Ichthyostega
9461443e84
With this third test case, a fairly continuous processing can be demonstrated, while also coordinating allocations in a decentralised way. The implementation behaves correct, and seemingly with satisfactory performance -- while there is certainly some room for improvement: with the processing pattern in this test, a nominal computation load of 4 seconds can be processed with 4 cores in ~ 1.3 seconds
86 lines
2.8 KiB
C++
86 lines
2.8 KiB
C++
/*
|
||
LOCAL-SLICE.hpp - access front-end to thread-local instances
|
||
|
||
Copyright (C)
|
||
2026, Hermann Vosseler <Ichthyostega@web.de>
|
||
|
||
**Lumiera** is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU General Public License as published by the
|
||
Free Software Foundation; either version 2 of the License, or (at your
|
||
option) any later version. See the file COPYING for further details.
|
||
|
||
*/
|
||
|
||
/** @file local-slice.hpp
|
||
** Front-end to attach to a set of thread-local instances.
|
||
** This setup helps to adapt a given service implementation to be deployed
|
||
** as per-thread instances, operating in a massively concurrent situation.
|
||
** The services installed this way must be able to work as self-contained
|
||
** instances transparently, possibly cooperating with a central hub behind
|
||
** the scenes, which however must be coordinated by the services themselves.
|
||
**
|
||
** Since thread-local storage is effectively static, the configuration of
|
||
** instances happens at some point _prior_ to the first use from within a
|
||
** thread, and otherwise not further specified. The LocalSlice access front-end
|
||
** is a _monostate_ and all instances thus expose the same set of per-thread
|
||
** service instances, which are created on-demand (by the C++ runtime system).
|
||
**
|
||
** @warning as of 2022 the implementation of `thread_local` in the GNU runtime
|
||
** was observed to incur seemingly unnecessary overhead, which however
|
||
** is relevant only in a high-performance environment. However, some
|
||
** [casual benchmarks](\ref LocalSlice_test::investigatePerformance)
|
||
** indicated that the problem does not seem to be _that serious_...
|
||
** @see LocalSlice_test
|
||
** @see LocalBufferStage (usage example)
|
||
** @see buffer-provider-load-test.cpp
|
||
**
|
||
*/
|
||
|
||
#ifndef LIB_LOCAL_SLICE_H_
|
||
#define LIB_LOCAL_SLICE_H_
|
||
|
||
#include "lib/integral.hpp"
|
||
|
||
|
||
namespace lib {
|
||
|
||
/** Extension point for LocalSlice: Service initialisation */
|
||
template<class SRV>
|
||
struct LocalSlice_DefaultSetup
|
||
{
|
||
using Service = SRV;
|
||
static Service init() { return Service(); }
|
||
};
|
||
|
||
|
||
/**
|
||
* Common access point to thread-local service instances.
|
||
* @tparam CONF setup to initialise the service.
|
||
*/
|
||
template<class SRV, class CONF =LocalSlice_DefaultSetup<SRV>>
|
||
struct LocalSlice
|
||
{
|
||
LocalSlice() = default;
|
||
// using default copy/assignment
|
||
|
||
|
||
using Service = CONF::Service;
|
||
|
||
/** service access */
|
||
Service&
|
||
operator*() const
|
||
{
|
||
thread_local Service srvInstance{CONF::init()};
|
||
return srvInstance;
|
||
}
|
||
|
||
Service*
|
||
operator->() const
|
||
{
|
||
return & LocalSlice::operator*();
|
||
}
|
||
};
|
||
|
||
|
||
} // namespace lib
|
||
#endif /*LIB_LOCAL_SLICE_H_*/
|