[giow] (1) Make seeking async since some implementations can't tell i…

…f something is seekable synchronously. Also, make it not throw ever, and make it sanely re-entrant. git-svn-id: http://svn.whatwg.org/webapps@4868 340c8d12-0b0e-0410-8428-c7bf67bfef74
whatwg · Mar 25, 2010 · 5e4248e · 5e4248e
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diff --git a/complete.html b/complete.html
@@ -24435,12 +24435,35 @@ <h5 id=seeking><span class=secno>4.8.9.9 </span>Seeking</h5>
 
   <p>When the user agent is required to <dfn id=dom-media-seek title=dom-media-seek>seek</dfn> to a particular <var title="">new
   playback position</var> in the <a href=#media-resource>media resource</a>, it means
-  that the user agent must run the following steps:</p>
+  that the user agent must run the following steps. This algorithm
+  interacts closely with the <a href=#event-loop>event loop</a> mechanism; in
+  particular, it has a <a href=#synchronous-section>synchronous
+  section</a> (which is triggered as part of the <a href=#event-loop>event
+  loop</a> algorithm). Steps in that section are marked with
+  &#8987;.</p>
+
+  <ol><li><p>If the <a href=#media-element>media element</a>'s <code title=dom-media-readyState><a href=#dom-media-readystate>readyState</a></code> is <code title=dom-media-HAVE_NOTHING><a href=#dom-media-have_nothing>HAVE_NOTHING</a></code>, then raise an
+   <code><a href=#invalid_state_err>INVALID_STATE_ERR</a></code> exception (if the seek was in
+   response to a DOM method call or setting of an IDL attribute), and
+   abort these steps.</li>
+
+   <li><p>If the element's <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL attribute is true,
+   then another instance of this algorithm is already running. Abort
+   that other instance of the algorithm without waiting for the step
+   that it is running to complete.</li>
+
+   <li><p>Set the <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL
+   attribute to true.</li>
+
+   <li id=seekUpdate><p><a href=#queue-a-task>Queue a task</a> to <a href=#fire-a-simple-event>fire a
+   simple event</a> named <code title=event-media-timeupdate><a href=#event-media-timeupdate>timeupdate</a></code> at the
+   element.</li>
 
-  <ol><li><p>If the <a href=#media-element>media element</a>'s <code title=dom-media-readyState><a href=#dom-media-readystate>readyState</a></code> is <code title=dom-media-HAVE_NOTHING><a href=#dom-media-have_nothing>HAVE_NOTHING</a></code>, then the user
-   agent must raise an <code><a href=#invalid_state_err>INVALID_STATE_ERR</a></code> exception (if
-   the seek was in response to a DOM method call or setting of an IDL
-   attribute), and abort these steps.</li>
+   <li><p>If the seek was in response to a DOM method call or setting
+   of an IDL attribute, then continue the script. The remainder of
+   these steps must be run asynchronously. With the exception of the
+   steps marked with &#8987;, they could be aborted at any time by
+   another instance of this algorithm being invoked.</li>
 
    <li><p>If the <var title="">new playback position</var> is later
    than the end of the <a href=#media-resource>media resource</a>, then let it be the
@@ -24451,49 +24474,49 @@ <h5 id=seeking><span class=secno>4.8.9.9 </span>Seeking</h5>
    position instead.</li>
 
    <li><p>If the (possibly now changed) <var title="">new playback
-   position</var> is not in one of the ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute, then the user
-   agent must raise an <code><a href=#index_size_err>INDEX_SIZE_ERR</a></code> exception (if the
-   seek was in response to a DOM method call or setting of an IDL
-   attribute), and abort these steps.</li>
-
-   <li><p>The <a href=#current-playback-position>current playback position</a> must be set to
-   the given <var title="">new playback position</var>.</li>
-
-   <li><p>The <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL
-   attribute must be set to true.</li>
-
-   <li id=seekUpdate><p>The user agent must <a href=#queue-a-task>queue a
-   task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-timeupdate><a href=#event-media-timeupdate>timeupdate</a></code> at the element.</li>
+   position</var> is not in one of the ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute, then let it
+   be the position in one of the ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute that is the
+   nearest to the <var title="">new playback position</var>. If two
+   positions both satisfy that constraint (i.e. the <var title="">new
+   playback position</var> is exactly in the middle of a range in the
+   <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute) then
+   use the position that is closest to the <a href=#current-playback-position>current playback
+   position</a>. If there are no ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute then set the
+   <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL attribute to
+   false and abort these steps.</li>
+
+   <li><p>Set the <a href=#current-playback-position>current playback position</a> to the given
+   <var title="">new playback position</var>.</li>
 
