projects / lttng-tools.git / blame
| Commit | Line | Data |
|---|---|---|
| b6bbb1d6 JG |
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_SCOPE_EXIT_H | |
| 9 | #define LTTNG_SCOPE_EXIT_H | |
| 10 | ||
| 11 | #include <utility> | |
| 12 | ||
| 13 | namespace lttng { | |
| 14 | ||
| 15 | namespace details { | |
| 16 | /* Is operator() of InvocableType is marked as noexcept? */ | |
| 17 | template <typename InvocableType> | |
| 18 | struct is_invocation_noexcept | |
| 19 | : std::integral_constant<bool, noexcept((std::declval<InvocableType>())())> { | |
| 20 | }; | |
| 21 | } /* namespace details. */ | |
| 22 | ||
| 23 | /* | |
| 24 | * Generic utility to run a lambda (or any other invocable object) when leaving | |
| 25 | * a scope. | |
| 26 | * | |
| 27 | * Notably, this makes it easy to specify an action (e.g. restore a context) | |
| 28 | * that must occur at the end of a function or roll-back operations in an | |
| 29 | * exception-safe way. | |
| 30 | */ | |
| 31 | template <typename ScopeExitInvocableType> | |
| 32 | class scope_exit { | |
| 33 | public: | |
| 34 | /* | |
| 35 | * Since ScopeExitInvocableType will be invoked in the destructor, it | |
| c91ccade JG |
36 | * must be `noexcept` lest we anger the undefined behaviour gods by throwing |
| 37 | * an exception while an exception is active. | |
| b6bbb1d6 JG |
38 | */ |
| 39 | static_assert(details::is_invocation_noexcept<ScopeExitInvocableType>::value, | |
| cd9adb8b | 40 | "scope_exit requires a noexcept invocable type"); |
| b6bbb1d6 JG |
41 | |
| 42 | explicit scope_exit(ScopeExitInvocableType&& scope_exit_callable) : | |
| cd9adb8b | 43 | _on_scope_exit{ std::forward<ScopeExitInvocableType>(scope_exit_callable) } |
| b6bbb1d6 JG |
44 | { |
| 45 | } | |
| 46 | ||
| cd9adb8b JG |
47 | scope_exit(scope_exit&& rhs) noexcept : |
| 48 | _on_scope_exit{ std::move(rhs._on_scope_exit) }, _armed{ rhs._armed } | |
| b6bbb1d6 JG |
49 | { |
| 50 | /* Don't invoke ScopeExitInvocableType for the moved-from copy. */ | |
| 51 | rhs.disarm(); | |
| 52 | } | |
| 53 | ||
| 54 | /* | |
| 55 | * The copy constructor is disabled to prevent the action from being | |
| 56 | * executed twice should a copy be performed accidentaly. | |
| 57 | * | |
| 58 | * The move-constructor is present to enable make_scope_exit() but to | |
| 59 | * also propagate the scope_exit to another scope, should it be needed. | |
| 60 | */ | |
| 61 | scope_exit(const scope_exit&) = delete; | |
| 9d89db29 JG |
62 | scope_exit& operator=(const scope_exit&) = delete; |
| 63 | scope_exit& operator=(scope_exit&&) = delete; | |
| b6bbb1d6 JG |
64 | scope_exit() = delete; |
| 65 | ||
| 66 | void disarm() noexcept | |
| 67 | { | |
| 68 | _armed = false; | |
| 69 | } | |
| 70 | ||
| 71 | ~scope_exit() | |
| 72 | { | |
| 73 | if (_armed) { | |
| 74 | _on_scope_exit(); | |
| 75 | } | |
| 76 | } | |
| 77 | ||
| 78 | private: | |
| 79 | ScopeExitInvocableType _on_scope_exit; | |
| 80 | bool _armed = true; | |
| 81 | }; | |
| 82 | ||
| 83 | template <typename ScopeExitInvocableType> | |
| 84 | scope_exit<ScopeExitInvocableType> make_scope_exit(ScopeExitInvocableType&& scope_exit_callable) | |
| 85 | { | |
| 86 | return scope_exit<ScopeExitInvocableType>( | |
| cd9adb8b | 87 | std::forward<ScopeExitInvocableType>(scope_exit_callable)); |
| b6bbb1d6 JG |
88 | } |
| 89 | ||
| 90 | } /* namespace lttng */ | |
| 91 | ||
| 92 | #endif /* LTTNG_SCOPE_EXIT_H */ |