diff --git a/libtorrent/include/libtorrent/asio/basic_socket.hpp b/libtorrent/include/libtorrent/asio/basic_socket.hpp
index b0dc52e48..2b2521b69 100644
--- a/libtorrent/include/libtorrent/asio/basic_socket.hpp
+++ b/libtorrent/include/libtorrent/asio/basic_socket.hpp
@@ -238,6 +238,9 @@ public:
    * with the asio::error::operation_aborted error.
    *
    * @throws asio::system_error Thrown on failure.
+   *
+   * @note For portable behaviour with respect to graceful closure of a
+   * connected socket, call shutdown() before closing the socket.
    */
   void close()
   {
@@ -265,6 +268,9 @@ public:
    *   // An error occurred.
    * }
    * @endcode
+   *
+   * @note For portable behaviour with respect to graceful closure of a
+   * connected socket, call shutdown() before closing the socket.
    */
   asio::error_code close(asio::error_code& ec)
   {
diff --git a/libtorrent/include/libtorrent/asio/buffer.hpp b/libtorrent/include/libtorrent/asio/buffer.hpp
index 7e5dc76c8..9fe76178c 100644
--- a/libtorrent/include/libtorrent/asio/buffer.hpp
+++ b/libtorrent/include/libtorrent/asio/buffer.hpp
@@ -542,9 +542,10 @@ inline const_buffers_1 buffer(const PodType (&data)[N],
         ? N * sizeof(PodType) : max_size_in_bytes));
 }
 
-#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))
+#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582)) \
+  || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
 
-// Borland C++ thinks the overloads:
+// Borland C++ and Sun Studio think the overloads:
 //
 //   unspecified buffer(boost::array<PodType, N>& array ...);
 //
@@ -610,6 +611,7 @@ buffer(boost::array<PodType, N>& data, std::size_t max_size_in_bytes)
 }
 
 #else // BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))
+      // || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
 
 /// Create a new modifiable buffer that represents the given POD array.
 template <typename PodType, std::size_t N>
@@ -650,6 +652,7 @@ inline const_buffers_1 buffer(boost::array<const PodType, N>& data,
 }
 
 #endif // BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))
+       // || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 template <typename PodType, std::size_t N>
diff --git a/libtorrent/include/libtorrent/asio/detail/null_event.hpp b/libtorrent/include/libtorrent/asio/detail/null_event.hpp
index df522ce0f..99bcbc6a4 100644
--- a/libtorrent/include/libtorrent/asio/detail/null_event.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/null_event.hpp
@@ -43,17 +43,20 @@ public:
   }
 
   // Signal the event.
-  void signal()
+  template <typename Lock>
+  void signal(Lock&)
   {
   }
 
   // Reset the event.
-  void clear()
+  template <typename Lock>
+  void clear(Lock&)
   {
   }
 
   // Wait for the event to become signalled.
-  void wait()
+  template <typename Lock>
+  void wait(Lock&)
   {
   }
 };
diff --git a/libtorrent/include/libtorrent/asio/detail/posix_event.hpp b/libtorrent/include/libtorrent/asio/detail/posix_event.hpp
index 408c23bb9..1197ac3f1 100644
--- a/libtorrent/include/libtorrent/asio/detail/posix_event.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/posix_event.hpp
@@ -24,6 +24,7 @@
 #if defined(BOOST_HAS_PTHREADS)
 
 #include "asio/detail/push_options.hpp"
+#include <boost/assert.hpp>
 #include <boost/throw_exception.hpp>
 #include <pthread.h>
 #include "asio/detail/pop_options.hpp"
@@ -42,7 +43,7 @@ public:
   posix_event()
     : signalled_(false)
   {
-    int error = ::pthread_mutex_init(&mutex_, 0);
+    int error = ::pthread_cond_init(&cond_, 0);
     if (error != 0)
     {
       asio::system_error e(
@@ -50,53 +51,43 @@ public:
           "event");
       boost::throw_exception(e);
     }
-
-    error = ::pthread_cond_init(&cond_, 0);
-    if (error != 0)
-    {
-      ::pthread_mutex_destroy(&mutex_);
-      asio::system_error e(
-          asio::error_code(error, asio::native_ecat),
-          "event");
-      boost::throw_exception(e);
-    }
   }
 
   // Destructor.
   ~posix_event()
   {
     ::pthread_cond_destroy(&cond_);
-    ::pthread_mutex_destroy(&mutex_);
   }
 
