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Add "geolocation task queue" (#87)
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@marcoscaceres
marcoscaceres authored Jul 8, 2021
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Expand Up @@ -118,6 +118,9 @@ <h2>
has received the following changes:
</p>
<ul>
<li>Added the [=geolocation task source=], which handles dispatching
position updates and errors.
</li>
<li>[=Request position=] only proceeds when a document is visible, or
the document becomes visible.
</li>
Expand Down Expand Up @@ -585,173 +588,180 @@ <h2>
|successCallback:PositionCallback|, a {{PositionErrorCallback}}`?`
|errorCallback:PositionErrorCallback|, {{PositionOptions}}
|options:PositionOptions|, a {{boolean}} |repeats:boolean|, and
optionally (and only if |repeats| is true) a |previous id:long|.
optionally (and only if |repeats| is true) a |previousId:long|.
</p>
<ol class="algorithm">
<li>Let |watchTasks:Set| be [=this=]'s
{{Geolocation/[[watchTasks]]}}.
</li>
<li>Acquire a watch id.
<ol>
<li>If |previous id| was provided, let |watchId:long| be
|previous id|; Otherwise, let |watchId:long| be an
[=implementation-defined=] {{long}} that is greater than or equal
to zero.
</li>
<li>[=Set/Append=] |watchId| to |watchTasks|.
</li>
<li>Return |watchId| and continue [=in parallel=].
</li>
</ol>
<li>If |previousId| was provided, let |watchId:long| be |previousId|;
Otherwise, let |watchId:long| be an [=implementation-defined=]
{{long}} that is greater than or equal to zero.
</li>
<li>Do security check.
<ol>
<li>If the <a>environment settings object</a> is a
<a data-cite="secure-contexts">non-secure context</a>, then:
<ol>
<li>[=Call back with error=] |errorCallback| and
{{GeolocationPositionError/PERMISSION_DENIED}}.
</li>
<li>[=List/Remove=] |watchId| from |watchTasks|.
</li>
<li>Terminate this algorithm.
</li>
</ol>
</li>
</ol>
<li>[=Set/Append=] |watchId| to |watchTasks|.
</li>
<li data-cite="page-visibility-2">Wait for document to become
visible.
<ol>
<li>Let |document:Document| be the [=current settings object=]'s
[=associated Document=].
</li>
<li>If |document:Document| is [=Document/hidden=], wait for the
|document| to become [=Document/visible=].
</li>
</ol>
<li>Let |global| be [=this=]'s [=relevant global object=].
</li>
<li data-tests=
"getCurrentPosition_permission_allow.https.html, getCurrentPosition_permission_deny.https.html">
[=Check permission=] passing |errorCallback|. If the check return
failure:
<li>[=Queue a global task=] using the [=geolocation task source=]
with |global| to run the following steps [=in parallel=]:
<ol>
<li>[=List/Remove=] |watchId| from |watchTasks|.
</li>
<li>Terminate this algorithm.
</li>
</ol>
</li>
<li>
<dfn data-local-lt=
"acquiring a position|acquire a position">Acquire position</dfn>.
<ol>
<li>Let |acquisitionTime:DOMTimeStamp| be a new {{DOMTimeStamp}}
that represents now in milliseconds, using 01 January, 1970 UTC
as the epoch.
</li>
<li>If |options|.{{PositionOptions/maximumAge}} is greater than
0, and |cachedPosition| is not null:
<li>Do security check.
<ol>
<li>Let |cachedPosition:GeolocationPosition| be [=this=]'s
{{Geolocation/[[cachedPosition]]}}.
</li>
<li>Let |cacheTime:long| be |acquisitionTime| minus the value
of |options|.{{PositionOptions/maximumAge}} member.
</li>
<li>If |cachedPosition|'s {{GeolocationPosition/timestamp}}'s
value is greater than |cacheTime|, and
|cachedPosition|.{{GeolocationPosition/[[isHighAccuracy]]}}
equals |options|.{{PositionOptions/enableHighAccuracy}}:
<li>If the <a>environment settings object</a> is a
<a data-cite="secure-contexts">non-secure context</a>, then:
<ol>
<li>[=Queue a microtask=] to invoke |successCallback|
with |cachedPosition|.
