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154 lines
4.1 KiB
JavaScript

var RSVP = require('rsvp');
var exit;
var handlers = [];
var lastTime;
var isExiting = false;
process.on('beforeExit', function (code) {
if (handlers.length === 0) { return; }
var own = lastTime = module.exports._flush(lastTime, code)
.finally(function () {
// if an onExit handler has called process.exit, do not disturb
// `lastTime`.
//
// Otherwise, clear `lastTime` so that we know to synchronously call the
// real `process.exit` with the given exit code, when our captured
// `process.exit` is called during a `process.on('exit')` handler
//
// This is impossible to reason about, don't feel bad. Just look at
// test-natural-exit-subprocess-error.js
if (own === lastTime) {
lastTime = undefined;
}
});
});
// This exists only for testing
module.exports._reset = function () {
module.exports.releaseExit();
handlers = [];
lastTime = undefined;
isExiting = false;
firstExitCode = undefined;
}
/*
* To allow cooperative async exit handlers, we unfortunately must hijack
* process.exit.
*
* It allows a handler to ensure exit, without that exit handler impeding other
* similar handlers
*
* for example, see: https://github.com/sindresorhus/ora/issues/27
*
*/
module.exports.releaseExit = function() {
if (exit) {
process.exit = exit;
exit = null;
}
};
var firstExitCode;
module.exports.captureExit = function() {
if (exit) {
// already captured, no need to do more work
return;
}
exit = process.exit;
process.exit = function(code) {
if (handlers.length === 0 && lastTime === undefined) {
// synchronously exit.
//
// We do this brecause either
//
// 1. The process exited due to a call to `process.exit` but we have no
// async work to do because no handlers had been attached. It
// doesn't really matter whether we take this branch or not in this
// case.
//
// 2. The process exited naturally. We did our async work during
// `beforeExit` and are in this function because someone else has
// called `process.exit` during an `on('exit')` hook. The only way
// for us to preserve the exit code in this case is to exit
// synchronously.
//
return exit.call(process, code);
}
if (firstExitCode === undefined) {
firstExitCode = code;
}
var own = lastTime = module.exports._flush(lastTime, firstExitCode)
.then(function() {
// if another chain has started, let it exit
if (own !== lastTime) { return; }
exit.call(process, firstExitCode);
})
.catch(function(error) {
// if another chain has started, let it exit
if (own !== lastTime) {
throw error;
}
console.error(error);
exit.call(process, 1);
});
};
};
module.exports._handlers = handlers;
module.exports._flush = function(lastTime, code) {
isExiting = true;
var work = handlers.splice(0, handlers.length);
return RSVP.Promise.resolve(lastTime).
then(function() {
var firstRejected;
return RSVP.allSettled(work.map(function(handler) {
return RSVP.resolve(handler.call(null, code)).catch(function(e) {
if (!firstRejected) {
firstRejected = e;
}
throw e;
});
})).then(function(results) {
if (firstRejected) {
throw firstRejected;
}
});
});
};
module.exports.onExit = function(cb) {
if (!exit) {
throw new Error('Cannot install handler when exit is not captured. Call `captureExit()` first');
}
if (isExiting) {
throw new Error('Cannot install handler while `onExit` handlers are running.');
}
var index = handlers.indexOf(cb);
if (index > -1) { return; }
handlers.push(cb);
};
module.exports.offExit = function(cb) {
var index = handlers.indexOf(cb);
if (index < 0) { return; }
handlers.splice(index, 1);
};
module.exports.exit = function() {
exit.apply(process, arguments);
};
module.exports.listenerCount = function() {
return handlers.length;
};