mirror of
https://github.com/matrix-construct/construct
synced 2024-11-09 03:21:15 +01:00
100 lines
2.7 KiB
C++
100 lines
2.7 KiB
C++
// Copyright (C) Matrix Construct Developers, Authors & Contributors
|
|
// Copyright (C) 2016-2018 Jason Volk
|
|
//
|
|
// Permission to use, copy, modify, and/or distribute this software for any
|
|
// purpose with or without fee is hereby granted, provided that the above
|
|
// copyright notice and this permission notice is present in all copies.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
|
|
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
// DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
|
|
// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
|
|
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
|
// IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
// POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
#pragma once
|
|
#define HAVE_IRCD_UTIL_UNWIND_H
|
|
|
|
namespace ircd::util
|
|
{
|
|
struct unwind;
|
|
};
|
|
|
|
//
|
|
// Fundamental scope-unwind utilities establishing actions during destruction
|
|
//
|
|
|
|
/// Unconditionally executes the provided code when the object goes out of scope.
|
|
///
|
|
struct ircd::util::unwind
|
|
{
|
|
struct nominal;
|
|
struct exceptional;
|
|
|
|
const std::function<void ()> func;
|
|
|
|
template<class F>
|
|
unwind(F &&func)
|
|
:func{std::forward<F>(func)}
|
|
{}
|
|
|
|
unwind(const unwind &) = delete;
|
|
unwind &operator=(const unwind &) = delete;
|
|
~unwind() noexcept
|
|
{
|
|
func();
|
|
}
|
|
};
|
|
|
|
/// Executes function only if the unwind takes place without active exception
|
|
///
|
|
/// The function is expected to be executed and the likely() should pipeline
|
|
/// that branch and make this device cheaper to use under normal circumstances.
|
|
///
|
|
struct ircd::util::unwind::nominal
|
|
{
|
|
const std::function<void ()> func;
|
|
|
|
template<class F>
|
|
nominal(F &&func)
|
|
:func{std::forward<F>(func)}
|
|
{}
|
|
|
|
~nominal() noexcept
|
|
{
|
|
if(likely(!std::uncaught_exception()))
|
|
func();
|
|
}
|
|
|
|
nominal(const nominal &) = delete;
|
|
};
|
|
|
|
/// Executes function only if unwind is taking place because exception thrown
|
|
///
|
|
/// The unlikely() intends for the cost of a branch misprediction to be paid
|
|
/// for fetching and executing this function. This is because we strive to
|
|
/// optimize the pipeline for the nominal path, making this device as cheap
|
|
/// as possible to use.
|
|
///
|
|
struct ircd::util::unwind::exceptional
|
|
{
|
|
const std::function<void ()> func;
|
|
|
|
template<class F>
|
|
exceptional(F &&func)
|
|
:func{std::forward<F>(func)}
|
|
{}
|
|
|
|
~exceptional() noexcept
|
|
{
|
|
if(unlikely(std::uncaught_exception()))
|
|
func();
|
|
}
|
|
|
|
exceptional(const exceptional &) = delete;
|
|
};
|