[DevTools]: Require explicit connection

third_party/WebKit/Source/devtools/front_end/sdk/SubTargetsManager.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @extends {WebInspector.SDKModel}
  * @param {!WebInspector.Target} target
  */
 WebInspector.SubTargetsManager = function(target)
 {
     WebInspector.SDKModel.call(this, WebInspector.SubTargetsManager, target);
     target.registerTargetDispatcher(new WebInspector.SubTargetsDispatcher(this));
     this._lastAnonymousTargetId = 0;
     this._agent = target.targetAgent();
 
     /** @type {!Map<string, !WebInspector.Target>} */
     this._attachedTargets = new Map();
     /** @type {!Map<string, !WebInspector.SubTargetConnection>} */
     this._connections = new Map();
+    /** @type {!Map<string, !WebInspector.PendingConnection>} */
+    this._pendingConnections = new Map();
 
     this._agent.setAutoAttach(true /* autoAttach */, true /* waitForDebuggerOnStart */);
     this._agent.setAttachToFrames(Runtime.experiments.isEnabled("autoAttachToCrossProcessSubframes"));
 
     if (Runtime.experiments.isEnabled("nodeDebugging") && !target.parentTarget()) {
         var defaultLocations = [{host: "localhost", port: 9229}];
         this._agent.setRemoteLocations(defaultLocations);
         this._agent.setDiscoverTargets(true);
     }
 };
@@ skipping 33 matching lines @@
 
     /**
      * @override
      */
     dispose: function()
     {
         for (var connection of this._connections.values()) {
             this._agent.detachFromTarget(connection._targetId);
             connection._onDisconnect.call(null, "disposed");
         }
+        for (var pending of this._pendingConnections.values())
+            WebInspector.targetConnectionManager.removeConnection(pending);
         this._connections.clear();
         this._attachedTargets.clear();
     },
 
     /**
      * @param {!TargetAgent.TargetID} targetId
      */
     activateTarget: function(targetId)
     {
         this._agent.activateTarget(targetId);
@@ skipping 67 matching lines @@
      */
     _attachedToTarget: function(targetInfo, waitingForDebugger)
     {
         var targetName = "";
         if (targetInfo.type === "node") {
             targetName = targetInfo.title;
         } else if (targetInfo.type !== "iframe") {
             var parsedURL = targetInfo.url.asParsedURL();
             targetName = parsedURL ? parsedURL.lastPathComponentWithFragment() : "#" + (++this._lastAnonymousTargetId);
         }
-        var target = WebInspector.targetManager.createTarget(targetName, this._capabilitiesForType(targetInfo.type), this._createConnection.bind(this, targetInfo.id), this.target());
+        var target = WebInspector.targetManager.createTarget(targetName, this._capabilitiesForType(targetInfo.type), this._createConnection.bind(this, targetInfo.id), this.target(), true);
+        var targetConnection = this._targetCreated(targetInfo);
+        targetConnection && targetConnection._attached(target);

[dgozman, 2016/10/26 22:14:06]

Why do we need this?

[eostroukhov, 2016/10/27 23:42:24]

For targets, that can be disconnected from, mapping to a "connection" object is
needed. This way UI knows to show the "Disconnect" button - and also avoids
reshuffling the list of targets when connect/disconnect happens (target node
replaces the connection node or vice versa).

+        WebInspector.targetManager.addTarget(target);
         target[WebInspector.SubTargetsManager._InfoSymbol] = targetInfo;
         this._attachedTargets.set(targetInfo.id, target);
 
         // Only pause new worker if debugging SW - we are going through the pause on start checkbox.
         var mainIsServiceWorker = !this.target().parentTarget() && this.target().hasWorkerCapability() && !this.target().hasBrowserCapability();
         if (mainIsServiceWorker && waitingForDebugger)
             target.debuggerAgent().pause();
         target.runtimeAgent().runIfWaitingForDebugger();
 
         this.dispatchEventToListeners(WebInspector.SubTargetsManager.Events.SubTargetAdded, target);
@@ skipping 16 matching lines @@
      */
     _detachedFromTarget: function(targetId)
     {
         var target = this._attachedTargets.get(targetId);
         this._attachedTargets.delete(targetId);
         this.dispatchEventToListeners(WebInspector.SubTargetsManager.Events.SubTargetRemoved, target);
         var connection = this._connections.get(targetId);
         if (connection)
             connection._onDisconnect.call(null, "target terminated");
         this._connections.delete(targetId);
+        var targetConnection = this._pendingConnections.get(targetId);
+        targetConnection && targetConnection._detached();

[dgozman, 2016/10/26 22:14:06]

style: let's follow the surrounding code and do proper if statement.

[eostroukhov, 2016/10/27 23:42:24]

Done.