   // Signal the event.
-  void signal()
+  template <typename Lock>
+  void signal(Lock& lock)
   {
-    ::pthread_mutex_lock(&mutex_); // Ignore EINVAL and EDEADLK.
+    BOOST_ASSERT(lock.locked());
+    (void)lock;
     signalled_ = true;
     ::pthread_cond_signal(&cond_); // Ignore EINVAL.
-    ::pthread_mutex_unlock(&mutex_); // Ignore EINVAL and EPERM.
   }
 
   // Reset the event.
-  void clear()
+  template <typename Lock>
+  void clear(Lock& lock)
   {
-    ::pthread_mutex_lock(&mutex_); // Ignore EINVAL and EDEADLK.
+    BOOST_ASSERT(lock.locked());
+    (void)lock;
     signalled_ = false;
-    ::pthread_mutex_unlock(&mutex_); // Ignore EINVAL and EPERM.
   }
 
   // Wait for the event to become signalled.
-  void wait()
+  template <typename Lock>
+  void wait(Lock& lock)
   {
-    ::pthread_mutex_lock(&mutex_); // Ignore EINVAL and EDEADLK.
+    BOOST_ASSERT(lock.locked());
     while (!signalled_)
-      ::pthread_cond_wait(&cond_, &mutex_); // Ignore EINVAL.
-    ::pthread_mutex_unlock(&mutex_); // Ignore EINVAL and EPERM.
+      ::pthread_cond_wait(&cond_, &lock.mutex().mutex_); // Ignore EINVAL.
   }
 
 private:
-  ::pthread_mutex_t mutex_;
   ::pthread_cond_t cond_;
   bool signalled_;
 };
diff --git a/libtorrent/include/libtorrent/asio/detail/posix_mutex.hpp b/libtorrent/include/libtorrent/asio/detail/posix_mutex.hpp
index 154089f3c..224722bb4 100644
--- a/libtorrent/include/libtorrent/asio/detail/posix_mutex.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/posix_mutex.hpp
@@ -35,6 +35,8 @@
 namespace asio {
 namespace detail {
 
+class posix_event;
+
 class posix_mutex
   : private noncopyable
 {
@@ -87,6 +89,7 @@ public:
   }
 
 private:
+  friend class posix_event;
   ::pthread_mutex_t mutex_;
 };
 
diff --git a/libtorrent/include/libtorrent/asio/detail/reactive_socket_service.hpp b/libtorrent/include/libtorrent/asio/detail/reactive_socket_service.hpp
index d5b8e4fc8..e4b4dfa7c 100644
--- a/libtorrent/include/libtorrent/asio/detail/reactive_socket_service.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/reactive_socket_service.hpp
@@ -86,7 +86,7 @@ public:
   };
 
   // The maximum number of buffers to support in a single operation.
-  enum { max_buffers = 16 };
+  enum { max_buffers = 64 < max_iov_len ? 64 : max_iov_len };
 
   // Constructor.
   reactive_socket_service(asio::io_service& io_service)
diff --git a/libtorrent/include/libtorrent/asio/detail/scoped_lock.hpp b/libtorrent/include/libtorrent/asio/detail/scoped_lock.hpp
index 64c77cbab..57f8cb8f6 100644
--- a/libtorrent/include/libtorrent/asio/detail/scoped_lock.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/scoped_lock.hpp
@@ -63,6 +63,18 @@ public:
     }
   }
 
+  // Test whether the lock is held.
+  bool locked() const
+  {
+    return locked_;
+  }
+
+  // Get the underlying mutex.
+  Mutex& mutex()
+  {
+    return mutex_;
+  }
+
 private:
   // The underlying mutex.
   Mutex& mutex_;
diff --git a/libtorrent/include/libtorrent/asio/detail/service_registry.hpp b/libtorrent/include/libtorrent/asio/detail/service_registry.hpp
index bd1c3ea5b..3a9e9f620 100644
--- a/libtorrent/include/libtorrent/asio/detail/service_registry.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/service_registry.hpp
@@ -166,7 +166,8 @@ private:
   }
 
   // Check if a service matches the given id.
-  bool service_id_matches(const asio::io_service::service& service,
+  static bool service_id_matches(
+      const asio::io_service::service& service,
       const asio::io_service::id& id)
   {
     return service.id_ == &id;
@@ -174,7 +175,8 @@ private:
 
