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Added MemoryPool and ObjectPool to project.

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William Moberg
2015-12-01 16:03:07 +01:00
parent 793b2f44cc
commit c147f17c11
2 changed files with 495 additions and 0 deletions
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include/Engine/Core/MemoryPool.h
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#ifndef MemoryPool_h__
#define MemoryPool_h__
#include <vector>
template <typename T>
class MemoryPoolForwardIterator;
//This is the class to use if you want to allocate blocks (slots) of raw memory, with a fixed maximum size (stride).
//Additionally, if you know that every memory-block will contain one object of a specific type, (i.e. the stride for the slot
//will the size of the object type) you should use ObjectPool<T> instead, your life will become easier.
//The memory returned by pool.Allocate() has has no type-information
//Works similarly to malloc(), but it allocates a number of slots of a certain size.
//Basically, pool.Allocate() does the same as malloc(m_Stride).
//
//When the pool goes out of scope (when it is destructed) it will free all memory that was allocated automatically.
//
//The template input type T does not affect the structure of the memory pool, it will
//only affect how the iterators access the pool data, for example:
//MemoryPool<int> p; MemoryPool<int>::iterator iter = p.begin();
//Here, *iter will return the data in the first allocated slot in the pool, interpreted as an int.
//If you only intend to use the pointers returned by Allocate(), and not iterate through the pool,
//T is never used and can safely be set to anything. e.g. char.
template <typename T>
class MemoryPool
{
template <typename T>
friend class MemoryPoolForwardIterator;
public:
typedef MemoryPoolForwardIterator<T> iterator;
typedef ptrdiff_t difference_type;
typedef size_t size_type;
typedef T value_type;
typedef T* pointer;
typedef T& reference;
MemoryPool()
: m_StartAddress(nullptr)
, m_SlotIsAllocated()
, m_NumSlots(0)
, m_Stride(0)
, m_NumAllocatedSlots(0)
, m_LowestAllocatedSlot(0)
{ }
//[stride] is the number of bytes allocated per slot in the pool,
//the smallest amount of memory you can get from Allocate(). (Usually, the maximum size of an object to allocate.)
//[numMaxElements] is the number of slots in the pool. That is, how many stride-sized memory blocks
//the pool will have. (Usually, how many objects can be allocated.)
//These parameters are used to preallocate memory for efficency.
//If numMaxElements is exceeded, the pool will start allocate memory dynamically, "outside the pool", and is much slower.
MemoryPool(size_t numMaxElements, size_t stride)
: m_StartAddress(new char[numMaxElements*stride])
, m_SlotIsAllocated(numMaxElements, false)
, m_NumSlots(numMaxElements)
, m_Stride(stride)
, m_NumAllocatedSlots(0)
, m_CurrentAllocSlot(0)
, m_LowestAllocatedSlot(m_NumSlots)
{ }
MemoryPool(size_t numMaxElements, size_t stride, char* allocatedMemory)
: m_StartAddress(allocatedMemory)
, m_SlotIsAllocated(numMaxElements, false)
, m_NumSlots(numMaxElements)
, m_Stride(stride)
, m_NumAllocatedSlots(0)
, m_CurrentAllocSlot(0)
, m_LowestAllocatedSlot(m_NumSlots)
{ }
//We may get problems with memory being released
//prematurely, etc. if we allow copies.
MemoryPool(const MemoryPool<T>& other) = delete;
MemoryPool(const MemoryPool<T>&& other) = delete;
//Free all memory that has been allocated.
~MemoryPool()
{
if (m_StartAddress != nullptr) {
delete[] m_StartAddress;
m_StartAddress = nullptr;
}
for (char* addr : m_ExtraMemory)
free(addr);
m_ExtraMemory.clear();
}
//Allocates space for a contingous block of memory the size of [stride] bytes, and returns a pointer to the data.
//The data is not touched, and remains uninitialized, i.e. it will have random values in it.
//If element cannot be allocated in the pool, because the memory ran out, memory is allocated dynamically with malloc() "outside the pool".
char* Allocate()
{
for (; m_CurrentAllocSlot < m_NumSlots && m_SlotIsAllocated[m_CurrentAllocSlot]; ++m_CurrentAllocSlot);
if (m_CurrentAllocSlot < m_NumSlots) {
if (m_LowestAllocatedSlot > m_CurrentAllocSlot)
m_LowestAllocatedSlot = m_CurrentAllocSlot;
//Mark the slot as allocated.
m_SlotIsAllocated[m_CurrentAllocSlot] = true;
++m_NumAllocatedSlots;
return m_StartAddress + m_Stride*m_CurrentAllocSlot++;
}
else {
m_ExtraMemory.push_back((char*)malloc(m_Stride));
//TODO: Log this later, we should preferably never enter here, set more memory in constructor instead.
return m_ExtraMemory.back();
}
}
//Free memory that was allocated earlier with Allocate().
void Free(char* obj)
{
//If memory was allocated in the memory pool.