<li>[=Call back with error=] |errorCallback| and
{{GeolocationPositionError/PERMISSION_DENIED}}.
</li>
<li>Go to <a href="#check-repeats">determine
repetition</a> steps below.
<li>[=List/Remove=] |watchId| from |watchTasks|.
</li>
<li>Terminate this algorithm.
</li>
</ol>
</li>
</ol>
</li>
<li>Let |timeout:Task| be a new timed [=task=] that runs in
|options|.{{PositionOptions/timeout}} milliseconds after
|acquisitionTime|, which performs the following sub-steps:
<aside class="note" title="Immediate cancellation">
<p>
An |options|.{{PositionOptions/timeout}} value 0
effectively runs the |timeout| task immediately.
</p>
</aside>
<li data-cite="page-visibility-2">Wait for document to become
visible.
<ol>
<li>If the entry for |timerId| in the [=list of active
timers=] has been cleared, then abort these steps.
<li>Let |document:Document| be the [=current settings
object=]'s [=associated Document=].
</li>
<li>[=Call back with error=] with |errorCallback| and
{{GeolocationPositionError/TIMEOUT}}.
<li>If |document:Document| is [=Document/hidden=], wait for
the |document| to become [=Document/visible=].
</li>
</ol>
</li>
<li>Let |timerId:long| be an [=implementation-defined=]
identifier that represents |timeout|.
</li>
<li>Add |timerId| to the [=list of active timers=].
<li data-tests=
"getCurrentPosition_permission_allow.https.html, getCurrentPosition_permission_deny.https.html">
[=Check permission=] passing |errorCallback|. If the check
returns failure:
<ol>
<li>[=List/Remove=] |watchId| from |watchTasks|.
</li>
<li>Terminate this algorithm.
</li>
</ol>
</li>
<li>Try to acquire the device's position, optionally taking into
consideration the value of
|options|.{{PositionOptions/enableHighAccuracy}}:
<li>
<dfn data-local-lt=
"acquiring a position|acquire a position">Acquire
position</dfn>.
<ol>
<li>If acquiring a position succeeds:
<li>Let |acquisitionTime:DOMTimeStamp| be a new
{{DOMTimeStamp}} that represents now in milliseconds, using
01 January, 1970 UTC as the epoch.
</li>
<li>If |options|.{{PositionOptions/maximumAge}} is greater
than 0, and |cachedPosition| is not null:
<ol>
<li>Let |position:GeolocationPosition| be [=a new
`GeolocationPosition`=] passing |acquisitionTime| and
|options|.{{PositionOptions/enableHighAccuracy}}.
<li>Let |cachedPosition:GeolocationPosition| be
[=this=]'s {{Geolocation/[[cachedPosition]]}}.
</li>
<li>Set [=this=]'s {{Geolocation/[[cachedPosition]]}} to
|position|.
<li>Let |cacheTime:long| be |acquisitionTime| minus the
value of |options|.{{PositionOptions/maximumAge}} member.
</li>
<li>[=Queue a microtask=] to [=invoke=] |successCallback|
with |position|.
<li>If |cachedPosition|'s
{{GeolocationPosition/timestamp}}'s value is greater than
|cacheTime|, and
|cachedPosition|.{{GeolocationPosition/[[isHighAccuracy]]}}
equals |options|.{{PositionOptions/enableHighAccuracy}}:
<ol>
<li>[=Queue a task=] on the [=geolocation task
source=] with a step that [=invokes=]
|successCallback| with |cachedPosition|.
</li>
<li>Go to <a href="#check-repeats">determine
repetition</a> steps below.
</li>
</ol>
</li>
</ol>
</li>
<li>If acquiring a position fails:
<li>Let |timeout:Task| be a new timed [=task=] that runs in
|options|.{{PositionOptions/timeout}} milliseconds after
|acquisitionTime|, which performs the following sub-steps:
<aside class="note" title="Immediate cancellation">
<p>
An |options|.{{PositionOptions/timeout}} value 0
effectively runs the |timeout| task immediately.
