From 19d650197679c4c943ca07db5ab52d5eca80c6fc Mon Sep 17 00:00:00 2001
From: Alexis Tyler <xo@wvvw.me>
Date: Mon, 3 Feb 2020 15:50:07 +1030
Subject: [PATCH] fix: make sure master doesnt die when worker does

---
 index.js | 60 +++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 44 insertions(+), 16 deletions(-)

diff --git a/index.js b/index.js
index 0778f8eec..5d76e6a65 100644
--- a/index.js
+++ b/index.js
@@ -1,58 +1,86 @@
 const path = require('path');
 const cluster = require('cluster');
 
-// Show real stack trace in development
-if (process.env.NODE_ENV === 'development') {
-    try {
-        require('source-map-support').install({
-            handleUncaughtExceptions: false
-        });
-    } catch {
-        console.error(`Could not load "source-map-supoort", do you have it installed?`);
-    }
-}
+const log = process.env.NODE_ENV === 'production' ? {
+    info() { },
+    log() { },
+    debug() { },
+    error() { }
+} : console;
 
 // Set current working directory
 process.chdir(__dirname);
 
 const RESTART_ATTEMPTS = 10;
 let currentRestartAttempt = 0;
+let currentWorker;
 
+// Master
 if (cluster.isMaster) {
-    cluster.fork();
+    // Show real stack trace in development
+    if (process.env.NODE_ENV === 'development') {
+        try {
+            require('source-map-support').install({
+                handleUncaughtExceptions: false
+            });
+        } catch {
+            log.error(`Could not load "source-map-supoort", do you have it installed?`);
+        }
+    }
+
+    log.info(`<master> pid = ${process.pid}`);
+    currentWorker = cluster.fork();
 
     cluster.on('exit', (_, code) => {
+        if (code === null || code === 0) {
+            const newWorker = cluster.fork();
+            newWorker.once('online', () => {
+                currentWorker = newWorker;
+            });
+            return;
+        }
+
         if (code !== 7) {
             process.exit(code);
         }
 
         if (currentRestartAttempt >= RESTART_ATTEMPTS) {
-            console.debug(`No restart attempts left. Exiting.`);
+            log.debug(`No restart attempts left. Exiting.`);
             process.exit(1);
         }
 
         currentRestartAttempt++;
-        cluster.fork();
+        currentWorker = cluster.fork();
+    });
+
+    // Allow reload on SIGHUP
+    process.on('SIGHUP', () => {
+        log.debug('<master> Reloading worker');
+        currentWorker.send('shutdown');
     });
 }
 
+// Worker
 if (cluster.isWorker) {
+    log.info(`<worker> pid = ${process.pid}`);
+
     // @ts-ignore
     const package = require('./package.json');
     const { main } = package;
 
     if (!main) {
-        console.error('Missing main field in package.json');
+        log.error('<worker> Missing main field in package.json');
         process.exit(1);
     }
 
     const mainPath = path.resolve(__dirname, main);
 
     try {
+        log.info('<worker> loaded');
         require(mainPath);
     } catch (error) {
-        console.error(error);
-        console.error(`Could not load main field "${mainPath}".`);
+        log.error(error);
+        log.error(`<worker> Could not load main field "${mainPath}".`);
         process.exit(1);
     }
 }
\ No newline at end of file