Use 'Directory.watch' on Windows in pkg/watcher, instead of pooling.

runtime/bin/eventhandler_win.cc

 // Copyright (c) 2013, 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/eventhandler.h"
 
 #include <winsock2.h>  // NOLINT
@@ skipping 399 matching lines @@
   if (ok || GetLastError() == ERROR_IO_PENDING) {
     // Completing asynchronously.
     pending_read_ = buffer;
     return true;
   }
   OverlappedBuffer::DisposeBuffer(buffer);
   return false;
 }
 
 
+void DirectoryWatchHandle::Stop() {
+  ScopedLock lock(this);
+  // Stop the outstanding read, so we can close the handle.
+
+  if (pending_read_ != NULL) {
+    CancelIoEx(handle(), pending_read_->GetCleanOverlapped());

[Søren Gjesse, 2014/06/04 10:04:52]

Check that this returns ERROR_OPERATION_ABORTED? Not sure what to do if it does
not tough.

[Anders Johnsen, 2014/06/04 10:15:53]

The thing is, even if it doesn't, we can't do anything. It might JSUT have been
completed. In that case we have no outstanding reads anyway, so all is fine.

+    // Don't dispose of the buffer, as it will still complete (with length 0).
+    pending_read_ = NULL;
+  }
+
+  CloseHandle(handle());
+  handle_ = (INVALID_HANDLE_VALUE);
+}
+
+
 void SocketHandle::HandleIssueError() {
   int error = WSAGetLastError();
   if (error == WSAECONNRESET) {
     HandleClosed(this);
   } else {
     HandleError(this);
   }
   WSASetLastError(error);
 }
 
@@ skipping 918 matching lines @@
 
 
 void EventHandlerImplementation::Shutdown() {
   SendData(kShutdownId, 0, 0);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)