Auto-reinstall broken packages in the system cache.

utils/pub/source.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.
 
 library source;
 
 import 'dart:async';
 import 'io.dart';
 import 'package.dart';
 import 'pubspec.dart';
@@ skipping 90 matching lines @@
   }
 
   /// Installs the package identified by [id] to the system cache. This is only
   /// called for sources with [shouldCache] set to true.
   ///
   /// By default, this uses [systemCacheDirectory] and [install].
   Future<Package> installToSystemCache(PackageId id) {
     var path;
     return systemCacheDirectory(id).then((p) {
       path = p;
-      if (dirExists(path)) return true;
+
+      // See if it's already cached.
+      if (!dirExists(path)) return false;
+
+      // Heuristic to make sure the cached package didn't get deleted
+      // somehow. If the directory is here but there's no pubspec, assume we
+      // got borked and reinstall.

[nweiz, 2013/02/13 00:19:21]

What if just "lib" or the contents of "lib" got wiped out? Isn't that an issue
we were seeing, since that's where the symlink points?

[Bob Nystrom, 2013/02/13 01:27:11]

Oh, great call. Duh.

Fixed this to look for an empty lib dir.

[nweiz, 2013/02/13 02:02:05]

I feel like having the pubspec check as well is still a good idea, in case the
entire directory is erased somehow.

[Bob Nystrom, 2013/02/13 18:00:26]

Done.

+      if (fileExists(join(path, 'pubspec.yaml'))) return true;
+
+      // No pubspec, so wipe it out and reinstall.
+      return deleteDir(path).then((_) => false);
+    }).then((isInstalled) {
+      if (isInstalled) return true;
       ensureDir(dirname(path));
       return install(id, path);
     }).then((found) {
       if (!found) throw 'Package $id not found.';
       return new Package.load(id.name, path, systemCache.sources);
     });
   }
 
   /// Returns the directory in the system cache that the package identified by
   /// [id] should be installed to. This should return a path to a subdirectory
@@ skipping 41 matching lines @@
   /// according to [validateDescription], although it must still be serializable
   /// to JSON and YAML. It must also be equal to [id] according to
   /// [descriptionsEqual].
   ///
   /// By default, this just returns [id].
   Future<PackageId> resolveId(PackageId id) => new Future.immediate(id);
 
   /// Returns the source's name.
   String toString() => name;
 }