56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
template<typename T>
|
|
class lock_free_queue
|
|
{
|
|
private:
|
|
void set_new_tail(counted_node_ptr &old_tail,
|
|
counted_node_ptr const &new_tail)
|
|
{
|
|
node* const current_tail_ptr=old_tail.ptr;
|
|
while(!tail.compare_exchange_weak(old_tail,new_tail) &&
|
|
old_tail.ptr==current_tail_ptr);
|
|
if(old_tail.ptr==current_tail_ptr)
|
|
free_external_counter(old_tail);
|
|
else
|
|
current_tail_ptr->release_ref();
|
|
}
|
|
public:
|
|
void push(T new_value)
|
|
{
|
|
std::unique_ptr<T> new_data(new T(new_value));
|
|
counted_node_ptr new_next;
|
|
new_next.ptr=new node;
|
|
new_next.external_count=1;
|
|
counted_node_ptr old_tail=tail.load();
|
|
for(;;)
|
|
{
|
|
increase_external_count(tail,old_tail);
|
|
T* old_data=nullptr;
|
|
if(old_tail.ptr->data.compare_exchange_strong(
|
|
old_data,new_data.get()))
|
|
{
|
|
counted_node_ptr old_next={0};
|
|
if(!old_tail.ptr->next.compare_exchange_strong(
|
|
old_next,new_next))
|
|
{
|
|
delete new_next.ptr;
|
|
new_next=old_next;
|
|
}
|
|
set_new_tail(old_tail, new_next);
|
|
new_data.release();
|
|
break;
|
|
}
|
|
else
|
|
{
|
|
counted_node_ptr old_next={0};
|
|
if(old_tail.ptr->next.compare_exchange_strong(
|
|
old_next,new_next))
|
|
{
|
|
old_next=new_next;
|
|
new_next.ptr=new node;
|
|
}
|
|
set_new_tail(old_tail, old_next);
|
|
}
|
|
}
|
|
}
|
|
};
|