95 lines
3.5 KiB
C++
95 lines
3.5 KiB
C++
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/*
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ALLOCATOR-HANDLE.hpp - front-end handle for custom allocation schemes
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Copyright (C) Lumiera.org
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2023, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/** @file allocator-handle.hpp
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** A front-end/concept to allow access to custom memory management.
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** Minimalistic definition scheme for a functor-like object, which can be
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** passed to client code, offering a callback to generate new objects into
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** some custom allocation scheme not further disclosed.
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**
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** Lumiera employs various flavours of custom memory management, to handle
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** allocation demands from performance critical parts of the application.
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** Irrespective of the actual specifics of the allocation, typically there
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** is some _instance_ of an allocator maintained within a carefully crafted
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** context — leading to the necessity to dependency-inject a suitable front-end
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** into various connected parts of the application, to allow for coherent use
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** of allocation while avoiding tight coupling of implementation internals.
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**
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** Reduced to the bare minimum, the _ability to allocate_ can be represented
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** as a functor, which accepts arbitrary (suitable) arguments and returns a
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** reference to a newly allocated instance of some specific type; such an
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** _allocation front-end_ may then be passed as additional (template)
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** parameter to associated classes or functions, allowing to generate new
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** objects at stable memory location, which can then be wired internally.
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**
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** @todo 6/2023 this specification describes a *Concept*, not an actual
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** interface type. After the migration to C++20, it will thus be
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** possible to mark some arbitrary custom allocator / front-end
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** with such a concept, thereby documenting proper API usage.
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**
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** @see allocation-cluster.hpp
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** @see steam::fixture::Segment
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** @see steam::engine::JobTicket
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*/
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#ifndef LIB_ALLOCATOR_HANDLE_H
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#define LIB_ALLOCATOR_HANDLE_H
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#include "lib/error.hpp"
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#include "lib/nocopy.hpp"
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#include <utility>
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#include <list>
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namespace lib {
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/**
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* Placeholder implementation for a custom allocator
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* @todo shall be replaced by an AllocationCluster eventually
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* @note conforming to a prospective C++20 Concept `Allo<JobTicket>`
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* @remark using `std::list` container, since re-entrant allocation calls are possible,
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* meaning that `emplace_front` will be called recursively from another ctor
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* call invoked from `emplace_front`. Vector or Deque would be corrupted
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* by such re-entrant calls, since both would alias the same entry....
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*/
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template<typename T>
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class AllocatorHandle
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: public std::list<T>
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{
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public:
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template<typename...ARGS>
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T&
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operator() (ARGS&& ...args)
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{
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return this->emplace_front (std::forward<ARGS> (args)...);
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}
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};
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} // namespace lib
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#endif /*LIB_ALLOCATOR_HANDLE_H*/
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