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1 | #ifndef BABELTRACE_REF_H |
2 | #define BABELTRACE_REF_H | |
3 | ||
4 | /* | |
5 | * BabelTrace: common reference counting | |
6 | * | |
7 | * Copyright (c) 2015 EfficiOS Inc. and Linux Foundation | |
8 | * Copyright (c) 2015 Philippe Proulx <pproulx@efficios.com> | |
9 | * Copyright (c) 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com> | |
10 | * | |
11 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
12 | * of this software and associated documentation files (the "Software"), to deal | |
13 | * in the Software without restriction, including without limitation the rights | |
14 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
15 | * copies of the Software, and to permit persons to whom the Software is | |
16 | * furnished to do so, subject to the following conditions: | |
17 | * | |
18 | * The above copyright notice and this permission notice shall be included in | |
19 | * all copies or substantial portions of the Software. | |
20 | * | |
21 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
22 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
23 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
24 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
25 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
26 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
27 | * SOFTWARE. | |
28 | */ | |
29 | ||
30 | #ifdef __cplusplus | |
31 | extern "C" { | |
32 | #endif | |
33 | ||
34 | /* | |
35 | * BT_PUT: calls bt_put() with a variable, then sets this variable to NULL. | |
36 | * | |
37 | * A common action with Babeltrace objects is to create or get one, perform | |
38 | * an action with it, and then put it. To avoid putting it a second time | |
39 | * later (if an error occurs, for example), the variable is often reset | |
40 | * to NULL after putting the object it points to. Since this is so | |
41 | * common, the BT_PUT() macro can be used to do just that. | |
42 | * | |
43 | * It is safe to call this function with a variable containing NULL. | |
44 | * | |
45 | * @param obj Variable pointing to a Babeltrace object. | |
46 | */ | |
47 | #define BT_PUT(_obj) \ | |
48 | do { \ | |
49 | bt_put(_obj); \ | |
50 | (_obj) = NULL; \ | |
51 | } while (0) | |
52 | ||
53 | /* | |
54 | * BT_MOVE: transfers the ownership of an object, setting the old owner to NULL. | |
55 | * | |
56 | * This macro sets the variable _dst to the value of the variable _src, | |
57 | * then sets _src to NULL, effectively moving the ownership of an | |
58 | * object from one variable to the other. | |
59 | * | |
60 | * Before assigning _src to _dst, it puts _dst. Therefore it is not safe to | |
61 | * call this function with an uninitialized value of _dst. | |
62 | * | |
63 | * @param _dst Destination variable pointing to a Babeltrace object. | |
64 | * @param _src Source variable pointing to a Babeltrace object. | |
65 | */ | |
66 | #define BT_MOVE(_dst, _src) \ | |
67 | do { \ | |
68 | bt_put(_dst); \ | |
69 | (_dst) = (_src);\ | |
70 | (_src) = NULL; \ | |
71 | } while (0) | |
72 | ||
73 | /* | |
74 | * bt_get: increments the reference count of a Babeltrace object. | |
75 | * | |
76 | * The same number of bt_get() and bt_put() (plus one extra bt_put() to release | |
77 | * the initial reference acquired at creation) have to be performed to destroy a | |
78 | * Babeltrace object. | |
79 | * | |
80 | * It is safe to call this function with a NULL object. | |
81 | * | |
82 | * @param obj Babeltrace object. | |
83 | * | |
84 | * Returns obj. | |
85 | */ | |
86 | void *bt_get(void *obj); | |
87 | ||
88 | /* | |
89 | * bt_put: decrements the reference count of a Babeltrace object. | |
90 | * | |
91 | * The same number of bt_get() and bt_put() (plus one extra bt_put() to release | |
92 | * bt_put() to release the initial reference done at creation) have to be | |
93 | * performed to destroy a Babeltrace object. | |
94 | * | |
95 | * The object is freed when its reference count is decremented to 0 by a call to | |
96 | * bt_put(). | |
97 | * | |
98 | * It is safe to call this function with a NULL object. | |
99 | * | |
100 | * @param obj Babeltrace object. | |
101 | */ | |
102 | void bt_put(void *obj); | |
103 | ||
104 | #ifdef __cplusplus | |
105 | } | |
106 | #endif | |
107 | ||
108 | #endif /* BABELTRACE_REF_H */ |