John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2020 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #pragma once |
| 18 | |
| 19 | #include <algorithm> |
| 20 | #include <array> |
| 21 | #include <cinttypes> |
| 22 | #include <cstddef> |
| 23 | #include <cstdlib> |
| 24 | #include <type_traits> |
| 25 | #include <utility> |
| 26 | |
| 27 | namespace android::uirenderer { |
| 28 | |
| 29 | template <typename T> |
| 30 | struct OpBufferItemHeader { |
| 31 | T type : 8; |
| 32 | uint32_t size : 24; |
| 33 | }; |
| 34 | |
| 35 | struct OpBufferAllocationHeader { |
| 36 | // Used size, including header size |
| 37 | size_t used = 0; |
| 38 | // Capacity, including header size |
| 39 | size_t capacity = 0; |
| 40 | // Offset relative to `this` at which the first item is |
| 41 | size_t startOffset = 0; |
| 42 | // Offset relative to `this` at which the last item is |
| 43 | size_t endOffset = 0; |
| 44 | }; |
| 45 | |
| 46 | #define BE_OPBUFFERS_FRIEND() \ |
| 47 | template <typename ItemTypes, template <ItemTypes> typename, typename, typename> \ |
| 48 | friend class OpBuffer |
| 49 | |
| 50 | template <typename ItemTypes, template <ItemTypes> typename ItemContainer, |
| 51 | typename BufferHeader = OpBufferAllocationHeader, |
| 52 | typename ItemTypesSequence = std::make_index_sequence<static_cast<int>(ItemTypes::COUNT)>> |
| 53 | class OpBuffer { |
| 54 | // Instead of re-aligning individual inserts, just pad the size of everything |
| 55 | // to a multiple of pointer alignment. This assumes we never work with doubles. |
| 56 | // Which we don't. |
| 57 | static constexpr size_t Alignment = alignof(void*); |
| 58 | |
| 59 | static constexpr size_t PadAlign(size_t size) { |
| 60 | return (size + (Alignment - 1)) & -Alignment; |
| 61 | } |
| 62 | |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 63 | public: |
John Reck | b5eeb18 | 2020-12-09 13:45:39 -0500 | [diff] [blame] | 64 | static constexpr auto STARTING_SIZE = PadAlign(sizeof(BufferHeader)); |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 65 | using ItemHeader = OpBufferItemHeader<ItemTypes>; |
| 66 | |
John Reck | 064650b | 2021-01-19 21:29:24 -0500 | [diff] [blame] | 67 | explicit OpBuffer() = default; |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 68 | |
| 69 | // Prevent copying by default |
| 70 | OpBuffer(const OpBuffer&) = delete; |
| 71 | void operator=(const OpBuffer&) = delete; |
| 72 | |
| 73 | OpBuffer(OpBuffer&& other) { |
| 74 | mBuffer = other.mBuffer; |
| 75 | other.mBuffer = nullptr; |
| 76 | } |
| 77 | |
| 78 | void operator=(OpBuffer&& other) { |
| 79 | destroy(); |
| 80 | mBuffer = other.mBuffer; |
| 81 | other.mBuffer = nullptr; |
| 82 | } |
| 83 | |
| 84 | ~OpBuffer() { |
| 85 | destroy(); |
| 86 | } |
| 87 | |
| 88 | constexpr size_t capacity() const { return mBuffer ? mBuffer->capacity : 0; } |
| 89 | |
| 90 | constexpr size_t size() const { return mBuffer ? mBuffer->used : 0; } |
| 91 | |
| 92 | constexpr size_t remaining() const { return capacity() - size(); } |
| 93 | |
| 94 | // TODO: Add less-copy'ing variants of this. emplace_back? deferred initialization? |
| 95 | template <ItemTypes T> |
| 96 | void push_container(ItemContainer<T>&& op) { |
| 97 | static_assert(alignof(ItemContainer<T>) <= Alignment); |
| 98 | static_assert(offsetof(ItemContainer<T>, header) == 0); |
| 99 | |
| 100 | constexpr auto padded_size = PadAlign(sizeof(ItemContainer<T>)); |
| 101 | if (remaining() < padded_size) { |
| 102 | resize(std::max(padded_size, capacity()) * 2); |
| 103 | } |
| 104 | mBuffer->endOffset = mBuffer->used; |
