Core synchronous queue with an example worker

app.js

@@ -0,0 +1,91 @@
+const dotenv = require('dotenv')
+const compression = require('compression')
+const express = require('express')
+const morgan = require('morgan')
+const bodyParser = require('body-parser')
+const path = require('path')
+const rfs = require('rotating-file-stream')
+const cors = require('cors')
+const errorhandler = require('errorhandler')
+const statusCodes = require('http-status-codes').StatusCodes
+const createError = require('http-errors')
+
+const apiRouter = require('./routes')
+
+// load .env config file
+dotenv.config()
+
+// main app file
+const app = express()
+
+// create a rotating write stream
+const accessLogStream = rfs.createStream('access.log', {
+  interval: '1d', // rotate daily
+  path: path.join(__dirname, 'log')
+})
+
+// setup the file logger
+app.use(morgan('common', { stream: accessLogStream }))
+
+// setup the console logger
+if (process.env.NODE_ENV === 'development') {
+  // [debug]
+  app.use(morgan('dev'))
+} else {
+  // [production]
+  app.use(morgan('dev', {
+    skip: function (req, res) { return res.statusCode < 400 }
+  }))
+}
+
+// be proxy aware
+app.enable('trust proxy')
+
+// cross-origin resource sharing
+app.use(cors())
+
+// json middleware
+app.use(bodyParser.json())
+
+// healthcheck (can be used for heart-beat)
+app.get('/status', (req, res) => {
+  res.status(200).end()
+});
+app.head('/status', (req, res) => {
+  res.status(200).end()
+});
+
+// routes
+app.use('/api', apiRouter)
+
+// 404 middleware
+app.use((req, res, next) => {
+  next(createError(statusCodes.NOT_FOUND))
+})
+
+// error handling
+app.use((err, req, res, next) => {
+  /* Handle 401 */
+  if (err.status === statusCodes.UNAUTHORIZED) {
+    return res
+      .status(err.status)
+      .send({ message: err.message })
+      .end()
+  }
+  return next(err)
+})
+if (process.env.NODE_ENV !== 'development') {
+  app.use((err, req, res, next) => {
+    res.status(err.status || 500)
+    res.json({
+      errors: {
+        message: err.message,
+      },
+    })
+  })
+}
+
+// start the server
+app.listen(process.env.PORT, process.env.HOST)
+
+console.log('service started on port ' process.env.HOST + ':' + process.env.PORT)

example.env

@@ -0,0 +1,16 @@
+# Choices for NODE_ENV:
+#   development: for extra debug logging including all requests displayed in console
+#   production: reduced logging, only errors in console, all requests logged to file
+NODE_ENV=development
+
+# API key clients should use when talking to this server
+#   TODO: Add capability for multiple API keys for different clients
+API_KEY=
+
+# Host (ip address) the server should listen on.
+#   Change to 0.0.0.0 to allow access from network. Ideally use a local front-end server
+#   (for example nginx or apache) for https handling.
+HOST=127.0.0.1
+
+# Port the server should listen on
+PORT=3000

package-lock.json

@@ -0,0 +1,552 @@
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+      "requires": {
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+}

package.json

@@ -2,7 +2,7 @@
   "name": "Calc-Scheduler",
   "version": "0.1.0",
   "description": "A schedular for the calculation of FIDGITS/MIBAT scenarios",
-  "main": "index.js",
+  "main": "app.js",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
@@ -12,5 +12,18 @@
   "repository": {
     "type": "git",
     "url": "https://git.avsdev.uk/AVSDev/calc-scheduler"
+  },
+  "dependencies": {
+    "body-parser": "^1.19.0",
+    "compression": "^1.7.4",
+    "cors": "^2.8.5",
+    "dotenv": "^8.2.0",
+    "errorhandler": "^1.5.1",
+    "express": "^4.17.1",
+    "http-errors": "^1.8.0",
+    "http-status-codes": "^2.1.4",
+    "morgan": "^1.10.0",
+    "path": "^0.12.7",
+    "rotating-file-stream": "^2.1.3"
   }
 }

