Reset JfrMetadata between profiler sessions

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: jbachorik

ddprof-lib/src/main/cpp/jfrMetadata.cpp

@@ -26,6 +26,16 @@ bool JfrMetadata::_initialized = false;
 
 JfrMetadata::JfrMetadata() : Element("root") {}
 
+void JfrMetadata::reset() {
+  _root._children.clear();
+  _root._attributes.clear();
+  _strings.clear();
+  _string_map.clear();
+  // Re-register "root" at ID 0 so _root._name (const 0) stays valid
+  getId("root");
+  _initialized = false;
+}
+
 void JfrMetadata::initialize(
     const std::vector<std::string> &contextAttributes) {
   if (_initialized) {

ddprof-lib/src/main/cpp/jfrMetadata.h

@@ -259,6 +259,7 @@ class JfrMetadata : Element {
   JfrMetadata();
 
   static void initialize(const std::vector<std::string> &contextAttributes);
+  static void reset();
 
   static Element *root() { return &_root; }
 

ddprof-lib/src/main/cpp/profiler.cpp

@@ -1448,6 +1448,7 @@ Error Profiler::start(Arguments &args, bool reset) {
   // Always enable library trap to catch wasmtime loading and patch its broken sigaction
   switchLibraryTrap(true);
 
+  JfrMetadata::reset();
   JfrMetadata::initialize(args._context_attributes);
   _num_context_attributes = args._context_attributes.size();
   error = _jfr.start(args, reset);