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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
/* global require, module */
const { logTest } = require("./utils/profiling");
const EAGERNESS_LEVELS = ["immediate", "eager", "moderate", "conservative"];
const SOURCES = ["document", "list"];
// Drive the click so each eagerness level gets a fair chance to fire and
// complete its prefetch before navigation. `dwellMs` is the settle/hold
// window, sized to clear the target page's server stall.
async function navigateWithPrefetch(commands, eagerness, selector, dwellMs) {
switch (eagerness) {
case "immediate":
// Prefetch starts at parse time; just let it finish, then click.
await commands.wait.byTime(dwellMs);
await commands.mouse.singleClick.bySelector(selector);
break;
case "eager":
case "moderate":
// Both fire on hover (eager sooner); sustain the hover, then click.
await commands.mouse.moveTo.bySelector(selector);
await commands.wait.byTime(dwellMs);
await commands.mouse.singleClick.bySelector(selector);
break;
case "conservative":
// Fires on pointerdown: press, hold so the prefetch can complete, then
// release on the link to navigate.
await commands.mouse.clickAndHold.bySelector(selector);
await commands.wait.byTime(dwellMs);
await commands.mouse.clickAndHold.releaseAtSelector(selector);
break;
default:
throw new Error(
`speculation-rules-prefetch: unknown eagerness "${eagerness}"`
);
}
}
module.exports = logTest(
"speculation rules prefetch",
async function (context, commands) {
const serverUrl = context.options.browsertime.server_url;
if (!serverUrl) {
throw new Error(
"speculation-rules-prefetch: missing --browsertime.server_url; " +
"is support_class=speculation_rules.py wired in?"
);
}
const buttonId = context.options.browsertime.button_id || "btn-a";
const eagerness = context.options.browsertime.eagerness || "moderate";
if (!EAGERNESS_LEVELS.includes(eagerness)) {
throw new Error(
`speculation-rules-prefetch: unsupported eagerness "${eagerness}"; ` +
`expected one of ${EAGERNESS_LEVELS.join(", ")}`
);
}
const source = context.options.browsertime.source || "document";
if (!SOURCES.includes(source)) {
throw new Error(
`speculation-rules-prefetch: unsupported source "${source}"; ` +
`expected one of ${SOURCES.join(", ")}`
);
}
// Covers each level's trigger latency plus the 500 ms backend stall.
const dwellMs = Number(context.options.browsertime.dwell_ms ?? 1000);
context.log.info(
`speculation-rules-prefetch: button=${buttonId}, source=${source}, ` +
`eagerness=${eagerness}, dwell_ms=${dwellMs}`
);
await commands.navigate(
`${serverUrl}/landing.html?eagerness=${eagerness}&source=${source}`
);
await commands.wait.byTime(250);
await commands.measure.start();
await navigateWithPrefetch(commands, eagerness, `#${buttonId}`, dwellMs);
await commands.wait.byTime(2500);
await commands.measure.stop();
const navInfo = await commands.js.run(`
const nav = performance.getEntriesByType('navigation')[0];
return nav ? {
deliveryType: nav.deliveryType || "",
type: nav.type,
duration: nav.duration,
responseStart: nav.responseStart,
domContentLoadedEventEnd: nav.domContentLoadedEventEnd,
loadEventEnd: nav.loadEventEnd,
href: location.href,
} : null;
`);
context.log.info(
`speculation-rules-prefetch: navigation entry = ${JSON.stringify(navInfo)}`
);
if (!navInfo) {
throw new Error(
"speculation-rules-prefetch: no navigation entry found on target page"
);
}
await commands.measure.addObject({
custom_data: {
delivery_type: navInfo.deliveryType,
navigation_duration: navInfo.duration,
response_start: navInfo.responseStart,
},
});
return true;
}
);