/*!
* child.js - child processes for bcoin
* Copyright (c) 2014-2017, Christopher Jeffrey (MIT License).
* https://github.com/bcoin-org/bcoin
*/
'use strict';
const EventEmitter = require('events');
const path = require('path');
const cp = require('child_process');
const children = new Set();
let exitBound = false;
/**
* Child
* Represents a child process.
* @alias module:workers.Child
* @extends EventEmitter
* @ignore
*/
class Child extends EventEmitter {
/**
* Represents a child process.
* @constructor
* @param {String} file
*/
constructor(file) {
super();
bindExit();
children.add(this);
this.init(file);
}
/**
* Test whether child process support is available.
* @returns {Boolean}
*/
static hasSupport() {
return true;
}
/**
* Initialize child process (node.js).
* @private
* @param {String} file
*/
init(file) {
const bin = process.argv[0];
const filename = path.resolve(__dirname, file);
const options = { stdio: 'pipe', env: process.env };
this.child = cp.spawn(bin, [filename], options);
this.child.unref();
this.child.stdin.unref();
this.child.stdout.unref();
this.child.stderr.unref();
this.child.on('error', (err) => {
this.emit('error', err);
});
this.child.once('exit', (code, signal) => {
children.delete(this);
this.emit('exit', code == null ? -1 : code, signal);
});
this.child.stdin.on('error', (err) => {
this.emit('error', err);
});
this.child.stdout.on('error', (err) => {
this.emit('error', err);
});
this.child.stderr.on('error', (err) => {
this.emit('error', err);
});
this.child.stdout.on('data', (data) => {
this.emit('data', data);
});
}
/**
* Send data to child process.
* @param {Buffer} data
* @returns {Boolean}
*/
write(data) {
return this.child.stdin.write(data);
}
/**
* Destroy the child process.
*/
destroy() {
this.child.kill('SIGTERM');
}
}
/**
* Cleanup all child processes.
* @private
*/
function bindExit() {
if (exitBound)
return;
exitBound = true;
listenExit(() => {
for (const child of children)
child.destroy();
});
}
/**
* Listen for exit.
* @param {Function} handler
* @private
*/
function listenExit(handler) {
const onSighup = () => {
process.exit(1 | 0x80);
};
const onSigint = () => {
process.exit(2 | 0x80);
};
const onSigterm = () => {
process.exit(15 | 0x80);
};
const onError = (err) => {
if (err && err.stack)
console.error(String(err.stack));
else
console.error(String(err));
process.exit(1);
};
process.once('exit', handler);
if (process.listenerCount('SIGHUP') === 0)
process.once('SIGHUP', onSighup);
if (process.listenerCount('SIGINT') === 0)
process.once('SIGINT', onSigint);
if (process.listenerCount('SIGTERM') === 0)
process.once('SIGTERM', onSigterm);
if (process.listenerCount('uncaughtException') === 0)
process.once('uncaughtException', onError);
process.on('newListener', (name) => {
switch (name) {
case 'SIGHUP':
process.removeListener(name, onSighup);
break;
case 'SIGINT':
process.removeListener(name, onSigint);
break;
case 'SIGTERM':
process.removeListener(name, onSigterm);
break;
case 'uncaughtException':
process.removeListener(name, onError);
break;
}
});
}
/*
* Expose
*/
module.exports = Child;