routes/calc-queue.js

@@ -0,0 +1,89 @@
+const express = require('express')
+const statusCodes = require('http-status-codes').StatusCodes
+const calcQueueSvc = require('../src/services/calc-queue')
+const CalcQueueExceptions = require('../src/services/calc-queue/exceptions.js')
+
+const router = express.Router()
+
+// Return busy/not busy flag
+router.get('/busy', function(req, res) {
+  res.send({ busy: calcQueueSvc.isBusy() })
+})
+
+// Get the current queue of tasks
+router.get('/queue', function(req, res) {
+  res.send({ 'queue': calcQueueSvc.getQueue() })
+})
+
+// Add a calc task to the queue
+router.put('/queue/:id/:calcFn', function(req, res) {
+  try {
+    calcQueueSvc.enqueue(req.params.id, req.params.calcFn)
+    res.send({ success: true })
+  } catch(ex) {
+    if (ex instanceof CalcQueueExceptions.AlreadyQueued
+      || ex instanceof CalcQueueExceptions.AlreadyInProgress
+      || ex instanceof CalcQueueExceptions.CalculationUnknown) {
+      res.status(
+        statusCodes.BAD_REQUEST
+      ).send(
+        { success: false, error: ex.message }
+      )
+    } else {
+      throw ex
+    }
+  }
+})
+
+// Remove a task or collection of tasks from the queue
+router.delete('/queue/:id', function(req, res) {
+  calcQueueSvc.dequeue(req.params.id, null)
+  res.send({ success: true })
+})
+// Remove a task from the queue
+router.delete('/queue/:id/:calcFn', function(req, res) {
+  calcQueueSvc.dequeue(req.params.id, req.params.calcFn)
+  res.send({ success: true })
+})
+
+
+// Get the status of a task as a text string
+const processStatus = function(id, calcFn) {
+  if (calcQueueSvc.isInProgress(id, calcFn)) {
+    return 'in_progress'
+  } else if (calcQueueSvc.isQueued(id, calcFn)) {
+    return 'queued'
+  } else if (calcQueueSvc.isFinished(id, calcFn)) {
+    return 'finished'
+  } else {
+    return 'not_queued'
+  }
+}
+
+// Get the status of the queue and all tasks
+router.get('/status', function(req, res) {
+  res.status(statusCodes.OK).send({
+    'queued': calcQueueSvc.getQueue(),
+    'in_progress': calcQueueSvc.getInProgress(),
+    'finished': calcQueueSvc.getFinished()
+  })
+})
+
+// Get the status of all tasks with by id
+router.get('/status/:id', function(req, res) {
+  res.status(statusCodes.OK).send({
+    'id': req.params.id,
+    'status': processStatus(req.params.id, null)
+  })
+})
+
+// Get the status of an individual task
+router.get('/status/:id/:calcFn', function(req, res) {
+  res.status(statusCodes.OK).send({
+    'id': req.params.id,
+    'calcFn': req.params.calcFn,
+    'status': processStatus(req.params.id, req.params.calcFn)
+  })
+})
+
+module.exports = router

routes/index.js

@@ -0,0 +1,37 @@
+const dotenv = require('dotenv')
+const express = require('express')
+const statusCodes = require('http-status-codes').StatusCodes
+const createError = require('http-errors')
+
+dotenv.config()
+
+const router = express.Router()
+
+// TODO: Add a mechanism for multiple clients/API keys
+const apiKeys = [
+  process.env.API_KEY
+]
+
+// Middleware to verify API access is granted
+router.use('/', function(req, res, next){
+  var key = req.query['api_key'];
+
+  // key isn't present
+  if (!key) {
+    return next(createError(statusCodes.BAD_REQUEST, 'api key required'))
+  }
+
+  // key is invalid
+  if (!~apiKeys.indexOf(key)) {
+    return next(createError(statusCodes.UNAUTHORIZED, 'invalid api key'))
+  }
+
+  // all good, store req.key for route access
+  req.key = key
+  next()
+})
+
+// Add API routes to default router
+router.use('/', require('./calc-queue.js'))
+
+module.exports = router

