C++内存泄露

原文  http://blog.csdn.net/zmyer/article/details/21475101
从事C++研发的筒子们，最挥之不去可能要算内存泄露带来的痛苦吧，在C++中，虽说其实现底层代码方面所凸显出来的性能要远高于其他类型语言，但是其由于缺乏天生的内存回收机制，从而也被业界予以诟病，那有没有办法能够监测到程序中的内存泄露问题呢，其实是有很多的办法，例如efence ，vagrind类型的工具等，但是这些工具最大的问题就是太重量级了，需要在自己的代码中安插部分调试代码，使用起来也是不很方便，基于此，本人通过学习前人的一些方法，稍微对new，delete进行了重载，基本上实现了检查程序中的内存泄露问题，好了，下面来看代码吧：

#include #include #include #include using namespace boost; #define MEM_CHECK_TABLESIZE 1024*1024 #define MEM_HASH_FUNC(ptr) ((reinterpret_cast(ptr))%MEM_CHECK_TABLESIZE) #define MEM_FILENAME_SIZE 1024 boost::mutex mut;
boost::mutex mem_mut; struct allocMem_ptr_t
{  allocMem_ptr_t()  {   bzero(fileName,sizeof(fileName));   size = 0;   line = 0;   next = NULL;  }  char fileName[MEM_FILENAME_SIZE];  int size;  int line;  allocMem_ptr_t* next;
}; struct allocMem_ptr_t* allocMem_list[MEM_CHECK_TABLESIZE]; int tableSize = 0; struct memLeak_ptr_t
{  memLeak_ptr_t()  {   bzero(fileName,sizeof(fileName));   size = 0;  }  char fileName[MEM_FILENAME_SIZE];  int size;
}; std::map<int,memLeak_ptr_t> memLeak_map; void memCheck()
{  size_t index = 0;  mem_mut.lock();  for(int i=0;i {   allocMem_ptr_t* alloc = allocMem_list[i];   if(NULL == alloc) continue;   while(alloc)   {    memLeak_ptr_t memLeak;    sprintf(memLeak.fileName,"%s:%d",alloc->fileName,alloc->line);    memLeak.size = alloc->size;    memLeak_map.insert(std::make_pair(index,memLeak));    alloc = alloc->next;    index++;   }  }  mem_mut.unlock();  std::map<std::string,int> leakCount;  for(int i =0;i  leakCount[memLeak_map[i].fileName] += memLeak_map[i].size;  typedef std::map<std::string,int>::iterator leakCount_iter;  for(leakCount_iter iter = leakCount.begin();iter != leakCount.end();++iter)  {   printf("%s LEAK MEMORY SIZE:%d\n",iter->first.c_str(),iter->second);  }
} void* operator new(size_t size,const char* file,int line)
{  size_t siz = size + sizeof(allocMem_ptr_t);  allocMem_ptr_t* ptr = (allocMem_ptr_t*)::malloc(siz);  if(NULL == ptr) abort();  void* p = (char*)ptr + sizeof(allocMem_ptr_t);  strncpy(ptr->fileName,file,MEM_FILENAME_SIZE-1);  ptr->size = size;  ptr->line = line;  mem_mut.lock();  size_t index = MEM_HASH_FUNC(p);  ptr->next = allocMem_list[index];  allocMem_list[index] = ptr;  ++tableSize;  mem_mut.unlock();  return p;
} void* operator new[](size_t size,const char* file,int line)
{  return operator new(size,file,line);
} void operator delete(void* ptr)
{  if(NULL == ptr) return;  allocMem_ptr_t* pre = NULL;  size_t index = MEM_HASH_FUNC(ptr);  mem_mut.lock();  allocMem_ptr_t* pointer = allocMem_list[index];  while(pointer)  {   if((char*)pointer + sizeof(allocMem_ptr_t) == ptr)   {    if(NULL == pre)     allocMem_list[index] = pointer->next;    else     pre->next = pointer->next;    --tableSize;    break;   }   pre = pointer;   pointer = pointer->next;  }  mem_mut.unlock();  free(pointer);
} void operator delete[](void* pointer)
{  operator delete(pointer);
} void operator delete(void* pointer,const char* file,int line)
{  operator delete(pointer);
} void operator delete[](void* pointer,const char* file,int line)
{  operator delete(pointer);
}

#ifndef __MEM_CHECK__H #define __MEM_CHECK__H #include #include #define MEM_CHECK memCheck() void memCheck(); void* operator new(size_t size,const char* file,int line); void* operator new[](size_t size,const char* file,int line); void operator delete(void* pointer,const char* file,int line); void operator delete[](void* pointer,const char* file,int line); #define MEM_ALLOC new(__FILE__,__LINE__) #define MEM_DELETE delete #endif

测试程序：

#include "MemCheck.h" struct point
{  point()  {   posX = 0;   posY = 0;  }  int posX;  int posY;
}; int main(int argc,char* argv[])
{  int* pointer = MEM_ALLOC int();  double* doub = MEM_ALLOC double();  std::string* str = MEM_ALLOC std::string();  point* po = MEM_ALLOC point();  MEM_DELETE pointer;  MEM_DELETE po;  MEM_CHECK;  return 0;
}

测试结果：

Test.cpp:18 LEAK MEMORY SIZE:8 Test.cpp:19 LEAK MEMORY SIZE:4

总结

       本篇博文主要是通过封装new、delete操作，实现了一个简单版的检查内存泄露工具，原理很简单：通过一个简单的hash表来存放相关的内存分配信息，这个hash表会随着内存分配操作而动态的调整，这个实现思路其实还是有部分的问题，但总体上来将还是应用于实际的项目，好好地体会吧，有机会的话，我们可以使用redis来改写下这个功能，好了，本篇博文到此结束。

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