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mc_test/node_modules/async-exit-hook/readme.md

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+# async-exit-hook
+[![Build Status](https://api.travis-ci.org/Tapppi/async-exit-hook.svg)](https://travis-ci.org/Tapppi/async-exit-hook)
+[![Coverage Status](https://coveralls.io/repos/github/Tapppi/async-exit-hook/badge.svg?branch=master)](https://coveralls.io/github/Tapppi/async-exit-hook?branch=master)
+
+> Run some code when the process exits
+
+The `process.on('exit')` event doesn't catch all the ways a process can exit. This module catches:
+
+* process SIGINT, SIGTERM and SIGHUP, SIGBREAK signals  
+* process beforeExit and exit events  
+* PM2 clustering process shutdown message ([PM2 graceful reload](http://pm2.keymetrics.io/docs/usage/cluster-mode/#graceful-reload))  
+
+Useful for cleaning up. You can also include async handlers, and add custom events to hook and exit on.
+
+Forked and pretty much rewritten from [exit-hook](https://npmjs.com/package/exit-hook).
+
+
+## Install
+
+```
+$ npm install --save async-exit-hook
+```
+
+## Usage
+
+### Considerations and warning
+#### On `process.exit()` and asynchronous code
+**If you use asynchronous exit hooks, DO NOT use `process.exit()` to exit.
+The `exit` event DOES NOT support asynchronous code.**
+>['beforeExit' is not emitted for conditions causing explicit termination, such as process.exit()]
+(https://nodejs.org/api/process.html#process_event_beforeexit)
+
+#### Windows and `process.kill(signal)`
+On windows `process.kill(signal)` immediately kills the process, and does not fire signal events, 
+and as such, cannot be used to gracefully exit. See *Clustering and child processes* for a
+workaround when killing child processes. I'm planning to support gracefully exiting 
+with async support on windows soon.
+
+### Clustering and child processes
+If you use custom clustering / child processes, you can gracefully shutdown your child process
+by sending a shutdown message (`childProc.send('shutdown')`).
+
+### Example
+```js
+const exitHook = require('async-exit-hook');
+
+exitHook(() => {
+    console.log('exiting');
+});
+
+// you can add multiple hooks, even across files
+exitHook(() => {
+    console.log('exiting 2');
+});
+
+// you can add async hooks by accepting a callback
+exitHook(callback => {
+    setTimeout(() => {
+        console.log('exiting 3');
+        callback();
+    }, 1000);
+});
+
+// You can hook uncaught errors with uncaughtExceptionHandler(), consequently adding 
+// async support to uncaught errors (normally uncaught errors result in a synchronous exit).
+exitHook.uncaughtExceptionHandler(err => {
+    console.error(err);
+});
+
+// You can hook unhandled rejections with unhandledRejectionHandler()
+exitHook.unhandledRejectionHandler(err => {
+    console.error(err);
+});
+
+// You can add multiple uncaught error handlers
+// Add the second parameter (callback) to indicate async hooks
+exitHook.uncaughtExceptionHandler((err, callback) => {
+    sendErrorToCloudOrWhatever(err) // Returns promise
+        .then(() => { 
+             console.log('Sent err to cloud'); 
+         });
+        .catch(sendError => {
+             console.error('Error sending to cloud: ', err.stack));
+        })
+        .then(() => callback);
+    });
+});
+
+// Add exit hooks for a signal or custom message:
+
+// Custom signal
+// Arguments are `signal, exitCode` (SIGBREAK is already handled, this is an example)
+exitHook.hookEvent('SIGBREAK', 21);
+
+// process event: `message` with a filter
+// filter gets all arguments passed to *handler*: `process.on(message, *handler*)`
+// Exits on process event `message` with msg `customShutdownMessage` only
+exitHook.hookEvent('message', 0, msg => msg !== 'customShutdownMessage');
+
+// All async hooks will work with uncaught errors when you have specified an uncaughtExceptionHandler
+throw new Error('awesome');
+
+//=> // Sync uncaughtExcpetion hooks called and retun
+//=> '[Error: awesome]'
+//=> // Sync hooks called and retun
+//=> 'exiting'
+//=> 'exiting 2'
+//=> // Async uncaughtException hooks return
+//=> 'Sent error to cloud'
+//=> // Sync uncaughtException hooks return
+//=> 'exiting 3'
+```
+
+
+## License
+
+MIT © Tapani Moilanen  
+MIT © [Sindre Sorhus](http://sindresorhus.com)