   // Check if a service matches the given id.
   template <typename Service>
-  bool service_id_matches(const asio::io_service::service& service,
+  static bool service_id_matches(
+      const asio::io_service::service& service,
       const asio::detail::service_id<Service>& /*id*/)
   {
     return service.type_info_ != 0 && *service.type_info_ == typeid(Service);
diff --git a/libtorrent/include/libtorrent/asio/detail/socket_option.hpp b/libtorrent/include/libtorrent/asio/detail/socket_option.hpp
index ee867e6b2..1a03936ab 100644
--- a/libtorrent/include/libtorrent/asio/detail/socket_option.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/socket_option.hpp
@@ -110,8 +110,19 @@ public:
   template <typename Protocol>
   void resize(const Protocol&, std::size_t s)
   {
-    if (s != sizeof(value_))
+    // On some platforms (e.g. Windows Vista), the getsockopt function will
+    // return the size of a boolean socket option as one byte, even though a
+    // four byte integer was passed in.
+    switch (s)
+    {
+    case sizeof(char):
+      value_ = *reinterpret_cast<char*>(&value_) ? 1 : 0;
+      break;
+    case sizeof(value_):
+      break;
+    default:
       throw std::length_error("boolean socket option resize");
+    }
   }
 
 private:
diff --git a/libtorrent/include/libtorrent/asio/detail/socket_types.hpp b/libtorrent/include/libtorrent/asio/detail/socket_types.hpp
index 49d1c7fc2..02c3a78d5 100644
--- a/libtorrent/include/libtorrent/asio/detail/socket_types.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/socket_types.hpp
@@ -98,6 +98,7 @@
 # include <arpa/inet.h>
 # include <netdb.h>
 # include <net/if.h>
+# include <limits.h>
 # if defined(__sun)
 #  include <sys/filio.h>
 #  include <sys/sockio.h>
@@ -141,6 +142,11 @@ const int shutdown_both = SD_BOTH;
 const int message_peek = MSG_PEEK;
 const int message_out_of_band = MSG_OOB;
 const int message_do_not_route = MSG_DONTROUTE;
+# if defined (_WIN32_WINNT)
+const int max_iov_len = 64;
+# else
+const int max_iov_len = 16;
+# endif
 #else
 typedef int socket_type;
 const int invalid_socket = -1;
@@ -166,6 +172,7 @@ const int shutdown_both = SHUT_RDWR;
 const int message_peek = MSG_PEEK;
 const int message_out_of_band = MSG_OOB;
 const int message_do_not_route = MSG_DONTROUTE;
+const int max_iov_len = IOV_MAX;
 #endif
 const int custom_socket_option_level = 0xA5100000;
 const int enable_connection_aborted_option = 1;
diff --git a/libtorrent/include/libtorrent/asio/detail/strand_service.hpp b/libtorrent/include/libtorrent/asio/detail/strand_service.hpp
index f10289090..d987cb98d 100644
--- a/libtorrent/include/libtorrent/asio/detail/strand_service.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/strand_service.hpp
@@ -239,6 +239,7 @@ public:
 #else
       BOOST_ASSERT(size <= strand_impl::handler_storage_type::size);
 #endif
+      (void)size;
       return impl_->handler_storage_.address();
     }
 
@@ -415,14 +416,14 @@ public:
     }
     else
     {
-      asio::detail::mutex::scoped_lock lock(impl->mutex_);
-
       // Allocate and construct an object to wrap the handler.
       typedef handler_wrapper<Handler> value_type;
       typedef handler_alloc_traits<Handler, value_type> alloc_traits;
       raw_handler_ptr<alloc_traits> raw_ptr(handler);
       handler_ptr<alloc_traits> ptr(raw_ptr, handler);
 
+      asio::detail::mutex::scoped_lock lock(impl->mutex_);
+
       if (impl->current_handler_ == 0)
       {
         // This handler now has the lock, so can be dispatched immediately.
@@ -455,14 +456,14 @@ public:
   template <typename Handler>
   void post(implementation_type& impl, Handler handler)
   {
-    asio::detail::mutex::scoped_lock lock(impl->mutex_);
-
     // Allocate and construct an object to wrap the handler.
     typedef handler_wrapper<Handler> value_type;
     typedef handler_alloc_traits<Handler, value_type> alloc_traits;
     raw_handler_ptr<alloc_traits> raw_ptr(handler);
     handler_ptr<alloc_traits> ptr(raw_ptr, handler);
 
