Avoid capturing logger pointer in callback lambda (envoyproxy#2492)

* fix sd filter bugs

* fix test

* remove mesh uid change

extensions/stackdriver/log/exporter.cc

@@ -42,19 +42,23 @@ namespace Stackdriver {
 namespace Log {
 
 ExporterImpl::ExporterImpl(RootContext* root_context,
-                           const std::string& logging_service_endpoint)
-    : export_call_(MetricType::Counter, "stackdriver_logging_filter",
-                   {MetricTag{"type", MetricTag::TagType::String},
-                    MetricTag{"success", MetricTag::TagType::Bool}}) {
+                           const std::string& logging_service_endpoint) {
   context_ = root_context;
-  success_callback_ = [this](google::protobuf::Empty&&) {
-    export_call_.increment(1, "logging", true);
+  Metric export_call(MetricType::Counter, "stackdriver_filter",
+                     {MetricTag{"type", MetricTag::TagType::String},
+                      MetricTag{"success", MetricTag::TagType::Bool}});
+  auto success_counter = export_call.resolve("logging", true);
+  auto failure_counter = export_call.resolve("logging", false);
+  success_callback_ = [success_counter](google::protobuf::Empty&&) {
+    // TODO(bianpengyuan): replace this with envoy's generic gRPC counter.
+    incrementMetric(success_counter, 1);
     logDebug("successfully sent Stackdriver logging request");
   };
 
-  failure_callback_ = [this](GrpcStatus status, StringView message) {
+  failure_callback_ = [failure_counter](GrpcStatus status, StringView message) {
     // TODO(bianpengyuan): add retry.
-    export_call_.increment(1, "logging", false);
+    // TODO(bianpengyuan): replace this with envoy's generic gRPC counter.
+    incrementMetric(failure_counter, 1);
     logWarn("Stackdriver logging api call error: " +
             std::to_string(static_cast<int>(status)) + std::string(message));
   };

extensions/stackdriver/log/exporter.h

@@ -74,11 +74,6 @@ class ExporterImpl : public Exporter {
   // Callbacks for gRPC calls.
   std::function<void(google::protobuf::Empty&&)> success_callback_;
   std::function<void(GrpcStatus, StringView)> failure_callback_;
-
-  // Counter of stackdriver export calls, with a boolean label to indicate if
-  // the call is successful or not and a string label to indicate the type of
-  // export call.
-  Metric export_call_;
 };
 
 }  // namespace Log