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
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
/* -*- C++ -*- */
// $Id$
// ============================================================================
//
// = LIBRARY
// ace
//
// = FILENAME
// Singleton.h
//
// = DESCRIPTION
//
// = AUTHOR
// Tim Harrison (harrison@cs.wustl.edu), Douglas C. Schmidt, Chris
// Lahey, Rich Christy, and David Levine.
//
// ============================================================================
#ifndef ACE_SINGLETON_H
#define ACE_SINGLETON_H
#include "ace/Synch.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
template <class TYPE, class ACE_LOCK>
class ACE_Singleton : public ACE_Cleanup
{
// = TITLE
// A Singleton Adapter uses the Adapter pattern to turn ordinary
// classes into Singletons optimized with the Double-Checked
// Locking optimization pattern.
//
// = DESCRIPTION
// This implementation is a slight variation on the GoF
// Singleton pattern. In particular, a single
// <ACE_Singleton<TYPE, ACE_LOCK> > instance is allocated here,
// not a <TYPE> instance. The reason for this is to allow
// registration with the <ACE_Object_Manager>, so that the
// Singleton can be cleaned up when the process exits. For this
// scheme to work, a (static) <cleanup> function must be
// provided. <ACE_Singleton> provides one so that TYPE doesn't
// need to.
//
// If you want to make sure that only the singleton instance of
// <T> is created, and that users cannot create their own
// instances of <T>, do the following to class <T>:
//
// (a) Make the constructor of <T> private (or protected)
// (b) Make Singleton a friend of <T>
//
// Here is an example:
//
// class foo
// {
// friend class ACE_Singleton<foo, ACE_Null_Mutex>;
// private:
// foo () { cout << "foo constructed" << endl; }
// ~foo () { cout << "foo destroyed" << endl; }
// };
//
// typedef ACE_Singleton<foo, ACE_Null_Mutex> FOO;
//
// NOTE: the best types to use for ACE_LOCK are
// ACE_Recursive_Thread_Mutex and ACE_Null_Mutex.
// ACE_Recursive_Thread_Mutex should be used in multi-threaded
// programs in which it is possible for more than one thread to
// access the <ACE_Singleton<TYPE, ACE_LOCK>> instance.
// ACE_Null_Mutex can be used otherwise. The reason that these
// types of locks are best has to do with their allocation by
// the ACE_Object_Manager. Single ACE_Recursive_Thread_Mutex
// and ACE_Null_Mutex instances are used for all ACE_Singleton
// instantiations. However, other types of locks are allocated
// per ACE_Singleton instantiation.
//
public:
static TYPE *instance (void);
// Global access point to the Singleton.
virtual void cleanup (void *param = 0);
// Cleanup method, used by <ace_cleanup_destroyer> to destroy the
// <ACE_Singleton>.
static void dump (void);
// Dump the state of the object.
protected:
ACE_Singleton (void);
// Default constructor.
TYPE instance_;
// Contained instance.
#if !defined (ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES)
static ACE_Singleton<TYPE, ACE_LOCK> *singleton_;
// Pointer to the Singleton (ACE_Cleanup) instance.
#endif /* ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES */
static ACE_Singleton<TYPE, ACE_LOCK> *&instance_i (void);
// Get pointer to the Singleton instance.
};
template <class TYPE, class ACE_LOCK>
class ACE_Unmanaged_Singleton : public ACE_Singleton <TYPE, ACE_LOCK>
{
// = TITLE
// Same as <ACE_Singleton>, except does _not_ register with
// <ACE_Object_Manager> for destruction.
//
// = DESCRIPTION
// This version of <ACE_Singleton> can be used if, for example,
// its DLL will be unloaded before the <ACE_Object_Manager>
// destroys the instance. Unlike with <ACE_Singleton>, the
// application is responsible for explicitly destroying the
// instance after it is no longer needed (if it wants to avoid
// memory leaks, at least). The <close> static member function
// must be used to explicitly destroy the Singleton.
//
public:
static TYPE *instance (void);
// Global access point to the Singleton.
static void close (void);
// Explicitly delete the Singleton instance.
static void dump (void);
// Dump the state of the object.
protected:
ACE_Unmanaged_Singleton (void);
// Default constructor.