| 105 | mBuffer->used += padded_size; |
| 106 | |
| 107 | void* allocateAt = reinterpret_cast<uint8_t*>(mBuffer) + mBuffer->endOffset; |
| 108 | auto temp = new (allocateAt) ItemContainer<T>{std::move(op)}; |
| 109 | temp->header = {.type = T, .size = padded_size}; |
| 110 | } |
| 111 | |
| 112 | void resize(size_t newsize) { |
| 113 | // Add the header size to newsize |
| 114 | const size_t adjustedSize = newsize + STARTING_SIZE; |
| 115 | |
| 116 | if (adjustedSize < size()) { |
| 117 | // todo: throw? |
| 118 | return; |
| 119 | } |
| 120 | if (newsize == 0) { |
| 121 | free(mBuffer); |
| 122 | mBuffer = nullptr; |
| 123 | } else { |
| 124 | if (mBuffer) { |
| 125 | mBuffer = reinterpret_cast<BufferHeader*>(realloc(mBuffer, adjustedSize)); |
| 126 | mBuffer->capacity = adjustedSize; |
| 127 | } else { |
| 128 | mBuffer = new (malloc(adjustedSize)) BufferHeader(); |
| 129 | mBuffer->capacity = adjustedSize; |
| 130 | mBuffer->used = STARTING_SIZE; |
| 131 | mBuffer->startOffset = STARTING_SIZE; |
| 132 | } |
| 133 | } |
| 134 | } |
| 135 | |
| 136 | template <typename F> |
| 137 | void for_each(F&& f) const { |
John Reck | 064650b | 2021-01-19 21:29:24 -0500 | [diff] [blame] | 138 | do_for_each(std::forward<F>(f), ItemTypesSequence{}); |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 139 | } |
| 140 | |
| 141 | void clear(); |
| 142 | |
| 143 | ItemHeader* first() const { return isEmpty() ? nullptr : itemAt(mBuffer->startOffset); } |
| 144 | |
| 145 | ItemHeader* last() const { return isEmpty() ? nullptr : itemAt(mBuffer->endOffset); } |
| 146 | |
John Reck | 9573505 | 2020-12-15 13:39:22 -0500 | [diff] [blame] | 147 | class sentinal { |
| 148 | public: |
| 149 | explicit sentinal(const uint8_t* end) : end(end) {} |
| 150 | private: |
| 151 | const uint8_t* const end; |
| 152 | }; |
| 153 | |
| 154 | sentinal end() const { |
| 155 | return sentinal{end_ptr()}; |
| 156 | } |
| 157 | |
| 158 | template <ItemTypes T> |
| 159 | class filtered_iterator { |
| 160 | public: |
| 161 | explicit filtered_iterator(uint8_t* start, const uint8_t* end) |
| 162 | : mCurrent(start), mEnd(end) { |
| 163 | ItemHeader* header = reinterpret_cast<ItemHeader*>(mCurrent); |
| 164 | if (header->type != T) { |
| 165 | advance(); |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | filtered_iterator& operator++() { |
| 170 | advance(); |
| 171 | return *this; |
| 172 | } |
| 173 | |
| 174 | // Although this iterator self-terminates, we need a placeholder to compare against |
| 175 | // to make for-each loops happy |
| 176 | bool operator!=(const sentinal& other) const { |
| 177 | return mCurrent != mEnd; |
| 178 | } |
| 179 | |
| 180 | ItemContainer<T>& operator*() { |
| 181 | return *reinterpret_cast<ItemContainer<T>*>(mCurrent); |
| 182 | } |
| 183 | private: |
| 184 | void advance() { |
| 185 | ItemHeader* header = reinterpret_cast<ItemHeader*>(mCurrent); |
| 186 | do { |
| 187 | mCurrent += header->size; |
| 188 | header = reinterpret_cast<ItemHeader*>(mCurrent); |
| 189 | } while (mCurrent != mEnd && header->type != T); |
| 190 | } |
| 191 | uint8_t* mCurrent; |
| 192 | const uint8_t* const mEnd; |
| 193 | }; |
| 194 | |
| 195 | template <ItemTypes T> |
| 196 | class filtered_view { |
| 197 | public: |
| 198 | explicit filtered_view(uint8_t* start, const uint8_t* end) : mStart(start), mEnd(end) {} |
| 199 | |
| 200 | filtered_iterator<T> begin() const { |
| 201 | return filtered_iterator<T>{mStart, mEnd}; |
| 202 | } |
| 203 | |
| 204 | sentinal end() const { |
| 205 | return sentinal{mEnd}; |
| 206 | } |