+    asio::detail::mutex::scoped_lock lock(impl->mutex_);
+
     if (impl->current_handler_ == 0)
     {
       // This handler now has the lock, so can be dispatched immediately.
diff --git a/libtorrent/include/libtorrent/asio/detail/task_io_service.hpp b/libtorrent/include/libtorrent/asio/detail/task_io_service.hpp
index 07df1c18a..802d7ea95 100644
--- a/libtorrent/include/libtorrent/asio/detail/task_io_service.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/task_io_service.hpp
@@ -40,6 +40,7 @@ public:
     : asio::detail::service_base<task_io_service<Task> >(io_service),
       mutex_(),
       task_(use_service<Task>(io_service)),
+      task_interrupted_(true),
       outstanding_work_(0),
       handler_queue_(&task_handler_),
       handler_queue_end_(&task_handler_),
@@ -80,8 +81,7 @@ public:
     typename call_stack<task_io_service>::context ctx(this);
 
     idle_thread_info this_idle_thread;
-    this_idle_thread.prev = &this_idle_thread;
-    this_idle_thread.next = &this_idle_thread;
+    this_idle_thread.next = 0;
 
     asio::detail::mutex::scoped_lock lock(mutex_);
 
@@ -98,8 +98,7 @@ public:
     typename call_stack<task_io_service>::context ctx(this);
 
     idle_thread_info this_idle_thread;
-    this_idle_thread.prev = &this_idle_thread;
-    this_idle_thread.next = &this_idle_thread;
+    this_idle_thread.next = 0;
 
     asio::detail::mutex::scoped_lock lock(mutex_);
 
@@ -134,7 +133,7 @@ public:
   void stop()
   {
     asio::detail::mutex::scoped_lock lock(mutex_);
-    stop_all_threads();
+    stop_all_threads(lock);
   }
 
   // Reset in preparation for a subsequent run invocation.
@@ -156,7 +155,7 @@ public:
   {
     asio::detail::mutex::scoped_lock lock(mutex_);
     if (--outstanding_work_ == 0)
-      stop_all_threads();
+      stop_all_threads(lock);
   }
 
   // Request invocation of the given handler.
@@ -201,9 +200,14 @@ public:
     ++outstanding_work_;
 
     // Wake up a thread to execute the handler.
-    if (!interrupt_one_idle_thread())
-      if (task_handler_.next_ == 0 && handler_queue_end_ != &task_handler_)
+    if (!interrupt_one_idle_thread(lock))
+    {
+      if (!task_interrupted_)
+      {
+        task_interrupted_ = true;
         task_.interrupt();
+      }
+    }
   }
 
 private:
@@ -214,7 +218,7 @@ private:
   {
     if (outstanding_work_ == 0 && !stopped_)
     {
-      stop_all_threads();
+      stop_all_threads(lock);
       ec = asio::error_code();
       return 0;
     }
@@ -230,11 +234,14 @@ private:
         handler_queue_ = h->next_;
         if (handler_queue_ == 0)
           handler_queue_end_ = 0;
-        bool more_handlers = (handler_queue_ != 0);
-        lock.unlock();
+        h->next_ = 0;
 
         if (h == &task_handler_)
         {
+          bool more_handlers = (handler_queue_ != 0);
+          task_interrupted_ = more_handlers || polling;
+          lock.unlock();
+
           // If the task has already run and we're polling then we're done.
           if (task_has_run && polling)
           {
@@ -252,6 +259,7 @@ private:
         }
         else
         {
+          lock.unlock();
           handler_cleanup c(lock, *this);
 
           // Invoke the handler. May throw an exception.
@@ -264,31 +272,10 @@ private:
       else if (this_idle_thread)
       {
         // Nothing to run right now, so just wait for work to do.
-        if (first_idle_thread_)
-        {
-          this_idle_thread->next = first_idle_thread_;
-          this_idle_thread->prev = first_idle_thread_->prev;
-          first_idle_thread_->prev->next = this_idle_thread;
-          first_idle_thread_->prev = this_idle_thread;
-        }
+        this_idle_thread->next = first_idle_thread_;
         first_idle_thread_ = this_idle_thread;
-        this_idle_thread->wakeup_event.clear();
-        lock.unlock();
-        this_idle_thread->wakeup_event.wait();
-        lock.lock();
-        if (this_idle_thread->next == this_idle_thread)
-        {
-          first_idle_thread_ = 0;
-        }
-        else
-        {
-          if (first_idle_thread_ == this_idle_thread)
-            first_idle_thread_ = this_idle_thread->next;
-          this_idle_thread->next->prev = this_idle_thread->prev;
-          this_idle_thread->prev->next = this_idle_thread->next;
-          this_idle_thread->next = this_idle_thread;
-          this_idle_thread->prev = this_idle_thread;
-        }
+        this_idle_thread->wakeup_event.clear(lock);
+        this_idle_thread->wakeup_event.wait(lock);
       }
       else
       {
@@ -302,39 +289,44 @@ private:
   }
 
