90 lines
1.8 KiB
C++
90 lines
1.8 KiB
C++
#ifndef cwSpScQueueTmpl_H
|
|
#define cwSpScQueueTmpl_H
|
|
|
|
namespace cw
|
|
{
|
|
|
|
template< typename T >
|
|
class spScQueueTmpl
|
|
{
|
|
public:
|
|
spScQueueTmpl( unsigned eleN )
|
|
{
|
|
_aN = eleN;
|
|
_aV = mem::allocZ<T>(eleN);
|
|
_wi.store(0,std::memory_order_release);
|
|
_ri.store(0,std::memory_order_release);
|
|
}
|
|
|
|
virtual ~spScQueueTmpl()
|
|
{
|
|
mem::release(_aV);
|
|
}
|
|
|
|
|
|
T* get()
|
|
{
|
|
unsigned ri = _ri.load( std::memory_order_acquire );
|
|
unsigned wi = _wi.load( std::memory_order_relaxed ); // _wi is written in this thread
|
|
|
|
// calc. the count of full elements
|
|
unsigned n = wi >= ri ? wi-ri : (_aN-ri) + wi;
|
|
|
|
// there must always be at least one empty element because
|
|
// wi can never be advanced to equal ri.
|
|
if( n >= _aN-1 )
|
|
return nullptr;
|
|
|
|
return _aV + wi;
|
|
}
|
|
|
|
void publish()
|
|
{
|
|
unsigned wi = _wi.load( std::memory_order_relaxed ); // _wi is written in this thread
|
|
|
|
wi = (wi+1) % _aN;
|
|
|
|
// advance the write position
|
|
_wi.store( wi, std::memory_order_release );
|
|
|
|
}
|
|
|
|
T* pop()
|
|
{
|
|
unsigned ri = _ri.load( std::memory_order_relaxed );
|
|
unsigned wi = _wi.load( std::memory_order_acquire );
|
|
|
|
unsigned n = wi >= ri ? wi-ri : (_aN-ri) + wi;
|
|
|
|
if( n == 0 )
|
|
return nullptr;
|
|
|
|
T* v = _aV + ri;
|
|
|
|
ri = (ri+1) % _aN;
|
|
|
|
_ri.store( ri, std::memory_order_release);
|
|
|
|
return v;
|
|
}
|
|
|
|
|
|
|
|
|
|
private:
|
|
unsigned _aN = 0;
|
|
T* _aV = nullptr;
|
|
std::atomic<unsigned> _wi;
|
|
std::atomic<unsigned> _ri;
|
|
|
|
// Note: // _wi==_ri indicates an empty buffer.
|
|
// _wi may never be advanced such that it equals _ri, however
|
|
// _ri may be advanced such that it equals _wi.
|
|
};
|
|
|
|
|
|
rc_t testSpScQueueTmpl();
|
|
|
|
}
|
|
#endif
|