#if !defined (ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES)
static ACE_Unmanaged_Singleton<TYPE, ACE_LOCK> *singleton_;
// Pointer to the Singleton (ACE_Cleanup) instance.
#endif /* ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES */
static ACE_Unmanaged_Singleton<TYPE, ACE_LOCK> *&instance_i (void);
// Get pointer to the Singleton instance.
};
template <class TYPE, class ACE_LOCK>
class ACE_TSS_Singleton : public ACE_Cleanup
{
// = TITLE
// This class uses the Adapter pattern to turn ordinary classes
// into Thread-specific Singletons optimized with the
// Double-Checked Locking optimization pattern.
//
// = DESCRIPTION
// This implementation is another variation on the GoF Singleton
// pattern. In this case, a single <ACE_TSS_Singleton<TYPE,
// LOCK> > instance is allocated here, not a <TYPE> instance.
// Each call to the <instance> static method returns a Singleton
// whose pointer resides in thread-specific storage. As with
// <ACE_Singleton>, we use the <ACE_Object_Manager> so that the
// Singleton can be cleaned up when the process exits. For this
// scheme to work, a (static) <cleanup> function must be
// provided. <ACE_Singleton> provides one so that TYPE doesn't
// need to.
public:
static TYPE *instance (void);
// Global access point to the Singleton.
virtual void cleanup (void *param = 0);
// Cleanup method, used by <ace_cleanup_destroyer> to destroy the
// singleton.
static void dump (void);
// Dump the state of the object.
protected:
ACE_TSS_Singleton (void);
// Default constructor.
ACE_TSS_TYPE (TYPE) instance_;
// Contained instance.
#if !defined (ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES)
static ACE_TSS_Singleton<TYPE, ACE_LOCK> *singleton_;
// Pointer to the Singleton (ACE_Cleanup) instance.
#endif /* ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES */
static ACE_TSS_Singleton<TYPE, ACE_LOCK> *&instance_i (void);
// Get pointer to the TSS Singleton instance.
};
template <class TYPE, class ACE_LOCK>
class ACE_Unmanaged_TSS_Singleton : public ACE_TSS_Singleton <TYPE, ACE_LOCK>
{
// = TITLE
// Same as <ACE_TSS_Singleton>, except does _not_ register with
// <ACE_Object_Manager> for destruction.
//
// = DESCRIPTION
// This version of <ACE_TSS_Singleton> can be used if, for
// example, its DLL will be unloaded before the
// <ACE_Object_Manager> destroys the instance. Unlike with
// <ACE_Singleton>, the application is responsible for
// explicitly destroying the instance after it is no longer
// needed (if it wants to avoid memory leaks, at least). The
// <close> static member function must be used to explicitly
// destroy the Singleton.
//
public:
static TYPE *instance (void);
// Global access point to the Singleton.
static void close (void);
// Explicitly delete the Singleton instance.
static void dump (void);
// Dump the state of the object.
protected:
ACE_Unmanaged_TSS_Singleton (void);
// Default constructor.
#if !defined (ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES)
static ACE_Unmanaged_TSS_Singleton<TYPE, ACE_LOCK> *singleton_;
// Pointer to the Singleton (ACE_Cleanup) instance.
#endif /* ACE_LACKS_STATIC_DATA_MEMBER_TEMPLATES */
static ACE_Unmanaged_TSS_Singleton<TYPE, ACE_LOCK> *&instance_i (void);
// Get pointer to the Singleton instance.
};
#if defined (__ACE_INLINE__)
#include "ace/Singleton.i"
#endif /* __ACE_INLINE__ */
#if defined (ACE_TEMPLATES_REQUIRE_SOURCE)
#include "ace/Singleton.cpp"
#endif /* ACE_TEMPLATES_REQUIRE_SOURCE */
#if defined (ACE_TEMPLATES_REQUIRE_PRAGMA)
#pragma implementation ("Singleton.cpp")
#endif /* ACE_TEMPLATES_REQUIRE_PRAGMA */
#endif /* ACE_SINGLETON_H */
|
