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Add code to allocate agent clusters.
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Store shared agent clusters in the browsing context group via a map of
scheme & registrable domain.

Hook the document initialization methods to obtain a similar-orgin
window agent.

Fixes whatwg#4361
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@dtapuska
dtapuska committed Jul 29, 2019
1 parent 2a397f6 commit 752de10
Showing 1 changed file with 111 additions and 72 deletions.
183 changes: 111 additions & 72 deletions source
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Original file line number Diff line number Diff line change
Expand Up @@ -2643,6 +2643,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
<li><dfn data-dfn-for="url" data-x="concept-url-origin" data-x-href="https://url.spec.whatwg.org/#concept-url-origin">Origin</dfn> of URLs</li>
<li><dfn data-x-href="https://url.spec.whatwg.org/#syntax-url-absolute">Absolute URL</dfn></li>
<li><dfn data-x-href="https://url.spec.whatwg.org/#syntax-url-relative">Relative URL</dfn></li>
<li><dfn data-x-href="https://url.spec.whatwg.org/#host-registrable-domain">registrable domain</dfn></li>
<li>
The <dfn data-x-href="https://url.spec.whatwg.org/#concept-url-parser">URL parser</dfn> and
<dfn data-x-href="https://url.spec.whatwg.org/#concept-basic-url-parser">basic URL
Expand Down Expand Up @@ -78029,7 +78030,11 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
</ol>

<p>To <dfn data-x="creating a new browsing context">create a new browsing context</dfn>, given
null or a <code>Document</code> object <var>creator</var>:</p>
null or a <code>Document</code> object <var>creator</var>, and <span>browsing context group</span>
<var>group</var>:</p>

<!-- Note: Do not append the new browsing context to group as we might be creating a nested browsing
context and not a top level browsing context -->

<ol>
<li><p>Let <var>browsingContext</var> be a new <span>browsing context</span>.</p></li>
Expand All @@ -78051,11 +78056,19 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
<li><p>Let <var>featurePolicy</var> be the result of <span>creating a feature policy</span>
given <var>browsingContext</var> and <var>origin</var>. <ref spec="FEATUREPOLICY"></p></li>

<li><p>Let <var>agent</var> be the result of <span
data-x="obtain-similar-origin-window-agent">obtaining a similar-origin window agent</span> given
<var>origin</var> and <var>group</var>.</p></li>

<li>
<p>Let <var>realm execution context</var> be the result of <span>creating a new JavaScript
realm</span> with the following customizations:</p>

<ul>
<li><p>For the agent, use <var>agent</var>. <span class="XXX">This pointer is not yet defined
in the JavaScript specification; see <a
href="https://github.com/tc39/ecma262/issues/1357">tc39/ecma262#1357</a>.</span></p></li>

<li><p>For the global object, create a new <code>Window</code> object.</p></li>

<li><p>For the global <b>this</b> binding, use <var>browsingContext</var>'s
Expand Down Expand Up @@ -78110,15 +78123,17 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
context</dfn>, given a <span>browsing context</span> <var>opener</var>:</p>

<ol>
<li><p>Let <var>browsingContext</var> be the result of <span>creating a new browsing
context</span> with <var>opener</var>'s <span>active document</span>.</p></li>
<li><p>Let <var>group</var> be <var>opener</var>'s <span>top-level browsing context</span>'s
<span data-x="tlbc group">group</span></p></li>

<li><p>Assert: <var>opener</var>'s <span>top-level browsing context</span>'s <span data-x="tlbc
group">group</span> is non-null, as <span data-x="navigate">navigating</span> invokes this
directly.</p></li>
<li><p>Assert: <var>group</var> is non-null, as <span data-x="navigate">navigating</span> invokes
this directly.</p></li>

<li><p><span data-x="bcg append">Append</span> <var>browsingContext</var> to <var>opener</var>'s
<span>top-level browsing context</span>'s <span data-x="tlbc group">group</span>.</p></li>
<li><p>Let <var>browsingContext</var> be the result of <span>creating a new browsing
context</span> with <var>opener</var>'s <span>active document</span> and <var>group</var>.</p></li>

<li><p><span data-x="bcg append">Append</span> <var>browsingContext</var> to
<var>group</var>.</p></li>

<li><p>Set <var>browsingContext</var>'s <span>opener browsing context</span> to
<var>opener</var>.</p></li>
Expand Down Expand Up @@ -78146,7 +78161,8 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {

<ol>
<li><p>Let <var>browsingContext</var> be the result of <span>creating a new browsing
context</span> with <var>element</var>'s <span>node document</span>.</p></li>
context</span> with <var>element</var>'s <span>node document</span>, and <var>element</var>'s
<span>top-level browsing context</span>'s <span data-x="tlbc group">group</span>.</p></li>

