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79 lines
1.9 KiB
79 lines
1.9 KiB
const Waterfall = require('./waterfall')
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/**
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* Executes operations sequentially.
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* Has an option for a buffer that can be triggered afterwards.
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* @private
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*/
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class Executor {
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/**
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* Instantiates a new Executor.
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*/
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constructor () {
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/**
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* If this.ready is `false`, then every task pushed will be buffered until this.processBuffer is called.
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* @type {boolean}
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* @private
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*/
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this.ready = false
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/**
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* The main queue
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* @type {Waterfall}
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* @private
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*/
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this.queue = new Waterfall()
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/**
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* The buffer queue
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* @type {Waterfall}
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* @private
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*/
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this.buffer = null
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/**
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* Method to trigger the buffer processing.
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*
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* Do not be use directly, use `this.processBuffer` instead.
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* @function
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* @private
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*/
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this._triggerBuffer = null
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this.resetBuffer()
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}
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/**
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* If executor is ready, queue task (and process it immediately if executor was idle)
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* If not, buffer task for later processing
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* @param {AsyncFunction} task Function to execute
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* @param {boolean} [forceQueuing = false] Optional (defaults to false) force executor to queue task even if it is not ready
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* @return {Promise<*>}
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* @async
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* @see Executor#push
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*/
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pushAsync (task, forceQueuing = false) {
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if (this.ready || forceQueuing) return this.queue.waterfall(task)()
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else return this.buffer.waterfall(task)()
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}
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/**
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* Queue all tasks in buffer (in the same order they came in)
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* Automatically sets executor as ready
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*/
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processBuffer () {
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this.ready = true
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this._triggerBuffer()
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this.queue.waterfall(() => this.buffer.guardian)
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}
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/**
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* Removes all tasks queued up in the buffer
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*/
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resetBuffer () {
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this.buffer = new Waterfall()
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this.buffer.chain(new Promise(resolve => {
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this._triggerBuffer = resolve
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}))
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if (this.ready) this._triggerBuffer()
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}
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}
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// Interface
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module.exports = Executor
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