   // Stop the task and all idle threads.
-  void stop_all_threads()
+  void stop_all_threads(
+      asio::detail::mutex::scoped_lock& lock)
   {
     stopped_ = true;
-    interrupt_all_idle_threads();
-    if (task_handler_.next_ == 0 && handler_queue_end_ != &task_handler_)
+    interrupt_all_idle_threads(lock);
+    if (!task_interrupted_)
+    {
+      task_interrupted_ = true;
       task_.interrupt();
+    }
   }
 
   // Interrupt a single idle thread. Returns true if a thread was interrupted,
   // false if no running thread could be found to interrupt.
-  bool interrupt_one_idle_thread()
+  bool interrupt_one_idle_thread(
+      asio::detail::mutex::scoped_lock& lock)
   {
     if (first_idle_thread_)
     {
-      first_idle_thread_->wakeup_event.signal();
-      first_idle_thread_ = first_idle_thread_->next;
+      idle_thread_info* idle_thread = first_idle_thread_;
+      first_idle_thread_ = idle_thread->next;
+      idle_thread->next = 0;
+      idle_thread->wakeup_event.signal(lock);
       return true;
     }
     return false;
   }
 
   // Interrupt all idle threads.
-  void interrupt_all_idle_threads()
+  void interrupt_all_idle_threads(
+      asio::detail::mutex::scoped_lock& lock)
   {
-    if (first_idle_thread_)
+    while (first_idle_thread_)
     {
-      first_idle_thread_->wakeup_event.signal();
-      idle_thread_info* current_idle_thread = first_idle_thread_->next;
-      while (current_idle_thread != first_idle_thread_)
-      {
-        current_idle_thread->wakeup_event.signal();
-        current_idle_thread = current_idle_thread->next;
-      }
+      idle_thread_info* idle_thread = first_idle_thread_;
+      first_idle_thread_ = idle_thread->next;
+      idle_thread->next = 0;
+      idle_thread->wakeup_event.signal(lock);
     }
   }
 
@@ -440,6 +432,7 @@ private:
     {
       // Reinsert the task at the end of the handler queue.
       lock_.lock();
+      task_io_service_.task_interrupted_ = true;
       task_io_service_.task_handler_.next_ = 0;
       if (task_io_service_.handler_queue_end_)
       {
@@ -478,7 +471,7 @@ private:
     {
       lock_.lock();
       if (--task_io_service_.outstanding_work_ == 0)
-        task_io_service_.stop_all_threads();
+        task_io_service_.stop_all_threads(lock_);
     }
 
   private:
@@ -503,6 +496,9 @@ private:
     }
   } task_handler_;
 
+  // Whether the task has been interrupted.
+  bool task_interrupted_;
+
   // The count of unfinished work.
   int outstanding_work_;
 
@@ -522,7 +518,6 @@ private:
   struct idle_thread_info
   {
     event wakeup_event;
-    idle_thread_info* prev;
     idle_thread_info* next;
   };
 
diff --git a/libtorrent/include/libtorrent/asio/detail/win_event.hpp b/libtorrent/include/libtorrent/asio/detail/win_event.hpp
index 8de9383da..68f55ff13 100644
--- a/libtorrent/include/libtorrent/asio/detail/win_event.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/win_event.hpp
@@ -28,6 +28,7 @@
 #include "asio/detail/socket_types.hpp"
 
 #include "asio/detail/push_options.hpp"
+#include <boost/assert.hpp>
 #include <boost/throw_exception.hpp>
 #include "asio/detail/pop_options.hpp"
 
@@ -59,21 +60,31 @@ public:
   }
 
   // Signal the event.
-  void signal()
+  template <typename Lock>
+  void signal(Lock& lock)
   {
+    BOOST_ASSERT(lock.locked());
+    (void)lock;
     ::SetEvent(event_);
   }
 
