090824项目进展：学习emule源码3，CAICHHashTree

最新推荐文章于 2017-10-09 15:45:00 发布

ensungm

最新推荐文章于 2017-10-09 15:45:00 发布

阅读量513

点赞数

分类专栏： SearchTool项目文章标签： null buffer

本文链接：https://blog.youkuaiyun.com/ensungm/article/details/4479966

版权

SearchTool项目专栏收录该内容

106 篇文章

订阅专栏

1，依据文件块的位置和单元块的大小PARTSIZE查找hashTree。

FindHash是被重载的：

public:
CAICHHashTree* FindHash(uint64 nStartPos, uint64 nSize)
{uint8 buffer = 0;
return FindHash(nStartPos, nSize, &buffer);}

和：

protected:
CAICHHashTree* FindHash(uint64 nStartPos, uint64 nSize, uint8* nLevel);

KnownFile.cpp中当然只能调用那个public的了：

CreateFromFile函数中，使用循环，获取各位置的HashTree：

for (hashcount = 0; togo >= PARTSIZE; )
{
CAICHHashTree* pBlockAICHHashTree = m_pAICHHashSet->m_pHashTree.FindHash((uint64)hashcount*PARTSIZE, PARTSIZE);
ASSERT( pBlockAICHHashTree != NULL ); ......
}

public的FindHash是需要调用protected的FindHash才能实现功能的：

CAICHHashTree* CAICHHashTree::FindHash(uint64 nStartPos, uint64 nSize, uint8* nLevel){

停止条件是：

if (nStartPos == 0 && nSize == m_nDataSize){
// this is the searched hash
return this;

否则：部署并递归recursive

  if (nStartPos < nLeft){
   if (nStartPos + nSize > nLeft){ // sanity
    ASSERT ( false );
    return NULL;
   }
   if (m_pLeftTree == NULL)

{//
m_pLeftTree = new CAICHHashTree(nLeft, true, (nLeft <= PARTSIZE) ? EMBLOCKSIZE : PARTSIZE);

}
   else{
    ASSERT( m_pLeftTree->m_nDataSize == nLeft );
   }
   return m_pLeftTree->FindHash(nStartPos, nSize, nLevel);
  }
  else{
   nStartPos -= nLeft;
   if (nStartPos + nSize > nRight){ // sanity
    ASSERT ( false );
    return NULL;
   }
   if (m_pRightTree == NULL)
    m_pRightTree = new CAICHHashTree(nRight, false, (nRight <= PARTSIZE) ? EMBLOCKSIZE : PARTSIZE);
   else{
    ASSERT( m_pRightTree->m_nDataSize == nRight );
   }
   return m_pRightTree->FindHash(nStartPos, nSize, nLevel);

}