Imported existing code

libraries/include/boost/asio/detail/indirect_handler_queue.hpp

@@ -0,0 +1,293 @@
+//
+// indirect_handler_queue.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_INDIRECT_HANDLER_QUEUE_HPP
+#define BOOST_ASIO_DETAIL_INDIRECT_HANDLER_QUEUE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/push_options.hpp>
+
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1310)
+extern "C" void _ReadWriteBarrier();
+# pragma intrinsic(_ReadWriteBarrier)
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1310)
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+class indirect_handler_queue
+  : private noncopyable
+{
+public:
+  class handler;
+
+  // Element for a node in the queue.
+  class node
+  {
+  public:
+    node()
+      : version_(0),
+        handler_(0),
+        next_(0)
+    {
+    }
+
+  private:
+    friend class indirect_handler_queue;
+    unsigned long version_;
+    handler* handler_;
+    node* next_;
+  };
+
+  // Base class for handlers in the queue.
+  class handler
+    : private noncopyable
+  {
+  public:
+    void invoke()
+    {
+      invoke_func_(this);
+    }
+
+    void destroy()
+    {
+      destroy_func_(this);
+    }
+
+  protected:
+    typedef void (*invoke_func_type)(handler*);
+    typedef void (*destroy_func_type)(handler*);
+
+    handler(invoke_func_type invoke_func,
+        destroy_func_type destroy_func)
+      : node_(new node),
+        invoke_func_(invoke_func),
+        destroy_func_(destroy_func)
+    {
+    }
+
+    ~handler()
+    {
+      if (node_)
+        delete node_;
+    }
+
+  private:
+    friend class indirect_handler_queue;
+    node* node_;
+    invoke_func_type invoke_func_;
+    destroy_func_type destroy_func_;
+  };
+
+  // Smart point to manager handler lifetimes.
+  class scoped_ptr
+    : private noncopyable
+  {
+  public:
+    explicit scoped_ptr(handler* h)
+      : handler_(h)
+    {
+    }
+
+    ~scoped_ptr()
+    {
+      if (handler_)
+        handler_->destroy();
+    }
+
+    handler* get() const
+    {
+      return handler_;
+    }
+
+    handler* release()
+    {
+      handler* tmp = handler_;
+      handler_ = 0;
+      return tmp;
+    }
+
+  private:
+    handler* handler_;
+  };
+
+  // Constructor.
+  indirect_handler_queue()
+    : front_(new node),
+      back_(front_),
+      next_version_(1)
+  {
+  }
+
+  // Destructor.
+  ~indirect_handler_queue()
+  {
+    while (front_)
+    {
+      node* tmp = front_;
+      front_ = front_->next_;
+      delete tmp;
+    }
+  }
+
+  // Wrap a handler to be pushed into the queue.
+  template <typename Handler>
+  static handler* wrap(Handler h)
+  {
+    // 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(h);
+    handler_ptr<alloc_traits> ptr(raw_ptr, h);
+    return ptr.release();
+  }
+
+  // Determine whether the queue has something ready to pop.
+  bool poppable()
+  {
+    return front_->next_ != 0;
+  }
+
+  // The version number at the front of the queue.
+  unsigned long front_version()
+  {
+    return front_->version_;
+  }
+
+  // The version number at the back of the queue.
+  unsigned long back_version()
+  {
+    return back_->version_;
+  }
+
+  // Pop a handler from the front of the queue.
+  handler* pop()
+  {
+    node* n = front_;
+    node* new_front = n->next_;
+    if (new_front)
+    {
+      handler* h = new_front->handler_;
+      h->node_ = n;
+      new_front->handler_ = 0;
+      front_ = new_front;
+      return h;
+    }
+    return 0;
+  }
+
+  // Push a handler on to the back of the queue.
+  void push(handler* h)
+  {
+    node* n = h->node_;
+    h->node_ = 0;
+    n->version_ = next_version_;
+    next_version_ += 2;
+    n->handler_ = h;
+    n->next_ = 0;
+    memory_barrier();
+    back_->next_ = n;
+    back_ = n;
+  }
+
+private:
+  // Template wrapper for handlers.
+  template <typename Handler>
+  class handler_wrapper
+    : public handler
+  {
+  public:
+    handler_wrapper(Handler h)
+      : handler(
+          &handler_wrapper<Handler>::do_call,
+          &handler_wrapper<Handler>::do_destroy),
+        handler_(h)
+    {
+    }
+
+    static void do_call(handler* base)
+    {
+      // Take ownership of the handler object.
+      typedef handler_wrapper<Handler> this_type;
+      this_type* h(static_cast<this_type*>(base));
+      typedef handler_alloc_traits<Handler, this_type> alloc_traits;
+      handler_ptr<alloc_traits> ptr(h->handler_, h);
+
+      // Make a copy of the handler so that the memory can be deallocated before
+      // the upcall is made.
+      Handler handler(h->handler_);
+
+      // Free the memory associated with the handler.
+      ptr.reset();
+
+      // Make the upcall.
+      boost_asio_handler_invoke_helpers::invoke(handler, &handler);
+    }
+
+    static void do_destroy(handler* base)
+    {
+      // Take ownership of the handler object.
+      typedef handler_wrapper<Handler> this_type;
+      this_type* h(static_cast<this_type*>(base));
+      typedef handler_alloc_traits<Handler, this_type> alloc_traits;
+      handler_ptr<alloc_traits> ptr(h->handler_, h);
+
+      // A sub-object of the handler may be the true owner of the memory
+      // associated with the handler. Consequently, a local copy of the handler
+      // is required to ensure that any owning sub-object remains valid until
+      // after we have deallocated the memory here.
+      Handler handler(h->handler_);
+      (void)handler;
+
+      // Free the memory associated with the handler.
+      ptr.reset();
+    }
+
+  private:
+    Handler handler_;
+  };
+
+  // Helper function to create a memory barrier.
+  static void memory_barrier()
+  {
+#if defined(_GLIBCXX_WRITE_MEM_BARRIER)
+    _GLIBCXX_WRITE_MEM_BARRIER;
+#elif defined(_MSC_VER) && (_MSC_VER >= 1310)
+    _ReadWriteBarrier();
+#else
+# error memory barrier required
+#endif
+  }
+
+  // The front of the queue.
+  node* front_;
+
+  // The back of the queue.
+  node* back_;
+
+  // The next version counter to be assigned to a node.
+  unsigned long next_version_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_INDIRECT_HANDLER_QUEUE_HPP