     },
 
     /**
      * @param {string} targetId
      * @param {string} message
      */
     _receivedMessageFromTarget: function(targetId, message)
     {
         var connection = this._connections.get(targetId);
         if (connection)
             connection._onMessage.call(null, message);
     },
 
     /**
      * @param {!WebInspector.TargetInfo} targetInfo
+     * @return {?WebInspector.PendingConnection}
      */
     _targetCreated: function(targetInfo)
     {
         if (targetInfo.type !== "node")
-            return;
-        this._agent.attachToTarget(targetInfo.id);
+            return null;
+        var connection = this._pendingConnections.get(targetInfo.id);

[dgozman, 2016/10/26 22:14:06]

How come we could have one?

[eostroukhov, 2016/10/27 23:42:24]

Speculatively, the code supports a case when attachedToTarget comes without
prior targetCreated notification.

This is mostly a vestige from the previous code that I can cleanup.

+        if (connection)
+            return connection;
+        connection = new WebInspector.PendingConnection(targetInfo, this.target().targetAgent());

[dgozman, 2016/10/26 22:14:06]

this._agent

[eostroukhov, 2016/10/27 23:42:24]

Done.

+        WebInspector.targetConnectionManager.addConnection(connection);
+        this._pendingConnections.set(targetInfo.id, connection);
+        return connection;
     },
 
     /**
      * @param {string} targetId
      */
     _targetDestroyed: function(targetId)
     {
-        // All the work is done in _detachedFromTarget.
+        var connection = this._pendingConnections.get(targetId);
+        if (!connection)
+            return;
+        WebInspector.targetConnectionManager.removeConnection(connection);
+        this._pendingConnections.delete(targetId);
     },
 
     __proto__: WebInspector.SDKModel.prototype
 };
 
 /**
  * @constructor
  * @implements {TargetAgent.Dispatcher}
  * @param {!WebInspector.SubTargetsManager} manager
  */
@@ skipping 88 matching lines @@
 
 /**
  * @constructor
  * @param {!TargetAgent.TargetInfo} payload
  */
 WebInspector.TargetInfo = function(payload)
 {
     this.id = payload.targetId;
     this.url = payload.url;
     this.type = payload.type;
-    if (this.type !== "page" && this.type !== "iframe") {
+    if (this.type !== "page" && this.type !== "iframe" && this.type !== "node") {
         this.title = WebInspector.UIString("Worker: %s", this.url);
         this.canActivate = false;
     } else {
         this.title = payload.title;
         this.canActivate = true;
     }
 };
+
+/**
+ * @constructor
+ * @implements {WebInspector.TargetConnectionManager.Connection}
+ * @param {!WebInspector.TargetInfo} info
+ * @param {!Protocol.TargetAgent} targetAgent
+ */
+WebInspector.PendingConnection = function(info, targetAgent)
+{
+    this._info = info;
+    this._targetAgent = targetAgent;
+    /** @type {?Promise} */
+    this._connectPromise = null;
+    /** @type {?WebInspector.Target} */
+    this._target = null;
+};
+
+WebInspector.PendingConnection.prototype = {
+    /**
+     * @override
+     * @return {string}
+     */
+    id: function()
+    {
+        return this._info.id;
+    },
+
+    /**
+     * @override
+     * @return {string}
+     */
+    name: function()
+    {
+        return this._info.title;
+    },
+
+    /**
+     * @override
+     * @return {!Promise}
+     */
+    connect: function()
+    {
+        if (this._target)
+            return Promise.resolve(this._target);
+        if (this._connectPromise)
+            return this._connectPromise;
+        var resolveFn, rejectFn;
+        var promise = new Promise((resolve, reject) => {

[dgozman, 2016/10/26 22:14:06]

The following pattern is used heavily in inspector:

var fulfill;
var promise = new Promise(f => fulfill = f);
...
fulfill(value);

[eostroukhov, 2016/10/27 23:42:24]

Done (TIL - parentheses are optional for arrow functions :) )

+            resolveFn = resolve;
+            rejectFn = reject;
+        }).then((target) => {
+            this._target = target
+            this._connectPromise = null;
+        });
+        promise[WebInspector.PendingConnection._resolveSymbol] = resolveFn;
+        this._connectPromise = promise;
+        this._targetAgent.attachToTarget(this.id());
+        return promise;
+    },
+
+    /**
+     * @override
+     * @return {!Promise}
+     */
+    disconnect: function()
+    {
+        var agent = this._targetAgent;
+        var detachFn = agent.detachFromTarget.bind(agent, this.id());
+        if (this._connectPromise)
+            return this._connectPromise.then(detachFn);
+        if (this._target)
+            detachFn();
+        return Promise.resolve();
+    },
+
+    /**
+     * @return {?WebInspector.Target}
+     */
+    target: function()
+    {
+        return this._target;
+    },
+
+    _attached: function(target) {
+        target[WebInspector.TargetConnectionManager.Connection.symbol] = this;
+        this._connectPromise && this._connectPromise[WebInspector.PendingConnection._resolveSymbol](target);
+    },
+
+    _detached: function()
+    {
+        this._target = null;
+    },
+};
+
+WebInspector.PendingConnection._LastAnonymousTargetId = 0;
+WebInspector.PendingConnection._resolveSymbol = Symbol("resolve");