   // Reset the event.
-  void clear()
+  template <typename Lock>
+  void clear(Lock& lock)
   {
+    BOOST_ASSERT(lock.locked());
+    (void)lock;
     ::ResetEvent(event_);
   }
 
   // Wait for the event to become signalled.
-  void wait()
+  template <typename Lock>
+  void wait(Lock& lock)
   {
+    BOOST_ASSERT(lock.locked());
+    lock.unlock();
     ::WaitForSingleObject(event_, INFINITE);
+    lock.lock();
   }
 
 private:
diff --git a/libtorrent/include/libtorrent/asio/detail/win_iocp_socket_service.hpp b/libtorrent/include/libtorrent/asio/detail/win_iocp_socket_service.hpp
index d0078978a..dcef56576 100644
--- a/libtorrent/include/libtorrent/asio/detail/win_iocp_socket_service.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/win_iocp_socket_service.hpp
@@ -137,7 +137,7 @@ public:
     enum
     {
       enable_connection_aborted = 1, // User wants connection_aborted errors.
-      user_set_linger = 2, // The user set the linger option.
+      close_might_block = 2, // User set linger option for blocking close.
       user_set_non_blocking = 4 // The user wants a non-blocking socket.
     };
 
@@ -170,7 +170,7 @@ public:
   typedef detail::select_reactor<true> reactor_type;
 
   // The maximum number of buffers to support in a single operation.
-  enum { max_buffers = 16 };
+  enum { max_buffers = 64 < max_iov_len ? 64 : max_iov_len };
 
   // Constructor.
   win_iocp_socket_service(asio::io_service& io_service)
@@ -192,7 +192,7 @@ public:
     while (impl)
     {
       asio::error_code ignored_ec;
-      close(*impl, ignored_ec);
+      close_for_destruction(*impl);
       impl = impl->next_;
     }
   }
@@ -217,34 +217,7 @@ public:
   // Destroy a socket implementation.
   void destroy(implementation_type& impl)
   {
-    if (impl.socket_ != invalid_socket)
-    {
-      // Check if the reactor was created, in which case we need to close the
-      // socket on the reactor as well to cancel any operations that might be
-      // running there.
-      reactor_type* reactor = static_cast<reactor_type*>(
-            interlocked_compare_exchange_pointer(
-              reinterpret_cast<void**>(&reactor_), 0, 0));
-      if (reactor)
-        reactor->close_descriptor(impl.socket_);
-
-      if (impl.flags_ & implementation_type::user_set_linger)
-      {
-        ::linger opt;
-        opt.l_onoff = 0;
-        opt.l_linger = 0;
-        asio::error_code ignored_ec;
-        socket_ops::setsockopt(impl.socket_,
-            SOL_SOCKET, SO_LINGER, &opt, sizeof(opt), ignored_ec);
-      }
-
-      asio::error_code ignored_ec;
-      socket_ops::close(impl.socket_, ignored_ec);
-      impl.socket_ = invalid_socket;
-      impl.flags_ = 0;
-      impl.cancel_token_.reset();
-      impl.safe_cancellation_thread_id_ = 0;
-    }
+    close_for_destruction(impl);
 
     // Remove implementation from linked list of all implementations.
     asio::detail::mutex::scoped_lock lock(mutex_);
@@ -353,6 +326,24 @@ public:
     {
       ec = asio::error::bad_descriptor;
     }
+    else if (FARPROC cancel_io_ex_ptr = ::GetProcAddress(
+          ::GetModuleHandle("KERNEL32"), "CancelIoEx"))
+    {
+      // The version of Windows supports cancellation from any thread.
+      typedef BOOL (WINAPI* cancel_io_ex_t)(HANDLE, LPOVERLAPPED);
+      cancel_io_ex_t cancel_io_ex = (cancel_io_ex_t)cancel_io_ex_ptr;
+      socket_type sock = impl.socket_;
+      HANDLE sock_as_handle = reinterpret_cast<HANDLE>(sock);
+      if (!cancel_io_ex(sock_as_handle, 0))
+      {
+        DWORD last_error = ::GetLastError();
+        ec = asio::error_code(last_error, asio::native_ecat);
+      }
+      else
+      {
+        ec = asio::error_code();
+      }
+    }
     else if (impl.safe_cancellation_thread_id_ == 0)
     {
       // No operations have been started, so there's nothing to cancel.
@@ -475,7 +466,12 @@ public:
       if (option.level(impl.protocol_) == SOL_SOCKET
           && option.name(impl.protocol_) == SO_LINGER)
       {
-        impl.flags_ |= implementation_type::user_set_linger;
+        const ::linger* linger_option =
+          reinterpret_cast<const ::linger*>(option.data(impl.protocol_));
+        if (linger_option->l_onoff != 0 && linger_option->l_linger != 0)
+          impl.flags_ |= implementation_type::close_might_block;
+        else
+          impl.flags_ &= ~implementation_type::close_might_block;
       }
 
