Skip to content

Commit 4991ab7

Browse files
noamrnoamr
committed
Deferred fetching
Add a JS-exposed function to request a deferred fetch. A deferred fetch would be invoked in one of two scenarios: - The document is destroyed (the fetch group is terminated) - The document is backgrounded (the fetch group is deactivated) and not restored after a certain time. A few constraints: - Deferred fetch body sizes are limited to 64KB per origin. Exceeding this would immediately reject with a QuotaExceeded. - Request body streams are not allowed. A request body, if exists, has to be a byte sequence. The JS function is called `requestDeferredFetch` but that's bikesheddable. See WICG/pending-beacon#70
1 parent 4502481 commit 4991ab7

File tree

1 file changed

+208
-7
lines changed

1 file changed

+208
-7
lines changed

‎fetch.bs

Lines changed: 208 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -2678,6 +2678,9 @@ functionality.
26782678
<p>A <a for=fetch>fetch group</a> holds an ordered list of
26792679
<dfn lt="fetch record" export for="fetch group" id=concept-fetch-record>fetch records</dfn>.
26802680

2681+
<p>A <a for=fetch>fetch group</a> holds an ordered list of
2682+
<dfn export for="fetch group" id=concept-defer=fetch-record>deferred fetch records</dfn>.
2683+
26812684
<p>A <a for="fetch group">fetch record</a> has an associated
26822685
<dfn export for="fetch record" id=concept-fetch-record-request>request</dfn> (a
26832686
<a for=/>request</a>).
@@ -2686,16 +2689,103 @@ functionality.
26862689
<dfn export for="fetch record" id=concept-fetch-record-fetch>controller</dfn> (a
26872690
<a for=/>fetch controller</a> or null).
26882691

2692+
<p>A <dfn export>deferred fetch record</dfn> is a <a for=/>struct</a> used to maintain state needed
2693+
to invoke a fetch at a later time, e.g. when a <code>Document</code> is unloaded or backgrounded. It
2694+
has the following <a for=struct>items</a>:
2695+
2696+
<dl>
2697+
<dt><dfn export for="deferred fetch record">request</dfn>
2698+
<dd>A <a for=/>request</a>
2699+
2700+
<dt><dfn export for="deferred fetch record">background timeout</dfn> (default null)
2701+
<dd>Null or a <a>duration</a>
2702+
2703+
<dt><dfn export for="deferred fetch record">pending steps</dfn> (default null)
2704+
<dt><dfn export for="deferred fetch record">invoked callback</dfn> (default null)
2705+
<dd>Null or an algortihm accepting nothing
2706+
2707+
<dt><dfn export for="deferred fetch record">invoked</dfn> (default false)
2708+
<dd>A boolean
2709+
</dl>
2710+
2711+
26892712
<hr>
26902713

2691-
<p>When a <a for=fetch>fetch group</a> is
2692-
<dfn export for="fetch group" id=concept-fetch-group-terminate>terminated</dfn>, for each associated
2693-
<a for="fetch group">fetch record</a> whose <a for="fetch group">fetch record</a>'s
2694-
<a for="fetch record">controller</a> is non-null, and whose <a for="fetch record">request</a>'s
2695-
<a>done flag</a> is unset or <a for=request>keepalive</a> is false,
2696-
<a for="fetch controller">terminate</a> the <a for="fetch group">fetch record</a>'s
2697-
<a for="fetch record">controller</a>.
2714+
<p>When a <a for=fetch>fetch group</a> <var>fetchGroup</var> is
2715+
<dfn export for="fetch group" id=concept-fetch-group-terminate>terminated</dfn>:
26982716

