Tracing: use only lower 32bits for thread, to make capture compatible with perfetto UI

src/libs/core/impl/TraceLogger.cpp

@@ -141,7 +141,7 @@ namespace lms::core::tracing
                 os << "\t\t{ ";
                 os << "\"name\" : \"thread_name\", ";
                 os << "\"pid\" : 1, ";
-                os << "\"tid\" : " << threadId << ", ";
+                os << "\"tid\" : " << toTraceThreadId(threadId) << ", ";
                 os << "\"ph\" : \"M\", ";
                 os << "\"args\" : { \"name\" : \"" + threadName + "\" }";
                 os << " }";
@@ -171,7 +171,7 @@ namespace lms::core::tracing
                     os << "\"name\" : \"" << event.name.c_str() << "\", ";
                     os << "\"cat\" : \"" << event.category.c_str() << "\", ";
                     os << "\"pid\": 1, ";
-                    os << "\"tid\" : " << event.threadId << ", ";
+                    os << "\"tid\" : " << toTraceThreadId(event.threadId) << ", ";
                     os << "\"ts\" : " << std::fixed << std::setprecision(3) << std::chrono::duration_cast<clockMicro>(event.start - _start).count() << ", ";
                     os << "\"dur\" : " << std::fixed << std::setprecision(3) << std::chrono::duration_cast<clockMicro>(event.duration).count() << ", ";
                     os << "\"ph\" : \"X\"";
@@ -198,4 +198,25 @@ namespace lms::core::tracing
         std::scoped_lock lock{ _threadNameMutex };
         _threadNames.emplace(id, threadName);
     }
+
+    std::uint32_t TraceLogger::toTraceThreadId(std::thread::id threadId) const
+    {
+        {
+            auto it{ _cachedTraceThreadIds.find(threadId) };
+            if (it != std::cend(_cachedTraceThreadIds))
+            return it->second;
+        }
+
+        // Pefetto UI does not accept 64bits thread ids
+        std::ostringstream oss;
+        oss << threadId;
+
+        std::istringstream iss{ oss.str() };
+        std::uint64_t id;
+        iss >> id;
+
+        const std::uint32_t res{ static_cast<std::uint32_t>(id) };
+        _cachedTraceThreadIds.emplace(threadId, res);
+        return res;
+    }
 }

src/libs/core/impl/TraceLogger.hpp

@@ -42,6 +42,7 @@ namespace lms::core::tracing
         void write(const CompleteEvent& event) override;
         void dumpCurrentBuffer(std::ostream& os) override;
         void setThreadName(std::thread::id id, std::string_view threadName) override;
+        std::uint32_t toTraceThreadId(std::thread::id threadId) const;
 
         static constexpr std::size_t BufferSize{ 32 * 1024 };
 
@@ -64,6 +65,7 @@ namespace lms::core::tracing
 
         std::mutex _threadNameMutex;
         std::unordered_map<std::thread::id, std::string> _threadNames;
+        mutable std::unordered_map<std::thread::id, std::uint32_t> _cachedTraceThreadIds;
 
         std::mutex _mutex;
         std::deque<Buffer*> _freeBuffers;