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Aborting fetch #523

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merged 6 commits into from Sep 20, 2017
Merged

Aborting fetch #523

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349e066
Abortable fetch
jakearchibald Aug 30, 2017
a993825
Adding note back
jakearchibald Sep 5, 2017
e8f7129
Replacing termination reason with aborted flag
jakearchibald Sep 5, 2017
a66142f
Be specific about which steps to abort
jakearchibald Sep 5, 2017
185a0c9
Allow the trailer promise to reject if the fetch is terminated in ano…
jakearchibald Sep 7, 2017
8e1d2d5
Nits
jakearchibald Sep 14, 2017
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183 changes: 122 additions & 61 deletions fetch.bs
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Expand Up @@ -1220,8 +1220,11 @@ or "<code>worker</code>".
property is true, then <a>queue a fetch task</a> on <var>request</var> to
<a>process request end-of-body</a> for <var>request</var> and abort these in-parallel steps.

<li><p>Otherwise, <a lt=terminated for=fetch>terminate</a> the ongoing fetch with reason
<i>fatal</i>.
<li><p>Otherwise, if <var>read</var> is rejected with an
"<code><a exception>AbortError</a></code>" {{DOMException}},
<a lt=terminated for=fetch>terminate</a> the ongoing fetch with the aborted flag set.

<li><p>Otherwise, <a lt=terminated for=fetch>terminate</a> the ongoing fetch.
</ol>

<li><p>If the ongoing fetch is <a for=fetch>terminated</a>, then abort these in-parallel steps.
Expand All @@ -1245,8 +1248,11 @@ evolves over time. That is, not all its fields are available straight away.
Unless stated otherwise, it is "<code>default</code>".

<p>A <a for=/>response</a> can have an associated
<dfn export for=response id=concept-response-termination-reason>termination reason</dfn>
which is <i>end-user abort</i>, <i>fatal</i>, or <i>timeout</i>.
<dfn export for=response id=concept-response-aborted>aborted flag</dfn>
which is initially unset.

<p class="note">This is set for <a>network errors</a> that should appear as "aborted" to developers.
This should be limited to requests that are intentionally aborted by the developer or end-user.

<p>A <a for=/>response</a> has an associated
<dfn export for=response id=concept-response-url>url</dfn>. It is a pointer to the
Expand Down Expand Up @@ -1317,6 +1323,10 @@ navigate algorithm. It ensures `<code>Location</code>` has

<hr>

<p>A <a for=/>response</a> whose
<a for=response>type</a> is "<code>error</code>" and <a for=response>aborted flag</a> is set is
known as a <dfn export id=concept-aborted-network-error>aborted network error</dfn>.
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an*


<p>A <a for=/>response</a> whose
<a for=response>type</a> is "<code>error</code>" is known as a
<dfn export id=concept-network-error>network error</dfn>.
Expand Down Expand Up @@ -1479,7 +1489,7 @@ for each associated <a for="fetch group">fetch record</a> whose
<a>keepalive flag</a> is unset,
<a lt=terminated for=fetch>terminate</a> the
<a for="fetch group">fetch record</a>'s
<a for="fetch record">fetch</a> with reason <i>fatal</i>.
<a for="fetch record">fetch</a>.


<h3 id=connections>Connections</h3>
Expand Down Expand Up @@ -1803,6 +1813,9 @@ from a {{ReadableStream}} object with <var>reader</var>, run these steps:
{{ReadableStream}} object <var>stream</var> with <var>reason</var>, return the result of calling
<a abstract-op>ReadableStreamCancel</a>(<var>stream</var>, <var>reason</var>).

<p class="note no-backref">Because the reader grants exclusive access, the actual mechanism of how
to read cannot be observed. Implementations could use more direct mechanism if convenient.
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It seems the reference to a reader no longer makes sense given the change you made above.


