update to 1.7.0

This commit is contained in:
proddy
2024-06-04 21:19:48 +02:00
parent 26ac0057a5
commit 7f1dbbcb94
23 changed files with 2025 additions and 1428 deletions

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MIT License
Copyright (c) 2024 Bert Melis
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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# Memory Pool
EARLY VERSION. USE AT OWN RISK.
### Description
This is a simple memory pool that doesn't solve the fragmentation problem but contains it. Inside the pool you will still suffer memory fragmentation. The upside is that you're not restricted on memory size. As long as it fits in the pool, you can request any size!
For applications where the (maximum) size to allocate is known, a simple fixed block size memory pool is available. There is no memory fragmentation happening in this case. The downside is wastage of memory if you need less then the specified blocksize.
#### Features
- pool memory is statically allocated
- pool size adjusts on architecture
- no size calculation required: input number of blocks and size of block
- header-only library
- Variable size pool: no restriction on allocated size
- Variable size pool: malloc and free are O(n); The number of allocated blocks affects lookup.
- Fixed size pool: malloc and free are O(1).
[![Test with Platformio](https://github.com/bertmelis/MemoryPool/actions/workflows/test-platformio.yml/badge.svg)](https://github.com/bertmelis/MemoryPool/actions/workflows/test-platformio.yml)
[![cpplint](https://github.com/bertmelis/MemoryPool/actions/workflows/cpplint.yml/badge.svg)](https://github.com/bertmelis/MemoryPool/actions/workflows/cpplint.yml)
<!---[![cppcheck](https://github.com/bertmelis/MemoryPool/actions/workflows/cppcheck.yml/badge.svg)](https://github.com/bertmelis/MemoryPool/actions/workflows/cppcheck.yml)--->
### Usage
#### Variable size pool
```cpp
#include <MemoryPool.h>
Struct MyStruct {
unsigned int id;
std::size_t size;
unsigned char data[256];
};
// pool will be able to hold 10 blocks the size of MyStruct
MemoryPool::Variable<10, sizeof(MyStruct)> pool;
// you can allocate the specified blocksize
// allocation is done in number of 'unsigned char'
MyStruct* s = reinterpret_cast<MyStruct*>(pool.malloc(sizeof(MyStruct)));
// you can allocate less than the specified blocksize
int* i = reinterpret_cast<int*>(pool.malloc(sizeof(int)));
// you can allocate more than the specified blocksize
unsigned char* m = reinterpret_cast<unsigned char*>(pool.malloc(400));
pool.free(s);
pool.free(i);
pool.free(m);
```
#### Fixed size pool
```cpp
#include <MemoryPool.h>
Struct MyStruct {
unsigned int id;
std::size_t size;
unsigned char data[256];
};
// pool will be able to hold 10 blocks the size of MyStruct
MemoryPool::Fixed<10, sizeof(MyStruct)> pool;
// there is no size argument in the malloc function!
MyStruct* s = reinterpret_cast<MyStruct*>(pool.malloc());
// you can allocate less than the specified blocksize
int* i = reinterpret_cast<int*>(pool.malloc());
pool.free(s);
pool.free(i);
```
#### How it works
##### Variable size pool
Free blocks are organized as a linked list with their header (contains pointer to next and size). An allocated block also has this header with it's pointer set to `nullptr`. Therefore, each allocation wastes memory the size of the header (`sizeof(void*) + sizeof(std::size_t)`). On creation, the pool calculations the needed space to store the number of blocks wich each their header.
However, memory allocation isn't restricted the the specified blocksize. So in reality, you can allocate more if you allocate larger chunks because less memory blocks means less headers. After all, memory needs to be contiguous.
If you inspect the pool you'll see that a free pool only has one big block.
Allocation is linear: the pool is iterated until a suitable spot is found.
Freeing is also linear as the pool is traversed to insert the chunk in the linked list of free blocks
When freeing, free blocks which are adjacent are combined into one.
##### Fixed size pool
The fixed size pool is implemented as an array. Free blocks are saved as a linked list in this array.
### Bugs and feature requests
Please use Github's facilities to get in touch.
### License
This library is released under the MIT Licence. A copy is included in the repo.

