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/*
* Copyright (c) 2017-2019 Cisco and/or its affiliates.
* 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.sudo make instamake install
*/
#pragma once
#include <memory>
namespace utils {
template <class T, std::size_t growSize = 1024>
class MemoryPool {
struct Block {
Block *next;
};
class Buffer {
static const std::size_t blockSize = sizeof(T) > sizeof(Block)
? sizeof(T)
: sizeof(Block);
uint8_t data[blockSize * growSize];
public:
Buffer *const next;
Buffer(Buffer *next) : next(next) {}
T *getBlock(std::size_t index) {
return reinterpret_cast<T *>(&data[blockSize * index]);
}
};
Block *firstFreeBlock = nullptr;
Buffer *firstBuffer = nullptr;
std::size_t bufferedBlocks = growSize;
public:
MemoryPool() = default;
MemoryPool(MemoryPool &&memoryPool) = delete;
MemoryPool(const MemoryPool &memoryPool) = delete;
MemoryPool operator=(MemoryPool &&memoryPool) = delete;
MemoryPool operator=(const MemoryPool &memoryPool) = delete;
~MemoryPool() {
while (firstBuffer) {
Buffer *buffer = firstBuffer;
firstBuffer = buffer->next;
delete buffer;
}
}
T *allocate() {
if (firstFreeBlock) {
Block *block = firstFreeBlock;
firstFreeBlock = block->next;
return reinterpret_cast<T *>(block);
}
if (bufferedBlocks >= growSize) {
firstBuffer = new Buffer(firstBuffer);
bufferedBlocks = 0;
}
return firstBuffer->getBlock(bufferedBlocks++);
}
void deallocate(T *pointer) {
Block *block = reinterpret_cast<Block *>(pointer);
block->next = firstFreeBlock;
firstFreeBlock = block;
}
};
template <class T, std::size_t growSize = 1024>
class Allocator : private MemoryPool<T, growSize> {
#ifdef _WIN32
Allocator *copyAllocator;
std::allocator<T> *rebindAllocator = nullptr;
#endif
public:
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
typedef T *pointer;
typedef const T *const_pointer;
typedef T &reference;
typedef const T &const_reference;
typedef T value_type;
template <class U>
struct rebind {
typedef Allocator<U, growSize> other;
};
#ifdef _WIN32
Allocator() = default;
Allocator(Allocator &allocator) : copyAllocator(&allocator) {}
template <class U>
Allocator(const Allocator<U, growSize> &other) {
if (!std::is_same<T, U>::value) rebindAllocator = new std::allocator<T>();
}
~Allocator() { delete rebindAllocator; }
#endif
pointer allocate(size_type n, const void *hint = 0) {
#ifdef _WIN32
if (copyAllocator) return copyAllocator->allocate(n, hint);
if (rebindAllocator) return rebindAllocator->allocate(n, hint);
#endif
if (n != 1 || hint) throw std::bad_alloc();
return MemoryPool<T, growSize>::allocate();
}
void deallocate(pointer p, size_type n) {
#ifdef _WIN32
if (copyAllocator) {
copyAllocator->deallocate(p, n);
return;
}
if (rebindAllocator) {
rebindAllocator->deallocate(p, n);
return;
}
#endif
MemoryPool<T, growSize>::deallocate(p);
}
void construct(pointer p, const_reference val) { new (p) T(val); }
void destroy(pointer p) { p->~T(); }
};
}
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