From f0a88ffa1f11cc9484a87965fea408982cf914a8 Mon Sep 17 00:00:00 2001
From: Philippe Canal <pcanal@fnal.gov>
Date: Thu, 11 Feb 2021 18:04:40 -0600
Subject: [PATCH] Improve TClass::GetBaseClassOffset parallelism.
TClass::GetBaseClassOffset is a 'often' used routine in the I/O.
In the fast path (looking up in a cache), rather than taking the
global read lock (which is not only global but also 'slower' than
a regular mutex), we are now use a instance specific mutex to
protect the cache.
---
core/metacling/src/TClingClassInfo.cxx | 3 ++-
core/metacling/src/TClingClassInfo.h | 15 ++++++++++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/core/metacling/src/TClingClassInfo.cxx b/core/metacling/src/TClingClassInfo.cxx
index a6275d495cf..726c2788e9a 100644
--- a/core/metacling/src/TClingClassInfo.cxx
+++ b/core/metacling/src/TClingClassInfo.cxx
@@ -135,6 +135,7 @@ void TClingClassInfo::AddBaseOffsetValue(const clang::Decl* decl, ptrdiff_t offs
// determined by the parameter decl.
OffsetPtrFunc_t executableFunc = 0;
+ std::unique_lock<std::mutex> lock(fOffsetCacheMutex);
fOffsetCache[decl] = std::make_pair(offset, executableFunc);
}
@@ -611,7 +612,7 @@ ptrdiff_t TClingClassInfo::GetBaseOffset(TClingClassInfo* base, void* address, b
{
{
- R__READ_LOCKGUARD(ROOT::gCoreMutex);
+ std::unique_lock<std::mutex> lock(fOffsetCacheMutex);
// Check for the offset in the cache.
auto iter = fOffsetCache.find(base->GetDecl());
diff --git a/core/metacling/src/TClingClassInfo.h b/core/metacling/src/TClingClassInfo.h
index 32d395b3d14..f89388301a2 100644
--- a/core/metacling/src/TClingClassInfo.h
+++ b/core/metacling/src/TClingClassInfo.h
@@ -34,6 +34,7 @@
#include <vector>
#include <string>
#include <utility>
+#include <mutex>
#include "llvm/ADT/DenseMap.h"
@@ -69,6 +70,8 @@ private:
std::vector<clang::DeclContext::decl_iterator> fIterStack; // Recursion stack for traversing nested scopes.
std::string fTitle; // The meta info for the class.
std::string fDeclFileName; // Name of the file where the underlying entity is declared.
+
+ std::mutex fOffsetCacheMutex;
llvm::DenseMap<const clang::Decl*, std::pair<ptrdiff_t, OffsetPtrFunc_t> > fOffsetCache; // Functions already generated for offsets.
explicit TClingClassInfo() = delete;
@@ -82,11 +85,21 @@ public: // Types
public:
+ TClingClassInfo(const TClingClassInfo &rhs) : // Copy all but the mutex
+ TClingDeclInfo(rhs),
+ fInterp(rhs.fInterp), fFirstTime(rhs.fFirstTime), fDescend(rhs.fDescend),
+ fIterAll(rhs.fIterAll), fIsIter(rhs.fIsIter), fIter(rhs.fIter),
+ fType(rhs.fType), fIterStack(rhs.fIterStack), fTitle(rhs.fTitle),
+ fDeclFileName(rhs.fDeclFileName), fOffsetCache(rhs.fOffsetCache)
+ {}
explicit TClingClassInfo(cling::Interpreter *, Bool_t all = kTRUE);
explicit TClingClassInfo(cling::Interpreter *, const char *classname, bool intantiateTemplate = kTRUE);
explicit TClingClassInfo(cling::Interpreter *, const clang::Type &);
explicit TClingClassInfo(cling::Interpreter *, const clang::Decl *);
- void AddBaseOffsetFunction(const clang::Decl* decl, OffsetPtrFunc_t func) { fOffsetCache[decl] = std::make_pair(0L, func); }
+ void AddBaseOffsetFunction(const clang::Decl* decl, OffsetPtrFunc_t func) {
+ std::unique_lock<std::mutex> lock(fOffsetCacheMutex);
+ fOffsetCache[decl] = std::make_pair(0L, func);
+ }
void AddBaseOffsetValue(const clang::Decl* decl, ptrdiff_t offset);
long ClassProperty() const;
void Delete(void *arena, const ROOT::TMetaUtils::TNormalizedCtxt &normCtxt) const;
--
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