34 lines
889 B
C++
34 lines
889 B
C++
template<typename T>
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class lock_free_queue
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{
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private:
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struct node
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{
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std::atomic<T*> data;
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std::atomic<node_counter> count;
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std::atomic<counted_node_ptr> next;
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};
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public:
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std::unique_ptr<T> pop()
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{
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counted_node_ptr old_head=head.load(std::memory_order_relaxed);
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for(;;)
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{
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increase_external_count(head,old_head);
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node* const ptr=old_head.ptr;
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if(ptr==tail.load().ptr)
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{
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return std::unique_ptr<T>();
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}
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counted_node_ptr next=ptr->next.load();
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if(head.compare_exchange_strong(old_head,next))
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{
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T* const res=ptr->data.exchange(nullptr);
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free_external_counter(old_head);
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return std::unique_ptr<T>(res);
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}
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ptr->release_ref();
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}
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}
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};
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