//We are guaranteed to enter here if we have zero malloc() allocations,
//or if the obj was allocated in the pool,
//however, comparisons is technically undefined
//(i.e. IsAllocatedInPool may give false positives)
//if it was malloc():ed
//so, we may enter here even if we shouldn't.
if (IsAllocatedInPool(obj)) {
--m_NumAllocatedSlots;
const size_t freeSlot = (obj - m_StartAddress) / m_Stride;
m_SlotIsAllocated[freeSlot] = false;
if (freeSlot < m_CurrentAllocSlot)
m_CurrentAllocSlot = freeSlot;
//If we happened to remove the begin() slot, find the next one.
//Increment until we find an allocated slot, or go out of bounds.
while (m_LowestAllocatedSlot != m_NumSlots && !m_SlotIsAllocated[m_LowestAllocatedSlot])
++m_LowestAllocatedSlot;
}
//If memory was allocated dynamically with malloc because we didn't have enough storage in pool.
//I.e: if numMallocs > 0 and obj is outside [m_StartAddress-->m_NumSlots].
else {
m_ExtraMemory.erase(find(m_ExtraMemory.begin(), m_ExtraMemory.end(), obj));
free(obj);
}
}
//Returns an iterator pointing to the first element.
//If pool is empty it will be equal to end() and shall not be dereferenced.
iterator begin() const
{
//If pool is empty, lowest slot will be numSlots,
//and m_ExtraMemory.size will be 0, so begin == end.
return iterator(this, m_LowestAllocatedSlot);
}
//Returns an iterator pointing beyond the last element.
//This shall not be dereferenced (Gives a run-time error).
iterator end() const
{
return iterator(this, m_NumSlots + m_ExtraMemory.size());
}
//Returns true iff the pool has no allocated elements.
bool empty() const
{
return m_LowestAllocatedSlot == m_NumSlots && m_ExtraMemory.empty();
}
//Returns the total number of allocated elements.
size_t size() const
{
return m_NumAllocatedSlots + m_ExtraMemory.size();
}
//Returns the number of elements allocated inside the pool boundary.
size_t PoolSize() const
{
return m_NumAllocatedSlots;
}
//Returns the number of elements allocated outside the pool boundary (in dynamic extra space).
size_t ExtraSize() const
{
return m_ExtraMemory.size();
}
//Dumps information about what the pool memory looks like right now
//into an output stream (e.g. file/std::cout, anything that has an operator<<)
//Interpret the data in the memory as InterpretType.
template <typename InterpretType = char, typename OutStream>
void Dump(OutStream& out) const
{
out << "Primary pool memory: Allocated Slots=" << m_NumAllocatedSlots << std::endl;
for (size_t i = 0; i < m_NumSlots; ++i) {
out << "Slot nr " << i << ": ";
for (size_t c = 0; c < m_Stride/sizeof(InterpretType); ++c)
out << (*reinterpret_cast<InterpretType*>(m_StartAddress + i*m_Stride + c)) << "\t";
out << "Allocated = " << m_SlotIsAllocated[i] << std::endl;
}
out << "Dynamic extra pool memory: Slots=" << m_ExtraMemory.size() << std::endl;
for (size_t i = 0; i < m_ExtraMemory.size(); ++i) {
out << "Extra " << i << ": ";
for (size_t c = 0; c < m_Stride / sizeof(InterpretType); ++c)
out << (*reinterpret_cast<InterpretType*>(m_ExtraMemory[i] + c)) << "\t";
out << std::endl;
}
}
//Dumps information about what the pool memory looks like right now
//into std::cout. Interpret the data in the memory as InterpretType.
template <typename InterpretType = char>
void Dump() const
{
Dump<InterpretType>(std::cout);
}
private:
char* m_StartAddress;
std::vector<bool> m_SlotIsAllocated;
std::vector<char*> m_ExtraMemory;
size_t m_NumSlots;
size_t m_LowestAllocatedSlot;
size_t m_NumAllocatedSlots;
size_t m_Stride;
size_t m_CurrentAllocSlot;
bool IsAllocatedInPool(char* p)
{
//If we went outside the pool limits and used dynamic allocation.
if (!m_ExtraMemory.empty())
{
//Assumes that std::uintptr_t is a thing here. No idea what linux does here.
