diagnostics_channel: fix unsubscribe during publish

PR-URL: #55116
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Claudio Wunder <cwunder@gnome.org>

Author: simon-id

lib/diagnostics_channel.js

@@ -4,6 +4,8 @@ const {
  ArrayPrototypeAt,
  ArrayPrototypeIndexOf,
  ArrayPrototypePush,
+ ArrayPrototypePushApply,
+ ArrayPrototypeSlice,
  ArrayPrototypeSplice,
  ObjectDefineProperty,
  ObjectGetPrototypeOf,
@@ -97,6 +99,7 @@ function wrapStoreRun(store, data, next, transform = defaultTransform) {
 classActiveChannel{
 subscribe(subscription){
 validateFunction(subscription,'subscription');
+this._subscribers=ArrayPrototypeSlice(this._subscribers);
 ArrayPrototypePush(this._subscribers,subscription);
 channels.incRef(this.name);
 }
@@ -105,7 +108,10 @@ class ActiveChannel {
 constindex=ArrayPrototypeIndexOf(this._subscribers,subscription);
 if(index===-1)returnfalse;
 
-ArrayPrototypeSplice(this._subscribers,index,1);
+constbefore=ArrayPrototypeSlice(this._subscribers,0,index);
+constafter=ArrayPrototypeSlice(this._subscribers,index+1);
+this._subscribers=before;
+ArrayPrototypePushApply(this._subscribers,after);
 
 channels.decRef(this.name);
 maybeMarkInactive(this);
@@ -137,9 +143,10 @@ class ActiveChannel {
 }
 
 publish(data){
-for(leti=0;i<(this._subscribers?.length||0);i++){
+constsubscribers=this._subscribers;
+for(leti=0;i<(subscribers?.length||0);i++){
 try{
-constonMessage=this._subscribers[i];
+constonMessage=subscribers[i];
 onMessage(data,this.name);
 }catch(err){
 process.nextTick(()=>{

test/parallel/test-diagnostics-channel-sync-unsubscribe.js

@@ -9,6 +9,7 @@ const published_data = 'some message';
 constonMessageHandler=common.mustCall(()=>dc.unsubscribe(channel_name,onMessageHandler));
 
 dc.subscribe(channel_name,onMessageHandler);
+dc.subscribe(channel_name,common.mustCall());
 
 // This must not throw.
 dc.channel(channel_name).publish(published_data);