1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
//
// detail/call_stack.hpp
// ~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 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 ASIO_DETAIL_CALL_STACK_HPP
#define ASIO_DETAIL_CALL_STACK_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#include "asio/detail/noncopyable.hpp"
#include "asio/detail/tss_ptr.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
namespace detail {
// Helper class to determine whether or not the current thread is inside an
// invocation of io_context::run() for a specified io_context object.
template <typename Key, typename Value = unsigned char>
class call_stack
{
public:
// Context class automatically pushes the key/value pair on to the stack.
class context
: private noncopyable
{
public:
// Push the key on to the stack.
explicit context(Key* k)
: key_(k),
next_(call_stack<Key, Value>::top_)
{
value_ = reinterpret_cast<unsigned char*>(this);
call_stack<Key, Value>::top_ = this;
}
// Push the key/value pair on to the stack.
context(Key* k, Value& v)
: key_(k),
value_(&v),
next_(call_stack<Key, Value>::top_)
{
call_stack<Key, Value>::top_ = this;
}
// Pop the key/value pair from the stack.
~context()
{
call_stack<Key, Value>::top_ = next_;
}
// Find the next context with the same key.
Value* next_by_key() const
{
context* elem = next_;
while (elem)
{
if (elem->key_ == key_)
return elem->value_;
elem = elem->next_;
}
return 0;
}
private:
friend class call_stack<Key, Value>;
// The key associated with the context.
Key* key_;
// The value associated with the context.
Value* value_;
// The next element in the stack.
context* next_;
};
friend class context;
// Determine whether the specified owner is on the stack. Returns address of
// key if present, 0 otherwise.
static Value* contains(Key* k)
{
context* elem = top_;
while (elem)
{
if (elem->key_ == k)
return elem->value_;
elem = elem->next_;
}
return 0;
}
// Obtain the value at the top of the stack.
static Value* top()
{
context* elem = top_;
return elem ? elem->value_ : 0;
}
private:
// The top of the stack of calls for the current thread.
static tss_ptr<context> top_;
};
template <typename Key, typename Value>
tss_ptr<typename call_stack<Key, Value>::context>
call_stack<Key, Value>::top_;
} // namespace detail
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // ASIO_DETAIL_CALL_STACK_HPP
|
