Yet another POSIX signal handler.

Features

• Ensures provided functions are called before any other event listeners and are run concurrently, minimizing shutdown time.
• Works with any combination of synchronous and asynchronous functions.
• Ensures a clean exit if all functions resolve/return.
• Exits with an error if any functions reject/throw.
• Ensures processes exit cleanly, even when they have asynchronous shut-down functions and the Node debugger is in use. (See this issue)

Install

npm i @darkobits/adeiu

Use

Adeiu accepts an asynchronous or synchronous handler function. By default, the handler will be registered to respond to the following signals:

• SIGINT
• SIGQUIT
• SIGTERM
• SIGUSR2

import adeiu from '@darkobits/adeiu';

adeiu(async signal => {
  console.log(`Received signal ${signal}; performing shut-down tasks...`);

  await someAsyncStuff();

  console.log('All done!');
});

Unregistering Handlers

Adeiu returns a function that can be invoked to unregister a handler.

import adeiu from '@darkobits/adeiu';

const unregister = adeiu(() => {
  // Handler implementation here.
});

// Un-register the handler.
unregister();

Customizing Signals

Usually, responding to signals dynamically can be accomplished by inspecting the signal argument passed to your handler. However, if it is important that handlers are only invoked for a particular signal, or if you'd like to respond to signals other than the defaults, you may optionally provide an array of signals as a second argument:

import adeiu from '@darkobits/adeiu';

// Register callback that will _only_ be invoked on SIGINT:
adeiu(() => {
  // SIGINT cleanup tasks.
}, ['SIGINT']);

import adeiu from '@darkobits/adeiu';

// Register callback with the default signals _and_ SIGUSR1:
adeiu(() => {
  // Custom cleanup tasks.
}, [...adeiu.SIGNALS, 'SIGUSR1']);