| 207 | private: |
| 208 | uint8_t* mStart; |
| 209 | const uint8_t* const mEnd; |
| 210 | }; |
| 211 | |
| 212 | template <ItemTypes T> |
| 213 | filtered_view<T> filter() const { |
| 214 | return filtered_view<T>{start_ptr(), end_ptr()}; |
| 215 | } |
| 216 | |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 217 | private: |
John Reck | 9573505 | 2020-12-15 13:39:22 -0500 | [diff] [blame] | 218 | |
| 219 | uint8_t* start_ptr() const { |
| 220 | return reinterpret_cast<uint8_t*>(mBuffer) + mBuffer->startOffset; |
| 221 | } |
| 222 | |
| 223 | const uint8_t* end_ptr() const { |
| 224 | return reinterpret_cast<uint8_t*>(mBuffer) + mBuffer->used; |
| 225 | } |
| 226 | |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 227 | template <typename F, std::size_t... I> |
John Reck | 064650b | 2021-01-19 21:29:24 -0500 | [diff] [blame] | 228 | void do_for_each(F&& f, std::index_sequence<I...>) const { |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 229 | // Validate we're not empty |
| 230 | if (isEmpty()) return; |
| 231 | |
| 232 | // Setup the jump table, mapping from each type to a springboard that invokes the template |
| 233 | // function with the appropriate concrete type |
| 234 | using F_PTR = decltype(&f); |
| 235 | using THUNK = void (*)(F_PTR, void*); |
| 236 | static constexpr auto jump = std::array<THUNK, sizeof...(I)>{[](F_PTR fp, void* t) { |
John Reck | 90b0a1c | 2020-11-12 12:37:30 -0500 | [diff] [blame] | 237 | (*fp)(reinterpret_cast<const ItemContainer<static_cast<ItemTypes>(I)>*>(t)); |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 238 | }...}; |
| 239 | |
| 240 | // Do the actual iteration of each item |
John Reck | 9573505 | 2020-12-15 13:39:22 -0500 | [diff] [blame] | 241 | uint8_t* current = start_ptr(); |
| 242 | const uint8_t* end = end_ptr(); |
John Reck | 013127b | 2020-10-29 20:53:51 -0400 | [diff] [blame] | 243 | while (current != end) { |
| 244 | auto header = reinterpret_cast<ItemHeader*>(current); |
| 245 | // `f` could be a destructor, so ensure all accesses to the OP happen prior to invoking |
| 246 | // `f` |
| 247 | auto it = (void*)current; |
| 248 | current += header->size; |
| 249 | jump[static_cast<int>(header->type)](&f, it); |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | void destroy() { |
| 254 | clear(); |
| 255 | resize(0); |
| 256 | } |
| 257 | |
| 258 | bool offsetIsValid(size_t offset) const { |
| 259 | return offset >= mBuffer->startOffset && offset < mBuffer->used; |
| 260 | } |
| 261 | |
| 262 | ItemHeader* itemAt(size_t offset) const { |
| 263 | if (!offsetIsValid(offset)) return nullptr; |
| 264 | return reinterpret_cast<ItemHeader*>(reinterpret_cast<uint8_t*>(mBuffer) + offset); |
| 265 | } |
| 266 | |
| 267 | bool isEmpty() const { return mBuffer == nullptr || mBuffer->used == STARTING_SIZE; } |
| 268 | |
| 269 | BufferHeader* mBuffer = nullptr; |
| 270 | }; |
| 271 | |
| 272 | template <typename ItemTypes, template <ItemTypes> typename ItemContainer, typename BufferHeader, |
| 273 | typename ItemTypeSequence> |
| 274 | void OpBuffer<ItemTypes, ItemContainer, BufferHeader, ItemTypeSequence>::clear() { |
| 275 | |
| 276 | // Don't need to do anything if we don't have a buffer |
| 277 | if (!mBuffer) return; |
| 278 | |
| 279 | for_each([](auto op) { |
| 280 | using T = std::remove_reference_t<decltype(*op)>; |
| 281 | op->~T(); |
| 282 | }); |
| 283 | mBuffer->used = STARTING_SIZE; |
| 284 | mBuffer->startOffset = STARTING_SIZE; |
| 285 | mBuffer->endOffset = 0; |
| 286 | } |
| 287 | |
| 288 | } // namespace android::uirenderer |