MessagePort API:add a close event

source

@@ -102361,6 +102361,12 @@ new PaymentRequest(…); // Allowed to use
    <li><p>Set <var>document</var>'s <i data-x="concept-document-salvageable">salvageable</i> state
    to false.</p></li>
 
+   <li><p>Let <var>ports </var>be the list of <code>MessagePort</code>s whose <span>relevant global
+    object</span>'s <span data-x="concept-document-window">associated
+    <code>Document</code></span> is <var>document</var>.</p></li>
+
+   <li><p>For each <var>port</var> in <var>ports</var>, <span>disentangle</span> <var>port</var>.</p></li>
+
    <li><p>Run any <span>unloading document cleanup steps</span> for <var>document</var> that
    are defined by this specification and <span>other applicable specifications</span>.</p></li>
 
@@ -114575,6 +114581,7 @@ interface <dfn interface>MessagePort</dfn> : <span>EventTarget</span> {
   // event handlers
   attribute <span>EventHandler</span> <span data-x="handler-MessagePort-onmessage">onmessage</span>;
   attribute <span>EventHandler</span> <span data-x="handler-MessagePort-onmessageerror">onmessageerror</span>;
+  attribute <span>EventHandler</span> <span data-x="handler-MessagePort-onclose">onclose</span>;
 };
 
 dictionary <dfn dictionary>StructuredSerializeOptions</dfn> {
@@ -114669,6 +114676,25 @@ dictionary <dfn dictionary>StructuredSerializeOptions</dfn> {
    </li>
   </ol>
 
+  <p>The <dfn>disentangle</dfn> steps, given a <code>MessagePort</code> <var>initiatorPort</var> which initiates disentangling,
+    are as follows:</p>
+   <ol>
+     <li><p>Let <var>otherPort</var> be the <code>MessagePort</code> which <var>initiatorPort</var> was entangled with.</p></li>
+     <li><p>Assert: <var>otherPort</var> exists.</p></li>
+     <li><p>Disentangle <var>initiatorPort</var> and <var>otherPort</var>, so that they are no longer entangled or associated with each other.</p></li>
+     <li><p><span data-x="concept-event-dispatch">Dispatch</span> close event at <var>otherPort</var>.</p></li>
+     <div class="note">
+       <p>The close event <!--non-normative-->must be fired even if the port is not explicitly closed. The cases where this event is dispatched are:</p>
+       <ul>
+        <li><code data-x="dom-MessagePort-close">close()</code> method was called.</li>
+        <li>Document was <span data-x="destroy a document">destroyed.</span></li>
+        <li>Port was garbage collected.</li>
+       </ul>
+       <p>We only dispatch the event on <var>otherPort</var> because <var>initiatorPort</var> explicitly triggered the close, its document no longer exists, or
+         it was already garbage collected, as described above.</p>
+     </div>
+   </ol>
+
   <hr>
 
   <p id="transferMessagePort"><code>MessagePort</code> objects are <span>transferable
@@ -114829,7 +114855,7 @@ dictionary <dfn dictionary>StructuredSerializeOptions</dfn> {
   <ol>
    <li><p>Set <span>this</span>'s <span>[[Detached]]</span> internal slot value to true.</p></li>
 
-   <li><p>If <span>this</span> is entangled, disentangle it.</p></li>
+   <li><p>If <span>this</span> is entangled, <span>disentangle</span> it.</p></li>
   </ol>
 
   <hr>
@@ -114845,6 +114871,7 @@ dictionary <dfn dictionary>StructuredSerializeOptions</dfn> {
    <tbody>
     <tr><td><dfn attribute for="MessagePort"><code data-x="handler-MessagePort-onmessage">onmessage</code></dfn> <td> <code data-x="event-message">message</code>
     <tr><td><dfn attribute for="MessagePort"><code data-x="handler-MessagePort-onmessageerror">onmessageerror</code></dfn> <td> <code data-x="event-messageerror">messageerror</code>
+    <tr><td><dfn attribute for="MessagePort"><code data-x="handler-MessagePort-onclose">onclose</code></dfn> <td> <code data-x="event-close">close</code>
   </table>
 
   <p>The first time a <code>MessagePort</code> object's <code
@@ -114855,19 +114882,6 @@ dictionary <dfn dictionary>StructuredSerializeOptions</dfn> {
   </div>
 
 
-  <h4>Broadcasting to many ports</h4>
-
-  <!-- NON-NORMATIVE SECTION -->
-
-  <p>Broadcasting to many ports is in principle relatively simple: keep an array of
-  <code>MessagePort</code> objects to send messages to, and iterate through the array to send a
-  message. However, this has one rather unfortunate effect: it prevents the ports from being garbage
-  collected, even if the other side has gone away. To avoid this problem, implement a simple
-  protocol whereby the other side acknowledges it still exists. If it doesn't do so after a certain
-  amount of time, assume it's gone, close the <code>MessagePort</code> object, and let it be garbage
-  collected.</p>
-
-
   <h4 id="ports-and-garbage-collection">Ports and garbage collection</h4>
 
   <div w-nodev>