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# Datatypes (KEYWORD1)
Fixed KEYWORD1
Variable KEYWORD1
# Methods and Functions (KEYWORD2)
malloc KEYWORD2
free KEYWORD2
freeMemory KEYWORD2
maxBlockSize KEYWORD2
print KEYWORD2
# Structures (KEYWORD3)
# structure KEYWORD3
# Constants (LITERAL1)
MemoryPool LITERAL1

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{
"name": "MemoryPool",
"keywords": "memory",
"description": "A simple memory pool for fixed and variable sizes",
"authors":
{
"name": "Bert Melis",
"url": "https://github.com/bertmelis"
},
"license": "MIT",
"homepage": "https://github.com/bertmelis/MemoryPool",
"repository":
{
"type": "git",
"url": "https://github.com/bertmelis/MemoryPool.git"
},
"version": "0.1.0",
"frameworks": "*",
"platforms": "*",
"headers": ["MemoryPool.h"]
}

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name=MemoryPool
version=0.1.0
author=Bert Melis
maintainer=Bert Melis
sentence=A simple memory pool for fixed and variable sizes
paragraph=
category=Other
url=https://github.com/bertmelis/MemoryPool
architectures=*
includes=MemoryPool.h

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/*
Copyright (c) 2024 Bert Melis. All rights reserved.
This work is licensed under the terms of the MIT license.
For a copy, see <https://opensource.org/licenses/MIT> or
the LICENSE file.
*/
#pragma once
#include <cstddef> // std::size_t
#include <cassert> // assert
#if _GLIBCXX_HAS_GTHREADS
#include <mutex> // NOLINT [build/c++11] std::mutex, std::lock_guard
#else
#warning "The memory pool is not thread safe"
#endif
#ifdef MEMPOL_DEBUG
#include <iostream>
#endif
namespace MemoryPool {
template <std::size_t nrBlocks, std::size_t blocksize>
class Fixed {
public:
Fixed() // cppcheck-suppress uninitMemberVar
: _buffer{0}
, _head(_buffer) {
unsigned char* b = _head;
std::size_t adjustedBlocksize = sizeof(std::size_t) > blocksize ? sizeof(std::size_t) : blocksize;
for (std::size_t i = 0; i < nrBlocks - 1; ++i) {
*reinterpret_cast<unsigned char**>(b) = b + adjustedBlocksize;
b += adjustedBlocksize;
}
*reinterpret_cast<unsigned char**>(b) = nullptr;
}
// no copy nor move
Fixed (const Fixed&) = delete;
Fixed& operator= (const Fixed&) = delete;
void* malloc() {
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
if (_head) {
void* retVal = _head;
_head = *reinterpret_cast<unsigned char**>(_head);
return retVal;
}
return nullptr;
}
void free(void* ptr) {
if (!ptr) return;
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
*reinterpret_cast<unsigned char**>(ptr) = _head;
_head = reinterpret_cast<unsigned char*>(ptr);
}
std::size_t freeMemory() {
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
unsigned char* i = _head;
std::size_t retVal = 0;
while (i) {
retVal += blocksize;
i = reinterpret_cast<unsigned char**>(i)[0];
}
return retVal;
}
#ifdef MEMPOL_DEBUG
void print() {
std::size_t adjustedBlocksize = sizeof(std::size_t) > blocksize ? sizeof(std::size_t) : blocksize;
std::cout << "+--------------------" << std::endl;
std::cout << "|start:" << reinterpret_cast<void*>(_buffer) << std::endl;
std::cout << "|blocks:" << nrBlocks << std::endl;
std::cout << "|blocksize:" << adjustedBlocksize << std::endl;
std::cout << "|head: " << reinterpret_cast<void*>(_head) << std::endl;
unsigned char* currentBlock = _buffer;
for (std::size_t i = 0; i < nrBlocks; ++i) {
std::cout << "|" << i + 1 << ": " << reinterpret_cast<void*>(currentBlock) << std::endl;
if (_isFree(currentBlock)) {
std::cout << "| free" << std::endl;
std::cout << "| next: " << reinterpret_cast<void*>(*reinterpret_cast<unsigned char**>(currentBlock)) << std::endl;
} else {
std::cout << "| allocated" << std::endl;
}
currentBlock += adjustedBlocksize;
}
std::cout << "+--------------------" << std::endl;
}
bool _isFree(const unsigned char* ptr) {
unsigned char* b = _head;
while (b) {
if (b == ptr) return true;
b = *reinterpret_cast<unsigned char**>(b);
}
return false;
}
#endif
private:
unsigned char _buffer[nrBlocks * (sizeof(std::size_t) > blocksize ? sizeof(std::size_t) : blocksize)];
unsigned char* _head;
#if _GLIBCXX_HAS_GTHREADS
std::mutex _mutex;
#endif
};
} // end namespace MemoryPool

