Optimize absl::StrFormat calls showing up on profiles (#32647)

- construct string for tracing in chttp2_transport only if tracing is
enabled
- use equivalent absl::StrCat/StrAppend instead of
absl::StrFormat/StrJoin for formatting showing up on cpu profiles

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

@@ -205,20 +205,14 @@ static void keepalive_watchdog_fired_locked(
 static void maybe_reset_keepalive_ping_timer_locked(grpc_chttp2_transport* t);
 
 namespace {
-void MaybeRecordTransportAnnotation(grpc_chttp2_stream* s,
-                                    absl::string_view annotation) {
-  GPR_ASSERT(s->context);
-  if (!grpc_core::IsTraceRecordCallopsEnabled()) {
-    return;
+grpc_core::CallTracerInterface* CallTracerIfEnabled(grpc_chttp2_stream* s) {
+  if (s->context == nullptr || !grpc_core::IsTraceRecordCallopsEnabled()) {
+    return nullptr;
   }
-  auto* call_tracer = static_cast<grpc_core::CallTracerInterface*>(
+  return static_cast<grpc_core::CallTracerInterface*>(
       static_cast<grpc_call_context_element*>(
           s->context)[GRPC_CONTEXT_CALL_TRACER_ANNOTATION_INTERFACE]
           .value);
-  if (!call_tracer) {
-    return;
-  }
-  call_tracer->RecordAnnotation(annotation);
 }
 }  // namespace
 
@@ -369,8 +363,8 @@ static void read_channel_args(grpc_chttp2_transport* t,
         grpc_core::MakeRefCounted<grpc_core::channelz::SocketNode>(
             std::string(grpc_endpoint_get_local_address(t->ep)),
             std::string(t->peer_string.as_string_view()),
-            absl::StrFormat("%s %s", get_vtable()->name,
-                            t->peer_string.as_string_view()),
+            absl::StrCat(get_vtable()->name, " ",
+                         t->peer_string.as_string_view()),
             channel_args
                 .GetObjectRef<grpc_core::channelz::SocketNode::Security>());
   }
@@ -1231,10 +1225,11 @@ void grpc_chttp2_complete_closure_step(grpc_chttp2_transport* t,
         write_state_name(t->write_state));
   }
 
-  if (s->context != nullptr) {
-    MaybeRecordTransportAnnotation(
-        s, absl::StrFormat("on_complete: s=%p %p desc=%s err=%s", s, closure,
-                           desc, grpc_core::StatusToString(error).c_str()));
+  auto* tracer = CallTracerIfEnabled(s);
+  if (tracer != nullptr) {
+    tracer->RecordAnnotation(
+        absl::StrFormat("on_complete: s=%p %p desc=%s err=%s", s, closure, desc,
+                        grpc_core::StatusToString(error).c_str()));
   }
 
   if (!error.ok()) {
@@ -1309,12 +1304,12 @@ static void perform_stream_op_locked(void* stream_op,
     }
   }
 
-  if (s->context != nullptr) {
-    MaybeRecordTransportAnnotation(
-        s, absl::StrFormat(
-               "perform_stream_op_locked[s=%p; op=%p]: %s; on_complete = %p", s,
-               op, grpc_transport_stream_op_batch_string(op, true).c_str(),
-               op->on_complete));
+  auto* tracer = CallTracerIfEnabled(s);
+  if (tracer != nullptr) {
+    tracer->RecordAnnotation(absl::StrFormat(
+        "perform_stream_op_locked[s=%p; op=%p]: %s; on_complete = %p", s, op,
+        grpc_transport_stream_op_batch_string(op, true).c_str(),
+        op->on_complete));
   }
 
   grpc_closure* on_complete = op->on_complete;

src/core/lib/transport/transport_op_string.cc

@@ -18,15 +18,12 @@
 
 #include <grpc/support/port_platform.h>
 
-#include <algorithm>
 #include <initializer_list>
 #include <memory>
 #include <string>
-#include <vector>
 
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
-#include "absl/strings/str_join.h"
 
 #include <grpc/support/log.h>
 
@@ -45,111 +42,112 @@
 
 std::string grpc_transport_stream_op_batch_string(
     grpc_transport_stream_op_batch* op, bool truncate) {
-  std::vector<std::string> out;
+  std::string out;
 
   if (op->send_initial_metadata) {
-    out.push_back(" SEND_INITIAL_METADATA{");
+    absl::StrAppend(&out, " SEND_INITIAL_METADATA{");
     if (truncate) {
-      out.push_back(absl::StrFormat(
-          "Length=%zu", op->payload->send_initial_metadata
-                            .send_initial_metadata->TransportSize()));
+      absl::StrAppend(&out, "Length=",
+                      op->payload->send_initial_metadata.send_initial_metadata
+                          ->TransportSize());
     } else {
-      out.push_back(op->payload->send_initial_metadata.send_initial_metadata
-                        ->DebugString());
+      absl::StrAppend(&out, op->payload->send_initial_metadata
+                                .send_initial_metadata->DebugString());
     }
-    out.push_back("}");
+    absl::StrAppend(&out, "}");
   }
 
