From 4b82f4f8639282ef5b9af1411fb43dde620d8ba8 Mon Sep 17 00:00:00 2001
From: Harry Chen <czy88840616@gmail.com>
Date: Thu, 16 May 2024 13:35:50 +0800
Subject: [PATCH] feat: add keepalive args (#22)

---
 README.md        |  3 +++
 lib/constants.js |  1 +
 lib/process.js   | 23 ++++++++++++++++++++++-
 lib/wrap.js      | 15 +++++++++++++++
 4 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 lib/constants.js

diff --git a/README.md b/README.md
index 1b1e9f0..e819763 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,9 @@ $ npx mwtsc --watch --run ./bootstrap.js
 
 # run with tsc options
 $ npx mwtsc --watch --project tsconfig.production.json --run ./bootstrap.js
+
+# the child process keep avaliable during the development
+$ npx mwtsc --watch --run ./bootstrap.js --keepalive
 ```
 
 ## Different with tsc and tsc-watch
diff --git a/lib/constants.js b/lib/constants.js
new file mode 100644
index 0000000..fdc3e75
--- /dev/null
+++ b/lib/constants.js
@@ -0,0 +1 @@
+exports.CHILD_PROCESS_EXCEPTION_EXIT_CODE = 10;
diff --git a/lib/process.js b/lib/process.js
index d4a8007..b06073f 100644
--- a/lib/process.js
+++ b/lib/process.js
@@ -1,5 +1,6 @@
 const { fork, spawn } = require('child_process');
-const { filterFileChangedText, debug } = require('./util');
+const { filterFileChangedText, debug, output, colors } = require('./util');
+const { CHILD_PROCESS_EXCEPTION_EXIT_CODE } = require('./constants');
 // is windows
 const isWin = process.platform === 'win32';
 
@@ -110,6 +111,26 @@ const forkRun = (runCmdPath, runArgs = [], options = {}) => {
       }
     };
     runChild.on('message', onServerReady);
+    if (runArgs.includes('--keepalive')) {
+      runChild.once('exit', code => {
+        if (code === CHILD_PROCESS_EXCEPTION_EXIT_CODE) {
+          output(colors.red('*'.repeat(120)));
+          output(
+            `A ${colors.red(
+              `${colors.bright(
+                'Critical unhandledRejection or uncaughtException'
+              )}`
+            )} was detected and the process has exited automatically.`
+          );
+          output('Please make sure to handle it.');
+          output(
+            'The --keepalive parameter was enabled, we will do our best to ensure the process remains normal..'
+          );
+          output(colors.red('*'.repeat(120)));
+          innerFork(false);
+        }
+      });
+    }
   }
 
   innerFork(true);
diff --git a/lib/wrap.js b/lib/wrap.js
index 6f16dba..0be2076 100644
--- a/lib/wrap.js
+++ b/lib/wrap.js
@@ -2,6 +2,21 @@
 const childPath = process.env.CHILD_CMD_PATH;
 const childCwd = process.env.CHILD_CWD;
 const { join, isAbsolute } = require('path');
+const { CHILD_PROCESS_EXCEPTION_EXIT_CODE } = require('./constants');
+
+// get the child process execArgs
+const runArgs = process.argv.slice(2);
+if (runArgs.includes('--keepalive')) {
+  process.once('unhandledRejection', err => {
+    console.error(err);
+    process.exit(CHILD_PROCESS_EXCEPTION_EXIT_CODE);
+  });
+
+  process.once('uncaughtException', err => {
+    console.error(err);
+    process.exit(CHILD_PROCESS_EXCEPTION_EXIT_CODE);
+  });
+}
 
 process.on('message', data => {
   if (data.title === 'server-kill') {