Add watcher on sketch files

Reloads sketch content if the Editor is not in foreground and isomething happens in the backing storage files. Note that no confirmation dialog is displayed (same behaviour as SublimeText, differs from other IDEs) Fixes #4551 and #5345
arduino · facchinm · Mar 14, 2017 · Jul 4, 2017 · Jul 4, 2017 · Jul 3, 2017
commit 46677c2f22b04acd29fe941dbb7b4ef8e76be2c3
diff --git a/app/src/processing/app/EditorTab.java b/app/src/processing/app/EditorTab.java
@@ -30,6 +30,8 @@
 import java.awt.Font;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
+import java.awt.event.FocusEvent;
+import java.awt.event.FocusListener;
 import java.io.IOException;

 import javax.swing.Action;
@@ -47,6 +49,14 @@
 import javax.swing.text.DefaultCaret;
 import javax.swing.text.Document;

+import static java.nio.file.StandardWatchEventKinds.*;
+import java.nio.file.WatchService;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchEvent;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.io.File;
+
 import org.fife.ui.rsyntaxtextarea.RSyntaxDocument;
 import org.fife.ui.rsyntaxtextarea.RSyntaxTextAreaEditorKit;
 import org.fife.ui.rsyntaxtextarea.RSyntaxUtilities;
@@ -60,18 +70,21 @@
 import processing.app.syntax.SketchTextArea;
 import processing.app.syntax.SketchTextAreaEditorKit;
 import processing.app.tools.DiscourseFormat;
+import processing.app.tools.WatchDir;

 /**
 * Single tab, editing a single file, in the main window.
 */
-public class EditorTab extends JPanel implements SketchFile.TextStorage {
+public class EditorTab extends JPanel implements SketchFile.TextStorage, FocusListener {
  protected Editor editor;
  protected SketchTextArea textarea;
  protected RTextScrollPane scrollPane;
  protected SketchFile file;
  protected boolean modified;
  /** Is external editing mode currently enabled? */
  protected boolean external;
+  protected Thread watcher = null;
+  protected Runnable task = null;

  /**
   * Create a new EditorTab
@@ -106,6 +119,27 @@ public EditorTab(Editor editor, SketchFile file, String contents)
    file.setStorage(this);
    applyPreferences();
    add(scrollPane, BorderLayout.CENTER);
+    addFocusListener(this);
+    textarea.addFocusListener(this);
+    scrollPane.addFocusListener(this);
+    setFocusable(true);
+    setRequestFocusEnabled(true);
+  }
+
+  @Override
+  public void focusGained(FocusEvent fe){
+    if (watcher != null) {
+      watcher.interrupt();
+      watcher = null;
+    }
+  }
+
+  @Override
+  public void focusLost(FocusEvent fe){
+    if (watcher == null) {
+      watcher = new Thread(task);
+      watcher.start();
+    }
  }

  private RSyntaxDocument createDocument(String contents) {
@@ -120,6 +154,25 @@ private RSyntaxDocument createDocument(String contents) {
    }
    document.addDocumentListener(new DocumentTextChangeListener(
        () -> setModified(true)));
+
+    // Add FS watcher for modification
+    File dir_s = this.file.getFile();
+    Path dir = dir_s.toPath().getParent();
+    EditorTab tab = this;
+
+    task = new Runnable() {
+      public void run() {
+        try {
+          new WatchDir(dir, true).processEvents(tab);
+        } catch (IOException x) {
+          System.err.println(x);
+        }
+      }
+    };
+
+    watcher = new Thread(task);
+    watcher.start();
+
    return document;
  }


diff --git a/app/src/processing/app/tools/WatchDir.java b/app/src/processing/app/tools/WatchDir.java
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   - Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *   - Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ *   - Neither the name of Oracle nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package processing.app.tools;
+
+import java.nio.file.*;
+import static java.nio.file.StandardWatchEventKinds.*;
+import static java.nio.file.LinkOption.*;
+import java.nio.file.attribute.*;
+import java.io.*;
+import java.util.*;
+import processing.app.EditorTab;
+
+/**
+ * Example to watch a directory (or tree) for changes to files.
+ */
+
+public class WatchDir {
+
+    private final WatchService watcher;
+    private final Map<WatchKey,Path> keys;
+    private final boolean recursive;
+    private boolean trace = false;
+
+    @SuppressWarnings("unchecked")
+    static <T> WatchEvent<T> cast(WatchEvent<?> event) {
+        return (WatchEvent<T>)event;
+    }
+
+    /**
+     * Register the given directory with the WatchService
+     */
+    private void register(Path dir) throws IOException {
+        WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
+        if (trace) {
+            Path prev = keys.get(key);
+            if (prev == null) {
+            } else {
+                if (!dir.equals(prev)) {
+                }
+            }
+        }
+        keys.put(key, dir);
+    }
+
+    /**
+     * Register the given directory, and all its sub-directories, with the
+     * WatchService.
+     */
+    private void registerAll(final Path start) throws IOException {
+        // register directory and sub-directories
+        Files.walkFileTree(start, new SimpleFileVisitor<Path>() {
+            @Override
+            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
+                throws IOException
+            {
+                register(dir);
+                return FileVisitResult.CONTINUE;
+            }
+        });
+    }
+
+    /**
+     * Creates a WatchService and registers the given directory
+     */
+    public WatchDir(Path dir, boolean recursive) throws IOException {
+        this.watcher = FileSystems.getDefault().newWatchService();
+        this.keys = new HashMap<WatchKey,Path>();
+        this.recursive = recursive;
+
+        if (recursive) {
+            registerAll(dir);
+        } else {
+            register(dir);
+        }
+
+        // enable trace after initial registration
+        this.trace = true;
+    }
+
+    /**
+     * Process all events for keys queued to the watcher
+     */
+    public void processEvents(EditorTab tab) {
+        for (;;) {
+
+            // wait for key to be signalled
+            WatchKey key;
+            try {
+                key = watcher.take();
+            } catch (InterruptedException x) {
+                return;
+            }
+
+            Path dir = keys.get(key);
+            if (dir == null) {
+                continue;
+            }
+
+            for (WatchEvent<?> event: key.pollEvents()) {
+                WatchEvent.Kind kind = event.kind();
+
+                // TBD - provide example of how OVERFLOW event is handled
+                if (kind == OVERFLOW) {
+                    continue;
+                }
+
+                // Context for directory entry event is the file name of entry
+                WatchEvent<Path> ev = cast(event);
+                Path name = ev.context();
+                Path child = dir.resolve(name);
+
+                // reload the tab content
+                tab.reload();
+
+                // if directory is created, and watching recursively, then
+                // register it and its sub-directories
+                if (recursive && (kind == ENTRY_CREATE)) {
+                    try {
+                        if (Files.isDirectory(child, NOFOLLOW_LINKS)) {
+                            registerAll(child);
+                        }
+                    } catch (IOException x) {
+                        // ignore to keep sample readbale
+                    }
+                }
+            }
+
+            // reset key and remove from set if directory no longer accessible
+            boolean valid = key.reset();
+            if (!valid) {
+                keys.remove(key);
+
+                // all directories are inaccessible
+                if (keys.isEmpty()) {
+                    break;
+                }
+            }
+        }
+    }
+}