A simple way to wrap a single-instance module to enable it to work with node cluster.
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'use strict';
function getInstanceMethods(inst) {
var instanceMethods = Object.keys(inst)
.map(function (key) { return 'function' === typeof inst[key] ? key : null; })
.filter(function (key) { return key; })
;
var protoMethods = Object.keys(Object.getPrototypeOf(inst))
.map(function (key) { return 'function' === typeof Object.getPrototypeOf(inst)[key] ? key : null; })
.filter(function (key) { return key; })
;
return instanceMethods.concat(protoMethods);
}
function getMethods(inst, keys) {
if (!keys) {
keys = getInstanceMethods(inst);
}
return keys.filter(function (key) {
if ('function' === typeof inst[key]) {
return true;
}
});
}
function setup(opts) {
var crypto = require('crypto');
var methods = getMethods(opts.instance, opts.methods);
var token = crypto.randomBytes(16).toString('hex');
var inst = opts.instance;
var prefixes = require('./prefixes.js').create(opts); // uses opts.name
opts.master = opts.master || require('./process/master').create(prefixes);
opts.master.on('connection', function (w) {
if (opts.debug) { console.log('[cluster-rpc] [master] worker connected'); }
w.send({
methods: methods
, _token: token
, type: prefixes.init
});
w.on('message', function (cmd) {
if (0 !== (cmd.type||'').indexOf(prefixes.root)) {
//console.log('debug w: got unknown message type');
return;
}
if (token !== cmd._token) {
//console.log('debug w: got bad token');
return;
}
if (!Array.isArray(cmd.args)) {
throw new Error("[Sanity Fail] 'args' should be array of arguments");
}
switch (cmd.type) {
case prefixes.rpc:
cmd.args.push(function callback() {
// args is probably err, data in most cases
var args = Array.prototype.slice.call(arguments);
w.send({
args: args
, id: cmd.id
//, this: this
, _token: token
, type: prefixes.result
});
});
inst[cmd.func].apply(inst, cmd.args);
break;
default:
throw new Error("cluster-ipc UNKNOWN TYPE");
//break;
}
});
});
}
module.exports.create = function (opts) {
if (opts.debug) { console.log('[cluster-rpc] [master] create'); }
var cluster = require('cluster');
var PromiseA = opts.PromiseA || global.Promise || require('bluebird');
var init = false;
opts._promise = PromiseA.resolve(opts.instance);
opts._promise.addWorker = function (w) {
if (opts.debug) { console.log('[cluster-rpc] [master] addWorker wrapper'); }
if (!init) {
init = true;
setup(opts);
}
return opts.master.addWorker(w);
};
if (false !== opts.addOnFork) {
if (opts.debug) { console.log('[cluster-rpc] [master] -- will call addWorker on each fork'); }
cluster.on('fork', opts._promise.addWorker);
}
return opts._promise;
};