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1 office 1 /**
2 * @file BRefTarget.h
3 * @author Ambroz Bizjak <ambrop7@gmail.com>
4 *
5 * @section LICENSE
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the author nor the
15 * names of its contributors may be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29  
30 #ifndef BADVPN_B_REF_TARGET_H
31 #define BADVPN_B_REF_TARGET_H
32  
33 #include <limits.h>
34  
35 #include <misc/debug.h>
36 #include <base/DebugObject.h>
37  
38 /**
39 * Represents a reference-counted object.
40 */
41 typedef struct BRefTarget_s BRefTarget;
42  
43 /**
44 * Callback function called after the reference count of a {@link BRefTarget}
45 * reaches has reached zero. At this point the BRefTarget object has already
46 * been invalidated, i.e. {@link BRefTarget_Ref} must not be called on this
47 * object after this handler is called.
48 */
49 typedef void (*BRefTarget_func_release) (BRefTarget *o);
50  
51 struct BRefTarget_s {
52 BRefTarget_func_release func_release;
53 int refcnt;
54 DebugObject d_obj;
55 };
56  
57 /**
58 * Initializes a reference target object. The initial reference count of the object
59 * is 1. The \a func_release argument specifies the function to be called from
60 * {@link BRefTarget_Deref} when the reference count reaches zero.
61 */
62 static void BRefTarget_Init (BRefTarget *o, BRefTarget_func_release func_release);
63  
64 /**
65 * Decrements the reference count of a reference target object. If the reference
66 * count has reached zero, the object's {@link BRefTarget_func_release} function
67 * is called, and the object is considered destroyed.
68 */
69 static void BRefTarget_Deref (BRefTarget *o);
70  
71 /**
72 * Increments the reference count of a reference target object.
73 * Returns 1 on success and 0 on failure.
74 */
75 static int BRefTarget_Ref (BRefTarget *o) WARN_UNUSED;
76  
77 static void BRefTarget_Init (BRefTarget *o, BRefTarget_func_release func_release)
78 {
79 ASSERT(func_release)
80  
81 o->func_release = func_release;
82 o->refcnt = 1;
83  
84 DebugObject_Init(&o->d_obj);
85 }
86  
87 static void BRefTarget_Deref (BRefTarget *o)
88 {
89 DebugObject_Access(&o->d_obj);
90 ASSERT(o->refcnt > 0)
91  
92 o->refcnt--;
93  
94 if (o->refcnt == 0) {
95 DebugObject_Free(&o->d_obj);
96 o->func_release(o);
97 }
98 }
99  
100 static int BRefTarget_Ref (BRefTarget *o)
101 {
102 DebugObject_Access(&o->d_obj);
103 ASSERT(o->refcnt > 0)
104  
105 if (o->refcnt == INT_MAX) {
106 return 0;
107 }
108  
109 o->refcnt++;
110  
111 return 1;
112 }
113  
114 #endif