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
|
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2006-2007. 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)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
//[doc_scoped_ptr
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/smart_ptr/scoped_ptr.hpp>
using namespace boost::interprocess;
class my_class
{};
class my_exception
{};
//A functor that destroys the shared memory object
template<class T>
class my_deleter
{
private:
//A typedef to save typing
typedef managed_shared_memory::segment_manager segment_manager;
//This my_deleter is created in the stack, not in shared memory,
//so we can use raw pointers
segment_manager *mp_segment_manager;
public:
//This typedef will specify the pointer type that
//scoped_ptr will store
typedef T *pointer;
//Constructor
my_deleter(segment_manager *s_mngr)
: mp_segment_manager(s_mngr){}
void operator()(pointer object_to_delete)
{ mp_segment_manager->destroy_ptr(object_to_delete); }
};
int main ()
{
//Create shared memory
shared_memory_object::remove("my_shmem");
try{
managed_shared_memory shmem(create_only, "my_shmem", 10000);
//In the first try, there will be no exceptions
//in the second try we will throw an exception
for(int i = 0; i < 2; ++i){
//Create an object in shared memory
my_class * my_object = shmem.construct<my_class>("my_object")();
my_class * my_object2 = shmem.construct<my_class>(anonymous_instance)();
shmem.destroy_ptr(my_object2);
//Since the next shared memory allocation can throw
//assign it to a scoped_ptr so that if an exception occurs
//we destroy the object automatically
my_deleter<my_class> d(shmem.get_segment_manager());
try{
scoped_ptr<my_class, my_deleter<my_class> > s_ptr(my_object, d);
//Let's emulate a exception capable operation
//In the second try, throw an exception
if(i == 1){
throw(my_exception());
}
//If we have passed the dangerous zone
//we can release the scoped pointer
//to avoid destruction
s_ptr.release();
}
catch(const my_exception &){}
//Here, scoped_ptr is destroyed
//so it we haven't thrown an exception
//the object should be there, otherwise, destroyed
if(i == 0){
//Make sure the object is alive
if(!shmem.find<my_class>("my_object").first){
return 1;
}
//Now we can use it and delete it manually
shmem.destroy<my_class>("my_object");
}
else{
//Make sure the object has been deleted
if(shmem.find<my_class>("my_object").first){
return 1;
}
}
}
}
catch(...){
shared_memory_object::remove("my_shmem");
throw;
}
shared_memory_object::remove("my_shmem");
return 0;
}
//]
#include <boost/interprocess/detail/config_end.hpp>
|
