Bug 1567210 - Use Thread actor reference to distinguish the event loops. r=loganfsmyth

Use thread actor reference instead of target's actor URL *and* connection
to distinguish the currently paused event loop from the other ones which
may be on-pause from another thread actor on another connection/tab.
This happens when connecting more than one client against the same tab.

Differential Revision: https://phabricator.services.mozilla.com/D39705

--HG--
extra : moz-landing-system : lando

devtools/server/actors/thread.js

@@ -347,7 +347,6 @@ const ThreadActor = ActorClassWithSpec(threadSpec, {
     // Initialize an event loop stack. This can't be done in the constructor,
     // because this.conn is not yet initialized by the actor pool at that time.
     this._nestedEventLoops = new EventLoopStack({
-      connection: this.conn,
       thread: this,
     });
 
@@ -1208,14 +1207,12 @@ const ThreadActor = ActorClassWithSpec(threadSpec, {
     // only allow resumption in a LIFO order.
     if (
       this._nestedEventLoops.size &&
-      this._nestedEventLoops.lastPausedUrl &&
-      (this._nestedEventLoops.lastPausedUrl !== this._parent.url ||
-        this._nestedEventLoops.lastConnection !== this.conn)
+      this._nestedEventLoops.lastPausedThreadActor &&
+      this._nestedEventLoops.lastPausedThreadActor !== this
     ) {
       return {
         error: "wrongOrder",
         message: "trying to resume in the wrong order.",
-        lastPausedUrl: this._nestedEventLoops.lastPausedUrl,
       };
     }
 

devtools/server/actors/utils/event-loop.js

@@ -14,12 +14,9 @@ const xpcInspector = require("xpcInspector");
  *
  * @param ThreadActor thread
  *        The thread actor instance that owns this EventLoopStack.
- * @param DebuggerServerConnection connection
- *        The remote protocol connection associated with this event loop stack.
  */
-function EventLoopStack({ thread, connection }) {
+function EventLoopStack({ thread }) {
   this._thread = thread;
-  this._connection = connection;
 }
 
 EventLoopStack.prototype = {
@@ -31,28 +28,13 @@ EventLoopStack.prototype = {
   },
 
   /**
-   * The URL of the debuggee who pushed the event loop on top of the stack.
+   * The thread actor of the debuggee who pushed the event loop on top of the stack.
    */
-  get lastPausedUrl() {
-    let url = null;
+  get lastPausedThreadActor() {
     if (this.size > 0) {
-      try {
-        url = xpcInspector.lastNestRequestor.url;
-      } catch (e) {
-        // The tab's URL getter may throw if the tab is destroyed by the time
-        // this code runs, but we don't really care at this point.
-        dumpn(e);
-      }
+      return xpcInspector.lastNestRequestor.thread;
     }
-    return url;
-  },
-
-  /**
-   * The DebuggerServerConnection of the debugger who pushed the event loop on
-   * top of the stack
-   */
-  get lastConnection() {
-    return xpcInspector.lastNestRequestor._connection;
+    return null;
   },
 
   /**
@@ -63,7 +45,6 @@ EventLoopStack.prototype = {
   push: function() {
     return new EventLoop({
       thread: this._thread,
-      connection: this._connection,
     });
   },
 };
@@ -74,12 +55,9 @@ EventLoopStack.prototype = {
  *
  * @param ThreadActor thread
  *        The thread actor that is creating this nested event loop.
- * @param DebuggerServerConnection connection
- *        The remote protocol connection associated with this event loop.
  */
-function EventLoop({ thread, connection }) {
+function EventLoop({ thread }) {
   this._thread = thread;
-  this._connection = connection;
 
   this.enter = this.enter.bind(this);
   this.resolve = this.resolve.bind(this);
@@ -88,8 +66,8 @@ function EventLoop({ thread, connection }) {
 EventLoop.prototype = {
   entered: false,
   resolved: false,
-  get url() {
-    return this._thread._parent.url;
+  get thread() {
+    return this._thread;
   },
 
   /**