2717+
<ol>
2718+
<li>
2719+
<p><a for=list>For each</a> <a for="fetch group">deferred fetch record</a>
2720+
<var>deferredRecord</var> in <var>fetchGroup</var>'s
2721+
<a for="fetch group">deferred fetch records</a> whose <a for="deferred fetch record">invoked</a> is
2722+
false:
2723+
2724+
<ol>
2725+
<li><p>If <var>deferredRecord</var>'s <a for="deferred fetch record">pending steps</a> is not
2726+
null then <a>abort</a> <var>deferredRecord</var>'s
2727+
<a for="deferred fetch record">pending steps</a>.
2728+
2729+
<li><p><a for=/>fetch</a> <var>deferredRecord</var>'s <a for="deferred fetch record">request</a>.
2730+
</ol>
2731+
2732+
<li><p>For each associated <a for="fetch group">fetch record</a> <var>record</var>,
2733+
if <var>record</var>'s <a for="fetch record">controller</a> is non-null and
2734+
<var>record</var>'s <a for="fetch record">request</a>'s <a>done flag</a> is unset or
2735+
<a for=request>keepalive</a> is false, <a for="fetch controller">terminate</a> <var>record</var>'s
2736+
<a for="fetch record">controller</a>.
2737+
</ol>
2738+
2739+
<p>When a <a for=fetch>fetch group</a> <var>fetchGroup</var> is
2740+
<dfn export for="fetch group" id=concept-fetch-group-activate>activated</dfn>:
2741+
<a for=list>for each</a> <a for=/>deferred fetch record</a> <var>deferredRecord</var> in
2742+
<var>fetchGroup</var>'s <a for="fetch group">deferred fetch records</a>:
2743+
2744+
<ol>
2745+
<li>
2746+
<p>If <var>deferredRecord</var>'s <a for="deferred fetch record">invoked</a> is true then:
2747+
<ol>
2748+
<li><p>If <var>deferredRecord</var>'s <a for="deferred fetch record">invoked callback</a> is not
2749+
null then call <var>deferredRecord</var>'s <a for="deferred fetch record">invoked callback</a>.
2750+
2751+
<li><p><a for=list>Remove</a> <var>deferredRecord</var> from <var>fetchGroup</var>'s
2752+
<a for="fetch group">deferred fetch records</a>.
2753+
</ol>
2754+
2755+
<li><p>Otherwise, if <var>deferredRecord</var>'s
2756+
<a for="deferred fetch record">pending steps</a> is not null, then <a>abort</a>
2757+
<var>deferredRecord</var>'s <a for="deferred fetch record">pending steps</a> and set
2758+
<var>deferredRecord</var>'s <a for="deferred fetch record">pending steps</a> to null.
2759+
</ol>
2760+
2761+
<p>When a <a for=fetch>fetch group</a> <var>fetchGroup</var> is
2762+
<dfn export for="fetch group" id=concept-fetch-group-deactivate>deactivated</dfn>:
2763+
2764+
<ol>
2765+
<li>
2766+
<p><a for=list>For each</a> <a>deferred fetch record</a> <var>deferredRecord</var> in
2767+
<var>fetchGroup</var>'s <a for="fetch group">deferred fetch records</a> whose
2768+
<a for="deferred fetch record">background timeout</a> is not null: set <var>deferredRecord</var>'s
2769+
<a for="deferred fetch record">pending steps</a> to running the following steps <a>in parallel</a>:
2770+
2771+
<ol>
2772+
<li><p>Wait until <var>deferredRecord</var>'s
2773+
<a for="deferred fetch record">background timeout</a> have passed.
2774+
2775+
<li>
2776+
<p><a>Queue a fetch task</a> to run the following steps with
2777+
<a for="fetch record">request</a>'s <a for=request>client</a>'s
2778+
<a for="environment settings object">global object</a>:
2779+
2780+
<ol>
2781+
<li><p><a for=/>Fetch</a> <var>record</var>'s <a for="fetch record">request</a>.
2782+
2783+
<li><p>Set <var>deferredRecord</var> <a for="deferred fetch record">invoked</a> to true.
2784+
</ol>
2785+
</li>
2786+
</ol>
2787+
</li>
2788+
</ol>
26992789

