PPCSymbolDB: Reduce lock contention in LoadMap/LoadMapOnBoot

By building the map in a local variable and then swapping it with the
member variable, we avoid the need to hold a lock while building the
map.

2 files changed, 13 insertions, 1 deletions

diff --git a/Source/Core/Common/SymbolDB.cpp b/Source/Core/Common/SymbolDB.cpp
index 88f281e497..ad438b8277 100644
--- a/Source/Core/Common/SymbolDB.cpp
+++ b/Source/Core/Common/SymbolDB.cpp
@@ -5,6 +5,7 @@
 
 #include <cstring>
 #include <map>
+#include <mutex>
 #include <string>
 #include <utility>
 
@@ -49,6 +50,8 @@ bool SymbolDB::IsEmpty() const
 
 bool SymbolDB::Clear(const char* prefix)
 {
+  std::lock_guard lock(m_mutex);
+
   // TODO: honor prefix
   m_map_name.clear();
   if (IsEmpty())
@@ -62,8 +65,13 @@ bool SymbolDB::Clear(const char* prefix)
 
 void SymbolDB::Index()
 {
+  Index(&m_functions);
+}
+
+void SymbolDB::Index(XFuncMap* functions)
+{
   int i = 0;
-  for (auto& func : m_functions)
+  for (auto& func : *functions)
   {
     func.second.index = i++;
   }
diff --git a/Source/Core/Common/SymbolDB.h b/Source/Core/Common/SymbolDB.h
index 7763999453..69515532b1 100644
--- a/Source/Core/Common/SymbolDB.h
+++ b/Source/Core/Common/SymbolDB.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <map>
+#include <mutex>
 #include <set>
 #include <string>
 #include <string_view>
@@ -105,9 +106,12 @@ public:
   void Index();
 
 protected:
+  static void Index(XFuncMap* functions);
+
   XFuncMap m_functions;
   XNoteMap m_notes;
   XFuncPtrMap m_checksum_to_function;
   std::string m_map_name;
+  std::mutex m_mutex;
 };
 }  // namespace Common