1 /*
2 * Copyright (C) 1996-2021 The Squid Software Foundation and contributors
3 *
4 * Squid software is distributed under GPLv2+ license and includes
5 * contributions from numerous individuals and organizations.
6 * Please see the COPYING and CONTRIBUTORS files for details.
7 */
8
9 #ifndef SQUID_IPC_MEM_POINTER_H
10 #define SQUID_IPC_MEM_POINTER_H
11
12 #include "base/RefCount.h"
13 #include "base/TextException.h"
14 #include "ipc/mem/Segment.h"
15
16 namespace Ipc
17 {
18
19 namespace Mem
20 {
21
22 /// allocates/deallocates shared memory; creates and later destroys a
23 /// Class object using that memory
24 template <class Class>
25 class Owner
26 {
27 public:
28 static Owner *New(const char *const id);
29 template <class P1>
30 static Owner *New(const char *const id, const P1 &p1);
31 template <class P1, class P2>
32 static Owner *New(const char *const id, const P1 &p1, const P2 &p2);
33 template <class P1, class P2, class P3>
34 static Owner *New(const char *const id, const P1 &p1, const P2 &p2, const P3 &p3);
35 template <class P1, class P2, class P3, class P4>
36 static Owner *New(const char *const id, const P1 &p1, const P2 &p2, const P3 &p3, const P4 &p4);
37
38 ~Owner();
39
40 /// Raw access; handy to finalize initiatization, but avoid if possible.
object()41 Class *object() { return theObject; }
42
43 private:
44 Owner(const char *const id, const off_t sharedSize);
45
46 // not implemented
47 Owner(const Owner &);
48 Owner &operator =(const Owner &);
49
50 Segment theSegment; ///< shared memory segment that holds the object
51 Class *theObject; ///< shared object
52 };
53
54 template <class Class> class Pointer;
55
56 /// attaches to a shared memory segment with Class object owned by Owner
57 template <class Class>
58 class Object: public RefCountable
59 {
60 public:
61 static Pointer<Class> Old(const char *const id);
62
63 private:
64 explicit Object(const char *const id);
65
66 // not implemented
67 Object(const Object &);
68 Object &operator =(const Object &);
69
70 Segment theSegment; ///< shared memory segment that holds the object
71 Class *theObject; ///< shared object
72
73 friend class Pointer<Class>;
74 };
75
76 /// uses a refcounted pointer to Object<Class> as a parent, but
77 /// translates its API to return raw Class pointers
78 template <class Class>
79 class Pointer: public RefCount< Object<Class> >
80 {
81 private:
82 typedef RefCount< Object<Class> > Base;
83
84 public:
Base(anObject)85 explicit Pointer(Object<Class> *const anObject = NULL): Base(anObject) {}
86
87 Class *operator ->() const { return Base::operator ->()->theObject; }
88 Class &operator *() const { return *Base::operator *().theObject; }
getRaw()89 const Class *getRaw() const { return Base::getRaw()->theObject; }
getRaw()90 Class *getRaw() { return Base::getRaw()->theObject; }
91 };
92
93 // Owner implementation
94
95 template <class Class>
Owner(const char * const id,const off_t sharedSize)96 Owner<Class>::Owner(const char *const id, const off_t sharedSize):
97 theSegment(id), theObject(NULL)
98 {
99 theSegment.create(sharedSize);
100 Must(theSegment.mem());
101 }
102
103 template <class Class>
~Owner()104 Owner<Class>::~Owner()
105 {
106 if (theObject)
107 theObject->~Class();
108 }
109
110 template <class Class>
111 Owner<Class> *
New(const char * const id)112 Owner<Class>::New(const char *const id)
113 {
114 const off_t sharedSize = Class::SharedMemorySize();
115 Owner *const owner = new Owner(id, sharedSize);
116 owner->theObject = new (owner->theSegment.reserve(sharedSize)) Class;
117 return owner;
118 }
119
120 template <class Class> template <class P1>
121 Owner<Class> *
New(const char * const id,const P1 & p1)122 Owner<Class>::New(const char *const id, const P1 &p1)
123 {
124 const off_t sharedSize = Class::SharedMemorySize(p1);
125 Owner *const owner = new Owner(id, sharedSize);
126 owner->theObject = new (owner->theSegment.reserve(sharedSize)) Class(p1);
127 return owner;
128 }
129
130 template <class Class> template <class P1, class P2>
131 Owner<Class> *
New(const char * const id,const P1 & p1,const P2 & p2)132 Owner<Class>::New(const char *const id, const P1 &p1, const P2 &p2)
133 {
134 const off_t sharedSize = Class::SharedMemorySize(p1, p2);
135 Owner *const owner = new Owner(id, sharedSize);
136 owner->theObject = new (owner->theSegment.reserve(sharedSize)) Class(p1, p2);
137 return owner;
138 }
139
140 template <class Class> template <class P1, class P2, class P3>
141 Owner<Class> *
New(const char * const id,const P1 & p1,const P2 & p2,const P3 & p3)142 Owner<Class>::New(const char *const id, const P1 &p1, const P2 &p2, const P3 &p3)
143 {
144 const off_t sharedSize = Class::SharedMemorySize(p1, p2, p3);
145 Owner *const owner = new Owner(id, sharedSize);
146 owner->theObject = new (owner->theSegment.reserve(sharedSize)) Class(p1, p2, p3);
147 return owner;
148 }
149
150 template <class Class> template <class P1, class P2, class P3, class P4>
151 Owner<Class> *
New(const char * const id,const P1 & p1,const P2 & p2,const P3 & p3,const P4 & p4)152 Owner<Class>::New(const char *const id, const P1 &p1, const P2 &p2, const P3 &p3, const P4 &p4)
153 {
154 const off_t sharedSize = Class::SharedMemorySize(p1, p2, p3, p4);
155 Owner *const owner = new Owner(id, sharedSize);
156 owner->theObject = new (owner->theSegment.reserve(sharedSize)) Class(p1, p2, p3, p4);
157 return owner;
158 }
159
160 // Object implementation
161
162 template <class Class>
Object(const char * const id)163 Object<Class>::Object(const char *const id): theSegment(id)
164 {
165 theSegment.open();
166 Must(theSegment.mem());
167 theObject = reinterpret_cast<Class*>(theSegment.mem());
168 Must(static_cast<off_t>(theObject->sharedMemorySize()) <= theSegment.size());
169 }
170
171 template <class Class>
172 Pointer<Class>
Old(const char * const id)173 Object<Class>::Old(const char *const id)
174 {
175 return Pointer<Class>(new Object(id));
176 }
177
178 // convenience macros for creating shared objects
179 #define shm_new(Class) Ipc::Mem::Owner<Class>::New
180 #define shm_old(Class) Ipc::Mem::Object<Class>::Old
181
182 } // namespace Mem
183
184 } // namespace Ipc
185
186 #endif /* SQUID_IPC_MEM_POINTER_H */
187
188