    <li><p>If the <a href=#media-element>media element</a> was <a href=#potentially-playing>potentially
    playing</a> immediately before it started seeking, but seeking
    caused its <code title=dom-media-readyState><a href=#dom-media-readystate>readyState</a></code>
-   attribute to change to a value lower than <code title=dom-media-HAVE_FUTURE_DATA><a href=#dom-media-have_future_data>HAVE_FUTURE_DATA</a></code>, the
-   user agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple
-   event</a> named <code title=event-media-waiting><a href=#event-media-waiting>waiting</a></code> at
-   the element.</li>
+   attribute to change to a value lower than <code title=dom-media-HAVE_FUTURE_DATA><a href=#dom-media-have_future_data>HAVE_FUTURE_DATA</a></code>, then
+   <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named
+   <code title=event-media-waiting><a href=#event-media-waiting>waiting</a></code> at the
+   element.</li>
 
    <li><p>If, when it reaches this step, the user agent has still not
    established whether or not the <a href=#media-data>media data</a> for the <var title="">new playback position</var> is available, and, if it is,
-   decoded enough data to play back that position, the user agent must
-   <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a>
-   named <code title=event-media-seeking><a href=#event-media-seeking>seeking</a></code> at the
-   element.</li>
+   decoded enough data to play back that position, then <a href=#queue-a-task>queue a
+   task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-seeking><a href=#event-media-seeking>seeking</a></code> at the element.</li>
 
-   <li><p>If the seek was in response to a DOM method call or setting
-   of an IDL attribute, then continue the script. The remainder of
-   these steps must be run asynchronously.</li>
+   <li><p>Wait until it has established whether or not the <a href=#media-data>media
+   data</a> for the <var title="">new playback position</var> is
+   available, and, if it is, until it has decoded enough data to play
+   back that position.</li>
 
-   <li><p>The user agent must wait until it has established whether or
-   not the <a href=#media-data>media data</a> for the <var title="">new playback
-   position</var> is available, and, if it is, until it has decoded
-   enough data to play back that position.</li>
+   <li><p><a href=#await-a-stable-state>Await a stable state</a>. The <a href=#synchronous-section>synchronous
+   section</a> consists of all the remaining steps of this
+   algorithm. (Steps in the <a href=#synchronous-section>synchronous section</a> are
+   marked with &#8987;.)</li>
 
-   <li><p>The <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL
-   attribute must be set to false.</li>
+   <li><p>&#8987; Set the <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL attribute to
+   false.</li>
 
-   <li><p>The user agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire
-   a simple event</a> named <code title=event-media-seeked><a href=#event-media-seeked>seeked</a></code> at the element.</li>
+   <li><p>&#8987; <a href=#queue-a-task>Queue a task</a> to <a href=#fire-a-simple-event>fire a simple
+   event</a> named <code title=event-media-seeked><a href=#event-media-seeked>seeked</a></code>
+   at the element.</li>
 
   </ol><p>The <dfn id=dom-media-seekable title=dom-media-seekable><code>seekable</code></dfn>
   attribute must return a new static <a href=#normalized-timeranges-object>normalized

