2 * Copyright (C) 2022 Jérémie Galarneau <jeremie.galarneau@efficios.com>
4 * SPDX-License-Identifier: LGPL-2.1-only
8 #ifndef LTTNG_SCOPE_EXIT_H
9 #define LTTNG_SCOPE_EXIT_H
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>())())> {
21 } /* namespace details. */
24 * Generic utility to run a lambda (or any other invocable object) when leaving
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
31 template <typename ScopeExitInvocableType>
35 * Since ScopeExitInvocableType will be invoked in the destructor, it
36 * must be `noexcept` lest we anger the undefined behaviour gods by throwing
37 * an exception while an exception is active.
39 static_assert(details::is_invocation_noexcept<ScopeExitInvocableType>::value,
40 "scope_exit requires a noexcept invocable type");
42 explicit scope_exit(ScopeExitInvocableType&& scope_exit_callable) :
43 _on_scope_exit{ std::forward<ScopeExitInvocableType>(scope_exit_callable) }
47 scope_exit(scope_exit&& rhs) noexcept :
48 _on_scope_exit{ std::move(rhs._on_scope_exit) }, _armed{ rhs._armed }
50 /* Don't invoke ScopeExitInvocableType for the moved-from copy. */
55 * The copy constructor is disabled to prevent the action from being
56 * executed twice should a copy be performed accidentaly.
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.
61 scope_exit(const scope_exit&) = delete;
62 scope_exit& operator=(const scope_exit&) = delete;
63 scope_exit& operator=(scope_exit&&) = delete;
64 scope_exit() = delete;
66 void disarm() noexcept
79 ScopeExitInvocableType _on_scope_exit;
83 template <typename ScopeExitInvocableType>
84 scope_exit<ScopeExitInvocableType> make_scope_exit(ScopeExitInvocableType&& scope_exit_callable)
86 return scope_exit<ScopeExitInvocableType>(
87 std::forward<ScopeExitInvocableType>(scope_exit_callable));
90 } /* namespace lttng */
92 #endif /* LTTNG_SCOPE_EXIT_H */