src/index.js

@@ -0,0 +1,4 @@
+
+module.exports = {
+  'services': require('./services')
+}

src/services/calc-queue/CalcQueue.js

@@ -0,0 +1,191 @@
+const EventEmitter = require('events')
+const threads = require('worker_threads')
+const path = require('path')
+const fs = require('fs')
+
+const Exceptions = require('./exceptions.js')
+const CalcTask = require('./CalcTask.js')
+
+// Basic utility functions to help the queue manager
+const CalcQueueUtils = {
+  getCalcWorker: function(calcFn) {
+    return path.resolve(path.join('src/workers', calcFn + '.js'))
+  },
+
+  isWorkerValid: function(workerPath) {
+    return fs.existsSync(workerPath)
+  },
+
+  // Start the next task if there are any queued
+  processNext: function() {
+    if (this.queue.length == 0) {
+      return false
+    }
+
+    /* TODO: work out if the process can be run in parallel with outer
+     * processes or must be done sequentially
+     */
+
+    const task = this.queue.shift()
+
+    task._worker = new threads.Worker(task.workerPath())
+
+    task._worker.on('message', (msg) => {
+      task._messages.push(msg)
+    })
+    task._worker.on('error', (err) => {
+      task._error = err
+      task._messages.push('Error: ' + err.message)
+    })
+    task._worker.on('exit', (exitCode) => {
+      task._result = exitCode
+      task._worker = null
+      const idx = this.inProgress.findIndex((t) => {
+        return t.id() == task.id() && t.calcFn() == task.calcFn()
+      })
+      this.inProgress.splice(idx, 1)
+      this.finished.push(task)
+      console.log(task)
+    })
+
+    this.inProgress.push(task)
+  }
+}
+
+
+// A calculation task. Only one of these per app
+/* Allows calculations to be queued as tasks. Currently tasks are ryun
+ * synchronously.
+ * TODO: Add async tasks.
+ */
+const CalcQueue = function() {
+  if (!(this instanceof CalcQueue)) {
+    return new CalcQueue()
+  }
+
+  this.queue = []
+  this.inProgress = []
+  this.finished = []
+
+  return this
+}
+CalcQueue.prototype = {
+  isBusy: function() {
+    return this.inProgress.length > 0;
+  },
+
+  // Report if a task or collection of tasks by id are finished
+  isFinished: function(id, calcFn = null) {
+    if (calcFn == null) {
+      const fin = this.finished.filter((el) => {
+        return el.id() == id
+      }).reduce((agg, el) => {
+        return agg && el.result() != null
+      }, true)
+      return fin
+    } else {
+      const idx = this.finished.findIndex((el) => {
+        return el.id() == id && (calcFn == null || el.calcFn() == calcFn)
+      })
+      return idx != -1
+    }
+  },
+  // Get the list of finished tasks
+  getFinished: function() {
+    return this.finished.map((q) => {
+      return {
+        'id': q.id(),
+        'calcFn': q.calcFn(),
+        'result': q.result(),
+        'messages': q.messages(),
+        'error': (q.error() == null ? null : q.error().message)
+      }
+    })
+  },
+
+  // Report if a task or collection of tasks by id are in progress
+  isInProgress: function(id, calcFn = null) {
+    const idx = this.inProgress.findIndex((el) => {
+      return el.id() == id && (calcFn == null || el.calcFn() == calcFn)
+    })
+    return idx != -1
+  },
+  // Get the list of in-progress tasks
+  getInProgress: function() {
+    return this.inProgress.map((q) => {
+      return { 'id': q.id(), 'calcFn': q.calcFn() }
+    })
+  },
+
+  // Report if a task or collection of tasks by id are queued
+  isQueued: function(id, calcFn = null) {
+    return (this.queuePosition(id, calcFn) != -1)
+  },
+  // Report the position of a task in the queue
+  queuePosition: function(id, calcFn = null) {
+    return this.queue.findIndex((el) => {
+      return el.id() == id && (calcFn == null || el.calcFn() == calcFn)
+    })
+  },
+  // Get the list of queued tasks
+  getQueue: function() {
+    return this.queue.map((q) => {
+      return { 'id': q.id(), 'calcFn': q.calcFn() }
+    })
+  },
+  // Remove all tasks from the queue, does not affect running tasks
+  clearQueue: function() {
+    var okay = true
+
+    while (this.queue.length > 0) {
+      okay |= this.dequeue(this.queue[0].id)
+      this.queue.splice(0, 1)
+    }
+
+    return okay
+  },
+
+  // Add a new task to the queue if it does not already exist
+  enqueue: function(id, calcFn) {
+    if (this.isQueued(id, calcFn)) {
+      throw new Exceptions.AlreadyQueued()
+    }
+
+    if (this.isInProgress(id, calcFn)) {
+      throw new Exceptions.AlreadyInProgress()
+    }
+
+    const workerPath = CalcQueueUtils.getCalcWorker(calcFn)
+    if (!CalcQueueUtils.isWorkerValid(workerPath)) {
+      throw new Exceptions.CalculationUnknown()
+    }
+
+    this.queue.push(new CalcTask(id, calcFn, workerPath))
+
+    if (!this.isBusy()) {
+      CalcQueueUtils.processNext.call(this)
+    }
+
+    return true
+  },
+  // Remove a task from the queue if it is queued
+  dequeue: function(id, calcFn) {
+    var idx = this.queuePosition(id, calcFn)
+    if (idx == -1) {
+      return false
+    }
+
+    // TODO: if item is in process, wait for it to finish
+
+    while (idx != -1) {
+      this.queue.splice(idx, 1)
+      idx = this.queuePosition(id, calcFn)
+    }
+
+    return true
+  }
+
+  // TODO: find, store & list worker scripts on start up instead of on request?
+}
+
+module.exports = new CalcQueue()

