55 lines
1.6 KiB
JavaScript
55 lines
1.6 KiB
JavaScript
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/**
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* Create a queue to run tasks sequentially
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* @returns {Object} - the queue
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* @returns {function} enqueue - Function to add a task to the queue
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* @returns {function} lock - Function to lock the queue
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* @returns {function} wait - Function to wait for the queue to be empty
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*/
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export default function createTaskQueue () {
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const queue = {
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queue: Promise.resolve(),
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/**
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* Enqueue a task to be run sequentially
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* @param {function} fn - The task function to be enqueued
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* @returns {Promise} - A promise that resolves with the result of the task function
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*/
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enqueue (fn) {
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return new Promise((resolve, reject) => {
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queue.queue = queue.queue.then(async () => {
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try {
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resolve(await fn())
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} catch (e) {
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reject(e)
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}
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})
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})
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},
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/**
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* Lock the queue so that it can't move forward until unlocked
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* @param {boolean} [wait=true] - Whether to wait for the lock to be acquired
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* @returns {Promise<function>} - A promise that resolves with the unlock function
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*/
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async lock (wait = true) {
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let unlock
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const lock = new Promise((resolve) => { unlock = resolve })
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const locking = new Promise((resolve) => {
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queue.queue = queue.queue.then(() => {
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resolve()
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return lock
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})
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})
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if (wait) await locking
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return unlock
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},
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/**
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* Wait for the queue to be empty
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* @returns {Promise} - A promise that resolves when the queue is empty
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*/
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async wait () {
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return queue.queue
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}
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}
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return queue
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}
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