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cwSpScQueueTmpl.h : Change operation such that get() ony returns empty records.

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This commit is contained in:
kevin.larke 2020-04-19 15:17:11 -04:00
parent 48ebcc89c7
commit 85d7098061
1 changed files with 9 additions and 8 deletions
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17
cwSpScQueueTmpl.h
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@ -21,13 +21,8 @@ namespace cw
mem::release(_aV); mem::release(_aV);
} }
T* get()
{
unsigned wi = _wi.load( std::memory_order_relaxed );
return _aV + wi;
}
rc_t publish() T* get()
{ {
unsigned ri = _ri.load( std::memory_order_acquire ); unsigned ri = _ri.load( std::memory_order_acquire );
unsigned wi = _wi.load( std::memory_order_relaxed ); // _wi is written in this thread unsigned wi = _wi.load( std::memory_order_relaxed ); // _wi is written in this thread
@ -38,14 +33,20 @@ namespace cw
// there must always be at least one empty element because // there must always be at least one empty element because
// wi can never be advanced to equal ri. // wi can never be advanced to equal ri.
if( n >= _aN-1 ) if( n >= _aN-1 )
return kBufTooSmallRC; 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; wi = (wi+1) % _aN;
// advance the write position // advance the write position
_wi.store( wi, std::memory_order_release ); _wi.store( wi, std::memory_order_release );
return kOkRC;
} }
T* pop() T* pop()