Make directory renaming more resilient on Windows.

utils/pub/io.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Helper functionality to make working with IO easier.
  */
 library io;
 
 import 'dart:io';
@@ skipping 291 matching lines @@
       return deleteDir(dir).chain((_) => createDir(dir));
     } else {
       // Just create it.
       return createDir(dir);
     }
   });
 }
 
 /// Renames (i.e. moves) the directory [from] to [to]. Returns a [Future] with
 /// the destination directory.
-Future<Directory> renameDir(from, String to) =>_getDirectory(from).rename(to);
+Future<Directory> renameDir(from, String to) {
+  from = _getDirectory(from);
+
+  if (Platform.operatingSystem != 'windows') return from.rename(to);
+
+  // On Windows, we sometimes get failures where the directory is still in use
+  // when we try to move it. To be a bit more resilient, we wait and retry a
+  // few times.
+  var attempts = 0;
+  attemptRename(_) {
+    attempts++;
+    return from.rename(to).transformException((e) {
+      if (attempts >= 10) {
+        throw 'Could not move directory "${from.path}" to "$to". Gave up '
+              'after $attempts attempts.';
+      }
+
+      // Wait a bit and try again.
+      return sleep(500).chain(attemptRename);
+    });
+
+    return from;
+  }
+
+  return attemptRename(null);
+}
 
 /**
  * Creates a new symlink that creates an alias from [from] to [to], both of
  * which can be a [String], [File], or [Directory]. Returns a [Future] which
  * completes to the symlink file (i.e. [to]).
  */
 Future<File> createSymlink(from, to) {
   from = _getPath(from);
   to = _getPath(to);
 
@@ skipping 642 matching lines @@
   return new Directory(entry);
 }
 
 /**
  * Gets a [Uri] for [uri], which can either already be one, or be a [String].
  */
 Uri _getUri(uri) {
   if (uri is Uri) return uri;
   return new Uri.fromString(uri);
 }