<li><p>Set <var>element</var>'s <span>nested browsing context</span> to
<var>browsingContext</var>.</p></li>
Expand Down Expand Up @@ -78623,8 +78639,11 @@ console.assert(iframeWindow.frameElement === null);
<li><p><span data-x="set append">Append</span> <var>group</var> to the user agent's
<span>browsing context group set</span>.</p></li>

<li><p><span data-x="bcg append">Append</span> the result of <span>creating a new browsing
context</span> with null to <var>group</var>.</p></li>
<li><p>Let <var>browsingContext</var> be the result of <span>creating a new browsing
context</span> with null and <var>group</var>.</p></li>

<li><p><span data-x="bcg append">Append</span> <var>browsingContext</var> to
<var>group</var>.</p></li>

<li><p>Return <var>group</var>.</p></li>
</ol>
Expand Down Expand Up @@ -83698,11 +83717,20 @@ interface <dfn>Location</dfn> { // but see also <a href="#the-location-interface
<p>Otherwise:</p>

<ol>
<li><p>Let <var>agent</var> be the result of <span
data-x="obtain-similar-origin-window-agent">obtaining a similar-origin window agent</span> given
<var>origin</var> and <var>browsingContext</var>'s <span data-x="tlbc
group">group</span>.</p></li>

<li>
<p>Let <var>realm execution context</var> be the result of <span>creating a new JavaScript
realm</span> with the following customizations:</p>

<ul>
<li><p>For the agent, use <var>agent</var>. <span class="XXX" data-x="">This pointer is not
yet defined in the JavaScript specification; see <a
href="https://github.com/tc39/ecma262/issues/1357">tc39/ecma262#1357</a>.</span></p></li>

<li><p>For the global object, create a new <code>Window</code> object.</p></li>

<li><p>For the global <b>this</b> binding, use <var>browsingContext</var>'s
Expand Down Expand Up @@ -90283,71 +90311,14 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
data-x="concept-global-object-realm">realms</span> that can synchronously access each other, and
thus needs to run in a single execution thread.</p>

<p>To determine whether a <code>Window</code> object <var>A</var> and a <code>Window</code> object
<var>B</var> are considered <dfn>same-agent <code>Window</code> objects</dfn>, run
these steps:</p>

<ol>
<li>
<p>If <var>A</var>'s <span>relevant settings object</span>'s <span>responsible browsing
context</span>'s <span>top-level browsing context</span>'s <span data-x="tlbc
group">group</span> is not <var>B</var>'s <span>relevant settings object</span>'s
<span>responsible browsing context</span>'s <span>top-level browsing context</span>'s <span
data-x="tlbc group">group</span>, then return false.</p>

<p class="XXX">Unfortunately this model falls apart the moment a <span>browsing context</span>
is <span data-x="a browsing context is discarded">discarded</span>. <a
href="https://github.com/whatwg/html/issues/4361">Issue #4361</a> sketches a setup that could
improve this situation.</p>
</li>

<li><p>Let <var>originA</var> be <var>A</var>'s <span>relevant settings object</span>'s <span
data-x="concept-settings-object-origin">origin</span> and <var>originB</var> be <var>B</var>'s
<span>relevant settings object</span>'s <span
data-x="concept-settings-object-origin">origin</span>.</p></li>
<p class="note">Two <code>Window</code> objects that have the same <span>agent</span> does not
indicate they can directly access all objects created in each others realms. Two windows might be
required to be in <span>same origin-domain</span>, see <span>IsPlatformObjectSameOrigin</span>.</p>

<li><p>If <var>originA</var> is <span>same origin</span> with <var>originB</var>, then return
true.</p></li>

<li><p>If <var>originA</var> or <var>originB</var> is not a <span
data-x="concept-origin-tuple">tuple origin</span>, then return false.</p></li>

<li><p>If <var>originA</var>'s <span data-x="concept-origin-scheme">scheme</span> is not
<var>originB</var>'s <span data-x="concept-origin-scheme">scheme</span>, then return
false.</p></li>

<li><p>If <var>originA</var>'s <span data-x="concept-origin-host">host</span> is <span>same
site</span> with <var>originB</var>'s <span data-x="concept-origin-host">host</span>, then return
true.</p></li>

<li><p>Return false.</p></li>
</ol>

<p class="note">All <span>same-agent <code>Window</code> objects</span> together represent a group
of <code>Window</code> objects that can synchronously access each other, though sometimes only
after setting the <code data-x="dom-document-domain">document.domain</code> attribute
(in)appropriately.</p>

<p>Until such a time that this standard has a better handle on lifetimes, it defines five types of
<p>Until such a time that this standard has a better handle on lifetimes, it defines four types of
<span data-x="agent">agents</span> that user agents must allocate at the appropriate time.</p>

