mirror of https://github.com/seald/nedb
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
105 lines
3.2 KiB
105 lines
3.2 KiB
const Waterfall = require('./waterfall')
|
|
|
|
/**
|
|
* Executes operations sequentially.
|
|
* Has an option for a buffer that can be triggered afterwards.
|
|
*/
|
|
class Executor {
|
|
/**
|
|
* Instantiates a new Executor.
|
|
*/
|
|
constructor () {
|
|
/**
|
|
* If this.ready is `false`, then every task pushed will be buffered until this.processBuffer is called.
|
|
* @type {boolean}
|
|
* @protected
|
|
*/
|
|
this.ready = false
|
|
/**
|
|
* The main queue
|
|
* @type {Waterfall}
|
|
* @protected
|
|
*/
|
|
this.queue = new Waterfall()
|
|
/**
|
|
* The buffer queue
|
|
* @type {Waterfall}
|
|
* @protected
|
|
*/
|
|
this.buffer = new Waterfall()
|
|
this.buffer.chain(new Promise(resolve => {
|
|
/**
|
|
* Method to trigger the buffer processing.
|
|
*
|
|
* Do not be use directly, use `this.processBuffer` instead.
|
|
* @function
|
|
* @protected
|
|
*/
|
|
this._triggerBuffer = resolve
|
|
}))
|
|
}
|
|
|
|
/**
|
|
* If executor is ready, queue task (and process it immediately if executor was idle)
|
|
* If not, buffer task for later processing
|
|
* @param {Object} task
|
|
* @param {Object} task.this - Object to use as this
|
|
* @param {function} task.fn - Function to execute
|
|
* @param {Array} task.arguments - Array of arguments, IMPORTANT: only the last argument may be a function
|
|
* (the callback) and the last argument cannot be false/undefined/null
|
|
* @param {Boolean} [forceQueuing = false] Optional (defaults to false) force executor to queue task even if it is not ready
|
|
*/
|
|
push (task, forceQueuing) {
|
|
const func = async () => {
|
|
const lastArg = task.arguments[task.arguments.length - 1]
|
|
await new Promise(resolve => {
|
|
if (typeof lastArg === 'function') {
|
|
// We got a callback
|
|
task.arguments.pop() // remove original callback
|
|
task.fn.apply(task.this, [...task.arguments, function () {
|
|
resolve() // triggers next task after next tick
|
|
lastArg.apply(null, arguments) // call original callback
|
|
}])
|
|
} else if (!lastArg && task.arguments.length !== 0) {
|
|
// We got a falsy callback
|
|
task.arguments.pop() // remove original callback
|
|
task.fn.apply(task.this, [...task.arguments, () => {
|
|
resolve()
|
|
}])
|
|
} else {
|
|
// We don't have a callback
|
|
task.fn.apply(task.this, [...task.arguments, () => {
|
|
resolve()
|
|
}])
|
|
}
|
|
})
|
|
}
|
|
this.pushAsync(func, forceQueuing)
|
|
}
|
|
|
|
/**
|
|
* If executor is ready, queue task (and process it immediately if executor was idle)
|
|
* If not, buffer task for later processing
|
|
* @param {function(...*):Promise<*>} task
|
|
* @param {boolean} [forceQueuing = false]
|
|
* @return {Promise<*>}
|
|
* @async
|
|
*/
|
|
pushAsync (task, forceQueuing = false) {
|
|
if (this.ready || forceQueuing) return this.queue.waterfall(task)()
|
|
else return this.buffer.waterfall(task)()
|
|
}
|
|
|
|
/**
|
|
* Queue all tasks in buffer (in the same order they came in)
|
|
* Automatically sets executor as ready
|
|
*/
|
|
processBuffer () {
|
|
this.ready = true
|
|
this._triggerBuffer()
|
|
this.queue.waterfall(() => this.buffer.guardian)
|
|
}
|
|
}
|
|
|
|
// Interface
|
|
module.exports = Executor
|
|
|