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//lock free queue template class by Herb Sutter
//Dr Dobbs Journal article http://www.drdobbs.com/cpp/210604448;jsessionid=OQGQPSMNL4X4XQE1GHPSKH4ATMY32JVN?pgno=1
template <typename T> class LockFreeQueue
{
private:
struct Node
{
Node( T val ) : value(val), next(nullptr) { }
T value;
Node* next;
};
Node* first; // for producer only
Node* divider, last; // shared
//not working in VC2008
//atomic<Node*> divider, last; // shared
public:
LockFreeQueue()
{
// add dummy separator
first = divider = last = new Node( T() );
}
~LockFreeQueue()
{
while( first != nullptr )
{
// release the list
Node* tmp = first;
first = tmp->next;
delete tmp;
}
}
void Produce( const T& t )
{
last->next = new Node(t); // add the new item
last = last->next; // publish it
while( first != divider )
{
// trim unused nodes
Node* tmp = first;
first = first->next;
delete tmp;
}
}
bool Consume( T& result )
{
if( divider != last )
{
// if queue is nonempty
result = divider->next->value; // copy it back
divider = divider->next; // publish that we took it
return true; // and report success
}
return false; // else report empty
}
};
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