       socket_ops::setsockopt(impl.socket_,
@@ -1950,6 +1946,43 @@ public:
   }
 
 private:
+  // Helper function to close a socket when the associated object is being
+  // destroyed.
+  void close_for_destruction(implementation_type& impl)
+  {
+    if (is_open(impl))
+    {
+      // Check if the reactor was created, in which case we need to close the
+      // socket on the reactor as well to cancel any operations that might be
+      // running there.
+      reactor_type* reactor = static_cast<reactor_type*>(
+            interlocked_compare_exchange_pointer(
+              reinterpret_cast<void**>(&reactor_), 0, 0));
+      if (reactor)
+        reactor->close_descriptor(impl.socket_);
+
+      // The socket destructor must not block. If the user has changed the
+      // linger option to block in the foreground, we will change it back to the
+      // default so that the closure is performed in the background.
+      if (impl.flags_ & implementation_type::close_might_block)
+      {
+        ::linger opt;
+        opt.l_onoff = 0;
+        opt.l_linger = 0;
+        asio::error_code ignored_ec;
+        socket_ops::setsockopt(impl.socket_,
+            SOL_SOCKET, SO_LINGER, &opt, sizeof(opt), ignored_ec);
+      }
+
+      asio::error_code ignored_ec;
+      socket_ops::close(impl.socket_, ignored_ec);
+      impl.socket_ = invalid_socket;
+      impl.flags_ = 0;
+      impl.cancel_token_.reset();
+      impl.safe_cancellation_thread_id_ = 0;
+    }
+  }
+
   // Helper function to emulate InterlockedCompareExchangePointer functionality
   // for:
   // - very old Platform SDKs; and
diff --git a/libtorrent/include/libtorrent/asio/detail/wrapped_handler.hpp b/libtorrent/include/libtorrent/asio/detail/wrapped_handler.hpp
index f757fd3dc..913a795dc 100644
--- a/libtorrent/include/libtorrent/asio/detail/wrapped_handler.hpp
+++ b/libtorrent/include/libtorrent/asio/detail/wrapped_handler.hpp
@@ -17,6 +17,10 @@
 
 #include "asio/detail/push_options.hpp"
 
+#include "asio/detail/push_options.hpp"
+#include <boost/type_traits.hpp>
+#include "asio/detail/pop_options.hpp"
+
 #include "asio/detail/bind_handler.hpp"
 #include "asio/detail/handler_alloc_helpers.hpp"
 #include "asio/detail/handler_invoke_helpers.hpp"
@@ -30,7 +34,9 @@ class wrapped_handler
 public:
   typedef void result_type;
 
-  wrapped_handler(Dispatcher& dispatcher, Handler handler)
+  wrapped_handler(
+      typename boost::add_reference<Dispatcher>::type dispatcher,
+      Handler handler)
     : dispatcher_(dispatcher),
       handler_(handler)
   {
@@ -117,7 +123,7 @@ public:
   }
 
 //private:
-  Dispatcher& dispatcher_;
+  Dispatcher dispatcher_;
   Handler handler_;
 };
 
@@ -171,9 +177,9 @@ inline void asio_handler_invoke(const Function& function,
         function, this_handler->handler_));
 }
 
