src: return early if nextTickQueue is empty

This brings the node::MakeCallback and node::AsyncWrap::MakeCallback implementations into alignment in that they return early if the nextTickQueue is empty after processing the MicrotaskQueue. Include test to make sure early return happens. Test has text explaining the conditions for the test to pass, since it relies on internal mechanisms that aren't guaranteed in the future. PR-URL: #10274 Reviewed-By: Ben Noordhuis <[email protected]> Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Jeremiah Senkpiel <[email protected]> Reviewed-By: Colin Ihrig <[email protected]>

Author: trevnorris

src/node.cc

@@ -1317,6 +1317,7 @@ Local<Value> MakeCallback(Environment* env,
 
 if (tick_info->length() == 0){
  tick_info->set_index(0);
+return ret;
  }
 
 if (env->tick_callback_function()->Call(process, 0, nullptr).IsEmpty()){

test/parallel/test-no-enter-tickcallback.js

@@ -0,0 +1,32 @@
+'use strict';
+
+constcommon=require('../common');
+constassert=require('assert');
+letallsGood=false;
+letcntr=0;
+
+process.on('exit',()=>{
+assert.ok(cntr>0,'_tickDomainCallback was never called');
+});
+
+/**
+ * This test relies upon the following internals to work as specified:
+ * - require('domain') causes node::Environment::set_tick_callback_function()
+ * to use process._tickDomainCallback() to process the nextTickQueue;
+ * replacing process._tickCallback().
+ * - setImmediate() uses node::MakeCallback() instead of
+ * node::AsyncWrap::MakeCallback(). Otherwise the test will always pass.
+ * Have not found a way to verify that node::MakeCallback() is used.
+ */
+process._tickDomainCallback=function_tickDomainCallback(){
+assert.ok(allsGood,'_tickDomainCallback should not have been called');
+cntr++;
+};
+
+setImmediate(common.mustCall(()=>{
+require('domain');
+setImmediate(common.mustCall(()=>setImmediate(common.mustCall(()=>{
+allsGood=true;
+process.nextTick(()=>{});
+}))));
+}));