src: add tracing category macros

Adds `TRACING_CATEGORY_NODE`, `TRACING_CATEGORY_NODE1` and
`TRACING_CATEGORY_NODE2` helper macros for consistently building
trace event category strings. For instance,

`TRACING_CATEGORY_NODE2(foo, bar)` would generate the category
string `node,node.foo,node.foo.bar`, such that...

```
TRACE_EVENT_NESTABLE_ASYNC_BEGIN0(
    TRACING_CATEGORY_NODE2(foo, bar),
    "baz", 1);
```

Would emit if trace events are enabled for categories: `node`,
`node.foo`, or `node.foo.bar`.

This allows a natural scoping down of what trace events a user
may want to receive. Enabling the `node` category would receive
everything Node.js produces.

Author: jasnell

src/async_wrap.cc

@@ -179,7 +179,8 @@ void AsyncWrap::EmitTraceEventBefore() {
   switch (provider_type()) {
 #define V(PROVIDER)                                                           \
     case PROVIDER_ ## PROVIDER:                                               \
-      TRACE_EVENT_NESTABLE_ASYNC_BEGIN0("node.async_hooks",                   \
+      TRACE_EVENT_NESTABLE_ASYNC_BEGIN0(                                      \
+        TRACING_CATEGORY_NODE1(async_hooks),                                  \
         #PROVIDER "_CALLBACK", static_cast<int64_t>(get_async_id()));         \
       break;
     NODE_ASYNC_PROVIDER_TYPES(V)
@@ -207,7 +208,8 @@ void AsyncWrap::EmitTraceEventAfter() {
   switch (provider_type()) {
 #define V(PROVIDER)                                                           \
     case PROVIDER_ ## PROVIDER:                                               \
-      TRACE_EVENT_NESTABLE_ASYNC_END0("node.async_hooks",                     \
+      TRACE_EVENT_NESTABLE_ASYNC_END0(                                        \
+        TRACING_CATEGORY_NODE1(async_hooks),                                  \
         #PROVIDER "_CALLBACK", static_cast<int64_t>(get_async_id()));         \
       break;
     NODE_ASYNC_PROVIDER_TYPES(V)
@@ -631,7 +633,8 @@ void AsyncWrap::EmitTraceEventDestroy() {
   switch (provider_type()) {
   #define V(PROVIDER)                                                         \
     case PROVIDER_ ## PROVIDER:                                               \
-      TRACE_EVENT_NESTABLE_ASYNC_END0("node.async_hooks",                     \
+      TRACE_EVENT_NESTABLE_ASYNC_END0(                                        \
+        TRACING_CATEGORY_NODE1(async_hooks),                                  \
         #PROVIDER, static_cast<int64_t>(get_async_id()));                     \
       break;
     NODE_ASYNC_PROVIDER_TYPES(V)
@@ -664,7 +667,8 @@ void AsyncWrap::AsyncReset(double execution_async_id, bool silent) {
   switch (provider_type()) {
 #define V(PROVIDER)                                                           \
     case PROVIDER_ ## PROVIDER:                                               \
-      TRACE_EVENT_NESTABLE_ASYNC_BEGIN2("node.async_hooks",                   \
+      TRACE_EVENT_NESTABLE_ASYNC_BEGIN2(                                      \
+        TRACING_CATEGORY_NODE1(async_hooks),                                  \
         #PROVIDER, static_cast<int64_t>(get_async_id()),                      \
         "executionAsyncId",                                                   \
         static_cast<int64_t>(env()->execution_async_id()),                    \

src/node_internals.h

@@ -776,6 +776,15 @@ static inline const char *errno_string(int errorno) {
 #define NODE_MODULE_CONTEXT_AWARE_INTERNAL(modname, regfunc)                  \
   NODE_MODULE_CONTEXT_AWARE_CPP(modname, regfunc, nullptr, NM_F_INTERNAL)
 
