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implemented cacheline alignment without extended alignas

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This commit is contained in:
joaquintides
2023-06-07 11:30:52 +02:00
parent ca193de243
commit 64f9370fff
1 changed files with 27 additions and 14 deletions
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41
include/boost/unordered/detail/foa/concurrent_table.hpp
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@ -64,20 +64,33 @@ using is_execution_policy=std::false_type;
namespace foa{
#if defined(BOOST_MSVC)
#pragma warning(push)
#pragma warning(disable:4324) /* padded structure due to alignas */
#endif
template<typename T>
struct alignas(64) cacheline_protected:T
template<typename T,std::size_t N>
class cache_aligned_array
{
using T::T;
};
public:
cache_aligned_array(){for(std::size_t n=0;n<N;)::new (data(n++)) T();}
~cache_aligned_array(){for(auto n=N;n>0;)data(n--)->~T();}
cache_aligned_array(const cache_aligned_array&)=delete;
cache_aligned_array& operator=(const cache_aligned_array&)=delete;
#if defined(BOOST_MSVC)
#pragma warning(pop) /* C4324 */
#endif
T& operator[](std::size_t pos)noexcept{return *data(pos);}
private:
static constexpr std::size_t cacheline=64;
static constexpr std::size_t element_offset=
(sizeof(T)+cacheline-1)/cacheline*cacheline;
BOOST_STATIC_ASSERT(alignof(T)<=cacheline);
T* data(std::size_t pos)noexcept
{
return reinterpret_cast<T*>(
(reinterpret_cast<uintptr_t>(&buf)+cacheline-1)/cacheline*cacheline+
pos*element_offset);
}
unsigned char buf[element_offset*N+cacheline-1];
};
template<typename Mutex,std::size_t N>
class multimutex
@ -95,7 +108,7 @@ public:
void unlock()noexcept{for(auto n=N;n>0;)mutexes[--n].unlock();}
private:
Mutex mutexes[N];
cache_aligned_array<Mutex,N> mutexes;
};
/* std::shared_lock is C++14 */
@ -785,7 +798,7 @@ public:
}
private:
using mutex_type=cacheline_protected<rw_spinlock>;
using mutex_type=rw_spinlock;
using multimutex_type=multimutex<mutex_type,128>; // TODO: adapt 128 to the machine
using shared_lock_guard=shared_lock<mutex_type>;
using exclusive_lock_guard=lock_guard<multimutex_type>;