实现一个内存池管理的类方法

模拟STL中的freelist,有这个思想在内。

union obj
{
 union obj* next;
 char p[1];   
};

class MemoryPool
{ 
   public:
      MemoryPool()
      {
        union obj* temp;
        m_memory.assign(5,(union obj*)NULL);     
        for(int i=0;i<m_memory.size();i++)
        {
          for(int j=0;j<m_memory.size();j++)
          {
           temp = (obj*)malloc(sizeof(char)*(1<<(i+3)));   
           temp->next = m_memory[i];
           m_memory[i] = temp; 
          }
        }
      }
      char* mem_get(int size)
      {
        int j;
        if( size > 128)
        {
         char* start = (char*)malloc(sizeof(char)*size);
         return start; 
        }
        int index = freelist_index(size);
        obj* temp = m_memory[index];
        if(temp == NULL) //
        {
         for(j = index+1;j<m_memory.size();j++)
         {
           temp = m_memory[j];
           if(temp != NULL)
           {
            m_memory[j] = temp->next;
            break;    
           }   
         }
         if(j>= m_memory.size())
         {
           for(int j=0;j<m_memory.size();j++)
          {
           temp = (obj*)malloc(sizeof(char)*(1<<(index+3)));   
           temp->next = m_memory[index];
           m_memory[index] = temp; 
          } 
          temp = m_memory[index];
          m_memory[index] = temp->next;
          return (char*)temp;
         }
         else
         {
           obj* cur;
          
           int up_size = round_up(size);
           for(int i=0;i<(1<<(j-index));i++)
           {
            cur = temp;
            cur->next = m_memory[index];
            m_memory[index] = cur;
            temp = cur+up_size;
         
           } 
           temp = m_memory[index];
           m_memory[index] = temp->next;
           return (char*)temp;
         }   
        }
        else
        { 
         m_memory[index] = temp->next;
         return (char*)temp; 
        }
      }
      void mem_free(void* p,int size)
      {
       if(size > 128)
       {
        free(p);
        return ;  
       }  
       obj* temp = (obj*)p;
       int index = freelist_index(size);
       temp->next = m_memory[index];
       m_memory[index] = temp;
      }
   private:
       enum {_ALIGN = 8};//
       int freelist_index(int __bytes) 
       {
         return (((__bytes) + (int)_ALIGN-1)/(size_t)_ALIGN - 1);
       }
       int round_up(int __bytes) 
       { 
        return (((__bytes) + (int) _ALIGN-1) & ~((int) _ALIGN - 1)); 
       }
       vector<union obj*> m_memory; 
   };

以上这篇实现一个内存池管理的类方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持呐喊教程。