<p>To <dfn export for=ReadableStream id=concept-tee-readablestream>tee</dfn> a {{ReadableStream}}
object <var>stream</var>, run these steps:

Expand Down Expand Up @@ -2299,9 +2312,8 @@ pertain to them. Also, considering "<code>image</code>" was not compatible with

<p>To perform a <dfn export id=concept-fetch>fetch</dfn> using <var>request</var>, run
the steps below. An ongoing <a for=/>fetch</a> can be
<dfn export for=fetch id=concept-fetch-terminate>terminated</dfn> with reason
<var>reason</var>, which must be <i>end-user abort</i>, <i>fatal</i>,
<i>timeout</i>, or <i>garbage collection</i>.
<dfn export for=fetch id=concept-fetch-terminate>terminated</dfn> with flag <var>aborted</var>,
which is unset unless otherwise specified.

<p>The user agent may be asked to
<dfn export for=fetch id=concept-fetch-suspend>suspend</dfn> the ongoing fetch.
Expand Down Expand Up @@ -2442,9 +2454,16 @@ the request.
</ol>
</ol>

<li><p>If the ongoing fetch is <a for=fetch>terminated</a>, then let <var>reason</var> be the
provided termination reason, and return a <a>network error</a> with
<a for=response>termination reason</a> set to <var>reason</var>.
<li>
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a>.
</ol>

<li><p>Return the result of performing a <a for=main>main fetch</a>
using <var>request</var>.
Expand Down Expand Up @@ -2544,9 +2563,16 @@ with a <i>CORS flag</i> and <i>recursive flag</i>, run these steps:
<!-- Per Mike West HSTS happens "probably after" Referrer -->
</ol>

<li><p>If the ongoing fetch is <a for=fetch>terminated</a>, then let <var>reason</var> be the
provided termination reason, and return a <a>network error</a> with
<a for=response>termination reason</a> set to <var>reason</var>.
<li>
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a>.
</ol>

<li><p>If <var>request</var>'s <a>synchronous flag</a> is unset and
<i>recursive flag</i> is unset, run the remaining steps
Expand Down Expand Up @@ -2736,13 +2762,11 @@ with a <i>CORS flag</i> and <i>recursive flag</i>, run these steps:
<li><p><a lt=wait for=body>Wait</a> for <var>response</var>'s
<a for=response>body</a>.

<li><p>If <var>response</var> does not have a
<a for=response>termination reason</a> and
<var>response</var> does not
<li><p>If <var>response</var>'s <a for=response>body</a>'s <a for=body>stream</a> has not
<a for=ReadableStream>errored</a>, and <var>response</var> does not
<a href=https://w3c.github.io/webappsec-subresource-integrity/#does-response-match-metadatalist>match</a>
<var>request</var>'s <a for=request>integrity metadata</a>,
set <var>response</var> and <var>internalResponse</var> to a
<a>network error</a>.
<var>request</var>'s <a for=request>integrity metadata</a>, set <var>response</var> and
<var>internalResponse</var> to a <a>network error</a>.
[[!SRI]]
</ol>

Expand Down Expand Up @@ -2873,10 +2897,11 @@ steps:
<li><p>Return <var>response</var>.
</ol>

<li><p>Let <var>reason</var> be the provided <a for=fetch lt=terminated>termination</a> reason.
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a> with <a for=response>termination reason</a> set to
<var>reason</var>.
<li><p>Return a <a>network error</a>.
</ol>

<dt>"<code>data</code>"
Expand Down Expand Up @@ -3505,9 +3530,16 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
</ol>
</ol>

<li><p>If the ongoing fetch is <a for=fetch>terminated</a>, then let <var>reason</var> be the
provided termination reason, and return a <a>network error</a> with
<a for=response>termination reason</a> set to <var>reason</var>.
<li>
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a>.
</ol>

<li>
<!-- If response is still null, we require a forwarded request. -->
Expand Down Expand Up @@ -3592,9 +3624,16 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<i>authentication-fetch flag</i> is set, then run these subsubsteps:

<ol>
<li><p>If the ongoing fetch is <a for=fetch>terminated</a>, then let <var>reason</var> be the
provided termination reason, and return a <a>network error</a> with
<a for=response>termination reason</a> set to <var>reason</var>.
<li>
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a>.
</ol>

<li><p>Let <var>username</var> and <var>password</var> be the result of prompting the end user
for a username and password, respectively, in <var>request</var>'s
Expand Down Expand Up @@ -3623,9 +3662,16 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<li class=XXX><p>Needs testing: multiple `<code>Proxy-Authenticate</code>` headers, missing,
parsing issues.

