| paul@93 | 1 | /* |
| paul@93 | 2 | * A pipe paging coordinator, permitting memory sharing pipe endpoints. |
| paul@93 | 3 | * |
| paul@426 | 4 | * Copyright (C) 2021, 2022 Paul Boddie <paul@boddie.org.uk> |
| paul@93 | 5 | * |
| paul@93 | 6 | * This program is free software; you can redistribute it and/or |
| paul@93 | 7 | * modify it under the terms of the GNU General Public License as |
| paul@93 | 8 | * published by the Free Software Foundation; either version 2 of |
| paul@93 | 9 | * the License, or (at your option) any later version. |
| paul@93 | 10 | * |
| paul@93 | 11 | * This program is distributed in the hope that it will be useful, |
| paul@93 | 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| paul@93 | 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| paul@93 | 14 | * GNU General Public License for more details. |
| paul@93 | 15 | * |
| paul@93 | 16 | * You should have received a copy of the GNU General Public License |
| paul@93 | 17 | * along with this program; if not, write to the Free Software |
| paul@93 | 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| paul@93 | 19 | * Boston, MA 02110-1301, USA |
| paul@93 | 20 | */ |
| paul@93 | 21 | |
| paul@426 | 22 | #include <algorithm> |
| paul@426 | 23 | |
| paul@94 | 24 | #include <mem/memory_preallocated.h> |
| paul@94 | 25 | |
| paul@72 | 26 | #include "page_queue_partitioned.h" |
| paul@65 | 27 | #include "pipe_paging.h" |
| paul@65 | 28 | |
| paul@72 | 29 | |
| paul@72 | 30 | |
| paul@70 | 31 | PipePaging::PipePaging(Memory *memory, offset_t size) |
| paul@426 | 32 | : NotificationSupport(2), _memory(NULL) |
| paul@70 | 33 | { |
| paul@426 | 34 | /* Employ a region size compatible with the configured page size. */ |
| paul@426 | 35 | |
| paul@426 | 36 | _size = std::max<offset_t>(size, PAGE_SIZE); |
| paul@426 | 37 | |
| paul@72 | 38 | /* Reserve space for two pipe regions. */ |
| paul@72 | 39 | |
| paul@89 | 40 | _memory = new MemoryPreallocated(memory, round(size, memory->region_size()) * 2); |
| paul@72 | 41 | _queue = new PageQueuePartitioned(); |
| paul@72 | 42 | _pages = new Pages(_memory, _queue); |
| paul@72 | 43 | |
| paul@114 | 44 | /* Reset the mappers associated with the regions. */ |
| paul@114 | 45 | |
| paul@72 | 46 | for (unsigned int i = 0; i < 2; i++) |
| paul@72 | 47 | _regions[i] = NULL; |
| paul@166 | 48 | |
| paul@166 | 49 | /* Initialise a region accessible by reader and writer. */ |
| paul@166 | 50 | |
| paul@166 | 51 | _add_region(); |
| paul@166 | 52 | _next_region(); |
| paul@117 | 53 | } |
| paul@117 | 54 | |
| paul@199 | 55 | PipePaging::~PipePaging() |
| paul@118 | 56 | { |
| paul@67 | 57 | /* Discard all regions from the pipe. */ |
| paul@67 | 58 | |
| paul@72 | 59 | for (unsigned int i = 0; i < 2; i++) |
| paul@118 | 60 | discard_region(i); |
| paul@70 | 61 | |
| paul@124 | 62 | /* Release notifiers. */ |
| paul@117 | 63 | |
| paul@133 | 64 | release_notifiers(); |
| paul@117 | 65 | |
| paul@72 | 66 | /* Delete the page collection and related objects. */ |
| paul@70 | 67 | |
| paul@70 | 68 | delete _pages; |
| paul@72 | 69 | delete _queue; |
| paul@72 | 70 | delete _memory; |
| paul@67 | 71 | } |
| paul@67 | 72 | |
| paul@199 | 73 | /* Return whether one or more endpoints have detached. */ |
| paul@199 | 74 | |
| paul@199 | 75 | int PipePaging::closed() |
| paul@199 | 76 | { |
| paul@199 | 77 | return _active_endpoints < 2; |
| paul@199 | 78 | } |
| paul@199 | 79 | |
| paul@199 | 80 | /* Detach one endpoint, returning the number still active. */ |
| paul@199 | 81 | |
| paul@199 | 82 | unsigned int PipePaging::detach() |
| paul@199 | 83 | { |
| paul@544 | 84 | std::lock_guard<std::mutex> guard(_lock); |
| paul@544 | 85 | |
| paul@199 | 86 | if (_active_endpoints) |
| paul@199 | 87 | _active_endpoints--; |
| paul@199 | 88 | |
| paul@199 | 89 | return _active_endpoints; |
| paul@199 | 90 | } |
| paul@199 | 91 | |
| paul@199 | 92 | /* Discard a region. */ |
| paul@199 | 93 | |
| paul@199 | 94 | void PipePaging::discard_region(unsigned int i) |