27002790
<h3 id=resolving-domains>Resolving domains</h3>
27012791

@@ -8486,6 +8576,117 @@ fetch("https://www.example.com/")
84868576

84878577

84888578

8579+
<h2 id=deferred-fetching>Deferred fetching</h2>
8580+
8581+
<p>Deferred fetches allow callers to request that a fetch is invoked at the latest possible moment,
8582+
when a <a>fetch group</a> is <a for="fetch group">terminated</a>, or after a timeout after it is
8583+
<a for="fetch group">deactivated</a>.
8584+
8585+
<h3 id="requesting-a-deferred-fetch">Requesting a deferred fetch</h3>
8586+
8587+
<div algorithm="request-a-deferred-fetch">
8588+
<p>To <dfn>request a deferred fetch</dfn> given a
8589+
<a for=/>request</a> <var>request</var> and a null-or-{{DOMHighResTimeStamp}}
8590+
<var>backgroundTimeout</var> (default null):
8591+
8592+
<ol>
8593+
<li><p>Assert: <var>request</var>'s <a for=request>client</a> is an
8594+
<a>environment settings object</a>.
8595+
8596+
<li>Let <var>totalScheduledDeferredBytesForOrigin</var> be 0.
8597+
8598+
<li>
8599+
<p>If <var>request</var>'s <a for=request>body</a> is not null then:
8600+
8601+
<ol>
8602+
<li><p>If <var>request</var>'s
8603+
<a for=request>body</a>'s <a for=body>length</a> is null, then throw a {{TypeError}}.
8604+
8605+
<li><p>Set <var>totalScheduledDeferredBytesForOrigin</var> to <var>request</var>'s
8606+
<a for=request>body</a>'s <a for=body>length</a>.
8607+
</ol>
8608+
</li>
8609+
8610+
<li><p><a for=list>For each</a> <a>deferred fetch record</a> <var>deferredRecord</var> in
8611+
<var>request</var>'s <a for=request>client</a>'s <a for=fetch>fetch group</a>'s
8612+
<a for="fetch group">deferred fetch records</a>: if <var>deferredRecord</var>'s
8613+
<a for="deferred fetch record">request</a>'s <a for=request>body</a> is not null and
8614+
<var>deferredRecord</var>'s <a for="deferred fetch record">request</a>'s <a for=request>URL</a>'s
8615+
<a for=url>origin</a> is <a>same origin</a> with <var>request</var>'s <a for=request>URL</a>'s
8616+
<a for=url>origin</a>, then increment <var>totalScheduledDeferredBytesForOrigin</var> by
8617+
<var>deferredRecord</var>'s <a for="deferred fetch record">request</a>'s <a for=request>body</a>'s
8618+
<a for=body>length</a>.
8619+
8620+
<li><p>If <var>totalScheduledDeferredBytesForOrigin</var> is greater than 64 kilobytes, then
8621+
throw a {{QuotaExceededError}}.
8622+
8623+
<li><p>Let <var>deferredRecord</var> be a new <a>deferred fetch record</a> whose
8624+
<a for="deferred fetch record">request</a> is <var>request</var>.
8625+
8626+
<li><p>Set <var>deferredRecord</var>'s <a for="deferred fetch record">background timeout</a> to
8627+
<var>backgroundTimeout</var>.
8628+
8629+
<li><p><a for=list>Append</a> <var>deferredRecord</var> to <var>request</var>'s
8630+
<a for=request>client</a>'s <a for=fetch>fetch group</a>'s
8631+
<a for="fetch group">deferred fetch records</a>.
8632+
8633+
<li><p>Return <var>deferredRecord</var>.
8634+
</ol>
8635+
</div>
8636+
8637+
<h3 id=request-deferred-fetch-method>RequestDeferredFetch method</h3>
8638+
8639+
<pre class=idl>
8640+
8641+
dictionary DeferredRequestInit : RequestInit {
8642+
DOMHighResTimeStamp? backgroundTimeout;
8643+
};
8644+
8645+
partial interface mixin WindowOrWorkerGlobalScope {
8646+
[NewObject] Promise&lt;Response> requestDeferredFetch(RequestInfo input, optional DeferredRequestInit init = {});
8647+
};
8648+
</pre>
8649+
8650+
<div algorithm="dom-requestdeferredfetch">
8651+
<p>The
8652+
<dfn id=dom-global-requestdeferredfetch method for=WindowOrWorkerGlobalScope><code>requestDeferredFetch(<var>input</var>, <var>init</var>)</code></dfn>
8653+
method steps are:
8654+
8655+
<ol>
8656+
<li><p>Let <var>promise</var> be a new promise.
8657+
8658+
<li><p>Let <var>requestObject</var> be the result of invoking the initial value of {{Request}} as
8659+
constructor with <var>input</var> and <var>init</var> as arguments. If that threw an exception,
8660+
<a for=/>reject</a> <var>promise</var> with that exception and return <var>promise</var>.
8661+
8662+
<li><p>If <var>requestObject</var>'s <a for=Request>signal</a> is <a for=AbortSignal>aborted</a>,
8663+
then <a for=/>reject</a> <var>promise</var> with <var>requestObject</var>'s
8664+
<a for=Request>signal</a>'s <a for=AbortSignal>abort reason</a> and return <var>promise</var>.
8665+
8666+
<li><p>Let <var>request</var> be <var>requestObject</var>'s <a for=Request>request</a>.
8667+
8668+
<li><p>Let <var>backgroundTimeout</var> be null.
8669+
8670+
<li><p>If <var>init</var> is given and <var>init</var>["<code>backgroundTimeout</code>"]
8671+
<a for=map>exists</a> then set <var>backgroundTimeout</var> to
8672+
<var>init</var>["<code>backgroundTimeout</code>"].
8673+
8674+
<li><p>If <var>backgroundTimeout</var> is not a {{DOMHighResTimeStamp}} then throw a {{TypeError}}.
8675+
8676+
<li><p>Let <var>deferredRecord</var> be the result of calling
8677+
<a>request a deferred fetch</a> given <var>request</var> and <var>backgroundTimeout</var>. If that
8678+
threw an exception, <a for=/>reject</a> <var>promise</var> with that exception and return
8679+
<var>promise</var>.
8680+
8681+
<li><p>Set <var>deferredRecord</var>'s <a for="deferred fetch record">invoke callback</a> to
8682+
<a for=/>resolve</a> <var>promise</var>.
8683+
8684+
<li><p><a for=AbortSignal lt=add>Add the following abort steps</a> to <var>requestObject</var>'s
8685+
<a for=Request>signal</a>: <a for=list>remove</a> <var>deferredRecord</var> from
8686+
<var>request</var>'s <a for=request>client</a>'s <a for=fetch>fetch group</a>'s
8687+
<a for="fetch group">deferred fetch records</a>.
8688+
</ol>
8689+
84898690
<h2 id=data-urls><code>data:</code> URLs</h2>
84908691

84918692
<p>For an informative description of <code>data:</code> URLs, see RFC 2397. This section replaces

0 commit comments

Comments
 (0)