Download packages to temp dir inside system cache.

utils/pub/system_cache.dart

Index: utils/pub/system_cache.dart
diff --git a/utils/pub/system_cache.dart b/utils/pub/system_cache.dart
index 1a4cdd08f4a36547ca1bb6fd43ababd8ce81bc84..a06838092a6b885f5f3b082e480d1b87adb3ceb7 100644
--- a/utils/pub/system_cache.dart
+++ b/utils/pub/system_cache.dart
@@ -4,7 +4,10 @@
 
 library system_cache;
 
+import 'dart:io';
+
 import 'io.dart';
+import 'io.dart' as io show createTempDir;
 import 'package.dart';
 import 'source.dart';
 import 'source_registry.dart';
@@ -23,6 +26,8 @@ class SystemCache {
    */
   final String rootDir;
 
+  String get tempDir => join(rootDir, '_temp');
+
   /**
    * Packages which are currently being asynchronously installed to the cache.
    */
@@ -70,4 +75,23 @@ class SystemCache {
     _pendingInstalls[id] = future;
     return future;
   }
+
+  /// Create a new temporary directory within the system cache. The system
+  /// cache maintains its own temporary directory that it uses to stage
+  /// packages into while installing. It uses this instead of the OS's system
+  /// temp directory to ensure that it's on the same volume as the pub system
+  /// cache so that it can move the directory from it.
+  Future<Directory> createTempDir() {
+    return ensureDir(join(rootDir, '_temp')).chain((tempDir) {

[kasperl, 2012/10/16 06:08:50]

Rename tempDir variable to avoid shadowing the getter? I'd suggest temp.

Use tempDir instead of join(rootDir, '_temp').

+      return io.createTempDir(join(tempDir, 'dir'));
+    });
+  }
+
+  /// Delete's the system cache's internal temp directory.
+  Future deleteTempDir() {
+    return dirExists(tempDir).chain((exists) {
+      if (!exists) return new Future.immediate(null);
+      return deleteDir(tempDir);
+    });
+  }
 }