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/*
Copyright (c) 2024 Bert Melis. All rights reserved.
This work is licensed under the terms of the MIT license.
For a copy, see <https://opensource.org/licenses/MIT> or
the LICENSE file.
*/
#pragma once
#include "Variable.h"
#include "Fixed.h"

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/*
Copyright (c) 2024 Bert Melis. All rights reserved.
This work is licensed under the terms of the MIT license.
For a copy, see <https://opensource.org/licenses/MIT> or
the LICENSE file.
*/
#pragma once
#include <cstddef> // std::size_t
#include <cassert> // assert
#if _GLIBCXX_HAS_GTHREADS
#include <mutex> // NOLINT [build/c++11] std::mutex, std::lock_guard
#else
#warning "The memory pool is not thread safe"
#endif
#ifdef MEMPOL_DEBUG
#include <iostream>
#endif
namespace MemoryPool {
template <std::size_t nrBlocks, std::size_t blocksize>
class Variable {
public:
Variable()
: _buffer{0}
, _head(nullptr)
#ifdef MEMPOL_DEBUG
, _bufferSize(0)
#endif
{
std::size_t _normBlocksize = blocksize / sizeof(BlockHeader) + ((blocksize % sizeof(BlockHeader)) ? 1 : 0);
size_t nrBlocksToAlloc = nrBlocks * (_normBlocksize + 1);
BlockHeader* h = reinterpret_cast<BlockHeader*>(_buffer);
h->next = nullptr;
h->size = nrBlocksToAlloc;
_head = h;
#ifdef MEMPOL_DEBUG
_bufferSize = nrBlocksToAlloc;
#endif
}
// no copy nor move
Variable (const Variable&) = delete;
Variable& operator= (const Variable&) = delete;
void* malloc(size_t size) {
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
if (size == 0) return nullptr;
size = (size / sizeof(BlockHeader) + (size % sizeof(BlockHeader) != 0)) + 1; // count by BlockHeader size, add 1 for header
#ifdef MEMPOL_DEBUG
std::cout << "malloc (raw) " << size << std::endl;
std::cout << "malloc (adj) " << size << " - ";
#endif
BlockHeader* currentBlock = _head;
BlockHeader* previousBlock = nullptr;
void* retVal = nullptr;
// iterate through linked free blocks
while (currentBlock) {
// consume whole block is size equals required size
if (currentBlock->size == size) {
if (previousBlock) previousBlock->next = currentBlock->next;
break;
// split block if size is larger and add second part to list of free blocks
} else if (currentBlock->size > size) {
BlockHeader* newBlock = currentBlock + size;
if (previousBlock) previousBlock->next = newBlock;
newBlock->next = currentBlock->next;
newBlock->size = currentBlock->size - size;
currentBlock->next = newBlock;
break;
}
previousBlock = currentBlock;
currentBlock = currentBlock->next;
}
if (currentBlock) {
if (currentBlock == _head) {
_head = currentBlock->next;
}
currentBlock->size = size;
currentBlock->next = nullptr; // used when freeing memory
retVal = currentBlock + 1;
#ifdef MEMPOL_DEBUG
std::cout << "ok" << std::endl;
#endif
} else {
#ifdef MEMPOL_DEBUG
std::cout << "nok" << std::endl;
#endif
(void)0;
}
return retVal;
}
void free(void* ptr) {
if (!ptr) return;
// check if ptr points to region in _buffer
#ifdef MEMPOL_DEBUG
std::cout << "free " << static_cast<void*>(reinterpret_cast<BlockHeader*>(ptr) - 1) << std::endl;
#endif
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
