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Clean up yield inheritance #115

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64 changes: 54 additions & 10 deletions spec/patches.md
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Original file line number Diff line number Diff line change
Expand Up @@ -32,8 +32,30 @@ determine task execution order across [=scheduler task queues=] of the same {{Ta
all {{Scheduler}}s associated with the same [=event loop=]. A timestamp would also suffice as long
as it is guaranteed to be strictly increasing and unique.

Add: An [=event loop=] has a <dfn for="event loop">current scheduling state</dfn> (a [=scheduling
state=] or null), which is initialized to null.
Add: An [=event loop=] has a <dfn for="event loop">current continuation state</dfn> (a
[=continuation state=] or null), which is initially null.

Add the following algorithms:

<div algorithm>
To <dfn>set the continuation state value</dfn> for |key| to |value| given an |eventLoop| (an
[=event loop=]):

1. If |eventLoop|'s [=event loop/current continuation state=] is null, then set |eventLoop|'s
[=event loop/current continuation state=] to a new [=continuation state=].
1. Let |continuationState| be |eventLoop|'s [=event loop/current continuation state=].
1. Assert: |continuationState|'s [=continuation state/state map=][|key|] does not [=map/exist=].
1. Set |continuationState|'s [=continuation state/state map=][|key|] to |value|.
</div>

<div algorithm>
To <dfn>get the continuation state value</dfn> for |key| given an |eventLoop| (an [=event loop=]):

1. Let |continuationState| be |eventLoop|'s [=event loop/current continuation state=].
1. If |continuationState| is not null and |continuationState|'s
[=continuation state/state map=][|key|] [=map/exists=], then return |continuationState|'s
[=continuation state/state map=][|key|], otherwise return null.
</div>

### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#event-loop-processing-model">Event loop: processing model</a> ### {#sec-patches-html-event-loop-processing}

Expand Down Expand Up @@ -80,33 +102,55 @@ Issue: The |taskQueue| in this step will either be a [=set=] of [=tasks=] or a [
*roughly* compatible. Ideally, there would be a common task queue interface that supports a `pop()`
method that would return a plain [=task=], but that would involve a fair amount of refactoring.

### <a href="https://html.spec.whatwg.org/#queuing-tasks">Event Loop: Queuing Tasks</a> ### {#sec-patches-html-queuing-tasks}

Change the <a href="">To queue a microtask</a> algorithm to accept an optional boolean
|ignoreContinuationState| (default false).

Change Step 5 to the following:

1. Let |continuationState| be |eventLoop|'s [=event loop/current continuation state=] if
|ignoreContinuationState| is false, otherwise null.
1. Set <var ignore=''>microtask</var>'s <a attribute for="task">steps</a> to the following:
1. If |ignoreContinuationState| is false, then set |eventLoop|'s
[=event loop/current continuation state=] to |continuationState|.
1. Run <var ignore=''>steps</var>.
1. If |ignoreContinuationState| is false, then set |eventLoop|'s
[=event loop/current continuation state=] to null.

### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#hostmakejobcallback">HostMakeJobCallback(callable)</a> ### {#sec-patches-html-hostmakejobcallback}

Add the following before step 5:

1. Let |event loop| be <var ignore=''>incumbent settings<var>'s
[=environment settings object/realm=]'s [=realm/agent=]'s [=agent/event loop=].
1. Let |state| be |event loop|'s [=event loop/current scheduling state=].
1. Let |state| be |event loop|'s [=event loop/current continuation state=].

Modify step 5 to read:

1. Return the <span>JobCallback Record</span> { \[[Callback]]: <var ignore=''>callable</var>,
\[[HostDefined]]: { \[[IncumbentSettings]]: <var ignore=''>incumbent settings</var>,
\[[ActiveScriptContext]]: <var ignore=''>script execution context</var>,
\[[SchedulingState]]: |state| } }.
\[[ContinuationState]]: |state| } }.

### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#hostcalljobcallback">HostCallJobCallback(callback, V, argumentsList)</a> ### {#sec-patches-html-hostcalljobcallback}

Add the following steps before step 5:

1. Let |event loop| be <var ignore=''>incumbent settings<var>'s
[=environment settings object/realm=]'s [=realm/agent=]'s [=agent/event loop=].
1. Set |event loop|'s [=event loop/current scheduling state=] to
<var ignore=''>callback</var>.\[[HostDefined]].\[[SchedulingState]].
1. Set |event loop|'s [=event loop/current continuation state=] to
<var ignore=''>callback</var>.\[[HostDefined]].\[[ContinuationState]].

Add the following after step 7:

1. Set |event loop|'s [=event loop/current scheduling state=] to null.
1. Set |event loop|'s [=event loop/current continuation state=] to null.

### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#hostenqueuepromisejob">HostEnqueuePromiseJob(job, realm)</a> ### {#sec-patches-html-hostenqueuepromisejob}

Change step 2 to:

1. Queue a microtask to perform the following steps with |ignoreContinuationState| set to true:

## <a href="https://w3c.github.io/requestidlecallback/">`requestIdleCallback()`</a> ## {#sec-patches-requestidlecallback}

Expand All @@ -118,9 +162,9 @@ Add the following step before step 3.3:
1. Let |state| be a new [=scheduling state=].
1. Set |state|'s [=scheduling state/priority source=] to the result of [=creating a fixed priority
unabortable task signal=] given "{{TaskPriority/background}}" and |realm|.
1. Let |event loop| be |realm|'s [=realm/agent=]'s [=agent/event loop=].
1. Set |event loop|'s [=event loop/current scheduling state=] to |state|.
1. Let |scheduler| be the {{Scheduler}} whose [=relevant realm=] is |realm|.
1. [=Set the current scheduling state=] for |scheduler| to |state|.

Add the following after step 3.3:

1. Set |event loop|'s [=event loop/current scheduling state=] to null.
1. Set |event loop|'s [=event loop/current continuation state=] to null.
40 changes: 34 additions & 6 deletions spec/scheduling-tasks.md
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Original file line number Diff line number Diff line change
Expand Up @@ -175,12 +175,22 @@ A <dfn>scheduler task queue</dfn> is a [=struct=] with the following [=struct/it
A <dfn>scheduling state</dfn> is a [=struct=] with the following [=struct/items=]:

: <dfn for="scheduling state">abort source</dfn>
:: An {{AbortSignal}} object or, initially null.
:: An {{AbortSignal}} object or null, initially null.
: <dfn for="scheduling state">priority source</dfn>
:: A {{TaskSignal}} object or null, initially null.

<br/>

A <dfn>continuation state</dfn> is a [=struct=] with the following [=struct/items=]:

: <dfn for="continuation state">state map</dfn>
:: An initially empty [=map=].

Note: The [=continuation state/state map=] can be implemented as weak map if its keys are
implemented as garbage collected objects.

<br/>

A <dfn>task handle</dfn> is a [=struct=] with the following [=struct/items=]:

: <dfn for="task handle">task</dfn>
Expand Down Expand Up @@ -289,6 +299,25 @@ A <dfn>task handle</dfn> is a [=struct=] with the following [=struct/items=]:

### Scheduling Tasks and Continuations ### {#sec-scheduler-alg-scheduling-tasks-and-continuations}

<div algorithm>
To <dfn>set the current scheduling state</dfn> for |scheduler| (a {{Scheduler}}) to |state| (a
[=scheduling state=]):

1. Let |eventLoop| be |scheduler|'s [=relevant agent=]'s [=agent/event loop=].
1. [=Set the continuation state value=] for |scheduler| to |state| given |eventLoop|.

Note: Any key can be used for the [=continuation state/state map=] as long as it is unique to the
{{Scheduler}}.
</div>

<div algorithm>
To <dfn>get the current scheduling state</dfn> for |scheduler| (a {{Scheduler}}):

1. Let |eventLoop| be |scheduler|'s [=relevant agent=]'s [=agent/event loop=].
1. Return the result of [=getting the continuation state value=] for |scheduler| given
|eventLoop|.
</div>

<div algorithm>
To <dfn>schedule a postTask task</dfn> for {{Scheduler}} |scheduler| given a
{{SchedulerPostTaskCallback}} |callback| and {{SchedulerPostTaskOptions}} |options|:
Expand Down Expand Up @@ -316,12 +345,12 @@ A <dfn>task handle</dfn> is a [=struct=] with the following [=struct/items=]:
for |scheduler| given |state|'s [=scheduling state/priority source=] and false.
1. [=Schedule a task to invoke an algorithm=] for |scheduler| given |handle| and the following
steps:
1. Let |event loop| be the |scheduler|'s [=relevant agent=]'s [=agent/event loop=].
1. Set |event loop|'s [=event loop/current scheduling state=] to |state|.
1. Let |eventLoop| be the |scheduler|'s [=relevant agent=]'s [=agent/event loop=].
1. [=Set the current scheduling state=] for |scheduler| to |state|.
1. Let |callbackResult| be the result of [=invoking=] |callback| with « » and "`rethrow`".
If that threw an exception, then [=reject=] |result| with that. Otherwise, [=resolve=]
|result| with |callbackResult|.
1. Set |event loop|'s [=event loop/current scheduling state=] to null.
1. Set |eventLoop|'s [=event loop/current continuation state=] to null.
1. Let |delay| be |options|["{{SchedulerPostTaskOptions/delay}}"].
1. If |delay| is greater than 0, then [=run steps after a timeout=] given |scheduler|'s [=relevant
global object=], "`scheduler-postTask`", |delay|, and the following steps:
Expand All @@ -340,8 +369,7 @@ Issue: [=Run steps after a timeout=] doesn't necessarily account for suspension;
To <dfn>schedule a yield continuation</dfn> for {{Scheduler}} |scheduler|:

1. Let |result| be [=a new promise=].
1. Let |inheritedState| be the |scheduler|'s [=relevant agent=]'s [=agent/event loop=]'s
[=event loop/current scheduling state=].
1. Let |inheritedState| be the result of [=getting the current scheduling state=] for |scheduler|.
1. Let |abortSource| be |inheritedState|'s [=scheduling state/abort source=] if |inheritedState|
is not null, or otherwise null.
1. If |abortSource| is not null and |abortSource| is [=AbortSignal/aborted=], then [=reject=]
Expand Down