1 | // |
2 | // detail/call_stack.hpp |
3 | // ~~~~~~~~~~~~~~~~~~~~~ |
4 | // |
5 | // Copyright (c) 2003-2015 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/config.hpp> |
19 | #include <boost/asio/detail/noncopyable.hpp> |
20 | #include <boost/asio/detail/tss_ptr.hpp> |
21 | |
22 | #include <boost/asio/detail/push_options.hpp> |
23 | |
24 | namespace boost { |
25 | namespace asio { |
26 | namespace detail { |
27 | |
28 | // Helper class to determine whether or not the current thread is inside an |
29 | // invocation of io_service::run() for a specified io_service object. |
30 | template <typename Key, typename Value = unsigned char> |
31 | class call_stack |
32 | { |
33 | public: |
34 | // Context class automatically pushes the key/value pair on to the stack. |
35 | class context |
36 | : private noncopyable |
37 | { |
38 | public: |
39 | // Push the key on to the stack. |
40 | explicit context(Key* k) |
41 | : key_(k), |
42 | next_(call_stack<Key, Value>::top_) |
43 | { |
44 | value_ = reinterpret_cast<unsigned char*>(this); |
45 | call_stack<Key, Value>::top_ = this; |
46 | } |
47 | |
48 | // Push the key/value pair on to the stack. |
49 | context(Key* k, Value& v) |
50 | : key_(k), |
51 | value_(&v), |
52 | next_(call_stack<Key, Value>::top_) |
53 | { |
54 | call_stack<Key, Value>::top_ = this; |
55 | } |
56 | |
57 | // Pop the key/value pair from the stack. |
58 | ~context() |
59 | { |
60 | call_stack<Key, Value>::top_ = next_; |
61 | } |
62 | |
63 | // Find the next context with the same key. |
64 | Value* next_by_key() const |
65 | { |
66 | context* elem = next_; |
67 | while (elem) |
68 | { |
69 | if (elem->key_ == key_) |
70 | return elem->value_; |
71 | elem = elem->next_; |
72 | } |
73 | return 0; |
74 | } |
75 | |
76 | private: |
77 | friend class call_stack<Key, Value>; |
78 | |
79 | // The key associated with the context. |
80 | Key* key_; |
81 | |
82 | // The value associated with the context. |
83 | Value* value_; |
84 | |
85 | // The next element in the stack. |
86 | context* next_; |
87 | }; |
88 | |
89 | friend class context; |
90 | |
91 | // Determine whether the specified owner is on the stack. Returns address of |
92 | // key if present, 0 otherwise. |
93 | static Value* contains(Key* k) |
94 | { |
95 | context* elem = top_; |
96 | while (elem) |
97 | { |
98 | if (elem->key_ == k) |
99 | return elem->value_; |
100 | elem = elem->next_; |
101 | } |
102 | return 0; |
103 | } |
104 | |
105 | // Obtain the value at the top of the stack. |
106 | static Value* top() |
107 | { |
108 | context* elem = top_; |
109 | return elem ? elem->value_ : 0; |
110 | } |
111 | |
112 | private: |
113 | // The top of the stack of calls for the current thread. |
114 | static tss_ptr<context> top_; |
115 | }; |
116 | |
117 | template <typename Key, typename Value> |
118 | tss_ptr<typename call_stack<Key, Value>::context> |
119 | call_stack<Key, Value>::top_; |
120 | |
121 | } // namespace detail |
122 | } // namespace asio |
123 | } // namespace boost |
124 | |
125 | #include <boost/asio/detail/pop_options.hpp> |
126 | |
127 | #endif // BOOST_ASIO_DETAIL_CALL_STACK_HPP |
128 | |