[tracing] Sub-msec time granularity in HttpAnnotation

Use gpr_timespec instead of Timestamp for better time granularity. Timestamp uses msec which is too coarse-grained.

PiperOrigin-RevId: 595194238

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -79,6 +79,7 @@
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/debug/stats_data.h"
 #include "src/core/lib/experiments/experiments.h"
+#include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/gprpp/bitset.h"
 #include "src/core/lib/gprpp/crash.h"
@@ -342,7 +343,7 @@ void ForEachContextListEntryExecute(void* arg, Timestamps* ts,
 }
 
 HttpAnnotation::HttpAnnotation(
-    Type type, Timestamp time,
+    Type type, gpr_timespec time,
     absl::optional<chttp2::TransportFlowControl::Stats> transport_stats,
     absl::optional<chttp2::StreamFlowControl::Stats> stream_stats)
     : CallTracerAnnotationInterface::Annotation(
@@ -367,7 +368,7 @@ std::string HttpAnnotation::ToString() const {
     default:
       absl::StrAppend(&s, "Unknown");
   }
-  absl::StrAppend(&s, " time: ", time_.ToString());
+  absl::StrAppend(&s, " time: ", gpr_format_timespec(time_));
   if (transport_stats_.has_value()) {
     absl::StrAppend(&s, " transport:[", transport_stats_->ToString(), "]");
   }
@@ -1508,7 +1509,7 @@ static void perform_stream_op_locked(void* stream_op,
   if (op->send_initial_metadata) {
     if (s->call_tracer) {
       s->call_tracer->RecordAnnotation(grpc_core::HttpAnnotation(
-          grpc_core::HttpAnnotation::Type::kStart, grpc_core::Timestamp::Now(),
+          grpc_core::HttpAnnotation::Type::kStart, gpr_now(GPR_CLOCK_REALTIME),
           s->t->flow_control.stats(), s->flow_control.stats()));
     }
     if (t->is_client && t->channelz_socket != nullptr) {

src/core/ext/transport/chttp2/transport/chttp2_transport.h

@@ -113,14 +113,14 @@ class HttpAnnotation : public CallTracerAnnotationInterface::Annotation {
   };
 
   HttpAnnotation(
-      Type type, Timestamp time,
+      Type type, gpr_timespec time,
       absl::optional<chttp2::TransportFlowControl::Stats> transport_stats,
       absl::optional<chttp2::StreamFlowControl::Stats> stream_stats);
 
   std::string ToString() const override;
 
   Type http_type() const { return type_; }
-  Timestamp time() const { return time_; }
+  gpr_timespec time() const { return time_; }
   absl::optional<chttp2::TransportFlowControl::Stats> transport_stats() const {
     return transport_stats_;
   }
@@ -130,7 +130,7 @@ class HttpAnnotation : public CallTracerAnnotationInterface::Annotation {
 
  private:
   const Type type_;
-  const Timestamp time_;
+  const gpr_timespec time_;
   absl::optional<chttp2::TransportFlowControl::Stats> transport_stats_;
   absl::optional<chttp2::StreamFlowControl::Stats> stream_stats_;
 };

src/core/ext/transport/chttp2/transport/writing.cc

@@ -34,6 +34,7 @@
 #include <grpc/event_engine/event_engine.h>
 #include <grpc/slice_buffer.h>
 #include <grpc/support/log.h>
+#include <grpc/support/time.h>
 
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/ext/transport/chttp2/transport/context_list_entry.h"
@@ -516,7 +517,7 @@ class StreamWriteContext {
     if (s_->call_tracer) {
       s_->call_tracer->RecordAnnotation(grpc_core::HttpAnnotation(
           grpc_core::HttpAnnotation::Type::kHeadWritten,
-          grpc_core::Timestamp::Now(), s_->t->flow_control.stats(),
+          gpr_now(GPR_CLOCK_REALTIME), s_->t->flow_control.stats(),
           s_->flow_control.stats()));
     }
   }
@@ -648,7 +649,7 @@ class StreamWriteContext {
                                    absl::OkStatus());
     if (s_->call_tracer) {
       s_->call_tracer->RecordAnnotation(grpc_core::HttpAnnotation(
-          grpc_core::HttpAnnotation::Type::kEnd, grpc_core::Timestamp::Now(),
+          grpc_core::HttpAnnotation::Type::kEnd, gpr_now(GPR_CLOCK_REALTIME),
           s_->t->flow_control.stats(), s_->flow_control.stats()));
     }
   }