BlockHeader* toFree = reinterpret_cast<BlockHeader*>(ptr) - 1;
BlockHeader* previous = reinterpret_cast<BlockHeader*>(_buffer);
BlockHeader* next = _head;
// toFree is the only free block
if (!next) {
_head = toFree;
return;
}
while (previous) {
if (!next || toFree < next) {
// 1. add block to linked list of free blocks
if (toFree < _head) {
toFree->next = _head;
_head = toFree;
} else {
previous->next = toFree;
toFree->next = next;
}
// 2. merge with previous if adjacent
if (toFree > _head && toFree == previous + previous->size) {
previous->size += toFree->size;
previous->next = toFree->next;
toFree = previous; // used in next check
}
// 3. merge with next if adjacent
if (toFree + toFree->size == next) {
toFree->size += next->size;
toFree->next = next->next;
}
// 4. done
return;
}
previous = next;
next = next->next;
}
}
std::size_t freeMemory() {
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
size_t retVal = 0;
BlockHeader* currentBlock = reinterpret_cast<BlockHeader*>(_head);
while (currentBlock) {
retVal += currentBlock->size - 1;
currentBlock = currentBlock->next;
}
return retVal * sizeof(BlockHeader);
}
std::size_t maxBlockSize() {
#if _GLIBCXX_HAS_GTHREADS
const std::lock_guard<std::mutex> lockGuard(_mutex);
#endif
size_t retVal = 0;
BlockHeader* currentBlock = reinterpret_cast<BlockHeader*>(_head);
while (currentBlock) {
retVal = (currentBlock->size - 1 > retVal) ? currentBlock->size - 1 : retVal;
currentBlock = currentBlock->next;
}
return retVal * sizeof(BlockHeader);
}
#ifdef MEMPOL_DEBUG
void print() {
std::cout << "+--------------------" << std::endl;
std::cout << "|start:" << static_cast<void*>(_buffer) << std::endl;
std::cout << "|size:" << _bufferSize << std::endl;
std::cout << "|headersize:" << sizeof(BlockHeader) << std::endl;
std::cout << "|head: " << static_cast<void*>(_head) << std::endl;
BlockHeader* nextFreeBlock = _head;
BlockHeader* currentBlock = reinterpret_cast<BlockHeader*>(_buffer);
size_t blockNumber = 1;
while (currentBlock < reinterpret_cast<BlockHeader*>(_buffer) + _bufferSize) {
std::cout << "|" << blockNumber << ": " << static_cast<void*>(currentBlock) << std::endl;
std::cout << "| " << static_cast<void*>(currentBlock->next) << std::endl;
std::cout << "| " << currentBlock->size << std::endl;
if (currentBlock == nextFreeBlock) {
std::cout << "| free" << std::endl;
nextFreeBlock = nextFreeBlock->next;
} else {
std::cout << "| allocated" << std::endl;
}
++blockNumber;
currentBlock += currentBlock->size;
}
std::cout << "+--------------------" << std::endl;
}
#endif
private:
struct BlockHeader {
BlockHeader* next;
std::size_t size;
};
/*
pool size is aligned to sizeof(BlockHeader).
requested blocksize is therefore multiple of blockheader (rounded up)
total size = nr requested blocks * multiplier * blockheadersize
see constructor for calculation
*/
unsigned char _buffer[(nrBlocks * ((blocksize / sizeof(BlockHeader) + ((blocksize % sizeof(BlockHeader)) ? 1 : 0)) + 1)) * sizeof(BlockHeader)];
BlockHeader* _head;
#if _GLIBCXX_HAS_GTHREADS
std::mutex _mutex;
#endif
#ifdef MEMPOL_DEBUG
std::size_t _bufferSize;
#endif
};
} // end namespace MemoryPool