feat: handle onDeath

Author: yjl9903

packages/death/README.md

@@ -18,6 +18,10 @@ onDeath(() => {
 })
 ```
 
+## Note
+
+In [Signal events](https://nodejs.org/dist/latest-v20.x/docs/api/process.html#signal-events), it says that `SIGTERM` and `SIGINT` have default handlers on non-Windows platforms that reset the terminal mode before exiting with code 128 + signal number. **If one of these signals has a listener installed, its default behavior will be removed (Node.js will no longer exit).**
+
 ## License
 
 MIT License © 2023 [XLor](https://github.com/yjl9903)

packages/death/scripts/play.ts

@@ -0,0 +1,16 @@
+import { onDeath } from '../src';
+
+function sleep(timeout: number): Promise<void> {
+  return new Promise((res) => {
+    setTimeout(() => res(), timeout);
+  });
+}
+
+onDeath((sig) => {
+  console.log(`Receive: ${sig}`);
+  console.log('Process is being killed');
+});
+
+console.log('Start sleep');
+
+await sleep(1000 * 1000);

packages/death/src/death.ts

@@ -0,0 +1,99 @@
+import { EventEmitter } from 'node:events';
+
+export type DeathSignals = 'SIGINT' | 'SIGTERM' | 'SIGQUIT';
+
+export interface OnDeathContext {
+  // Terminate process by which method or does nothing when callbacks are done
+  terminate: 'exit' | 'kill' | false;
+
+  // Call process.exit when callbacks are done
+  exit: number | undefined;
+
+  // Call process.kill when callbacks are done
+  kill: NodeJS.Signals | undefined;
+}
+
+export type OnDeathCallback = (
+  signal: DeathSignals,
+  context: OnDeathContext
+) => unknown | Promise<unknown>;
+
+export interface OnDeathOptions {
+  SIGINT?: boolean;
+  SIGTERM?: boolean;
+  SIGQUIT?: boolean;
+}
+
+const emitter = new EventEmitter();
+
+const handlers: Record<DeathSignals, NodeJS.SignalsListener> = {
+  SIGINT: makeHandler('SIGINT'),
+  SIGTERM: makeHandler('SIGTERM'),
+  SIGQUIT: makeHandler('SIGQUIT')
+};
+
+export function onDeath(
+  callback: OnDeathCallback,
+  { SIGINT = true, SIGTERM = true, SIGQUIT = true }: OnDeathOptions = {}
+): () => void {
+  const cleanUps: Array<() => void> = [];
+
+  if (SIGINT) {
+    registerCallback('SIGINT', handlers.SIGINT);
+    emitter.addListener('SIGINT', callback);
+    cleanUps.push(() => emitter.removeListener('SIGINT', callback));
+  }
+  if (SIGTERM) {
+    registerCallback('SIGTERM', handlers.SIGTERM);
+    emitter.addListener('SIGTERM', callback);
+    cleanUps.push(() => emitter.removeListener('SIGTERM', callback));
+  }
+  if (SIGQUIT) {
+    registerCallback('SIGQUIT', handlers.SIGQUIT);
+    emitter.addListener('SIGQUIT', callback);
+    cleanUps.push(() => emitter.removeListener('SIGQUIT', callback));
+  }
+
+  return () => {
+    for (const cleanUp of cleanUps) {
+      cleanUp();
+    }
+  };
+}
+
+function registerCallback(
+  signal: DeathSignals,
+  callback: NodeJS.SignalsListener
+) {
+  process.on(signal, callback);
+  return () => {
+    process.off(signal, callback);
+  };
+}
+
+function makeHandler(signal: DeathSignals) {
+  return async (signal: NodeJS.Signals) => {
+    const listeners = emitter.listeners(signal);
+    const context: OnDeathContext = {
+      terminate: 'kill',
+      exit: undefined,
+      kill: signal
+    };
+
+    // Iterate all the listener by reverse
+    for (const listener of listeners.reverse()) {
+      await listener(signal, context);
+    }
+
+    if (context.terminate === 'kill' || context.terminate === 'exit') {
+      process.removeListener('SIGINT', handlers.SIGINT);
+      process.removeListener('SIGTERM', handlers.SIGTERM);
+      process.removeListener('SIGQUIT', handlers.SIGQUIT);
+      if (context.terminate === 'kill') {
+        process.kill(process.pid, context.kill);
+      } else {
+        process.exit(context.exit);
+      }
+    }
+  };
+}

packages/death/src/index.ts

@@ -1 +1 @@
-export function onDeath() {}
+export * from './death';