 	}
 
+	/**
+	 * Read workspace lock file and parse all the properties present. Based on the
+	 * eclipse version and operating system some or all the properties may not
+	 * present. In such scenario it will return empty string.
+	 *
+	 * @return Previous lock owner details.
+	 */
+	private String getWorkspaceLockInfo(URL workspaceUrl) {
+		File lockFile = getLockFile(workspaceUrl);
+		StringBuilder sb = new StringBuilder();
+		Properties props = new Properties();
+		try (FileInputStream is = new FileInputStream(lockFile)) {
+			props.load(is);
+			String prop = props.getProperty(USER);
+			if (prop != null) {
+				sb.append("user: ").append(prop).append(System.lineSeparator()); //$NON-NLS-1$
+			}
+			prop = props.getProperty(HOST);
+			if (prop != null) {
+				sb.append("host: ").append(prop).append(System.lineSeparator()); //$NON-NLS-1$
+			}
+			prop = props.getProperty(DISPLAY);
+			if (prop != null) {
+				sb.append("display: ").append(prop).append(System.lineSeparator()); //$NON-NLS-1$
+			}
+			prop = props.getProperty(PROCESS_ID);
+			if (prop != null) {
+				sb.append("process-id: ").append(prop).append(System.lineSeparator()); //$NON-NLS-1$
+			}
+			return sb.toString();
+		} catch (Exception e) {
+			IDEWorkbenchPlugin.log("Could not read lock file: ", e); //$NON-NLS-1$
+		}
+		return null;
+	}
+
+	/**
+	 * Write lock owner details onto workspace lock file. Data includes user, host,
+	 * display and current java process id.
+	 */
+	private void writeWsLockInfo() {
+		Location instanceLoc = Platform.getInstanceLocation();
+		if (instanceLoc == null || instanceLoc.isReadOnly()) {
+			return;
+		}
+
+		File lockFile = getLockFile(instanceLoc.getURL());
+		if (lockFile == null) {
+			return;
+		}
+
+		Properties props = new Properties();
+
+		String user = System.getProperty(USER_NAME);
+		if (user != null) {
+			props.setProperty(USER, user);
+		}
+		String host = getHostName();
+		if (host != null) {
+			props.setProperty(HOST, host);
+		}
+		String display = getDisplay();
+		if (display != null) {
+			props.setProperty(DISPLAY, display);
+		}
+		String pid = getProcessId();
+		if (pid != null) {
+			props.setProperty(PROCESS_ID, pid);
+		}
+
+		try (OutputStream output = new FileOutputStream(lockFile)) {
+			props.store(output, null);
+		} catch (IOException e) {
+			IDEWorkbenchPlugin.log("Could not modify lock file", e); //$NON-NLS-1$
+		}
+	}
+
+	private String getDisplay() {
+		String displayEnv = null;
+		try {
+			displayEnv = System.getenv(DISPLAY_VAR);
+		} catch (Exception e) {
+			IDEWorkbenchPlugin.log("Failed to read DISPLAY variable.", e); //$NON-NLS-1$
+		}
+		return displayEnv;
+	}
+
+	private String getProcessId() {
+		Long pid = null;
+		try {
+			pid = ProcessHandle.current().pid();
+		} catch (Exception e) {
+			IDEWorkbenchPlugin.log("Failed to read Java process id.", e); //$NON-NLS-1$
+		}
+		return pid != null ? pid.toString() : null;
+	}
+
+	private String getHostName() {
+		String hostName = null;
+		try {
+			hostName = InetAddress.getLocalHost().getHostName();
+		} catch (UnknownHostException e) {
+			IDEWorkbenchPlugin.log("Failed to read host name.", e); //$NON-NLS-1$
+		}
+		return hostName;
+	}
+
+	private File getLockFile(URL workspaceUrl) {
+		if (workspaceUrl == null) {
+			return null;
+		}
+
+		// make sure the directory exists
+		File metaDir = new File(workspaceUrl.getPath(), METADATA_FOLDER);
+		if (!metaDir.exists()) {
+			return null;
+		}
+
+		// make sure the file exists
+		File lockFile = new File(metaDir, LOCK_FILENAME);
+		if (!lockFile.exists()) {
+			return null;
+		}
+
+		return lockFile;
+	}
+
 	@SuppressWarnings("rawtypes")
 	private static boolean isDevLaunchMode(Map args) {
 		// see org.eclipse.pde.internal.core.PluginPathFinder.isDevLaunchMode()