68 lines
2.1 KiB
ReStructuredText
68 lines
2.1 KiB
ReStructuredText
GeckoView Priority Hint API
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===========================
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Cathy Lu <calu@mozilla.com>, `Bug 1764998 <https://bugzilla.mozilla.org/show_bug.cgi?id=1764998>`_
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May 2nd, 2022
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Summary
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-------
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This document describes the API for setting a process to high priority by
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applying a high priority hint. Instead of deducing the priority based on the
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extension’s active priority, this will add an API to set it explicitly.
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Motivation
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----------
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This API will allow Glean metrics to be measured in order to compare
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performance and stability metrics for process prioritization on vs off.
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Previously, prioritization depended on whether or not a ``GeckoSession`` had a
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surface associated with it, which lowered the priority of background tabs and
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needed to be reloaded more often.
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Goals
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-----
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Apps can set ``priorityHint`` on a ``GeckoSession``.
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Existing Work
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-------------
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In `bug 1753700 <https://bugzilla.mozilla.org/show_bug.cgi?id=1753700>`_, we
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added an API in dom/ipc to allow ``GeckoViewWebExtension`` to set a specific
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``remoteTab``’s boolean ``priorityHint``. This allows tabs that do not have a
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surface but are active according to web extension to have high priority.
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Implementation
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--------------
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In ``GeckoSession``, add an API ``setPriorityHint`` that takes an integer as a
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parameter. The priority int can be ``PRIORITY_DEFAULT`` or ``PRIORITY_HIGH``.
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Specified and active tabs would be ``PRIORITY_HIGH``. The default would be
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``PRIORITY_DEFAULT``. The API will dispatch an event
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``GeckoView:SetPriorityHint``.
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.. code:: java
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public void setPriorityHint(final @Priority int priorityHint)
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Listeners in ``GeckoViewContent.sys.mjs`` will set
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``this.browser.frameLoader.remoteTab.priorityHint`` to the boolean passed in.
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.. code:: java
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case "GeckoView:setPriorityHint":
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if (this.browser.isRemoteBrowser) {
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let remoteTab = this.browser.frameLoader?.remoteTab;
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if (remoteTab) {
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remoteTab.renderLayers.priorityHint = val;
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}
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}
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break;
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Additional Complexities
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-----------------------
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Apps that use this API will need to manually use the API to set the
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priorityHint when the tab goes to foreground or background.
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