Remove the getaddrinfo mutex, but put mutex around winsock initialization.

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 28 matching lines @@
   socklen_t salen = SocketAddress::GetAddrLength(addr);
   DWORD l = len;
   return WSAAddressToStringA(&addr->addr,
                                 salen,
                                 NULL,
                                 address,
                                 &l) != 0;
 }
 
 
+static Mutex* init_mutex = new Mutex();
+static bool socket_initialized = false;
+
 bool Socket::Initialize() {
-  static bool socket_initialized = false;
+  MutexLocker lock(init_mutex);
   if (socket_initialized) return true;
   int err;
   WSADATA winsock_data;
   WORD version_requested = MAKEWORD(2, 2);
   err = WSAStartup(version_requested, &winsock_data);
   if (err == 0) {
     socket_initialized = true;
   } else {
     Log::PrintErr("Unable to initialize Winsock: %d\n", WSAGetLastError());
   }
@@ skipping 151 matching lines @@
   ListenSocket* listen_socket = reinterpret_cast<ListenSocket*>(fd);
   ClientSocket* client_socket = listen_socket->Accept();
   if (client_socket != NULL) {
     return reinterpret_cast<intptr_t>(client_socket);
   } else {
     return -1;
   }
 }
 
 
-static Mutex* getaddrinfo_mutex = new Mutex();
 AddressList<SocketAddress>* Socket::LookupAddress(const char* host,
                                                   int type,
                                                   OSError** os_error) {
   Initialize();
 
-  // getaddrinfo is not thread-safe on Windows. Use a mutex to get around it.
-  MutexLocker locker(getaddrinfo_mutex);
-
   // Perform a name lookup for a host name.
   struct addrinfo hints;
   memset(&hints, 0, sizeof(hints));
   hints.ai_family = SocketAddress::FromType(type);
   hints.ai_socktype = SOCK_STREAM;
   hints.ai_flags = AI_ADDRCONFIG;
   hints.ai_protocol = IPPROTO_TCP;
   struct addrinfo* info = NULL;
   int status = getaddrinfo(host, 0, &hints, &info);
   if (status != 0) {
@@ skipping 406 matching lines @@
                     proto,
                     MCAST_LEAVE_GROUP,
                     reinterpret_cast<char *>(&mreq),
                     sizeof(mreq)) == 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)