<p class="note">In the future, this standard hopes to define exactly when <span
data-x="agent">agents</span> and <span data-x="agent cluster">agent clusters</span> are
created.</p>

<dl>
<dt><dfn data-export="">Similar-origin window agent</dfn></dt>
<dd>
<p>An <span>agent</span> whose [[CanBlock]] is false and whose set of <span
data-x="JavaScript realm">realms</span> consists of all <span
data-x="concept-global-object-realm">realms</span> of all <span>same-agent <code>Window</code>
objects</span>.</p>

<p class="note">Two <code>Window</code> objects that are <span>same origin</span> can be in
different <span data-x="similar-origin window agent">similar-origin window agents</span>, for
instance if they are each in their own <span>browsing context group</span>.</p>
</dd>

<dt><dfn data-export="">Dedicated worker agent</dfn></dt>
<dd><p>An <span>agent</span> whose [[CanBlock]] is true and whose set of <span data-x="JavaScript
realm">realms</span> consists of a single <code>DedicatedWorkerGlobalScope</code> object's <span
Expand Down Expand Up @@ -90396,6 +90367,74 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
in particular among which <span data-x="agent">agents</span> the backing data of
<code>SharedArrayBuffer</code> objects can be shared.</p>

<p>A <span>browsing context group</span> has associated <dfn>agent cluster map</dfn> (a weak <span
data-x="ordered map">map</span> of <span>agent cluster key</span> to <span>agent
cluster</span>). User agents are responsible for collecting them when it is deemed that nothing
can access them anymore.</p>

<p>A <dfn data-export="">scheme-and-site</dfn> is a tuple of a <span
data-x="concept-url-scheme">scheme</span> and a <span data-x="concept-domain">domain</span>.</p>

<p>An <dfn data-export="">agent cluster key</dfn> is an <span>origin</span> or a
<span>scheme-and-site</span>.</p>

<p>To <dfn data-x="obtain-agent-cluster-key">obtain an agent cluster key</dfn>, given an origin
<var>origin</var>, run these steps:</p>

<ol>
<li><p>If <var>origin</var> is an <span data-x="concept-origin-opaque">opaque origin</span>, then
return <var>origin</var>.</p></li>

<li><p>If <var>origin</var>'s host's <span>registrable domain</span> is null, then return
<var>origin</var>.</p></li>

<li><p>Return (<var>origin</var>'s <span data-x="concept-url-scheme">scheme</span>,
<var>origin</var>'s <span>registrable domain</span>).</p></li>
</ol>

<p>To <dfn data-x="obtain-similar-origin-window-agent">obtain a similar-origin window agent</dfn>,
given an <span>origin</span> <var>origin</var> and <span>browsing context group</span>
<var>group</var>, run these steps:</p>

<ol>
<li><p>Let <var>clusterKey</var> be the result of <span
data-x="obtain-agent-cluster-key">obtaining an agent cluster key</span> given
<var>origin</var>.</p></li>

<li><p>Let <var>agentCluster</var> be the result of <span
data-x="obtain-browsing-agent-cluster">obtaining a browsing context agent cluster</span> with
<var>group</var> and <var>clusterKey</var>.</p></li>

<li><p>Return <var>agentCluster</var>'s <span>similar-origin window agent</span>.</p></li>
</ol>

<p>A <dfn data-export="">similar-origin window agent</dfn> is an <span>agent</span> whose
[[CanBlock]] is false. </p>

<p class="note">All global objects that use this agent all have the a similar <span>origin</span>
and are allocated via the <span data-x="obtain-similar-origin-window-agent">obtain similar-origin
window agent</span> algorithm.</p>

<p>To <dfn data-x="obtain-browsing-agent-cluster">obtain a browsing context agent cluster</dfn>,
given a <span>browsing context group</span> <var>group</var> and <span>agent cluster key</span>
<var>key</var>, run these steps:</p>

<ol>
<li>
<p>If <var>group</var>'s <span>agent cluster map</span>[<var>key</var>] <span data-x="map
exists">does not exist:</span></p>
<ol>
<li><p>Let <var>agentCluster</var> be a new <span>agent cluster</span>.</p></li>
<li><p>Set <var>agentCluster</var>'s <span>similar-origin window agent</span> be a new
<span>similar-origin window agent</span>.</p></li>
<li><p>Set <var>group</var>'s <span>agent cluster map</span>[<var>key</var>] to
<var>agentCluster</var>.</p></li>
</ol>
</li>

<li><p>Return <var>group</var>'s <span>agent cluster map</span>[<var>key</var>].</p></li>
</ol>

<p class="note">Conceptually, the <span>agent cluster</span> concept is an
architecture-independent, idealized "process boundary" that groups together multiple "threads"
(<span data-x="agent">agents</span>). The <span data-x="agent cluster">agent clusters</span>
Expand Down

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