#ifdef UINTPTR_MAX
//Assumes the memory has a linear address space, no weird jumps. Should work on modern platforms.
//Assumes unsigned values loop back to very positive when they go negative. Standard C++ behavior.
return (reinterpret_cast<std::uintptr_t>(p) - reinterpret_cast<std::uintptr_t>(m_StartAddress) < m_NumSlots * m_Stride);
#else
//Fallback on inefficient loop otherwise.
for (size_t i = 0; i < m_NumSlots; i++)
if (p == m_StartAddress + i * m_Stride)
return true;
return false;
#endif
}
return true; //If we don't go outside the pool boundary, this will always be true.
}
};
template <typename T>
class MemoryPoolForwardIterator
: public std::iterator<std::forward_iterator_tag, T>
{
public:
MemoryPoolForwardIterator(const MemoryPool<T>* pool, size_t slotPos)
: m_Pool(pool)
, m_Pos(slotPos)
{ }
MemoryPoolForwardIterator(const MemoryPoolForwardIterator<T>& other) = default;
MemoryPoolForwardIterator(MemoryPoolForwardIterator<T>&& other) = default;
~MemoryPoolForwardIterator() = default;
MemoryPoolForwardIterator<T>& operator= (const MemoryPoolForwardIterator<T>& other) = default;
//Prefix increment i.e. ++iter. More efficient than post increment.
MemoryPoolForwardIterator& operator++()
{
//Increment position, if pos is in the pool area and the slot isn't allocated,
//keep checking the next position.
while (++m_Pos < m_Pool->m_NumSlots && !m_Pool->m_SlotIsAllocated[m_Pos]);
return *this;
}
//Postfix increment i.e. iter++. Prefer pre-increment (++iter) for efficiency.
MemoryPoolForwardIterator& operator++(int)
{
MemoryPoolForwardIterator<T> copyIter(*this);
operator++();
return copyIter;
}
bool operator!= (const MemoryPoolForwardIterator& other) const
{
return m_Pos != other.m_Pos;
}
bool operator== (const MemoryPoolForwardIterator& other) const
{
return m_Pos == other.m_Pos;
}
T& operator* () const
{
return *this->operator->();
}
T* operator-> () const
{
//If pos < numSlots then the iterator is in the pool.
//Else it is in the extra memory.
//NOTE: If you get a "vector subscript out of range" error here,
//then you possibly dereferenced the end() iterator (don't do that).
return (m_Pos < m_Pool->m_NumSlots)
? (reinterpret_cast<T*>(m_Pool->m_StartAddress + m_Pool->m_Stride*m_Pos))
: (reinterpret_cast<T*>(m_Pool->m_ExtraMemory[m_Pos - m_Pool->m_NumSlots]));
}
private:
const MemoryPool<T>* m_Pool;
size_t m_Pos;
};
#endif
include/Engine/Core/ObjectPool.h
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#ifndef ObjectPool_h__
#define ObjectPool_h__
#include "MemoryPool.h"
// - Example usage code below class definition.
//
//This is the class to use if you want to dynamically allocate memory to hold a specific object type.
//
//When the pool goes out of scope (when it is destructed) it destruct all allocated objects and free all memory that was allocated in the pool.
template <typename T>
class ObjectPool
{
public:
typedef MemoryPoolForwardIterator<T> iterator;
typedef ptrdiff_t difference_type;
typedef size_t size_type;
typedef T value_type;
typedef T* pointer;
typedef T& reference;
ObjectPool()
: m_Pool()
{ }
//[numMaxElements] is the number of objects in the pool. This parameter is used to preallocate memory.
//If numMaxElements is exceeded, the pool will start allocate memory dynamically, "outside the pool", which is much slower.
ObjectPool(size_t numMaxElements)
: m_Pool(numMaxElements, sizeof(T))
{ }
//Destruct all elements in the pool that are still allocated.
//Lastly, m_Pool will go out of scope and destruct, freeing all the memory.
~ObjectPool()
{
for (T &o : *this)
o.~T();
}
//Allocates memory to hold one T object, constructs an object
//by supplying any arguments to T(...) constructor.
//Then returns a pointer to its memory.
//
//Works similiarly to new below:
//T* objPointer = new T(...); //<--
// ...