src/services/calc-queue/CalcTask.js

@@ -0,0 +1,50 @@
+
+// A calculation task.
+/* Contains the queued calculation and the results post calculation as well as
+ * any output messages from the task
+ */
+const CalcTask = function(id, calcFn, workerPath) {
+  if (!(this instanceof CalcTask)) {
+    return new CalcTask(id, calcFn, workerPath);
+  }
+
+  this._id = id
+  this._calcFn = calcFn
+  this._workerPath = workerPath
+  this._result = null
+  this._messages = []
+  this._error = null
+  this._worker = null
+
+  return this
+}
+CalcTask.prototype = {
+  id: function() {
+    return this._id
+  },
+  calcFn: function() {
+    return this._calcFn
+  },
+  workerPath: function() {
+    return this._workerPath
+  },
+
+  isInProgress: function() {
+    return this._worker != null
+  },
+  isFinished: function() {
+    return this._result != null
+  },
+
+  messages: function() {
+    return this._messages
+  },
+  error: function() {
+    return this._error
+  },
+  result: function() {
+    return this._result
+  }
+}
+
+module.exports = CalcTask

src/services/calc-queue/exceptions.js

@@ -0,0 +1,4 @@
+
+module.exports.AlreadyQueued = require('./exceptions/AlreadyQueued.js')
+module.exports.AlreadyInProgress = require('./exceptions/AlreadyInProgress.js')
+module.exports.CalculationUnknown = require('./exceptions/CalculationUnknown.js')

src/services/calc-queue/exceptions/AlreadyInProgress.js

@@ -0,0 +1,11 @@
+
+module.exports = function AlreadyInProgress(extra) {
+  Error.captureStackTrace(this, this.constructor)
+  this.name = this.constructor.name
+  this.message = 'calculation request is already in progress'
+  if (typeof extra !== 'undefined') {
+    this.extra = extra
+  }
+}
+
+require('util').inherits(module.exports, Error)

src/services/calc-queue/exceptions/AlreadyQueued.js

@@ -0,0 +1,11 @@
+
+module.exports = function AlreadyQueued(extra) {
+  Error.captureStackTrace(this, this.constructor)
+  this.name = this.constructor.name
+  this.message = 'calculation request is already queued'
+  if (typeof extra !== 'undefined') {
+    this.extra = extra
+  }
+};
+
+require('util').inherits(module.exports, Error)

src/services/calc-queue/exceptions/CalculationUnknown.js

@@ -0,0 +1,11 @@
+
+module.exports = function CalculationUnknown(extra) {
+  Error.captureStackTrace(this, this.constructor)
+  this.name = this.constructor.name
+  this.message = 'calculation requested is unknown'
+  if (typeof extra !== 'undefined') {
+    this.extra = extra
+  }
+};
+
+require('util').inherits(module.exports, Error)

src/services/calc-queue/index.js

@@ -0,0 +1,3 @@
+
+module.exports = require('./CalcQueue.js')
+module.exports.CalcQueueExceptions = require('./exceptions.js')

src/services/index.js

@@ -0,0 +1,4 @@
+
+module.exports = {
+  'calcQueue': require('./calc-queue')
+}

src/workers/example.js

@@ -0,0 +1,15 @@
+
+console.log('This is an example worker')
+
+new Promise((resolve, reject) => {
+  setTimeout((() => {
+    console.log('I did something (nothing) for 5 seconds!');
+    resolve()
+  }).bind(this), 5000)
+})
+
+if (!module.parent) {
+  console.log('not a module')
+} else {
+  console.log('loaded as a module')
+}