-template <typename Function, typename Dispatcher, typename Handler>
+template <typename Function, typename Handler, typename Context>
 inline void asio_handler_invoke(const Function& function,
-    rewrapped_handler<Dispatcher, Handler>* this_handler)
+    rewrapped_handler<Handler, Context>* this_handler)
 {
   asio_handler_invoke_helpers::invoke(
       function, &this_handler->context_);
diff --git a/libtorrent/include/libtorrent/asio/impl/io_service.ipp b/libtorrent/include/libtorrent/asio/impl/io_service.ipp
index e973619d1..f51d3697d 100644
--- a/libtorrent/include/libtorrent/asio/impl/io_service.ipp
+++ b/libtorrent/include/libtorrent/asio/impl/io_service.ipp
@@ -128,11 +128,11 @@ template <typename Handler>
 #if defined(GENERATING_DOCUMENTATION)
 unspecified
 #else
-inline detail::wrapped_handler<io_service, Handler>
+inline detail::wrapped_handler<io_service&, Handler>
 #endif
 io_service::wrap(Handler handler)
 {
-  return detail::wrapped_handler<io_service, Handler>(*this, handler);
+  return detail::wrapped_handler<io_service&, Handler>(*this, handler);
 }
 
 inline io_service::work::work(asio::io_service& io_service)
diff --git a/libtorrent/include/libtorrent/asio/io_service.hpp b/libtorrent/include/libtorrent/asio/io_service.hpp
index b694545db..2101e56c4 100644
--- a/libtorrent/include/libtorrent/asio/io_service.hpp
+++ b/libtorrent/include/libtorrent/asio/io_service.hpp
@@ -320,7 +320,7 @@ public:
 #if defined(GENERATING_DOCUMENTATION)
   unspecified
 #else
-  detail::wrapped_handler<io_service, Handler>
+  detail::wrapped_handler<io_service&, Handler>
 #endif
   wrap(Handler handler);
 
diff --git a/libtorrent/include/libtorrent/asio/ip/basic_endpoint.hpp b/libtorrent/include/libtorrent/asio/ip/basic_endpoint.hpp
index 3ca91dc03..499d82631 100644
--- a/libtorrent/include/libtorrent/asio/ip/basic_endpoint.hpp
+++ b/libtorrent/include/libtorrent/asio/ip/basic_endpoint.hpp
@@ -172,7 +172,7 @@ public:
   /// The protocol associated with the endpoint.
   protocol_type protocol() const
   {
-    if (is_v4())
+    if (is_v4(data_))
       return InternetProtocol::v4();
     return InternetProtocol::v6();
   }
@@ -192,7 +192,7 @@ public:
   /// Get the underlying size of the endpoint in the native type.
   size_type size() const
   {
-    if (is_v4())
+    if (is_v4(data_))
       return sizeof(asio::detail::sockaddr_in4_type);
     else
       return sizeof(asio::detail::sockaddr_in6_type);
@@ -218,7 +218,7 @@ public:
   /// the host's byte order.
   unsigned short port() const
   {
-    if (is_v4())
+    if (is_v4(data_))
     {
       return asio::detail::socket_ops::network_to_host_short(
           reinterpret_cast<const asio::detail::sockaddr_in4_type&>(
@@ -236,7 +236,7 @@ public:
   /// the host's byte order.
   void port(unsigned short port_num)
   {
-    if (is_v4())
+    if (is_v4(data_))
     {
       reinterpret_cast<asio::detail::sockaddr_in4_type&>(data_).sin_port
         = asio::detail::socket_ops::host_to_network_short(port_num);
@@ -252,7 +252,7 @@ public:
   asio::ip::address address() const
   {
     using namespace std; // For memcpy.
-    if (is_v4())
+    if (is_v4(data_))
     {
       const asio::detail::sockaddr_in4_type& data
         = reinterpret_cast<const asio::detail::sockaddr_in4_type&>(
@@ -306,15 +306,27 @@ public:
 
 private:
   // Helper function to determine whether the endpoint is IPv4.
-  bool is_v4() const
-  {
 #if defined(_AIX)
-    return data_.__ss_family == AF_INET;
-#else
-    return data_.ss_family == AF_INET;
-#endif
+  template <typename T, unsigned short (T::*)> struct is_v4_helper {};
+
+  template <typename T>
+  static bool is_v4(const T& ss, is_v4_helper<T, &T::ss_family>* = 0)
+  {
+    return ss.ss_family == AF_INET;
   }
 
+  template <typename T>
+  static bool is_v4(const T& ss, is_v4_helper<T, &T::__ss_family>* = 0)
+  {
+    return ss.__ss_family == AF_INET;
+  }
+#else
+  static bool is_v4(const asio::detail::sockaddr_storage_type& ss)
+  {
+    return ss.ss_family == AF_INET;
+  }
+#endif
+
   // The underlying IP socket address.
   asio::detail::sockaddr_storage_type data_;
 };