50 lines
1.2 KiB
C++
50 lines
1.2 KiB
C++
#include <atomic>
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#include <thread>
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unsigned const max_hazard_pointers=100;
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struct hazard_pointer
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{
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std::atomic<std::thread::id> id;
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std::atomic<void*> pointer;
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};
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hazard_pointer hazard_pointers[max_hazard_pointers];
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class hp_owner
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{
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hazard_pointer* hp;
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public:
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hp_owner(hp_owner const&)=delete;
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hp_owner operator=(hp_owner const&)=delete;
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hp_owner():
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hp(nullptr)
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{
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for(unsigned i=0;i<max_hazard_pointers;++i)
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{
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std::thread::id old_id;
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if(hazard_pointers[i].id.compare_exchange_strong(
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old_id,std::this_thread::get_id()))
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{
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hp=&hazard_pointers[i];
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break;
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}
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}
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if(!hp)
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{
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throw std::runtime_error("No hazard pointers available");
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}
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}
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std::atomic<void*>& get_pointer()
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{
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return hp->pointer;
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}
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~hp_owner()
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{
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hp->pointer.store(nullptr);
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hp->id.store(std::thread::id());
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}
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};
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std::atomic<void*>& get_hazard_pointer_for_current_thread()
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{
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thread_local static hp_owner hazard;
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return hazard.get_pointer();
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}
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