semaphore/routes/_utils/scheduleIdleTask.js

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// Wrapper to call requestIdleCallback() to schedule low-priority work.
// See https://developer.mozilla.org/en-US/docs/Web/API/Background_Tasks_API
// for a good breakdown of the concepts behind this.
import Queue from 'tiny-queue'
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import { mark, stop } from './marks'
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const taskQueue = new Queue()
let runningRequestIdleCallback = false
const liteRIC = cb => setTimeout(() => cb({timeRemaining: () => Infinity})) // eslint-disable-line
function getRIC () {
// we load polyfills asynchronously, so there's a tiny chance this is not defined
return typeof requestIdleCallback !== 'undefined' ? requestIdleCallback : liteRIC
}
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function runTasks (deadline) {
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mark('scheduleIdleTask:runTasks()')
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while (taskQueue.length && deadline.timeRemaining() > 0) {
let task = taskQueue.shift()
try {
task()
} catch (e) {
console.error(e)
}
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}
if (taskQueue.length) {
let rIC = getRIC()
rIC(runTasks)
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} else {
runningRequestIdleCallback = false
}
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stop('scheduleIdleTask:runTasks()')
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}
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export function scheduleIdleTask (task) {
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taskQueue.push(task)
if (!runningRequestIdleCallback) {
runningRequestIdleCallback = true
let rIC = getRIC()
rIC(runTasks)
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}
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}