55 lines
1.2 KiB
C++
55 lines
1.2 KiB
C++
#include <atomic>
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#include <memory>
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template <typename T>
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class lock_free_queue {
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private:
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struct node {
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std::shared_ptr<T> data;
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node* next;
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node() : next(nullptr) {}
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};
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std::atomic<node*> head;
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std::atomic<node*> tail;
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node* pop_head()
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{
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node* const old_head = head.load();
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if (old_head == tail.load()) {
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return nullptr;
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}
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head.store(old_head->next);
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return old_head;
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}
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public:
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lock_free_queue() : head(new node), tail(head.load()) {}
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lock_free_queue(const lock_free_queue& other) = delete;
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lock_free_queue& operator=(const lock_free_queue& other) = delete;
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~lock_free_queue()
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{
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while (node* const old_head = head.load()) {
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head.store(old_head->next);
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delete old_head;
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}
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}
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std::shared_ptr<T> pop()
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{
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node* old_head = pop_head();
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if (!old_head) {
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return std::shared_ptr<T>();
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}
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std::shared_ptr<T> const res(old_head->data);
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delete old_head;
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return res;
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}
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void push(T new_value)
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{
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std::shared_ptr<T> new_data(std::make_shared<T>(new_value));
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node* p = new node;
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node* const old_tail = tail.load();
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old_tail->data.swap(new_data);
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old_tail->next = p;
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tail.store(p);
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}
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};
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