+#define TRACING_CATEGORY_NODE "node"
+#define TRACING_CATEGORY_NODE1(one)                                           \
+    TRACING_CATEGORY_NODE ","                                                 \
+    TRACING_CATEGORY_NODE "." #one
+#define TRACING_CATEGORY_NODE2(one, two)                                      \
+    TRACING_CATEGORY_NODE ","                                                 \
+    TRACING_CATEGORY_NODE "." #one ","                                        \
+    TRACING_CATEGORY_NODE "." #one "." #two
+
 }  // namespace node
 
 

src/node_perf.cc

@@ -135,7 +135,8 @@ void Mark(const FunctionCallbackInfo<Value>& args) {
   (*marks)[*name] = now;
 
   TRACE_EVENT_COPY_MARK_WITH_TIMESTAMP(
-      "node.perf,node.perf.usertiming", *name, now / 1000);
+      TRACING_CATEGORY_NODE2(perf, usertiming),
+      *name, now / 1000);
 
   PerformanceEntry entry(env, *name, "mark", now, now);
   Local<Object> obj = entry.ToObject();
@@ -183,9 +184,11 @@ void Measure(const FunctionCallbackInfo<Value>& args) {
     endTimestamp = startTimestamp;
 
   TRACE_EVENT_COPY_NESTABLE_ASYNC_BEGIN_WITH_TIMESTAMP0(
-      "node.perf,node.perf.usertiming", *name, *name, startTimestamp / 1000);
+      TRACING_CATEGORY_NODE2(perf, usertiming),
+      *name, *name, startTimestamp / 1000);
   TRACE_EVENT_COPY_NESTABLE_ASYNC_END_WITH_TIMESTAMP0(
-      "node.perf,node.perf.usertiming", *name, *name, endTimestamp / 1000);
+      TRACING_CATEGORY_NODE2(perf, usertiming),
+      *name, *name, endTimestamp / 1000);
 
   PerformanceEntry entry(env, *name, "measure", startTimestamp, endTimestamp);
   Local<Object> obj = entry.ToObject();
@@ -301,13 +304,15 @@ void TimerFunctionCall(const FunctionCallbackInfo<Value>& args) {
   if (args.IsConstructCall()) {
     start = PERFORMANCE_NOW();
     TRACE_EVENT_COPY_NESTABLE_ASYNC_BEGIN_WITH_TIMESTAMP0(
-        "node.perf,node.perf.timerify", *name, *name, start / 1000);
+        TRACING_CATEGORY_NODE2(perf, timerify),
+        *name, *name, start / 1000);
     v8::MaybeLocal<Object> ret = fn->NewInstance(context,
                                                  call_args.size(),
                                                  call_args.data());
     end = PERFORMANCE_NOW();
     TRACE_EVENT_COPY_NESTABLE_ASYNC_END_WITH_TIMESTAMP0(
-        "node.perf,node.perf.timerify", *name, *name, end / 1000);
+        TRACING_CATEGORY_NODE2(perf, timerify),
+        *name, *name, end / 1000);
 
     if (ret.IsEmpty()) {
       try_catch.ReThrow();
@@ -317,14 +322,16 @@ void TimerFunctionCall(const FunctionCallbackInfo<Value>& args) {
   } else {
     start = PERFORMANCE_NOW();
     TRACE_EVENT_COPY_NESTABLE_ASYNC_BEGIN_WITH_TIMESTAMP0(
-        "node.perf,node.perf.timerify", *name, *name, start / 1000);
+        TRACING_CATEGORY_NODE2(perf, timerify),
+        *name, *name, start / 1000);
     v8::MaybeLocal<Value> ret = fn->Call(context,
                                          args.This(),
                                          call_args.size(),
                                          call_args.data());
     end = PERFORMANCE_NOW();
     TRACE_EVENT_COPY_NESTABLE_ASYNC_END_WITH_TIMESTAMP0(
-        "node.perf,node.perf.timerify", *name, *name, end / 1000);
+        TRACING_CATEGORY_NODE2(perf, timerify),
+        *name, *name, end / 1000);
 
     if (ret.IsEmpty()) {
       try_catch.ReThrow();