perf_hooks: add idleTime and event loop util

Use uv_metrics_idle_time() to return a high resolution millisecond timer
of the amount of time the event loop has been idle since it was
initialized.

Include performance.eventLoopUtilization() API to handle the math of
calculating the idle and active times. This has been added to prevent
accidental miscalculations of the event loop utilization. Such as not
taking into consideration offsetting nodeTiming.loopStart or timing
differences when being called from a Worker thread.

PR-URL: https://github.com/nodejs/node/pull/34938
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Adrian Estrada <edsadr@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>

3 files changed, 10 insertions, 0 deletions

diff --git a/src/node.cc b/src/node.cc
index d68c6d8d148..dd2cd0db75d 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -1079,6 +1079,7 @@ int Start(int argc, char** argv) {
         env_info = NodeMainInstance::GetEnvSerializeInfo();
       }
     }
+    uv_loop_configure(uv_default_loop(), UV_METRICS_IDLE_TIME);
 
     NodeMainInstance main_instance(&params,
                                    uv_default_loop(),
diff --git a/src/node_perf.cc b/src/node_perf.cc
index d71afc2d81c..5fa4eabc993 100644
--- a/src/node_perf.cc
+++ b/src/node_perf.cc
@@ -440,6 +440,13 @@ void Notify(const FunctionCallbackInfo<Value>& args) {
   }
 }
 
+// Return idle time of the event loop
+void LoopIdleTime(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  uint64_t idle_time = uv_metrics_idle_time(env->event_loop());
+  args.GetReturnValue().Set(1.0 * idle_time / 1e6);
+}
+
 
 // Event Loop Timing Histogram
 namespace {
@@ -629,6 +636,7 @@ void Initialize(Local<Object> target,
                  "removeGarbageCollectionTracking",
                  RemoveGarbageCollectionTracking);
   env->SetMethod(target, "notify", Notify);
+  env->SetMethod(target, "loopIdleTime", LoopIdleTime);
 
   Local<Object> constants = Object::New(isolate);
 
diff --git a/src/node_worker.cc b/src/node_worker.cc
index 2b7cc156db9..b3dd29bf9fb 100644
--- a/src/node_worker.cc
+++ b/src/node_worker.cc
@@ -135,6 +135,7 @@ class WorkerThreadData {
       return;
     }
     loop_init_failed_ = false;
+    uv_loop_configure(&loop_, UV_METRICS_IDLE_TIME);
 
     std::shared_ptr<ArrayBufferAllocator> allocator =
         ArrayBufferAllocator::Create();