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protected visitation against spurious insertion sentinels

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This commit is contained in:
joaquintides
2023-12-27 12:32:31 +01:00
parent 8365ccb78a
commit d689613172
1 changed files with 28 additions and 8 deletions
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36
include/boost/unordered/detail/foa/concurrent_table.hpp
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@ -1177,7 +1177,7 @@ private:
do{ do{
auto n=unchecked_countr_zero(mask); auto n=unchecked_countr_zero(mask);
if(BOOST_LIKELY( if(BOOST_LIKELY(
pg->is_occupied(n)&&bool(this->pred()(x,this->key_from(p[n]))))){ is_occupied(pg,n)&&bool(this->pred()(x,this->key_from(p[n]))))){
f(pg,n,p+n); f(pg,n,p+n);
return 1; return 1;
} }
@ -1236,7 +1236,7 @@ private:
do{ do{
auto n=unchecked_countr_zero(mask); auto n=unchecked_countr_zero(mask);
if(BOOST_LIKELY( if(BOOST_LIKELY(
pg->is_occupied(n)&& is_occupied(pg,n)&&
bool(this->pred()(*it,this->key_from(p[n]))))){ bool(this->pred()(*it,this->key_from(p[n]))))){
f(cast_for(access_mode,type_policy::value_from(p[n]))); f(cast_for(access_mode,type_policy::value_from(p[n])));
++res; ++res;
@ -1579,23 +1579,43 @@ private:
} }
} }
/* check occupation with previous unsynced match */
static bool is_occupied(group_type* pg,std::size_t pos)
{
return is_occupied(
std::integral_constant<bool,group_type::regular_layout>{},pg,pos);
}
static bool is_occupied(std::true_type,group_type* pg,std::size_t pos)
{
/* regular layout, almost-latch-free insertion -> possible reserved slot */
return reinterpret_cast<std::atomic<unsigned char>*>(pg)[pos]>1;
}
static bool is_occupied(std::false_type,group_type* pg,std::size_t pos)
{
/* non-regular layout, latched insertion -> no reserved slots */
return pg->is_occupied(pos);
}
/* check occupation with previous synced match */
static bool is_really_occupied(group_type* pg,std::size_t pos) static bool is_really_occupied(group_type* pg,std::size_t pos)
{ {
return is_really_occupied( return is_really_occupied(
std::integral_constant<bool,group_type::regular_layout>{},pg,pos); std::integral_constant<bool,group_type::regular_layout>{},pg,pos);
} }
static bool is_really_occupied( static bool is_really_occupied(std::true_type,group_type* pg,std::size_t pos)
/* regular layout, almost-latch-free insertion -> spurious non-zeros */
std::true_type,group_type* pg,std::size_t pos)
{ {
/* regular layout, almost-latch-free insertion -> possible reserved slot */
return reinterpret_cast<std::atomic<unsigned char>*>(pg)[pos]>1; return reinterpret_cast<std::atomic<unsigned char>*>(pg)[pos]>1;
} }
static bool is_really_occupied( static bool is_really_occupied(std::false_type,group_type*,std::size_t)
/* non-regular layout, latched insertion -> no false positives */
std::false_type,group_type*,std::size_t)
{ {
/* non-regular layout, latched insertion -> no false positives */
return true; return true;
} }