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73 lines
2.5 KiB
73 lines
2.5 KiB
/**
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* Responsible for sequentially executing actions on the database
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*/
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const async = require('async')
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class Executor {
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constructor () {
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this.buffer = []
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this.ready = false
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// This queue will execute all commands, one-by-one in order
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this.queue = async.queue(function (task, cb) {
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const newArguments = []
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// task.arguments is an array-like object on which adding a new field doesn't work, so we transform it into a real array
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for (let i = 0; i < task.arguments.length; i += 1) { newArguments.push(task.arguments[i]) }
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const lastArg = task.arguments[task.arguments.length - 1]
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// Always tell the queue task is complete. Execute callback if any was given.
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if (typeof lastArg === 'function') {
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// Callback was supplied
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newArguments[newArguments.length - 1] = function () {
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if (typeof setImmediate === 'function') {
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setImmediate(cb)
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} else {
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process.nextTick(cb)
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}
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lastArg.apply(null, arguments)
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}
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} else if (!lastArg && task.arguments.length !== 0) {
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// false/undefined/null supplied as callback
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newArguments[newArguments.length - 1] = function () { cb() }
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} else {
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// Nothing supplied as callback
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newArguments.push(function () { cb() })
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}
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task.fn.apply(task.this, newArguments)
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}, 1)
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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 {Object} task
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* task.this - Object to use as this
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* task.fn - Function to execute
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* task.arguments - Array of arguments, IMPORTANT: only the last argument may be a function (the callback)
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* and the last argument cannot be false/undefined/null
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* @param {Boolean} forceQueuing Optional (defaults to false) force executor to queue task even if it is not ready
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*/
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push (task, forceQueuing) {
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if (this.ready || forceQueuing) {
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this.queue.push(task)
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} else {
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this.buffer.push(task)
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}
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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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let i
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this.ready = true
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for (i = 0; i < this.buffer.length; i += 1) { this.queue.push(this.buffer[i]) }
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this.buffer = []
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}
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}
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// Interface
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module.exports = Executor
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