| /* |
| * Copyright (C) 2017 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #pragma once |
| |
| #include "Bits.h" |
| #include "DeferredTrigger.h" |
| #include "FreeList.h" |
| #include <climits> |
| |
| namespace bmalloc { |
| |
| template<typename Config> class IsoDirectoryBase; |
| template<typename Config> class IsoHeapImpl; |
| |
| class IsoPageBase { |
| public: |
| static constexpr size_t pageSize = 16384; |
| |
| protected: |
| BEXPORT static void* allocatePageMemory(); |
| }; |
| |
| template<typename Config> |
| class IsoPage : public IsoPageBase { |
| public: |
| static constexpr unsigned numObjects = pageSize / Config::objectSize; |
| |
| static_assert(numObjects, "IsoHeap size should allow at least one allocation per page"); |
| |
| static IsoPage* tryCreate(IsoDirectoryBase<Config>& directory, unsigned index); |
| |
| // It's expected that you will only use this with placement new and direct destruction. |
| IsoPage(IsoDirectoryBase<Config>& directory, unsigned index); |
| |
| static IsoPage* pageFor(void*); |
| |
| unsigned index() const { return m_index; } |
| |
| void free(void*); |
| |
| // Called after this page is already selected for allocation. |
| FreeList startAllocating(); |
| |
| // Called after the allocator picks another page to replace this one. |
| void stopAllocating(FreeList freeList); |
| |
| IsoDirectoryBase<Config>& directory() { return m_directory; } |
| bool isInUseForAllocation() const { return m_isInUseForAllocation; } |
| |
| template<typename Func> |
| void forEachLiveObject(const Func&); |
| |
| IsoHeapImpl<Config>& heap(); |
| |
| private: |
| static constexpr unsigned indexOfFirstObject() |
| { |
| return (sizeof(IsoPage) + Config::objectSize - 1) / Config::objectSize; |
| } |
| |
| IsoDirectoryBase<Config>& m_directory; |
| unsigned m_index { UINT_MAX }; |
| |
| // The possible states of a page are as follows. We mark these states by their corresponding |
| // eligible, empty, and committed bits (respectively). |
| // |
| // 000 - Deallocated. It has no objects and its memory is not paged in. |
| // 111 - Empty. |
| // 101 - Eligible for allocation, meaning that there is at least one free object in the page. |
| // 001 - Full. |
| // 001 - Currently being used for allocation. |
| // |
| // Note that the last two states have identical representation in the directory, which is fine - in |
| // both cases we are basically telling the directory that this page is off limits. But we keep track |
| // of the distinction internally. |
| |
| // We manage the bitvector ourselves. This bitvector works in a special way to enable very fast |
| // freeing. |
| |
| // This must have a trivial destructor. |
| |
| unsigned m_allocBits[bitsArrayLength(numObjects)]; |
| unsigned m_numNonEmptyWords { 0 }; |
| bool m_eligibilityHasBeenNoted { true }; |
| bool m_isInUseForAllocation { false }; |
| DeferredTrigger<IsoPageTrigger::Eligible> m_eligibilityTrigger; |
| DeferredTrigger<IsoPageTrigger::Empty> m_emptyTrigger; |
| }; |
| |
| } // namespace bmalloc |
| |