| paul@199 | 95 | { |
| paul@199 | 96 | PageMapper *mapper = _regions[i]; |
| paul@199 | 97 | |
| paul@199 | 98 | if (mapper != NULL) |
| paul@199 | 99 | { |
| paul@199 | 100 | _regions[i] = NULL; |
| paul@199 | 101 | delete mapper; |
| paul@199 | 102 | } |
| paul@199 | 103 | } |
| paul@199 | 104 | |
| paul@65 | 105 | /* Add a region to the sequence. */ |
| paul@65 | 106 | |
| paul@166 | 107 | PageMapper *PipePaging::_add_region() |
| paul@65 | 108 | { |
| paul@72 | 109 | /* If the writer already accesses a different region to the reader, no new |
| paul@72 | 110 | region is added. */ |
| paul@72 | 111 | |
| paul@72 | 112 | if (_writing != _reading) |
| paul@72 | 113 | return NULL; |
| paul@72 | 114 | |
| paul@72 | 115 | /* Select the other region of the pair being maintained. */ |
| paul@72 | 116 | |
| paul@72 | 117 | _writing = 1 - _writing; |
| paul@72 | 118 | |
| paul@72 | 119 | /* Make a new mapper for the region. */ |
| paul@72 | 120 | |
| paul@72 | 121 | PageMapper *mapper = new PageMapper(&_accessors[_writing], _pages); |
| paul@72 | 122 | |
| paul@72 | 123 | /* Initialise and record the mapper. */ |
| paul@72 | 124 | |
| paul@72 | 125 | mapper->set_data_size(0); |
| paul@72 | 126 | |
| paul@72 | 127 | _regions[_writing] = mapper; |
| paul@117 | 128 | |
| paul@166 | 129 | /* Return the next region's mapper. */ |
| paul@166 | 130 | |
| paul@166 | 131 | return mapper; |
| paul@166 | 132 | } |
| paul@166 | 133 | |
| paul@166 | 134 | PageMapper *PipePaging::add_region() |
| paul@166 | 135 | { |
| paul@166 | 136 | PageMapper *mapper = _add_region(); |
| paul@166 | 137 | |
| paul@117 | 138 | /* Let the writer notify the reader. */ |
| paul@117 | 139 | |
| paul@484 | 140 | notify_others(PipePaging::WRITER, NOTIFY_CONTENT_AVAILABLE, NOTIFY_VALUES_NULL); |
| paul@117 | 141 | |
| paul@117 | 142 | /* Return the next region's mapper. */ |
| paul@117 | 143 | |
| paul@72 | 144 | return mapper; |
| paul@65 | 145 | } |
| paul@65 | 146 | |
| paul@72 | 147 | /* Return the current region for reading. */ |
| paul@65 | 148 | |
| paul@72 | 149 | PageMapper *PipePaging::current_region() |
| paul@65 | 150 | { |
| paul@72 | 151 | return _regions[_reading]; |
| paul@65 | 152 | } |
| paul@65 | 153 | |
| paul@166 | 154 | /* Return the current region for reading or writing. */ |
| paul@166 | 155 | |
| paul@166 | 156 | PageMapper *PipePaging::current_region(bool writing) |
| paul@166 | 157 | { |
| paul@166 | 158 | return _regions[writing ? _writing : _reading]; |
| paul@166 | 159 | } |
| paul@166 | 160 | |
| paul@72 | 161 | /* Return the next region for the reader if the writer is using a different one. |
| paul@72 | 162 | Otherwise, return NULL. */ |
| paul@65 | 163 | |
| paul@166 | 164 | PageMapper *PipePaging::_next_region() |
| paul@65 | 165 | { |
| paul@166 | 166 | /* If the reader already accesses the same region as the writer, no next |
| paul@72 | 167 | region can be obtained. */ |
| paul@66 | 168 | |
| paul@72 | 169 | if (_reading == _writing) |
| paul@72 | 170 | return NULL; |
| paul@67 | 171 | |
| paul@72 | 172 | /* Detach and discard the current page mapper. */ |
| paul@72 | 173 | |
| paul@118 | 174 | discard_region(_reading); |
| paul@65 | 175 | |
| paul@114 | 176 | /* Select the next region. */ |
| paul@66 | 177 | |
| paul@72 | 178 | _reading = 1 - _reading; |
| paul@114 | 179 | |
| paul@114 | 180 | /* Return the next region's mapper. */ |
| paul@114 | 181 | |
| paul@72 | 182 | return _regions[_reading]; |
| paul@66 | 183 | } |
| paul@66 | 184 | |
| paul@166 | 185 | PageMapper *PipePaging::next_region() |
| paul@166 | 186 | { |
| paul@166 | 187 | PageMapper *mapper = _next_region(); |
| paul@166 | 188 | |
| paul@166 | 189 | /* Let the reader notify the writer. */ |
| paul@166 | 190 | |
| paul@484 | 191 | notify_others(PipePaging::READER, NOTIFY_SPACE_AVAILABLE, NOTIFY_VALUES_NULL); |
| paul@166 | 192 | |
| paul@166 | 193 | return mapper; |
| paul@166 | 194 | } |
| paul@166 | 195 | |
| paul@65 | 196 | // vim: tabstop=4 expandtab shiftwidth=4 |
