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83509119 JG |
1 | #ifndef BABELTRACE_REF_H |
2 | #define BABELTRACE_REF_H | |
de3dd40e PP |
3 | |
4 | /* | |
83509119 | 5 | * BabelTrace: common reference counting |
de3dd40e PP |
6 | * |
7 | * Copyright (c) 2015 EfficiOS Inc. and Linux Foundation | |
8 | * Copyright (c) 2015 Philippe Proulx <pproulx@efficios.com> | |
83509119 | 9 | * Copyright (c) 2015 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
de3dd40e PP |
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 | ||
de3dd40e | 30 | /* |
83509119 | 31 | * BT_PUT: calls bt_put() with a variable, then sets this variable to NULL. |
de3dd40e | 32 | * |
83509119 JG |
33 | * A common action with Babeltrace objects is to create or get one, perform |
34 | * an action with it, and then put it. To avoid putting it a second time | |
de3dd40e PP |
35 | * later (if an error occurs, for example), the variable is often reset |
36 | * to NULL after putting the object it points to. Since this is so | |
83509119 | 37 | * common, the BT_PUT() macro can be used to do just that. |
de3dd40e | 38 | * |
bdb59e02 | 39 | * It is safe to call this function with a variable containing NULL. |
de3dd40e | 40 | * |
bdb59e02 | 41 | * @param obj Variable pointing to a Babeltrace object. |
de3dd40e | 42 | */ |
83509119 JG |
43 | #define BT_PUT(_obj) \ |
44 | do { \ | |
45 | bt_put(_obj); \ | |
46 | (_obj) = NULL; \ | |
de3dd40e PP |
47 | } while (0) |
48 | ||
e693822d | 49 | /* |
83509119 | 50 | * BT_MOVE: transfers the ownership of an object, setting the old owner to NULL. |
e693822d PP |
51 | * |
52 | * This macro sets the variable _dst to the value of the variable _src, | |
83509119 | 53 | * then sets _src to NULL, effectively moving the ownership of an |
e693822d PP |
54 | * object from one variable to the other. |
55 | * | |
f62d1f55 PP |
56 | * Before assigning _src to _dst, it puts _dst. Therefore it is not safe to |
57 | * call this function with an uninitialized value of _dst. | |
58 | * | |
bdb59e02 PP |
59 | * @param _dst Destination variable pointing to a Babeltrace object. |
60 | * @param _src Source variable pointing to a Babeltrace object. | |
e693822d | 61 | */ |
83509119 JG |
62 | #define BT_MOVE(_dst, _src) \ |
63 | do { \ | |
f62d1f55 | 64 | bt_put(_dst); \ |
83509119 JG |
65 | (_dst) = (_src);\ |
66 | (_src) = NULL; \ | |
e693822d PP |
67 | } while (0) |
68 | ||
de3dd40e | 69 | /* |
83509119 | 70 | * bt_get: increments the reference count of a Babeltrace object. |
de3dd40e | 71 | * |
83509119 JG |
72 | * The same number of bt_get() and bt_put() (plus one extra bt_put() to release |
73 | * the initial reference acquired at creation) have to be performed to destroy a | |
74 | * Babeltrace object. | |
de3dd40e PP |
75 | * |
76 | * It is safe to call this function with a NULL object. | |
77 | * | |
83509119 | 78 | * @param obj Babeltrace object. |
b82cd9f0 JG |
79 | * |
80 | * Returns obj. | |
de3dd40e | 81 | */ |
b82cd9f0 | 82 | void *bt_get(void *obj); |
de3dd40e PP |
83 | |
84 | /* | |
83509119 | 85 | * bt_put: decrements the reference count of a Babeltrace object. |
de3dd40e | 86 | * |
83509119 JG |
87 | * The same number of bt_get() and bt_put() (plus one extra bt_put() to release |
88 | * bt_put() to release the initial reference done at creation) have to be | |
89 | * performed to destroy a Babeltrace object. | |
de3dd40e | 90 | * |
bdb59e02 | 91 | * The object is freed when its reference count is decremented to 0 by a call to |
83509119 | 92 | * bt_put(). |
de3dd40e PP |
93 | * |
94 | * It is safe to call this function with a NULL object. | |
95 | * | |
83509119 | 96 | * @param obj Babeltrace object. |
de3dd40e | 97 | */ |
83509119 | 98 | void bt_put(void *obj); |
de3dd40e | 99 | |
83509119 | 100 | #endif /* BABELTRACE_REF_H */ |