[Python Otel] Fix Segfault caused by callTracer method lifetime issue

src/python/grpcio_observability/grpc_observability/client_call_tracer.cc

@@ -88,7 +88,7 @@ void PythonOpenCensusCallTracer::RecordAnnotation(
 
 PythonOpenCensusCallTracer::~PythonOpenCensusCallTracer() {
   if (PythonCensusStatsEnabled()) {
-    context_.Labels().emplace_back(kClientMethod, std::string(method_));
+    context_.Labels().emplace_back(kClientMethod, method_);
     RecordIntMetric(kRpcClientRetriesPerCallMeasureName, retries_ - 1,
                     context_.Labels(), identifier_, registered_method_,
                     /*include_exchange_labels=*/true);  // exclude first attempt
@@ -159,8 +159,8 @@ PythonOpenCensusCallTracer::PythonOpenCensusCallAttemptTracer::
   if (!PythonCensusStatsEnabled()) {
     return;
   }
-  context_.Labels().emplace_back(kClientMethod, std::string(parent_->method_));
-  context_.Labels().emplace_back(kClientTarget, std::string(parent_->target_));
+  context_.Labels().emplace_back(kClientMethod, parent_->method_);
+  context_.Labels().emplace_back(kClientTarget, parent_->target_);
   RecordIntMetric(kRpcClientStartedRpcsMeasureName, 1, context_.Labels(),
                   parent_->identifier_, parent_->registered_method_,
                   /*include_exchange_labels=*/false);
@@ -264,8 +264,8 @@ void PythonOpenCensusCallTracer::PythonOpenCensusCallAttemptTracer::
   }
 
   std::string final_status = absl::StatusCodeToString(status_code_);
-  context_.Labels().emplace_back(kClientMethod, std::string(parent_->method_));
-  context_.Labels().emplace_back(kClientTarget, std::string(parent_->target_));
+  context_.Labels().emplace_back(kClientMethod, parent_->method_);
+  context_.Labels().emplace_back(kClientTarget, parent_->target_);
   context_.Labels().emplace_back(kClientStatus, final_status);
   if (parent_->add_csm_optional_labels_) {
     parent_->labels_injector_.AddXdsOptionalLabels(
@@ -323,7 +323,7 @@ void PythonOpenCensusCallTracer::PythonOpenCensusCallAttemptTracer::RecordEnd(
     const gpr_timespec& /*latency*/) {
   if (PythonCensusStatsEnabled()) {
     context_.Labels().emplace_back(kClientMethod,
-                                   std::string(parent_->method_));
+                                   parent_->method_);
     context_.Labels().emplace_back(kClientStatus,
                                    StatusCodeToString(status_code_));
     RecordIntMetric(kRpcClientSentMessagesPerRpcMeasureName,

src/python/grpcio_observability/grpc_observability/client_call_tracer.h

@@ -140,9 +140,9 @@ class PythonOpenCensusCallTracer : public grpc_core::ClientCallTracer {
   PythonCensusContext CreateCensusContextForCallAttempt();
 
   // Client method.
-  absl::string_view method_;
+  std::string method_;
   // Client target.
-  absl::string_view target_;
+  std::string target_;
   PythonCensusContext context_;
   bool tracing_enabled_;
   bool add_csm_optional_labels_;

src/python/grpcio_observability/grpc_observability/python_observability_context.h

@@ -272,16 +272,16 @@ void GenerateClientContext(absl::string_view method, absl::string_view trace_id,
 void GenerateServerContext(absl::string_view header, absl::string_view method,
                            PythonCensusContext* context);
 
-inline absl::string_view GetMethod(const char* method) {
+inline std::string GetMethod(const char* method) {
   if (std::string(method).empty()) {
     return "";
   }
   // Check for leading '/' and trim it if present.
-  return absl::StripPrefix(absl::string_view(method), "/");
+  return std::string(absl::StripPrefix(method, "/"));
 }
 
-inline absl::string_view GetTarget(const char* target) {
-  return absl::string_view(target);
+inline std::string GetTarget(const char* target) {
+  return std::string(target);
 }
 
 // Fills a pre-allocated buffer with the value for the grpc-trace-bin header.