Start accepting incoming sockets earlier on Windows, to associate a at AcceptEx error to 'ServerSoc…

runtime/bin/socket_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/builtin.h"
 #include "bin/eventhandler.h"
 #include "bin/file.h"
@@ skipping 507 matching lines @@
     closesocket(s);
     delete listen_socket;
     SetLastError(rc);
     return -1;
   }
 
   return reinterpret_cast<intptr_t>(listen_socket);
 }
 
 
+bool ServerSocket::StartAccept(intptr_t fd) {
+  ListenSocket* listen_socket = reinterpret_cast<ListenSocket*>(fd);
+  listen_socket->EnsureInitialized(EventHandler::delegate());
+  // Always keep 5 outstanding accepts going, to enhance performance.
+  for (int i = 0; i < 5; i++) {
+    if (!listen_socket->IssueAccept()) {
+      DWORD rc = WSAGetLastError();
+      listen_socket->Close();
+      if (!listen_socket->HasPendingAccept()) {
+        // Delete socket now, if there are no pending accepts. Otherwise,
+        // the event-handler will take care of deleting it.
+        delete listen_socket;
+      }
+      SetLastError(rc);
+      return false;
+    }
+  }
+  return true;
+}
+
+
 void Socket::Close(intptr_t fd) {
   ClientSocket* client_socket = reinterpret_cast<ClientSocket*>(fd);
   client_socket->Close();
 }
 
 
 static bool SetBlockingHelper(intptr_t fd, bool blocking) {
   SocketHandle* handle = reinterpret_cast<SocketHandle*>(fd);
   u_long iMode = blocking ? 0 : 1;
   int status = ioctlsocket(handle->socket(), FIONBIO, &iMode);
@@ skipping 162 matching lines @@
                     proto,
                     MCAST_LEAVE_GROUP,
                     reinterpret_cast<char *>(&mreq),
                     sizeof(mreq)) == 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)