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<locale>: Double-checked locking for locale::classic #3048

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Merged
merged 8 commits into from
Oct 27, 2022
Merged

<locale>: Double-checked locking for locale::classic #3048

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1446049
Double-checked locking for locale::classic
MattStephanson Aug 20, 2022
e9222c6
Replace `Interlocked` calls with intrinsic load/store and barriers.
MattStephanson Aug 31, 2022
a4dd979
always use locking for `/clr:pure`
MattStephanson Sep 3, 2022
8890971
Merge branch 'main' into classic-locale-locking
MattStephanson Oct 26, 2022
2907701
review feedback
MattStephanson Oct 26, 2022
5b944d5
D'oh
MattStephanson Oct 26, 2022
6519e24
Merge branch 'main' into classic-locale-locking
StephanTLavavej Oct 26, 2022
6160021
Add a benchmark. Also sort the list of benchmarks.
StephanTLavavej Oct 26, 2022
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18 changes: 13 additions & 5 deletions stl/src/locale0.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@

#include <crtdbg.h>
#include <internal_shared.h>
#include <synchapi.h>
#include <xfacet>

// This must be as small as possible, because its contents are
Expand Down Expand Up @@ -121,7 +122,8 @@ _MRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL std::locale::_Setgloballocale(void* p

__PURE_APPDOMAIN_GLOBAL static locale classic_locale(_Noinit); // "C" locale object, uninitialized

__PURE_APPDOMAIN_GLOBAL locale::_Locimp* locale::_Locimp::_Clocptr = nullptr; // pointer to classic_locale
__PURE_APPDOMAIN_GLOBAL alignas(
sizeof(locale::_Locimp*)) locale::_Locimp* locale::_Locimp::_Clocptr = nullptr; // pointer to classic_locale

__PURE_APPDOMAIN_GLOBAL int locale::id::_Id_cnt = 0; // unique id counter for facets

Expand All @@ -136,7 +138,12 @@ __PURE_APPDOMAIN_GLOBAL locale::id ctype<unsigned short>::id(0);
__PURE_APPDOMAIN_GLOBAL locale::id codecvt<unsigned short, char, mbstate_t>::id(0);

_MRTIMP2_PURE const locale& __CLRCALL_PURE_OR_CDECL locale::classic() { // get reference to "C" locale
_Init();
const auto ptr = reinterpret_cast<locale::_Locimp*>(InterlockedCompareExchangePointerAcquire(
reinterpret_cast<volatile PVOID*>(&locale::_Locimp::_Clocptr), nullptr, nullptr));
if (ptr == nullptr) {
_Init();
}

return classic_locale;
}

Expand All @@ -157,9 +164,10 @@ _MRTIMP2_PURE locale::_Locimp* __CLRCALL_PURE_OR_CDECL locale::_Init(bool _Do_in
ptr->_Catmask = all; // set current locale to "C"
ptr->_Name = "C";

_Locimp::_Clocptr = ptr; // set classic to match
_Locimp::_Clocptr->_Incref();
::new (&classic_locale) locale(_Locimp::_Clocptr);
// set classic to match
ptr->_Incref();
::new (&classic_locale) locale(ptr);
InterlockedExchangePointer(reinterpret_cast<volatile PVOID*>(&_Locimp::_Clocptr), ptr);
}

if (_Do_incref) {
Expand Down