diff --git a/index b/index
@@ -173,7 +173,7 @@
 
   <header class=head id=head><p><a class=logo href=http://www.whatwg.org/ rel=home><img alt=WHATWG src=/images/logo></a></p>
    <hgroup><h1>HTML5 (including next generation additions still in development)</h1>
-    <h2 class="no-num no-toc">Draft Standard &mdash; 24 March 2010</h2>
+    <h2 class="no-num no-toc">Draft Standard &mdash; 25 March 2010</h2>
    </hgroup><p>You can take part in this work. <a href=http://www.whatwg.org/mailing-list>Join the working group's discussion list.</a></p>
    <p><strong>Web designers!</strong> We have a <a href=http://blog.whatwg.org/faq/>FAQ</a>, a <a href=http://forums.whatwg.org/>forum</a>, and a <a href=http://www.whatwg.org/mailing-list#help>help mailing list</a> for you!</p>
    <!--<p class="impl"><strong>Implementors!</strong> We have a <a href="http://www.whatwg.org/mailing-list#implementors">mailing list</a> for you too!</p>-->
@@ -24336,12 +24336,35 @@ interface <dfn>CueRangeCallback</dfn> {
 
   <p>When the user agent is required to <dfn id=dom-media-seek title=dom-media-seek>seek</dfn> to a particular <var title="">new
   playback position</var> in the <a href=#media-resource>media resource</a>, it means
-  that the user agent must run the following steps:</p>
+  that the user agent must run the following steps. This algorithm
+  interacts closely with the <a href=#event-loop>event loop</a> mechanism; in
+  particular, it has a <a href=#synchronous-section>synchronous
+  section</a> (which is triggered as part of the <a href=#event-loop>event
+  loop</a> algorithm). Steps in that section are marked with
+  &#8987;.</p>
+
+  <ol><li><p>If the <a href=#media-element>media element</a>'s <code title=dom-media-readyState><a href=#dom-media-readystate>readyState</a></code> is <code title=dom-media-HAVE_NOTHING><a href=#dom-media-have_nothing>HAVE_NOTHING</a></code>, then raise an
+   <code><a href=#invalid_state_err>INVALID_STATE_ERR</a></code> exception (if the seek was in
+   response to a DOM method call or setting of an IDL attribute), and
+   abort these steps.</li>
+
+   <li><p>If the element's <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL attribute is true,
+   then another instance of this algorithm is already running. Abort
+   that other instance of the algorithm without waiting for the step
+   that it is running to complete.</li>
+
+   <li><p>Set the <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL
+   attribute to true.</li>
+
+   <li id=seekUpdate><p><a href=#queue-a-task>Queue a task</a> to <a href=#fire-a-simple-event>fire a
+   simple event</a> named <code title=event-media-timeupdate><a href=#event-media-timeupdate>timeupdate</a></code> at the
+   element.</li>
 
-  <ol><li><p>If the <a href=#media-element>media element</a>'s <code title=dom-media-readyState><a href=#dom-media-readystate>readyState</a></code> is <code title=dom-media-HAVE_NOTHING><a href=#dom-media-have_nothing>HAVE_NOTHING</a></code>, then the user
-   agent must raise an <code><a href=#invalid_state_err>INVALID_STATE_ERR</a></code> exception (if
-   the seek was in response to a DOM method call or setting of an IDL
-   attribute), and abort these steps.</li>
+   <li><p>If the seek was in response to a DOM method call or setting
+   of an IDL attribute, then continue the script. The remainder of
+   these steps must be run asynchronously. With the exception of the
+   steps marked with &#8987;, they could be aborted at any time by
+   another instance of this algorithm being invoked.</li>
 
    <li><p>If the <var title="">new playback position</var> is later
    than the end of the <a href=#media-resource>media resource</a>, then let it be the
@@ -24352,49 +24375,49 @@ interface <dfn>CueRangeCallback</dfn> {
    position instead.</li>
 
