【发布时间】：2014-03-01 05:22:42
【问题描述】：
我使用了来自source 的库streed2006.cpp。该代码在删除边缘时存在内存泄漏。我使用以下代码从哈希表中清除了边数：
//throwing away the edges from hashtable
for(int t=0;t<HASH_TABLE_SIZE;t++)
{
Edges[t].Remove();
Edges[t].start_node == -1
}
valgrind 输出：
3,920 bytes in 245 blocks are definitely lost in loss record 9 of 12
==6301== at 0x4029F34: operator new(unsigned int) (in /usr/lib/valgrind /vgpreload_memcheck-x86-linux.so)
==6301== by 0x804A683: Edge::SplitEdge(Suffix&) (suffix_tree.cpp:555)
==6301== by 0x804B02F: AddPrefix(Suffix&, int) (suffix_tree.cpp:753)
请指导我如何删除边缘。
能够消除内存泄漏。以下是解决方案：
void AddPrefix( Suffix &active, int last_char_index )
{
int parent_node;
int last_parent_node = -1;
for ( ; ; ) {
Edge edge;
parent_node = active.origin_node;
if ( active.Explicit() ) {
edge = Edge::Find( active.origin_node, T[ last_char_index ] );
if ( edge.start_node != -1 )
break;
} else { //implicit node, a little more complicated
edge = Edge::Find( active.origin_node, T[ active.first_char_index ] );
int span = active.last_char_index - active.first_char_index;
if ( T[ edge.first_char_index + span + 1 ] == T[ last_char_index ] )
break;
parent_node = edge.SplitEdge( active );
}
Edge *new_edge = new Edge( last_char_index, T.N, parent_node );
new_edge->Insert();
//cout << "Created edge to new leaf: " << *new_edge << "\n";
AddSuffixLink( last_parent_node, parent_node );
if ( active.origin_node == 0 ) {
//cout << "Can't follow suffix link, I'm at the root\n";
active.first_char_index++;
} else {
/*
cout << "Following suffix link from node "
<< active.origin_node
<< " to node "
<< Suffix_Nodes[ active.origin_node ].suffix_node
<< ".\n";
*/
active.origin_node = Suffix_Nodes[ active.origin_node ].suffix_node;
//cout << "New prefix : " << active << "\n";
}
active.Canonize();
delete(new_edge);
new_edge = NULL;
}
AddSuffixLink( last_parent_node, parent_node );
active.last_char_index++; //Now the endpoint is the next active point
active.Canonize();
};
和
int Edge::SplitEdge( Suffix &s )
{
//cout << "Splitting edge: " << *this << "\n";
Remove();
Edge *new_edge =
new Edge( first_char_index,
first_char_index + s.last_char_index - s.first_char_index,
s.origin_node );
new_edge->Insert();
Suffix_Nodes[ new_edge->end_node ].suffix_node = s.origin_node;
first_char_index += s.last_char_index - s.first_char_index + 1;
start_node = new_edge->end_node;
Insert();
//cout << "New edge: " << *new_edge << "\n";
//cout << "Old edge: " << *this << "\n";
delete(new_edge);
//return new_edge->end_node;
return(start_node);
}
【问题讨论】：
-
具体问题是？
-
@leonardo 程序内存泄漏。我的分析表明这是由于边缘没有被删除。所以我需要有人告诉我如何在不再需要边缘时删除它们。
-
你读过
Edges::Remove()函数上方的评论区吗？ -
@Leonardo 是的，我做到了，它不会删除边缘，只是将其从哈希表中删除。我需要做的。我怀疑我需要修改 `dump_edges()` 来删除边。但不知道怎么做？
-
是的，这段代码中肯定没有
delete，但是实现了new动态分配。所以，我认为你是对的。解决方案是为每个使用的new实现一个delete。
标签： c++ memory memory-management memory-leaks valgrind