| /* |
| * Copyright 2019, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef ANDROID_REGION_FAT_VECTOR_H |
| #define ANDROID_REGION_FAT_VECTOR_H |
| |
| #include <stddef.h> |
| #include <stdlib.h> |
| #include <utils/Log.h> |
| #include <type_traits> |
| |
| #include <vector> |
| |
| namespace android { |
| |
| template <typename T, size_t SIZE = 4> |
| class InlineStdAllocator { |
| public: |
| struct Allocation { |
| private: |
| Allocation(const Allocation&) = delete; |
| void operator=(const Allocation&) = delete; |
| |
| public: |
| Allocation() {} |
| // char array instead of T array, so memory is uninitialized, with no destructors run |
| char array[sizeof(T) * SIZE]; |
| bool inUse = false; |
| }; |
| |
| typedef T value_type; // needed to implement std::allocator |
| typedef T* pointer; // needed to implement std::allocator |
| |
| explicit InlineStdAllocator(Allocation& allocation) : mAllocation(allocation) {} |
| InlineStdAllocator(const InlineStdAllocator& other) : mAllocation(other.mAllocation) {} |
| ~InlineStdAllocator() {} |
| |
| T* allocate(size_t num, const void* = 0) { |
| if (!mAllocation.inUse && num <= SIZE) { |
| mAllocation.inUse = true; |
| return static_cast<T*>(static_cast<void*>(mAllocation.array)); |
| } else { |
| return static_cast<T*>(static_cast<void*>(malloc(num * sizeof(T)))); |
| } |
| } |
| |
| void deallocate(pointer p, size_t) { |
| if (p == static_cast<T*>(static_cast<void*>(mAllocation.array))) { |
| mAllocation.inUse = false; |
| } else { |
| // 'free' instead of delete here - destruction handled separately |
| free(p); |
| } |
| } |
| Allocation& mAllocation; |
| }; |
| |
| /** |
| * std::vector with SIZE elements preallocated into an internal buffer. |
| * |
| * Useful for avoiding the cost of malloc in cases where only SIZE or |
| * fewer elements are needed in the common case. |
| */ |
| template <typename T, size_t SIZE = 4> |
| class FatVector : public std::vector<T, InlineStdAllocator<T, SIZE>> { |
| public: |
| FatVector() |
| : std::vector<T, InlineStdAllocator<T, SIZE>>(InlineStdAllocator<T, SIZE>(mAllocation)) { |
| this->reserve(SIZE); |
| } |
| |
| FatVector(std::initializer_list<T> init) |
| : std::vector<T, InlineStdAllocator<T, SIZE>>(init, |
| InlineStdAllocator<T, SIZE>(mAllocation)) { |
| this->reserve(SIZE); |
| } |
| |
| explicit FatVector(size_t capacity) : FatVector() { this->resize(capacity); } |
| |
| private: |
| typename InlineStdAllocator<T, SIZE>::Allocation mAllocation; |
| }; |
| |
| } // namespace android |
| |
| #endif // ANDROID_REGION_FAT_VECTOR_H |