Ignore bogus links, such as those created by emacs for files being edited.

pkg/analysis_server/lib/src/context_directory_manager.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library context.directory.manager;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/package_map_provider.dart';
@@ skipping 126 matching lines @@
   }
 
   void _handleWatchEvent(Folder folder, _ContextDirectoryInfo info, WatchEvent event) {
     switch (event.type) {
       case ChangeType.ADD:
         if (_isInPackagesDir(event.path, folder)) {
           // TODO(paulberry): perhaps we should only skip packages dirs if
           // there is a pubspec.yaml?
           break;
         }
-        if (_shouldFileBeAnalyzed(event.path)) {
-          ChangeSet changeSet = new ChangeSet();
-          Resource resource = resourceProvider.getResource(event.path);
-          // If the file went away and was replaced by a folder before we
-          // had a chance to process the event, resource might be a Folder.  In
-          // that case don't add it.
-          if (resource is File) {
-            File file = resource;
+        Resource resource = resourceProvider.getResource(event.path);
+        // If the file went away and was replaced by a folder before we
+        // had a chance to process the event, resource might be a Folder.  In
+        // that case don't add it.
+        if (resource is File) {
+          File file = resource;
+          if (_shouldFileBeAnalyzed(file)) {
+            ChangeSet changeSet = new ChangeSet();
             Source source = file.createSource(UriKind.FILE_URI);
             changeSet.addedSource(source);
             applyChangesToContext(folder, changeSet);
             info.sources[event.path]= source;
           }
         }
         break;
       case ChangeType.REMOVE:
         Source source = info.sources[event.path];
         if (source != null) {
@@ skipping 39 matching lines @@
     return false;
   }
 
   /**
    * Resursively adds all Dart and HTML files to the [changeSet].
    */
   static void _addSourceFiles(ChangeSet changeSet, Folder folder, _ContextDirectoryInfo info) {
     List<Resource> children = folder.getChildren();
     for (Resource child in children) {
       if (child is File) {
-        if (_shouldFileBeAnalyzed(child.path)) {
+        if (_shouldFileBeAnalyzed(child)) {
           Source source = child.createSource(UriKind.FILE_URI);
           changeSet.addedSource(source);
           info.sources[child.path] = source;
         }
       } else if (child is Folder) {
         if (child.shortName == 'packages') {
           // TODO(paulberry): perhaps we should only skip packages dirs if
           // there is a pubspec.yaml?
           continue;
         }
         _addSourceFiles(changeSet, child, info);
       }
     }
   }
 
-  static bool _shouldFileBeAnalyzed(String path) {
-    return AnalysisEngine.isDartFileName(path)
-            || AnalysisEngine.isHtmlFileName(path);
+  static bool _shouldFileBeAnalyzed(File file) {
+    if (!(AnalysisEngine.isDartFileName(file.path)
+            || AnalysisEngine.isHtmlFileName(file.path))) {
+      return false;
+    }
+    // Emacs creates dummy links to track the fact that a file is open for
+    // editing and has unsaved changes (e.g. having unsaved changes to
+    // 'foo.dart' causes a link '.#foo.dart' to be created, which points to the
+    // non-existent file 'username@hostname.pid'.  To avoid these dummy links
+    // causing the analyzer to thrash, just ignore links to non-existent files.
+    return file.exists;
   }
 
   /**
    * Called when a new context needs to be created.
    */
   void addContext(Folder folder, HashMap<String, List<Folder>> packageMap);
 
   /**
    * Called when the set of files associated with a context have changed (or
    * some of those files have been modified).  [changeSet] is the set of
    * changes that need to be applied to the context.
    */
   void applyChangesToContext(Folder contextFolder, ChangeSet changeSet);
 
   /**
    * Remove the context associated with the given [folder].
    */
   void removeContext(Folder folder);
 
   /**
    * Called when the package map for a context has changed.
    */
   void updateContextPackageMap(Folder contextFolder,
                                Map<String, List<Folder>> packageMap);
 }