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