1 /* 2 * A pipe paging coordinator, permitting memory sharing pipe endpoints. 3 * 4 * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 * Boston, MA 02110-1301, USA 20 */ 21 22 #pragma once 23 24 #include <fsserver/page_mapper.h> 25 #include <fsserver/pages.h> 26 #include <fsserver/pipe_accessor.h> 27 28 29 30 /* Pipe paging support, maintaining the sequence of active regions or sections 31 in a pipe. */ 32 33 class PipePaging 34 { 35 protected: 36 Memory *_memory; 37 Pages *_pages; 38 PageQueue *_queue; 39 40 /* Regions acting as files with their own accessors. */ 41 42 PageMapper *_regions[2]; 43 PipeAccessor _accessors[2]; 44 45 /* The first region is initially exposed to both reader and writer. */ 46 47 int _reading = 0, _writing = 0; 48 49 /* Pipe section/region size. */ 50 51 offset_t _size; 52 53 /* Endpoint status. */ 54 55 unsigned int _endpoints = 2; 56 57 public: 58 explicit PipePaging(Memory *memory, offset_t size); 59 60 virtual void detach(); 61 62 virtual offset_t region_size() 63 { return _size; } 64 65 /* Region management. */ 66 67 virtual PageMapper *add_region(); 68 69 virtual PageMapper *current_region(); 70 71 virtual PageMapper *next_region(); 72 }; 73 74 // vim: tabstop=4 expandtab shiftwidth=4