    <li><p>If the (possibly now changed) <var title="">new playback
-   position</var> is not in one of the ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute, then the user
-   agent must raise an <code><a href=#index_size_err>INDEX_SIZE_ERR</a></code> exception (if the
-   seek was in response to a DOM method call or setting of an IDL
-   attribute), and abort these steps.</li>
-
-   <li><p>The <a href=#current-playback-position>current playback position</a> must be set to
-   the given <var title="">new playback position</var>.</li>
-
-   <li><p>The <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL
-   attribute must be set to true.</li>
-
-   <li id=seekUpdate><p>The user agent must <a href=#queue-a-task>queue a
-   task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-timeupdate><a href=#event-media-timeupdate>timeupdate</a></code> at the element.</li>
+   position</var> is not in one of the ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute, then let it
+   be the position in one of the ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute that is the
+   nearest to the <var title="">new playback position</var>. If two
+   positions both satisfy that constraint (i.e. the <var title="">new
+   playback position</var> is exactly in the middle of a range in the
+   <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute) then
+   use the position that is closest to the <a href=#current-playback-position>current playback
+   position</a>. If there are no ranges given in the <code title=dom-media-seekable><a href=#dom-media-seekable>seekable</a></code> attribute then set the
+   <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL attribute to
+   false and abort these steps.</li>
+
+   <li><p>Set the <a href=#current-playback-position>current playback position</a> to the given
+   <var title="">new playback position</var>.</li>
 
    <li><p>If the <a href=#media-element>media element</a> was <a href=#potentially-playing>potentially
    playing</a> immediately before it started seeking, but seeking
    caused its <code title=dom-media-readyState><a href=#dom-media-readystate>readyState</a></code>
-   attribute to change to a value lower than <code title=dom-media-HAVE_FUTURE_DATA><a href=#dom-media-have_future_data>HAVE_FUTURE_DATA</a></code>, the
-   user agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple
-   event</a> named <code title=event-media-waiting><a href=#event-media-waiting>waiting</a></code> at
-   the element.</li>
+   attribute to change to a value lower than <code title=dom-media-HAVE_FUTURE_DATA><a href=#dom-media-have_future_data>HAVE_FUTURE_DATA</a></code>, then
+   <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named
+   <code title=event-media-waiting><a href=#event-media-waiting>waiting</a></code> at the
+   element.</li>
 
    <li><p>If, when it reaches this step, the user agent has still not
    established whether or not the <a href=#media-data>media data</a> for the <var title="">new playback position</var> is available, and, if it is,
-   decoded enough data to play back that position, the user agent must
-   <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire a simple event</a>
-   named <code title=event-media-seeking><a href=#event-media-seeking>seeking</a></code> at the
-   element.</li>
+   decoded enough data to play back that position, then <a href=#queue-a-task>queue a
+   task</a> to <a href=#fire-a-simple-event>fire a simple event</a> named <code title=event-media-seeking><a href=#event-media-seeking>seeking</a></code> at the element.</li>
 
-   <li><p>If the seek was in response to a DOM method call or setting
-   of an IDL attribute, then continue the script. The remainder of
-   these steps must be run asynchronously.</li>
+   <li><p>Wait until it has established whether or not the <a href=#media-data>media
+   data</a> for the <var title="">new playback position</var> is
+   available, and, if it is, until it has decoded enough data to play
+   back that position.</li>
 
-   <li><p>The user agent must wait until it has established whether or
-   not the <a href=#media-data>media data</a> for the <var title="">new playback
-   position</var> is available, and, if it is, until it has decoded
-   enough data to play back that position.</li>
+   <li><p><a href=#await-a-stable-state>Await a stable state</a>. The <a href=#synchronous-section>synchronous
+   section</a> consists of all the remaining steps of this
+   algorithm. (Steps in the <a href=#synchronous-section>synchronous section</a> are
+   marked with &#8987;.)</li>
 
-   <li><p>The <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL
-   attribute must be set to false.</li>
+   <li><p>&#8987; Set the <code title=dom-media-seeking><a href=#dom-media-seeking>seeking</a></code> IDL attribute to
+   false.</li>
 
-   <li><p>The user agent must <a href=#queue-a-task>queue a task</a> to <a href=#fire-a-simple-event>fire
-   a simple event</a> named <code title=event-media-seeked><a href=#event-media-seeked>seeked</a></code> at the element.</li>
+   <li><p>&#8987; <a href=#queue-a-task>Queue a task</a> to <a href=#fire-a-simple-event>fire a simple
+   event</a> named <code title=event-media-seeked><a href=#event-media-seeked>seeked</a></code>
+   at the element.</li>
 
   </ol><p>The <dfn id=dom-media-seekable title=dom-media-seekable><code>seekable</code></dfn>
   attribute must return a new static <a href=#normalized-timeranges-object>normalized