async_hooks: rename internal emit functions

There are two categories of emit functions in async_hooks, those used by
c++ (native) and those used by JavaScript (script). Previously these
were named N for native and S for script. Finally, there was an odd case
where emitInitN was called just init. This makes it more explicit by
using the names emitInitNative and emitInitScript. The other emit
functions are also renamed.

PR-URL: #14152
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

lib/async_hooks.js

@@ -57,7 +57,7 @@ const emitDestroyNative = emitHookFactory(destroy_symbol, 'emitDestroyNative');
 // process. They use the same functions as the JS embedder API. These callbacks
 // are setup immediately to prevent async_wrap.setupHooks() from being hijacked
 // and the cost of doing so is negligible.
-async_wrap.setupHooks({ init,
+async_wrap.setupHooks({ init: emitInitNative,
                         before: emitBeforeNative,
                         after: emitAfterNative,
                         destroy: emitDestroyNative });
@@ -228,21 +228,21 @@ class AsyncResource {
     if (async_hook_fields[kInit] === 0)
       return;
 
-    init(this[async_id_symbol], type, triggerAsyncId, this);
+    emitInitNative(this[async_id_symbol], type, triggerAsyncId, this);
   }
 
   emitBefore() {
-    emitBeforeS(this[async_id_symbol], this[trigger_id_symbol]);
+    emitBeforeScript(this[async_id_symbol], this[trigger_id_symbol]);
     return this;
   }
 
   emitAfter() {
-    emitAfterS(this[async_id_symbol]);
+    emitAfterScript(this[async_id_symbol]);
     return this;
   }
 
   emitDestroy() {
-    emitDestroyS(this[async_id_symbol]);
+    emitDestroyScript(this[async_id_symbol]);
     return this;
   }
 
@@ -311,7 +311,7 @@ function setInitTriggerId(triggerAsyncId) {
 }
 
 
-function emitInitS(asyncId, type, triggerAsyncId, resource) {
+function emitInitScript(asyncId, type, triggerAsyncId, resource) {
   // Short circuit all checks for the common case. Which is that no hooks have
   // been set. Do this to remove performance impact for embedders (and core).
   // Even though it bypasses all the argument checks. The performance savings
@@ -334,7 +334,7 @@ function emitInitS(asyncId, type, triggerAsyncId, resource) {
   if (!Number.isSafeInteger(triggerAsyncId) || triggerAsyncId < 0)
     throw new RangeError('triggerAsyncId must be an unsigned integer');
 
-  init(asyncId, type, triggerAsyncId, resource);
+  emitInitNative(asyncId, type, triggerAsyncId, resource);
 }
 
 function emitHookFactory(symbol, name) {
@@ -370,9 +370,7 @@ function emitHookFactory(symbol, name) {
 }
 
 
-// Usage: emitBeforeS(asyncId[, triggerAsyncId]). If triggerAsyncId is omitted
-// then asyncId will be used instead.
-function emitBeforeS(asyncId, triggerAsyncId) {
+function emitBeforeScript(asyncId, triggerAsyncId) {
   // CHECK(Number.isSafeInteger(asyncId) && asyncId > 0)
   // CHECK(Number.isSafeInteger(triggerAsyncId) && triggerAsyncId > 0)
 
@@ -392,15 +390,15 @@ function emitBeforeS(asyncId, triggerAsyncId) {
 // TODO(trevnorris): Calling emitBefore/emitAfter from native can't adjust the
 // kIdStackIndex. But what happens if the user doesn't have both before and
 // after callbacks.
-function emitAfterS(asyncId) {
+function emitAfterScript(asyncId) {
   if (async_hook_fields[kAfter] > 0)
     emitAfterNative(asyncId);
 
   popAsyncIds(asyncId);
 }
 
 
-function emitDestroyS(asyncId) {
+function emitDestroyScript(asyncId) {
   // Return early if there are no destroy callbacks, or on attempt to emit
   // destroy on the void.
   if (async_hook_fields[kDestroy] === 0 || asyncId === 0)
@@ -422,7 +420,7 @@ function emitDestroyS(asyncId) {
 // change in the future depending on whether it can be determined if there's a
 // slim chance of the application remaining stable after handling one of these
 // exceptions.
-function init(asyncId, type, triggerAsyncId, resource) {
+function emitInitNative(asyncId, type, triggerAsyncId, resource) {
   processing_hook += 1;
   // Use a single try/catch for all hook to avoid setting up one per iteration.
   try {
@@ -467,10 +465,10 @@ module.exports = {
   newUid,
   initTriggerId,
   setInitTriggerId,
-  emitInit: emitInitS,
-  emitBefore: emitBeforeS,
-  emitAfter: emitAfterS,
-  emitDestroy: emitDestroyS,
+  emitInit: emitInitScript,
+  emitBefore: emitBeforeScript,
+  emitAfter: emitAfterScript,
+  emitDestroy: emitDestroyScript,
 };
 
 // currentId was renamed to executionAsyncId. This was in 8.2.0 during the