1 /* 2 * Copyright (c) 2025 Huawei Device Co., Ltd. 3 * Licensed under the Apache License, Version 2.0 (the "License"); 4 * you may not use this file except in compliance with the License. 5 * You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software 10 * distributed under the License is distributed on an "AS IS" BASIS, 11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 * See the License for the specific language governing permissions and 13 * limitations under the License. 14 */ 15 16 #ifndef COMMON_COMPONENTS_COMMON_PAGE_CACHE_H 17 #define COMMON_COMPONENTS_COMMON_PAGE_CACHE_H 18 19 #include "common_components/common/mem_common.h" 20 21 namespace common { 22 class PageCache { 23 public: 24 // Return the singleton object of PageCache GetInstance()25 static PageCache* GetInstance() { return &instance_; } 26 27 // Get a k-page Span 28 Span* NewSpan(size_t k); 29 30 std::mutex& GetPageMutex(); 31 32 // Pass in a small fixed-length memory block to obtain the Span object corresponding to the page it is located in. 33 Span* MapObjectToSpan(void* obj); 34 35 // Try to merge the pages before and after the span to alleviate the external fragmentation problem. 36 void ReleaseSpanToPageCache(Span* span); 37 38 private: 39 std::mutex pageMtx_; 40 SpanList pageCacheSpans_[MAX_NPAGES]; 41 std::unordered_map<pageID, Span*> idSpanMap_; // The mapping between page numbers and span objects. 42 43 private: PageCache()44 PageCache() noexcept {} 45 46 PageCache(const PageCache&) = delete; 47 PageCache& operator=(const PageCache&) = delete; 48 49 static PageCache instance_; 50 }; 51 52 class ScopedPageCacheMutex { 53 public: ScopedPageCacheMutex()54 explicit ScopedPageCacheMutex() { PageCache::GetInstance()->GetPageMutex().lock(); } 55 ~ScopedPageCacheMutex()56 ~ScopedPageCacheMutex() { PageCache::GetInstance()->GetPageMutex().unlock(); } 57 }; 58 } // namespace common 59 #endif 60