matrix-puppeteer-line/puppet/src/taskqueue.js

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2021-02-26 01:28:54 -05:00
// mautrix-line - A very hacky Matrix-LINE bridge based on running LINE's Chrome extension in Puppeteer
// Copyright (C) 2020-2021 Tulir Asokan, Andrew Ferrazzutti
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
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export default class TaskQueue {
constructor(id) {
this.id = id
this._tasks = []
this.running = false
this._wakeup = null
}
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log(...text) {
console.log(`[TaskQueue/${this.id}]`, ...text)
}
error(...text) {
console.error(`[TaskQueue/${this.id}]`, ...text)
}
async _run() {
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this.log("Started processing tasks")
while (this.running) {
if (this._tasks.length === 0) {
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this.log("Sleeping until a new task is received")
await new Promise(resolve => this._wakeup = () => {
resolve()
this._wakeup = null
})
if (!this.running) {
break
}
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this.log("Continuing processing tasks")
}
const { task, resolve, reject } = this._tasks.shift()
await task().then(resolve, reject)
}
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this.log("Stopped processing tasks")
}
/**
* @callback Task
* @return {Promise<any>}
*/
/**
* Push a task to the queue.
*
* @param {Task} task - The task to run
* @return {Promise<any>} - A promise that resolves to the return value of the task
*/
push(task) {
if (!this.running) {
throw Error("task queue is not running")
}
if (this._wakeup !== null) {
this._wakeup()
}
return new Promise((resolve, reject) => this._tasks.push({ task, resolve, reject }))
}
/**
* Start handling tasks
*/
start() {
if (this.running) {
return
}
this.running = true
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this._run().catch(err => this.error("Fatal error processing tasks:", err))
}
/**
* Stop handling tasks.
*/
stop() {
if (!this.running) {
return
}
this.running = false
if (this._wakeup !== null) {
this._wakeup()
}
}
}