1 /* 2 * Copyright (C) 2024 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 #ifndef CHRE_UTIL_FRAGMENTATION_MANAGER 18 #define CHRE_UTIL_FRAGMENTATION_MANAGER 19 #include <stddef.h> 20 #include <type_traits> 21 #include "chre/util/optional.h" 22 namespace chre { 23 24 /** 25 * Structure representing a fragment of continuous data. 26 * 27 * @tparam ObjectType the type of the data. 28 * 29 * @param data pointer to the start of the data. 30 * @param size number of count of the data. 31 */ 32 template <typename ObjectType> 33 struct Fragment { 34 ObjectType *data; 35 size_t size; FragmentFragment36 Fragment(ObjectType *data_, size_t size_) : data(data_), size(size_) {} 37 }; 38 39 /** 40 * A data structure designed to partition continuous sequences of data into 41 * manageable fragments. 42 * 43 * This class is particularly useful when dealing with large datasets, allowing 44 * for efficient processing. Each fragment represents a contiguous subset of the 45 * original data, with the size of each fragment determined by the 46 * @c fragmentSize parameter besides the last fragment. The last fragment might 47 * have less data then @c fragmentSize if there is no enough data left. 48 * It is also the creator's responsibility to make sure that the data is alive 49 * during the usage of FragmentationManager since FragmentationManager does not 50 * keep a copy of the data. 51 * 52 * @tparam ObjectType The specific type of data element (object) to be stored 53 * within this structure. 54 * @tparam fragmentSize The number of @c ObjectType elements that constitute a 55 * single fragment. 56 */ 57 template <typename ObjectType, size_t fragmentSize> 58 class FragmentationManager { 59 public: 60 /** 61 * Initializes the fragmentation manager, partitioning a continuous block of 62 * data into fragments. 63 * 64 * @param dataSource A raw pointer to pointing to the beginning of the 65 * continuous data block to be fragmented. 66 * @param dataSize The total number of bytes in the dataSource. 67 * 68 * @return false if dataSource is initialized with a nullptr; otherwise true. 69 */ 70 bool init(ObjectType *dataSource, size_t dataSize); 71 72 /** 73 * Deinitializes the fragmentation manager. 74 */ 75 void deinit(); 76 77 /** 78 * Retrieves the next available data fragment. 79 * 80 * @return a @c Fragment with @c data pointing to the address of the 81 * fragment's data; @c size with the size of the fragment. If there is no more 82 * fragments, return an empty optional. 83 */ 84 Optional<Fragment<ObjectType>> getNextFragment(); 85 86 /** 87 * @return the number of fragments that have been emitted so far. 88 */ getEmittedFragmentedCount()89 size_t getEmittedFragmentedCount() { 90 return mEmittedFragment; 91 } 92 /** 93 * @return True if all fragments have been emitted. 94 95 */ hasNoMoreFragment()96 bool hasNoMoreFragment() { 97 return mEmittedFragment * fragmentSize >= mDataSize; 98 } 99 100 private: 101 // A pointer to the beginning of the continuous block of data being 102 // fragmented. 103 ObjectType *mData; 104 // The number of bytes in the 'mData' block. 105 size_t mDataSize; 106 // The number of fragments that have been emitted. 107 size_t mEmittedFragment; 108 }; 109 } // namespace chre 110 111 #include "chre/util/fragmentation_manager_impl.h" // IWYU pragma: export 112 113 #endif // CHRE_UTIL_FRAGMENTATION_MANAGER 114