consumerd: send a buffer static sample on flush command
[lttng-tools.git] / src / common / make-unique-wrapper.hpp
1 /*
2 * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 *
4 * SPDX-License-Identifier: LGPL-2.1-only
5 *
6 */
7
8 #ifndef LTTNG_MAKE_UNIQUE_WRAPPER_H
9 #define LTTNG_MAKE_UNIQUE_WRAPPER_H
10
11 #include <common/macros.hpp>
12
13 #include <memory>
14
15 namespace lttng {
16
17 /*
18 * make_unique_wrapper is intended to facilitate the use of std::unique_ptr
19 * to wrap C-style APIs that don't provide RAII resource management facilities.
20 *
21 * Usage example:
22 *
23 * // API
24 * struct my_c_struct {
25 * // ...
26 * };
27 *
28 * struct my_c_struct *create_my_c_struct(void);
29 * void destroy_my_c_struct(struct my_c_struct *value);
30 *
31 * // Creating a unique_ptr to my_c_struct.
32 * auto safe_c_struct =
33 * lttng::make_unique_wrapper<my_c_struct, destroy_my_c_struct>(
34 * create_my_c_struct());
35 *
36 * Note that this facility is intended for use in the scope of a function.
37 * If you need to return this unique_ptr instance, you should consider writting
38 * a proper, idiomatic, wrapper.
39 */
40
41 namespace details
42 {
43 template <typename WrappedType, void (*DeleterFunction)(WrappedType *)>
44 struct create_unique_class {
45 struct deleter {
46 void operator()(WrappedType *instance) const
47 {
48 DeleterFunction(instance);
49 }
50 };
51
52 std::unique_ptr<WrappedType, deleter> operator()(WrappedType *instance) const
53 {
54 return std::unique_ptr<WrappedType, deleter>(instance);
55 }
56 };
57 } /* namespace details */
58
59 /*
60 * 'free' is a utility function for use with make_unique_wrapper. It makes it easier to
61 * wrap raw pointers that have to be deleted with `free`. Using libc's 'free' as
62 * a make_unique_wrapper template argument will result in an error as 'WrappedType *' will
63 * not match free's 'void *' argument.
64 */
65 template <class Type>
66 void free(Type *ptr)
67 {
68 std::free(ptr);
69 }
70
71 template <typename WrappedType, void (*DeleterFunc)(WrappedType *)>
72 std::unique_ptr<WrappedType, typename details::create_unique_class<WrappedType, DeleterFunc>::deleter>
73 make_unique_wrapper(WrappedType *instance)
74 {
75 const details::create_unique_class<WrappedType, DeleterFunc> unique_deleter;
76
77 return unique_deleter(instance);
78 }
79
80 } /* namespace lttng */
81
82 #endif /* LTTNG_MAKE_UNIQUE_WRAPPER_H */
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