   if (op->send_message) {
     if (op->payload->send_message.send_message != nullptr) {
-      out.push_back(absl::StrFormat(
-          " SEND_MESSAGE:flags=0x%08x:len=%d", op->payload->send_message.flags,
-          op->payload->send_message.send_message->Length()));
+      absl::StrAppendFormat(&out, " SEND_MESSAGE:flags=0x%08x:len=%d",
+                            op->payload->send_message.flags,
+                            op->payload->send_message.send_message->Length());
     } else {
       // This can happen when we check a batch after the transport has
       // processed and cleared the send_message op.
-      out.push_back(" SEND_MESSAGE(flag and length unknown, already orphaned)");
+      absl::StrAppend(
+          &out, " SEND_MESSAGE(flag and length unknown, already orphaned)");
     }
   }
 
   if (op->send_trailing_metadata) {
-    out.push_back(" SEND_TRAILING_METADATA{");
+    absl::StrAppend(&out, " SEND_TRAILING_METADATA{");
     if (truncate) {
-      out.push_back(absl::StrFormat(
-          "Length=%zu", op->payload->send_trailing_metadata
-                            .send_trailing_metadata->TransportSize()));
+      absl::StrAppend(&out, "Length=",
+                      op->payload->send_trailing_metadata
+                          .send_trailing_metadata->TransportSize());
     } else {
-      out.push_back(op->payload->send_trailing_metadata.send_trailing_metadata
-                        ->DebugString());
+      absl::StrAppend(&out, op->payload->send_trailing_metadata
+                                .send_trailing_metadata->DebugString());
     }
-    out.push_back("}");
+    absl::StrAppend(&out, "}");
   }
 
   if (op->recv_initial_metadata) {
-    out.push_back(" RECV_INITIAL_METADATA");
+    absl::StrAppend(&out, " RECV_INITIAL_METADATA");
   }
 
   if (op->recv_message) {
-    out.push_back(" RECV_MESSAGE");
+    absl::StrAppend(&out, " RECV_MESSAGE");
   }
 
   if (op->recv_trailing_metadata) {
-    out.push_back(" RECV_TRAILING_METADATA");
+    absl::StrAppend(&out, " RECV_TRAILING_METADATA");
   }
 
   if (op->cancel_stream) {
-    out.push_back(absl::StrCat(
-        " CANCEL:",
-        grpc_core::StatusToString(op->payload->cancel_stream.cancel_error)));
+    absl::StrAppend(
+        &out, " CANCEL:",
+        grpc_core::StatusToString(op->payload->cancel_stream.cancel_error));
   }
 
-  return absl::StrJoin(out, "");
+  return out;
 }
 
 std::string grpc_transport_op_string(grpc_transport_op* op) {
-  std::vector<std::string> out;
+  std::string out;
 
   if (op->start_connectivity_watch != nullptr) {
-    out.push_back(absl::StrFormat(
-        " START_CONNECTIVITY_WATCH:watcher=%p:from=%s",
+    absl::StrAppendFormat(
+        &out, " START_CONNECTIVITY_WATCH:watcher=%p:from=%s",
         op->start_connectivity_watch.get(),
-        grpc_core::ConnectivityStateName(op->start_connectivity_watch_state)));
+        grpc_core::ConnectivityStateName(op->start_connectivity_watch_state));
   }
 
   if (op->stop_connectivity_watch != nullptr) {
-    out.push_back(absl::StrFormat(" STOP_CONNECTIVITY_WATCH:watcher=%p",
-                                  op->stop_connectivity_watch));
+    absl::StrAppendFormat(&out, " STOP_CONNECTIVITY_WATCH:watcher=%p",
+                          op->stop_connectivity_watch);
   }
 
   if (!op->disconnect_with_error.ok()) {
-    out.push_back(absl::StrCat(
-        " DISCONNECT:", grpc_core::StatusToString(op->disconnect_with_error)));
+    absl::StrAppend(&out, " DISCONNECT:",
+                    grpc_core::StatusToString(op->disconnect_with_error));
   }
 
   if (!op->goaway_error.ok()) {
-    out.push_back(absl::StrCat(" SEND_GOAWAY:",
-                               grpc_core::StatusToString(op->goaway_error)));
+    absl::StrAppend(
+        &out, " SEND_GOAWAY:", grpc_core::StatusToString(op->goaway_error));
   }
 
   if (op->set_accept_stream) {
-    out.push_back(absl::StrFormat(" SET_ACCEPT_STREAM:%p(%p,...)",
-                                  op->set_accept_stream_fn,
-                                  op->set_accept_stream_user_data));
+    absl::StrAppendFormat(&out, " SET_ACCEPT_STREAM:%p(%p,...)",
+                          op->set_accept_stream_fn,
+                          op->set_accept_stream_user_data);
   }
 
   if (op->bind_pollset != nullptr) {
-    out.push_back(" BIND_POLLSET");
+    absl::StrAppend(&out, " BIND_POLLSET");
   }
 
   if (op->bind_pollset_set != nullptr) {
-    out.push_back(" BIND_POLLSET_SET");
+    absl::StrAppend(&out, " BIND_POLLSET_SET");
   }
 
   if (op->send_ping.on_initiate != nullptr || op->send_ping.on_ack != nullptr) {
-    out.push_back(" SEND_PING");
+    absl::StrAppend(&out, " SEND_PING");
   }
 
-  return absl::StrJoin(out, "");
+  return out;
 }
 
 void grpc_call_log_op(const char* file, int line, gpr_log_severity severity,