</p>
</aside>
<ol>
<li>[=Call back with error=] passing |errorCallback| and
{{GeolocationPositionError/POSITION_UNAVAILABLE}}.
<li>If the entry for |timerId| in the [=list of active
timers=] has been cleared, then abort these steps.
</li>
<li>[=Call back with error=] with |errorCallback| and
{{GeolocationPositionError/TIMEOUT}}.
</li>
</ol>
</li>
<li>Let |timerId:long| be an [=implementation-defined=]
identifier that represents |timeout|.
</li>
<li>Add |timerId| to the [=list of active timers=].
</li>
<li>Try to acquire the device's position, optionally taking
into consideration the value of
|options|.{{PositionOptions/enableHighAccuracy}}:
<ol>
<li>If acquiring a position succeeds:
<ol>
<li>Let |position:GeolocationPosition| be [=a new
`GeolocationPosition`=] passing |acquisitionTime| and
|options|.{{PositionOptions/enableHighAccuracy}}.
</li>
<li>Set [=this=]'s {{Geolocation/[[cachedPosition]]}}
to |position|.
</li>
<li>[=Queue a task=] on the [=geolocation task
source=] with a step that [=invokes=]
|successCallback| with |position|.
</li>
</ol>
</li>
<li>If acquiring a position fails:
<ol>
<li>[=Call back with error=] passing |errorCallback|
and
{{GeolocationPositionError/POSITION_UNAVAILABLE}}.
</li>
</ol>
</li>
</ol>
</li>
<li>Clear |timerId| from the [=list of active timers=].
</li>
</ol>
</li>
<li>Clear |timerId| from the [=list of active timers=].
</li>
</ol>
</li>
<li>
<span id="check-repeats">Determine repetition</span>.
<ol>
<li>If |repeats| is false:
<li>
<span id="check-repeats">Determine repetition</span>.
<ol>
<li>[=List/Remove=] |watchId| from |watchTasks|.
<li>If |repeats| is false:
<ol>
<li>[=List/Remove=] |watchId| from |watchTasks|.
</li>
<li>Terminate this algorithm.
</li>
</ol>
</li>
<li>Terminate this algorithm.
</ol>
</li>
<li>Wait for a significant change of geographic position. What
constitutes a significant change of geographic position is left
to the implementation. User agents MAY impose a rate limit on
the frequency position changes.
</li>
<li>If |watchTasks| [=list/contain|contains=] |watchId|, then:
<ol>
<li>[=Request position=] passing |successCallback|,
|errorCallback|, |options|, |repeats|, and |watchId|.
</li>
</ol>
</li>
</ol>
</li>
<li>Wait for a significant change of geographic position. What
constitutes a significant change of geographic position is
[=implementation-defined|left to the implementation=]. A user agent
MAY impose a rate limit on the frequency of position changes.
</li>
<li>If |watchTasks| [=list/contain|contains=] |watchId|, then:
<ol>
<li>[=Request position=] passing |successCallback|,
|errorCallback|, |options|, |repeats|, and |watchId|.
</li>
</ol>
<li>Return |watchId|.
</li>
</ol>
</section>
Expand Down Expand Up @@ -795,7 +805,8 @@ <h2>
{{GeolocationPositionError}} instance whose
{{GeolocationPositionError/code}} attribute is initialized to |code|.
</li>
<li>[=Invoke=] |callback| with |error|.
<li>[=Queue a task=] on the [=geolocation task source=] with a step
that [=invokes=] |callback| with |error|.
</li>
</ol>
</section>
Expand Down Expand Up @@ -917,6 +928,24 @@ <h2>
</tr>
</table>
</section>
<section>
<h2>
Task sources
</h2>
<p>
The following [=task source=] is defined by this specifications.
</p>
<dl>
<dt>
The <dfn>geolocation task source</dfn>
</dt>
<dd>
Used by this specification to queue up non-blocking
{{PositionCallback}} and {{PositionErrorCallback}} when performing
[=request position|position requests=].
</dd>
</dl>
</section>
</section>
<section id="coordinates_interface" data-dfn-for="GeolocationCoordinates">
<h2>
Expand Down

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