<li><p>If the ongoing fetch is <a for=fetch>terminated</a>, then let <var>reason</var> be the
provided termination reason, and return a <a>network error</a> with
<a for=response>termination reason</a> set to <var>reason</var>.
<li>
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a>.
</ol>

<li>
<p>Prompt the end user as appropriate in <var>request</var>'s
Expand Down Expand Up @@ -3656,6 +3702,8 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<ol>
<li><p>Let <var>credentials</var> be true if <i>credentials flag</i> is set, and false otherwise.

<li><p>Let <var>response</var> be null.

<li>
<p>Switch on <var>request</var>'s <a for=request>mode</a>:

Expand Down Expand Up @@ -3687,7 +3735,7 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<a for=request>header list</a>.

<li>
<p>Let <var>response</var> be the result of making an HTTP request over <var>connection</var>
<p>Set <var>response</var> to the result of making an HTTP request over <var>connection</var>
using <var>request</var> with the following caveats:

<ul>
Expand Down Expand Up @@ -3742,15 +3790,14 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>reason</var> be the provided termination reason.
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>If <var>connection</var> is an HTTP/2 connection, then transmit an
"<code>RST_STREAM</code>" to cancel the underlying stream.

<li><p>Otherwise, close <var>connection</var>.
<li><p>If <var>aborted</var> is set, then return an <a>aborted network error</a>.

<li><p>Return a <a>network error</a> with <a for=response>termination reason</a> set to
<var>reason</var>.
<li><p>Return a <a>network error</a>.
</ol>

<li>
Expand All @@ -3763,7 +3810,7 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
if it is <a lt=suspend for=fetch>suspended</a>.

<li><p>Let <var>cancel</var> be an action that <a lt=terminated for=fetch>terminates</a> the
ongoing fetch with reason <i>fatal</i>.
ongoing fetch with the aborted flag set.

<li>
<p>Let <var>stream</var> be the result of
Expand Down Expand Up @@ -3840,9 +3887,10 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<p>If the ongoing fetch is <a for=fetch>terminated</a>, then:

<ol>
<li><p>Let <var>reason</var> be the provided termination reason.
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>Set <var>response</var>'s <a for=response>termination reason</a> to <var>reason</var>.
<li><p>If <var>aborted</var> is set, then set <var>response</var>'s
<a for=response>aborted flag</a>.

<li><p>Return <var>response</var>.
</ol>
Expand Down Expand Up @@ -3874,11 +3922,10 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b
<p class="note no-backref">This makes the `<code>Content-Length</code>` <a for=/>header</a>
unreliable to the extent that it was reliable to begin with.

<li>
<p><a for=ReadableStream>Enqueue</a> a <code>Uint8Array</code> object wrapping an
<code>ArrayBuffer</code> containing <var>bytes</var> to <var>stream</var>. If that threw an
exception, <a lt=terminated for=fetch>terminate</a> the ongoing fetch with <i>fatal</i>, <a
abstract-op>error</a> <var>stream</var> with that exception.
<li><p><a for=ReadableStream>Enqueue</a> a <code>Uint8Array</code> object wrapping an
<code>ArrayBuffer</code> containing <var>bytes</var> to <var>stream</var>. If that threw an
exception, <a lt=terminated for=fetch>terminate</a> the ongoing fetch, and
<a abstract-op>error</a> <var>stream</var> with that exception.

<li><p>If <var>stream</var> doesn't <a lt="need more data" for=ReadableStream>need more
data</a> and <var>request</var>'s <a>synchronous flag</a> is unset, ask the user agent to <a
Expand All @@ -3887,18 +3934,25 @@ Range Requests</cite>. [[HTTP-RANGE]] However, this is not widely supported by b

<li><p>Otherwise, if the bytes transmission for <var>response</var>'s message body is done
normally and <var>stream</var> is <a for=ReadableStream>readable</a>, then
<a abstract-op>close</a> <var>stream</var> and abort these steps.
<a abstract-op>close</a> <var>stream</var> and abort these in-parallel steps.
</ol>

<p class=note>The following steps can only occur if the ongoing fetch terminates.

