1/* 2 * Copyright (C) 2014 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26#ifndef Chunk_h 27#define Chunk_h 28 29#include "ObjectType.h" 30#include "Sizes.h" 31#include "VMAllocate.h" 32 33namespace bmalloc { 34 35template<class Traits> 36class Chunk { 37public: 38 typedef typename Traits::Page Page; 39 typedef typename Traits::Line Line; 40 static const size_t lineSize = Traits::lineSize; 41 static const size_t chunkSize = Traits::chunkSize; 42 static const size_t chunkOffset = Traits::chunkOffset; 43 static const uintptr_t chunkMask = Traits::chunkMask; 44 45 static Chunk* create(); 46 static Chunk* get(void*); 47 48 Page* begin() { return Page::get(Line::get(m_memory)); } 49 Page* end() { return &m_pages[pageCount]; } 50 51 Line* lines() { return m_lines; } 52 Page* pages() { return m_pages; } 53 54private: 55 static_assert(!(vmPageSize % lineSize), "vmPageSize must be an even multiple of line size"); 56 static_assert(!(chunkSize % lineSize), "chunk size must be an even multiple of line size"); 57 58 static const size_t lineCount = chunkSize / lineSize; 59 static const size_t pageCount = chunkSize / vmPageSize; 60 61 Line m_lines[lineCount]; 62 Page m_pages[pageCount]; 63 64 // Align to vmPageSize to avoid sharing physical pages with metadata. 65 // Otherwise, we'll confuse the scavenger into trying to scavenge metadata. 66 alignas(vmPageSize) char m_memory[]; 67}; 68 69template<class Traits> 70inline auto Chunk<Traits>::create() -> Chunk* 71{ 72 size_t vmSize = bmalloc::vmSize(chunkSize); 73 std::pair<void*, Range> result = vmAllocate(vmSize, superChunkSize, chunkOffset); 74 return new (result.first) Chunk; 75} 76 77template<class Traits> 78inline auto Chunk<Traits>::get(void* object) -> Chunk* 79{ 80 BASSERT(isSmallOrMedium(object)); 81 return static_cast<Chunk*>(mask(object, chunkMask)); 82} 83 84}; // namespace bmalloc 85 86#endif // Chunk 87