DAR-7: Implement a dar-server.js file

server/src/DARServer.js

@@ -0,0 +1,98 @@
+import childProcess from 'child_process'
+import path from 'path'
+import chalk from 'chalk'
+import timers from 'timers'
+import autoBind from 'auto-bind2'
+
+export class DARServer {
+  constructor(toolName, log) {
+    autoBind(this)
+    this.toolName = toolName
+    this.log = log
+    this.actors = [
+      { name: 'api' },
+      { name: 'email' },
+      { name: 'image' },
+    ]
+  }
+
+  restart(actor) {
+    const timeSinceStart = Date.now() - actor.startTime
+
+    if (timeSinceStart < actor.timeToInit) {
+      actor.backOff += 1
+    } else {
+      actor.backOff = 0
+    }
+
+    const backOffTime = (Math.pow(2, Math.min(actor.backOff, 7)) - 1) * 1000
+
+    if (backOffTime > 0) {
+      this.log.warn(`Actor '${actor.name}' died quickly, waiting ${Math.floor(backOffTime / 1000)} seconds to restart`)
+    } else {
+      this.log.warn(`Actor ${actor.name} died, restarting`)
+    }
+
+    timers.setTimeout(() => {
+      actor.starts += 1
+      actor.startTime = Date.now()
+      actor.proc = childProcess.fork(actor.modulePath)
+      actor.proc.on('exit', (code, signal) => {
+        // Don't restart if the exit was clean or Control+C
+        if (code === 0 || signal === 'SIGINT') {
+          this.log.info(`Actor ${actor.name} terminated normally`)
+          return
+        }
+
+        this.restart(actor)
+      })
+      this.log.info(`Restarted actor '${actor.name}', pid ${actor.proc.pid}`)
+    }, backOffTime)
+  }
+
+  async run() {
+    let promises = []
+
+    this.actors.forEach((actor) => {
+      promises.push(new Promise((resolve, reject) => {
+        actor.modulePath = path.join(__dirname, actor.name)
+        actor.startTime = Date.now()
+        actor.backOff = 0
+        actor.timeToInit = actor.timeToInit || 3000
+        actor.proc = childProcess.fork(actor.modulePath)
+        actor.proc.on('exit', (code, signal) => {
+          const timeSinceStart = Date.now() - actor.startTime
+
+          if (timeSinceStart < actor.timeToInit) {
+            this.log.error(`Actor '${actor.name}' exited during initialization`)
+
+            if (this.actors) {
+              this.actors.forEach((otherActor) => {
+                if (otherActor !== actor) {
+                  this.log.info(`Terminating actor ${actor.name}, pid ${otherActor.proc.pid}`)
+                  otherActor.proc.kill('SIGINT')
+                  otherActor.proc = null
+                }
+              })
+
+              actor.proc = null
+              this.actors = null
+            }
+
+            return reject(new Error('All actors must initialize on first start'))
+          }
+
+          this.restart(actor)
+        })
+        timers.setTimeout(() => {
+          if (actor.proc) {
+            resolve()
+          }
+        }, actor.timeToInit)
+        this.log.info(`Started actor '${actor.name}', pid ${actor.proc.pid}`)
+      })) // new Promise()
+    })
+
+    return Promise.all(promises)
+  }
+}