From 11e0e6d6cde876fb4810596c2c5cb116601c0f42 Mon Sep 17 00:00:00 2001
From: Philippe Canal <pcanal@fnal.gov>
Date: Thu, 18 Feb 2021 11:26:19 -0600
Subject: [PATCH] TIsAProxy switch fClass to non-atomic.
Since fClass is modified only 'once' at init time of the IsAProxy object, it is actual more efficient
to protect the initialization by a lock rather than having fClass being atomic.
---
core/meta/inc/TIsAProxy.h | 2 +-
core/meta/src/TIsAProxy.cxx | 15 +++++++--------
2 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/core/meta/inc/TIsAProxy.h b/core/meta/inc/TIsAProxy.h
index 2680824b4c1..5b43db54e9a 100644
--- a/core/meta/inc/TIsAProxy.h
+++ b/core/meta/inc/TIsAProxy.h
@@ -36,7 +36,7 @@ private:
static constexpr UInt_t fgMaxLastSlot = 8;
const std::type_info *fType; //Actual typeid of the proxy
- Atomic_t<TClass*> fClass; //Actual TClass
+ TClass *fClass; //Actual TClass
Char_t fSubTypes[72];//map of known sub-types
mutable Atomic_t<UInt_t> fSubTypesReaders; //number of readers of fSubTypes
Atomic_t<Bool_t> fSubTypesWriteLockTaken; //True if there is a writer
diff --git a/core/meta/src/TIsAProxy.cxx b/core/meta/src/TIsAProxy.cxx
index 5039c659945..22e197ce53b 100644
--- a/core/meta/src/TIsAProxy.cxx
+++ b/core/meta/src/TIsAProxy.cxx
@@ -85,30 +85,29 @@ void TIsAProxy::SetClass(TClass *cl)
TClass* TIsAProxy::operator()(const void *obj)
{
if ( !fInit ) {
- if ( !fClass.load() && fType ) {
- auto cls = TClass::GetClass(*fType);
- TClass* expected = nullptr;
- fClass.compare_exchange_strong(expected,cls);
+ R__WRITE_LOCKGUARD(ROOT::gCoreMutex);
+ if ( !fClass && fType ) {
+ fClass = TClass::GetClass(*fType);
}
- if ( !fClass.load() ) return nullptr;
+ if ( !fClass ) return nullptr;
fVirtual = (*fClass).ClassProperty() & kClassHasVirtual;
fInit = kTRUE;
}
if ( !obj || !fVirtual ) {
- return fClass.load();
+ return fClass;
}
// Avoid the case that the first word is a virtual_base_offset_table instead of
// a virtual_function_table
Long_t offset = **(Long_t**)obj;
if ( offset == 0 ) {
- return fClass.load();
+ return fClass;
}
DynamicType* ptr = (DynamicType*)obj;
const std::type_info* typ = &typeid(*ptr);
if ( typ == fType ) {
- return fClass.load();
+ return fClass;
}
for(auto& slot : fLasts) {
auto last = ToPair(slot);
--
GitLab