//delete objPointer;
template<typename... Arguments>
T* New(Arguments... args)
{
return new (m_Pool.Allocate()) T(args...);
}
//Calls the destructor of the object pointed to by input parameter.
//Then frees the memory.
//Works similiarly to delete below:
//T* objPointer = new T(...);
// ...
//delete objPointer; //<--
void Delete(T* pObject)
{
pObject->~T();
m_Pool.Free(reinterpret_cast<char*>(pObject));
}
//Calls the destructor of the object pointed to by iterator.
//Then frees the memory.
void Delete(iterator objIterator)
{
pool.Delete(&(*objIterator));
}
//Returns an iterator pointing to the first element.
//If pool is empty it will be equal to end() and shall not be dereferenced.
iterator begin() const
{
return m_Pool.begin();
}
//Returns an iterator pointing beyond the last element.
//This shall not be dereferenced (Gives a run-time error).
iterator end() const
{
return m_Pool.end();
}
//Returns true iff the pool has no allocated elements.
bool empty() const
{
return m_Pool.empty();
}
//Returns the total number of allocated elements.
size_t size() const
{
return m_Pool.size();
}
//Returns the number of allocated elements but not from dynamically allocated extra space.
size_t PoolSize() const
{
return m_Pool.PoolSize();
}
//Returns the number of elements allocated outside the pool boundary (in dynamic extra space).
size_t ExtraSize() const
{
return m_Pool.ExtraSize();
}
//Dumps information about what the pool memory looks like right now
//into an output stream (e.g. file/std::cout, anything that has an operator<<)
//Interpret the data in the memory as InterpretType.
template <typename InterpretType = char, typename OutStream>
void Dump(OutStream& out) const
{
m_Pool.Dump<InterpretType>(out);
}
//Dumps information about what the pool memory looks like right now
//into std::cout. Interpret the data in the memory as InterpretType.
template <typename InterpretType = char>
void Dump() const
{
m_Pool.Dump<InterpretType>();
}
private:
MemoryPool<T> m_Pool;
};
//------------Simple use case example code scenario-----------------
//
// //User defined type that the pool will hold.
// struct HappyStruct {
// int i;
// float f;
// HappyStruct() = default;
// HappyStruct(int ii, float ff) : i(ii), f(ff) { }
// bool operator == (const HappyStruct& o) //std::find wants a == to search through the pool.
// {
// return o.i == i && o.f == f;
// }
// };
//
// //The pool can hold 100 HappyStruct's, before it starts to struggle and we get performance issues.
// ObjectPool<HappyStruct> pool(100);
//
// //For some reason, we want to allocate a struct dynamically.
// //Usually, you would do this: HappyStruct* s = new HappyStruct(17, 2.4142f);
// //Instead:
// HappyStruct* pHappy = pool.New(17, 2.4142f);
//
// //If you want to be able to free the memory manually (e.g. for temporary objects),
// //to free space for other objects, save the return value in pHappy and
// //when it is not needed anymore release it back to the pool.
// //Usually, you would do this: delete pHappy;
// //Instead:
// pool.Delete(pHappy);
//
// //Objects that are not deleted manually will be destructed and deallocated automatically when the pool
// //destructs, so elements can be added to the pool like this.
// pool.New(1, 0.0f);
// pool.New(2, 0.0f);
// pool.New(3, 0.0f);
// pool.New(5, 0.0f);
// pool.New(4, 0.0f);
//
// //You can use some standard functions that operate on iterators,
// //for example if you really want to destroy the element with a 5. (Less efficient (it loops) than deleting the pointer directly, as above)
// ObjectPool<S>::iterator it = find(pool.begin(), pool.end(), S(5, 0)); //Find the first element that is equal to S(5,0)
// pool.Delete(it);
//
// //You can iterate through all allocated elements in the pool, like you would through a collection such as vector:
// //Version with awesome C++11 range-based syntax:
// for (auto& element : pool)
// element.i += 2;
// //Version with standard looping:
// for (auto& iter = pool.begin(); iter != pool.end(); ++iter)
// iter->i += 2;
//
// //Output a snapshot of the memory in the pool, with the memory data interpreted as int, to a stream.
// std::ostream& out = std::cout;
// pool.Dump<int>(out);
// //Output a snapshot of the memory in the pool, with the memory data interpreted as char (bytedata), to a file.
// std::ofstream file("randomFile.txt");
// pool.Dump(file);
// file.close();
//
#endif