<li><p>Let <var>reason</var> be the provided termination reason.
<li><p>Let <var>aborted</var> be the termination's aborted flag.

<li><p>Set <var>response</var>'s <a lt="termination reason" for=response>termination reason</a>
to <var>reason</var>.
<li>
<p>If <var>aborted</var> is set, then:

<li><p>If <var>stream</var> is <a for=ReadableStream>readable</a>, <a abstract-op>error</a>
<var>stream</var> with a <code>TypeError</code>.
<ol>
<li><p>Set <var>response</var>'s <a for=response>aborted flag</a>.

<li><p>If <var>stream</var> is <a for=ReadableStream>readable</a>, <a abstract-op>error</a>
<var>stream</var> with an "<code><a exception>AbortError</a></code>" {{DOMException}}.
</ol>

<li><p>Otherwise, if <var>stream</var> is <a for=ReadableStream>readable</a>,
<a abstract-op>error</a> <var>stream</var> with a <code>TypeError</code>.

<li><p>If <var>connection</var> is an HTTP/2 connection, then transmit an
"<code>RST_STREAM</code>" to cancel the underlying stream.
Expand Down Expand Up @@ -5532,19 +5586,23 @@ method, must run these steps:
{{Headers}} object whose <a for=Headers>guard</a> is
"<code>immutable</code>".

<li><p>Let <var>aborted</var> be false.
<li>
<p>Let <var>locallyAborted</var> be false.

<p class=note>This lets us reject promises with predictable timing, when the request to abort
comes from the same thread as the call to fetch.

<li>
<p><a for=AbortSignal lt=add>Add the following abort steps</a> to <var>requestObject</var>'s
<a for=Request>signal</a>:

<ol>
<li><p>Set <var>aborted</var> to true.
<li><p>Set <var>locallyAborted</var> to true.

<li><p><a>Abort fetch</a> with <var>p</var>, <var>request</var>, and
<var>responseObject</var>.

<li><p><a lt=terminated for=fetch>Terminate</a> the ongoing fetch with reason <i>fatal</i>.
<li><p><a lt=terminated for=fetch>Terminate</a> the ongoing fetch with the aborted flag set.
</ol>

<li>
Expand All @@ -5555,11 +5613,14 @@ method, must run these steps:
<p>To <a>process response</a> for <var>response</var>, run these substeps:

<ol>
<li><p>If <var>aborted</var> is true, terminate these substeps.
<li><p>If <var>locallyAborted</var> is true, terminate these substeps.

<li><p>If <var>response</var>'s <a for=response>aborted flag</a> is set, then <a>abort fetch</a>
with <var>p</var>, <var>request</var>, and <var>responseObject</var>, and terminate these
substeps.

<li><p>If <var>response</var>'s <a for=response>type</a> is
"<code>error</code>", reject <var>p</var> with a <code>TypeError</code> and terminate
these substeps.
<li><p>If <var>response</var> is a <a>network error</a>, then reject <var>p</var> with a
<code>TypeError</code> and terminate these substeps.

<li><p>Associate <var>responseObject</var> with <var>response</var>.

Expand All @@ -5569,7 +5630,7 @@ method, must run these steps:
<p>To <a>process response done</a> for <var>response</var>, run these substeps:

<ol>
<li><p>If <var>aborted</var> is true, terminate these substeps.
<li><p>If <var>locallyAborted</var> is true, terminate these substeps.

<li><p>Let <var>trailerObject</var> be a new {{Headers}} object whose
<a for=Headers>guard</a> is "<code>immutable</code>".
Expand Down Expand Up @@ -5618,8 +5679,8 @@ method, must run these steps:

<h3 id=garbage-collection>Garbage collection</h3>

<p>The user agent may <a lt=terminated for=fetch>terminate</a> an ongoing fetch with
reason <i>garbage collection</i> if that termination is not observable through script.
<p>The user agent may <a lt=terminated for=fetch>terminate</a> an ongoing fetch with if that
termination is not observable through script.

<p class="note no-backref">"Observable through script" means observable through
<a><code>fetch()</code></a>'s arguments and return value. Other ways, such as
Expand Down