boost/asio/detail/call_stack.hpp

   1 //
   2 // call_stack.hpp
   3 // ~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
   6 //
   7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   9 //
  10
  11 #ifndef BOOST_ASIO_DETAIL_CALL_STACK_HPP
  12 #define BOOST_ASIO_DETAIL_CALL_STACK_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/push_options.hpp>
  19
  20 #include <boost/asio/detail/noncopyable.hpp>
  21 #include <boost/asio/detail/tss_ptr.hpp>
  22
  23 namespace boost {
  24 namespace asio {
  25 namespace detail {
  26
  27 // Helper class to determine whether or not the current thread is inside an
  28 // invocation of io_service::run() for a specified io_service object.
  29 template <typename Owner>
  30 class call_stack
  31 {
  32 public:
  33   // Context class automatically pushes an owner on to the stack.
  34   class context
  35     : private noncopyable
  36   {
  37   public:
  38     // Push the owner on to the stack.
  39     explicit context(Owner* d)
  40       : owner_(d),
  41         next_(call_stack<Owner>::top_)
  42     {
  43       call_stack<Owner>::top_ = this;
  44     }
  45
  46     // Pop the owner from the stack.
  47     ~context()
  48     {
  49       call_stack<Owner>::top_ = next_;
  50     }
  51
  52   private:
  53     friend class call_stack<Owner>;
  54
  55     // The owner associated with the context.
  56     Owner* owner_;
  57
  58     // The next element in the stack.
  59     context* next_;
  60   };
  61
  62   friend class context;
  63
  64   // Determine whether the specified owner is on the stack.
  65   static bool contains(Owner* d)
  66   {
  67     context* elem = top_;
  68     while (elem)
  69     {
  70       if (elem->owner_ == d)
  71         return true;
  72       elem = elem->next_;
  73     }
  74     return false;
  75   }
  76
  77 private:
  78   // The top of the stack of calls for the current thread.
  79   static tss_ptr<context> top_;
  80 };
  81
  82 template <typename Owner>
  83 tss_ptr<typename call_stack<Owner>::context>
  84 call_stack<Owner>::top_;
  85
  86 } // namespace detail
  87 } // namespace asio
  88 } // namespace boost
  89
  90 #include <boost/asio/detail/pop_options.hpp>
  91
  92 #endif // BOOST_ASIO_DETAIL_CALL_STACK_HPP