Prevent a temporary UI freeze when resolving local host name (#1793)

ahus1 · ahus1 · commit e4cc805a0e2b · 2025-04-21T17:03:30.000+02:00
diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
@@ -9,7 +9,7 @@ This document provides a high-level view of the changes introduced by release.
 
 === 0.44.5
 
-...
+- Prevent a temporary UI freeze when resolving local host name (#1793)
 
 === 0.44.4
 
diff --git a/src/main/java/org/asciidoc/intellij/editor/AsciiDocPreviewEditor.java b/src/main/java/org/asciidoc/intellij/editor/AsciiDocPreviewEditor.java
@@ -87,13 +87,6 @@
 public class AsciiDocPreviewEditor extends UserDataHolderBase implements FileEditor {
 
   private static final Logger LOG = Logger.getInstance(AsciiDocPreviewEditor.class);
-  private static final String EMPTY_HTML = "<html></html>";
-  private static final String JCEF_HTML = "<html>If you can read this and not the content of your document, your preview does not show. One possible reason is that you are using a remote desktop and " +
-    "GPU rendered content is not shown.<p>" +
-    "To fix this, update the IDE's registry and set the key 'ide.browser.jcef.gpu.disable' to the value 'true'.<p>" +
-    "To access the registry, open the menu 'Help | Find Action...' and then choose the action 'Registry...'. " +
-    "Once the registry opens, type the key to find the entry, and enable the checkbox to set the value to 'true'. " +
-    "Once you changed the value, restart the IDE for the setting to become effective.</html>";
   private final AsciiDocExtensionService extensionService = ApplicationManager.getApplication().getService(AsciiDocExtensionService.class);
   /**
    * single threaded with one task queue (one for each editor window).
@@ -219,6 +212,9 @@ private AsciiDocWrapper getAsciiDocInstance() {
   void renderIfVisible() {
     // visible = preview is enabled
     // displayable = editor window is visible as it is the active editor in a group
+    if (myPanel == null && getComponent().isVisible() && getComponent().isDisplayable()) {
+      setupPanel();
+    }
     if (myPanel != null && getComponent().isVisible() && getComponent().isDisplayable()) {
       render();
     }
@@ -298,13 +294,13 @@ public AsciiDocPreviewEditor(final Document document, Project project) {
     myHtmlPanelWrapper = new JPanel();
     LayoutManager overlay = new OverlayLayout(myHtmlPanelWrapper);
     myHtmlPanelWrapper.setLayout(overlay);
-    hint = new JLabel(EMPTY_HTML);
+    hint = new JLabel();
     myHtmlPanelWrapper.add(hint);
 
     myHtmlPanelWrapper.addComponentListener(new ComponentAdapter() {
       @Override
       public void componentShown(ComponentEvent e) {
-        setupPanel();
+        renderIfVisible();
       }
 
       @Override
@@ -467,10 +463,15 @@ private static AsciiDocHtmlPanel detachOldPanelAndCreateAndAttachNewOne(Document
     }
     panelWrapper.add(newPanel.getComponent(), BorderLayout.CENTER, 0);
 
-    String hintText = newPanel instanceof AsciiDocJCEFHtmlPanel ? JCEF_HTML : EMPTY_HTML;
-    if (!Objects.equals(hint.getText(), hintText)) {
-      // defer UI update to avoid flicking of the shown text
-      ApplicationManager.getApplication().invokeLater(() -> hint.setText(hintText));
+    if (newPanel instanceof AsciiDocJCEFHtmlPanel) {
+      hint.setText("<html>If you can read this and not the content of your document, your preview does not show. One possible reason is that you are using a remote desktop and " +
+        "GPU rendered content is not shown.<p>" +
+        "To fix this, update the IDE's registry and set the key 'ide.browser.jcef.gpu.disable' to the value 'true'.<p>" +
+        "To access the registry, open the menu 'Help | Find Action...' and then choose the action 'Registry...'. " +
+        "Once the registry opens, type the key to find the entry, and enable the checkbox to set the value to 'true'. " +
+        "Once you changed the value, restart the IDE for the setting to become effective.");
+    } else {
+      hint.setText("<html></html>");
     }
 
     return newPanel;
@@ -571,9 +572,7 @@ public boolean isValid() {
    */
   @Override
   public void selectNotify() {
-    if (myPanel == null) {
-      setupPanel();
-    }
+    renderIfVisible();
     if (FileDocumentManager.getInstance().getUnsavedDocuments().length > 0) {
       ApplicationManager.getApplication().invokeLater(() -> {
         // don't try to run save-all in parallel, therefore synchronize
diff --git a/src/main/java/org/asciidoc/intellij/editor/jcef/AsciiDocJCEFHtmlPanelProvider.java b/src/main/java/org/asciidoc/intellij/editor/jcef/AsciiDocJCEFHtmlPanelProvider.java
@@ -1,5 +1,6 @@
 package org.asciidoc.intellij.editor.jcef;
 
+import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.application.PathManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.Document;
@@ -28,26 +29,30 @@ public AsciiDocHtmlPanel createHtmlPanel(Document document, Path imagesPath, Run
     return new AsciiDocJCEFHtmlPanel(document, imagesPath, forceRefresh);
   }
 
-  private static synchronized void clearStaleJCEFlock() {
+  private static void clearStaleJCEFlock() {
     // Workaround for https://youtrack.jetbrains.com/issue/IJPL-148653,
     // when a lock file remains which the name of the old host name
     // Run this check everytime an AsciiDoc editor is opened to prevent problems, for example, after a computer comes back from suspend mode.
-    Path jcefCache = PathManager.getSystemDir().resolve("jcef_cache");
-    if (jcefCache.toFile().exists()) {
-      Path singletonLock = jcefCache.resolve("SingletonLock");
-      try {
-        String hostName = InetAddress.getLocalHost().getHostName();
-        String lockFile = Files.readSymbolicLink(singletonLock).toFile().getName();
-        if (!lockFile.matches(Pattern.quote(hostName) + "-[0-9]*")) {
-          // delete the stale lock to prevent the preview from appearing blank
-          Files.delete(singletonLock);
+    // This might be slow as the InetAddress.getLocalHost().getHostName() times out, therefore run it in a background thread.
+    // In the worst of all cases, this would clear any stale lock only on a second attempt.
+    ApplicationManager.getApplication().executeOnPooledThread(() -> {
+      Path jcefCache = PathManager.getSystemDir().resolve("jcef_cache");
+      if (jcefCache.toFile().exists()) {
+        Path singletonLock = jcefCache.resolve("SingletonLock");
+        try {
+          String hostName = InetAddress.getLocalHost().getHostName();
+          String lockFile = Files.readSymbolicLink(singletonLock).toFile().getName();
+          if (!lockFile.matches(Pattern.quote(hostName) + "-[0-9]*")) {
+            // delete the stale lock to prevent the preview from appearing blank
+            Files.delete(singletonLock);
+          }
+        } catch (NoSuchFileException ignore) {
+          // nop
+        } catch (IOException e) {
+          LOG.warn("Can't check lock", e);
         }
-      } catch (NoSuchFileException ignore) {
-        // nop
-      } catch (IOException e) {
-        LOG.warn("Can't check lock", e);
       }
-    }
+    });
   }
 
   @NotNull
