feat(process): auto load processMap while booting

Author: a632079

core.js

@@ -4,7 +4,7 @@
 const Koa = require('koa') // Koa v2
 const winston = require('winston')
 const nconf = require('nconf')
-const path = require('path')
+// const path = require('path')
 const colors = require('colors/safe')
 // const pkg = require('./package.json')
 // const mail = require('./src/mail')
@@ -27,50 +27,29 @@ if (program.dev) {
 // Register Server
 const app = new Koa()
 
-// Load CronJob
-const childProcess = require('child_process')
-function spawnCronProcess () {
-  const child = childProcess.fork(path.join(__dirname, './src/cron.js'), {
-    env: {
-      dev: program.dev
+// Load childProcesses
+let childProcessList = []
+async function registerProcesses () {
+  const processesMap = require('./processes')
+  const processesToStart = []
+  const isDev = program.dev
+  for (const process of processesMap) {
+    if ((process.isDev && isDev) || (process.isProd && !isDev) || (!process.isDev && !process.isDev)) {
+      processesToStart.push(process)
     }
-  })
-  child.on('message', (message) => {
-    if (message === 'loaded') {
-      winston.verbose('[init] all cronJobs are loaded.')
-    } else if (message.key) {
-      if (message.key === 'error') {
-        console.log(colors.red(message.data))
-        winston.error('[init] error was thrown while loading cron jobs, process existing.')
-      }
-    }
-  })
-  // register master exit process
-  let masterExitFlag = false
-  process.on('exit', () => {
-    // kill child process
-    masterExitFlag = true
-    child.send({
-      key: 'exit',
-      data: ''
-    })
-  })
-  child.on('exit', () => {
-    if (!masterExitFlag) {
-      winston.warn('[cronJob] cron job process is exited. Try to respawn it.')
-      spawnCronProcess()
-    }
-  })
+  }
+  const { staticProcess } = require('./src/process')
+  processesToStart.forEach(v => staticProcess().spawnProcess(v.path, v.name, v.messageListener))
+  childProcessList = staticProcess().ProcessList
 }
-spawnCronProcess()
 
 // Register Middlewares (Plugins)
 async function registerMiddlewares () {
   require('./src/middleware').register(app, program.dev)
 }
 
 // Run Task
-// TODO: crate a task tree file
+// TODO: create a task tree file
 const { Task: updateSentencesTask } = require('./src/task/updateSentencesTask')
 
 // Load Route
@@ -94,10 +73,33 @@ async function registerRoutes (routes) {
   }
 }
 
+// handle the process exit event
+function handleProcessExitSignal (signal) {
+  winston.verbose('[core] receive signal: ' + colors.yellow(signal) + ', starting the exit produre.')
+  for (const child of childProcessList) {
+    child.instance.kill('SIGTERM') // teng-koa exit signal code
+  }
+  winston.info('[core] Web server is shut down, Bye!')
+  process.exit(0)
+}
+process.on('SIGINT', handleProcessExitSignal) // Ctrl + C
+process.on('SIGTERM', handleProcessExitSignal)
+
+process.on('exit', (code) => { // handle unexpected exit event
+  if (code) { // ignore zero exit code
+    winston.error('[core] receiving exit code: ' + code + ', process will be destoryed.')
+    for (const child of childProcessList) {
+      child.instance.kill('SIGTERM') // teng-koa exit signal code
+    }
+    winston.info('[core] Web server is shut down, Bye!')
+  }
+})
+
 // Start Server
 async function start () {
   try {
     await updateSentencesTask()
+    await registerProcesses()
     await registerMiddlewares()
     const Routes = require('./src/route')
     await registerRoutes(new Routes())

processes.js

@@ -0,0 +1,25 @@
+// This file is a map of child processes
+const path = require('path')
+const winston = require('winston')
+const colors = require('colors')
+
+module.exports = [
+  {
+    path: path.join(__dirname, './src/cron.js'), // The absolute path of the process file
+    name: 'cronJob', // The name of the process module
+    messageListener: (message) => {
+      if (message === 'loaded') {
+        winston.verbose('[init] all cronJobs are loaded.')
+      } else if (message.key) {
+        if (message.key === 'error') {
+          console.log(colors.red(message.data))
+          winston.error('[init] error was thrown while loading cron jobs, process existing.')
+          process.exit(1)
+        }
+      }
+    }, // the handler of the receiving message
+    isDev: false, // if set true, this process will start only in Dev
+    isProd: false // if set true, this process will start only in prod
+    // if isDev and isProd both be set false, process will both start in Dev and Prod
+  }
+]

src/cron.js

@@ -102,11 +102,9 @@ if (process.env && process.env.dev) {
   winston.level = 'verbose'
   nconf.set('dev', true)
 }
-
-process.on('message', message => {
-  if (message.key === 'exit') {
-    winston.verbose('[cronJob] receive exit signal, cron process exiting.')
-    process.exit()
+process.on('exit', (code) => {
+  if (code && code === 1000) {
+    winston.info('[cronJob] receiving exiting signal, cronJob process exits.')
   }
 })
 Cron.load()

src/process.js

@@ -0,0 +1,73 @@
+// This module is intended to provide a helper of generating child processes
+const path = require('path')
+const childProcess = require('child_process')
+const winston = require('winston')
+const nconf = require('nconf')
+const colors = require('colors')
+
+class Process {
+  constructor () {
+    /**
+     * The childProcessList is a processes' instances collection
+     * struct is:
+     * [
+     *   {
+     *     name: String, // moduleName,
+     *     instance: Class/Object // the instance of the childProcess
+     *   },
+     *   ...
+     * ]
+     */
+    this.childProcessList = []
+  }
+
+  get ProcessList () {
+    return this.childProcessList
+  }
+
+  spawnProcess (execFileAbsolutePath, moduleName, messageLisenner = null) {
+    const child = childProcess.fork(path.join(execFileAbsolutePath), {
+      env: {
+        dev: !!nconf.get('dev')
+      }
+    })
+    this.childProcessList.push({
+      instance: child,
+      name: moduleName
+    })
+    const ml = typeof messageLisenner === 'function' ? messageLisenner : (message) => {
+      if (message && message.key === 'loaded') {
+        winston.verbose('[' + moduleName + '] process are started.')
+      }
+    }
+    child.on('message', ml)
+    child.on('exit', this.handleChildProcessExitEvent(moduleName, execFileAbsolutePath, ml))
+  }
+
+  handleChildProcessExitEvent (moduleName, path, messageLisenner) {
+    return (code, signal) => {
+      if (code === null && !signal) {
+        winston.warn('[' + moduleName + '] process is exited accidentally. Try to respawn it.')
+        this.spawnProcess(path, moduleName, messageLisenner)
+      } else if (code > 0) { // errors might be thrown
+        winston.error('[' + moduleName + '] child process exited with code: ' + code + ', master process exits to ensure the stablity.')
+        process.exit(1)
+      } else if (signal) { // exist ignore
+        winston.info('[' + moduleName + '] process is exited due to receive sinal: ' + colors.blue(signal))
+      } // ignore exit code: 0
+    }
+  }
+}
+
+let processes = null
+function staticProcess () {
+  if (!processes) {
+    processes = new Process()
+  }
+  return processes
+}
+
+module.exports = {
+  Process,
+  staticProcess
+}