57 lines
1.4 KiB
C++
57 lines
1.4 KiB
C++
#include <memory>
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#include <mutex>
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template <typename T>
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class threadsafe_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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std::unique_ptr<node> next;
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};
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std::mutex head_mutex;
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std::unique_ptr<node> head;
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std::mutex tail_mutex;
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node* tail;
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node* get_tail()
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{
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std::lock_guard<std::mutex> tail_lock(tail_mutex);
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return tail;
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}
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std::unique_ptr<node> pop_head()
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{
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std::lock_guard<std::mutex> head_lock(head_mutex);
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if (head.get() == get_tail()) {
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return nullptr;
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}
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std::unique_ptr<node> const old_head = std::move(head);
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head = std::move(old_head->next);
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return old_head;
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}
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public:
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threadsafe_queue() : head(new node), tail(head.get()) {}
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threadsafe_queue(const threadsafe_queue& other) = delete;
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threadsafe_queue& operator=(const threadsafe_queue& other) = delete;
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std::shared_ptr<T> try_pop()
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{
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std::unique_ptr<node> old_head = pop_head();
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return old_head ? old_head->data : std::shared_ptr<T>();
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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>(std::move(new_value)));
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std::unique_ptr<node> p(new node);
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node* const new_tail = p.get();
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std::lock_guard<std::mutex> tail_lock(tail_mutex);
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tail->data = new_data;
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tail->next = std::move(p);
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tail = new_tail;
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}
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};
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