memorypool.hh

#ifndef MIDDLEBOX_MEMORYPOOL_HH
#define MIDDLEBOX_MEMORYPOOL_HH
 
/*
 * memorypool.hh - Template for a memory pool
 *
 * Romain Gaillard.
 */
 
template <typename T>
class MemoryPool
{
    int const DEFAULT_ALLOC = 1024;
public:
    MemoryPool()
    {
        first = NULL;
    }
 
    MemoryPool(unsigned int initialSize)
    {
        first = NULL;
 
        // Perform the first allocation. 'initialSize' memory chunks will be
        // allocated
        initialize(initialSize);
    }
 
    ~MemoryPool()
    {
        MemoryPoolNode *node = first;
        MemoryPoolNode *toDelete = NULL;
 
        // Free each node of the list
        while(node != NULL)
        {
            toDelete = node;
            node = node->next;
 
            // Free the node
            delete toDelete;
        }
    }
 
    void initialize(unsigned int initialSize)
    {
        if(first != NULL)
            return;
 
        // Perform the first allocation. 'initialSize' memory chunks will be
        // allocated
        allocateMoreMemory(initialSize);
    }
 
    T* getMemory()
    {
        MemoryPoolNode *node = first;
 
        if(first == NULL)
        {
            allocateMoreMemory(DEFAULT_ALLOC);
            node = first;
        }
 
        first = node->next;
 
        return (T*)node;
    }
 
    void releaseMemory(T* p)
    {
        ((MemoryPoolNode*)p)->next = first;
        first = (MemoryPoolNode*)p;
    }
 
private:
    // Element of the pool
    union MemoryPoolNode
    {
        MemoryPoolNode *next; 
        T data; 
        // Constructors and destructors required since T can be an object with a constructor
        // that will be deleted from the union (C++11)
        MemoryPoolNode()
        {
            next = NULL;
        }
 
        ~MemoryPoolNode()
        {
 
        }
    };
 
    void allocateMoreMemory(unsigned int size)
    {
        MemoryPoolNode *node = NULL;
        // Creating 'initialSize' elements;
        for(unsigned i = 0; i < size; ++i)
        {
            // Allocate the node
            node = new MemoryPoolNode;
 
            node->next = first;
            first = node;
        }
    }
 
    MemoryPoolNode* first; 
};
 
#endif