124 lines
4.2 KiB
C++
124 lines
4.2 KiB
C++
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/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
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/* ***************************************************************************
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*
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* FastFlow is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License version 3 as
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* published by the Free Software Foundation.
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* Starting from version 3.0.1 FastFlow is dual licensed under the GNU LGPLv3
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* or MIT License (https://github.com/ParaGroup/WindFlow/blob/vers3.x/LICENSE.MIT)
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc., 59
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* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this file
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* does not by itself cause the resulting executable to be covered by the GNU
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* General Public License. This exception does not however invalidate any
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* other reasons why the executable file might be covered by the GNU General
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* Public License.
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*
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* **************************************************************************/
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#ifndef FF_STATIC_ALLOCATOR_HPP
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#define FF_STATIC_ALLOCATOR_HPP
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#include <sys/mman.h>
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#include <cstdlib>
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#include <cstdio>
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#include <ff/config.hpp>
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#include <new>
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/* Author: Massimo Torquati
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* December 2020
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*/
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namespace ff {
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class StaticAllocator {
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public:
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StaticAllocator(const size_t _nslot, const size_t slotsize, const int nchannels=1):
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ssize(slotsize), nchannels(nchannels), cnts(nchannels,0), segment(nullptr) {
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assert(nchannels>0);
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assert(slotsize>0);
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ssize = slotsize + sizeof(long*);
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// rounding up nslot to be multiple of nchannels
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nslot = ((_nslot + nchannels -1) / nchannels) * nchannels;
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slotsxchannel = nslot / nchannels;
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}
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~StaticAllocator() {
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if (segment) munmap(segment, nslot*ssize);
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segment=nullptr;
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}
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int init() {
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void* result = 0;
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result = mmap(NULL, nslot*ssize, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
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if (result == MAP_FAILED) return -1;
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segment = (char*)result;
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// initialize the "header"
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char* p = segment;
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for(size_t i=0; i<nslot;++i) {
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long** _p = (long**)p;
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_p[0] = (long*)FF_GO_ON; // this tells me that the slot is free!
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p+=ssize;
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}
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return 0;
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}
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template<typename T>
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void alloc(T*& p, int channel=0) {
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assert(channel>=0 && channel<nchannels) ;
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do {
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size_t m = cnts[channel]++ % slotsxchannel;
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char *mp = segment + (channel*slotsxchannel + m)*ssize;
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long** _p = (long**)mp;
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if (_p[0] == (long*)FF_GO_ON) {
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_p[0] = (long*)FF_EOS; // the slot is occupied
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p = new (mp+sizeof(long*)) T();
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return;
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}
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} while(1);
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}
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template<typename T>
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static inline void dealloc(T* p) {
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p->~T();
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long** _p = (long**)((char*)p-sizeof(long*));
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_p[0] = (long*)FF_GO_ON; // the slot is free and can be re-used
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}
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template<typename T, typename S>
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void realloc(T* in, S*& out) {
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in->~T();
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char* mp = reinterpret_cast<char*>(in);
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out = new (mp) S();
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}
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private:
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size_t nslot; // total number of slots in the data segment
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size_t slotsxchannel; // how many slots for each sub data segment
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size_t ssize; // size of a data slot (real size + sizeof(long*))
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int nchannels; // number of sub data segments
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std::vector<size_t> cnts; // counters
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char *segment; // data segment
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};
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};
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#endif /* FF_STATIC_ALLOCATOR_HPP */
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