Add tracing spans for input and output gates hold and wait

Author: shrima-cf

MODULE.bazel

@@ -81,6 +81,9 @@ archive_override(
 )
 
 include("//build/deps:deps.MODULE.bazel")
+
 include("//build/deps:nodejs.MODULE.bazel")
+
 include("//build/deps:python.MODULE.bazel")
+
 include("//build/deps:v8.MODULE.bazel")

src/workerd/io/BUILD.bazel

@@ -268,6 +268,7 @@ wd_cc_library(
     hdrs = ["io-gate.h"],
     visibility = ["//visibility:public"],
     deps = [
+        ":trace",
         "@capnp-cpp//src/kj",
         "@capnp-cpp//src/kj:kj-async",
     ],

src/workerd/io/io-gate.h

@@ -20,6 +20,8 @@
 //   to the application are still being flushed to disk. If the flush fails, these messages will
 //   never be sent, so that the rest of the world cannot observe a prematurely-confirmed write.
 
+#include <workerd/io/trace.h>
+
 #include <kj/async.h>
 #include <kj/list.h>
 #include <kj/one-of.h>
@@ -50,6 +52,10 @@ class InputGate {
     virtual void inputGateWaiterRemoved() {}
 
     static const Hooks DEFAULT;
+
+   protected:
+    kj::Maybe<SpanBuilder> inputGateWaitSpan;
+    kj::Maybe<SpanBuilder> inputGateHoldSpan;
   };
 
   // Hooks has no member variables, so const_cast is acceptable.
@@ -245,6 +251,10 @@ class OutputGate {
     virtual void outputGateWaiterRemoved() {}
 
     static const Hooks DEFAULT;
+
+   protected:
+    kj::Maybe<SpanBuilder> outputGateWaitSpan;
+    kj::Maybe<SpanBuilder> outputGateHoldSpan;
   };
 
   // Hooks has no member variables, so const_cast is acceptable.

src/workerd/io/worker.c++

@@ -3,6 +3,7 @@
 //     https://opensource.org/licenses/Apache-2.0
 
 #include "actor-cache.h"
+#include "workerd/io/io-gate.h"
 
 #include <workerd/api/actor-state.h>
 #include <workerd/api/global-scope.h>
@@ -3441,15 +3442,25 @@ struct Worker::Actor::Impl {
 
     void inputGateLocked() override {
       metrics.inputGateLocked();
+      if (IoContext::hasCurrent()) {
+        auto& ioContext = IoContext::current();
+        inputGateHoldSpan = ioContext.makeTraceSpan("actor_input_gate_hold"_kjc);
+      }
     }
     void inputGateReleased() override {
       metrics.inputGateReleased();
+      inputGateHoldSpan = kj::none;
     }
     void inputGateWaiterAdded() override {
       metrics.inputGateWaiterAdded();
+      if (IoContext::hasCurrent()) {
+        auto& ioContext = IoContext::current();
+        inputGateWaitSpan = ioContext.makeTraceSpan("actor_input_gate_wait"_kjc);
+      }
     }
     void inputGateWaiterRemoved() override {
       metrics.inputGateWaiterRemoved();
+      inputGateWaitSpan = kj::none;
     }
     // Implements InputGate::Hooks.
 
@@ -3469,15 +3480,25 @@ struct Worker::Actor::Impl {
 
     void outputGateLocked() override {
       metrics.outputGateLocked();
+      if (IoContext::hasCurrent()) {
+        auto& ioContext = IoContext::current();
+        outputGateHoldSpan = ioContext.makeTraceSpan("actor_output_gate_hold"_kjc);
+      }
     }
     void outputGateReleased() override {
       metrics.outputGateReleased();
+      outputGateHoldSpan = kj::none;
     }
     void outputGateWaiterAdded() override {
       metrics.outputGateWaiterAdded();
+      if (IoContext::hasCurrent()) {
+        auto& ioContext = IoContext::current();
+        outputGateWaitSpan = ioContext.makeTraceSpan("actor_output_gate_wait"_kjc);
+      }
     }
     void outputGateWaiterRemoved() override {
       metrics.outputGateWaiterRemoved();
+      outputGateWaitSpan = kj::none;
     }
 
     // Implements ActorCache::Hooks