concern
Version:
A library for seperating your application logic into concerns.
89 lines (60 loc) • 2.19 kB
JavaScript
import ChildProcess from 'child_process';
import beof from 'beof';
import Address from '../Address';
import RefState from '../RefState';
import Concern from '../Concern';
import ChildStateProvider from './ChildStateProvider';
import ChildReference from './ChildReference';
import SpawnChildProcessError from './SpawnChildProcessError';
import StateProvider from '../StateProvider';
/**
* ChildReferenceProvider provides a Reference for a Concern
* running on a child process.
* @implements {ReferenceProvider}
*/
class ChildReferenceProvider {
constructor() {
this._cache = {};
this._list = {};
}
/**
* getProcessList returns a map of child process
* created by this provider.
* @return {object}
*/
getProcessList() {
return this._list;
}
select(path, context) {
var addr = Address.fromString(path);
var concern = new Concern();
var child;
var provider;
if (this._cache.hasOwnProperty(path))
return this._cache[path];
//@todo move to validator class
if (typeof addr.uri.hash !== 'string')
throw new ReferenceError('A child process uri must have a path and hash part!');
if (this._list.hasOwnProperty(addr.uri.path)) {
child = this._list[addr.uri.path];
} else {
try {
child = ChildProcess.fork(addr.uri.path);
this._list[addr.uri.path] = child;
} catch (e) {
context.publish(new SpawnChildProcessError(e));
return new Reference(new RefState.UnknownState(
path, concern, context, new StateProvider()));
}
}
provider = new ChildStateProvider(path, addr.uri.hash.substring(1), child);
return this._cache[path] = new ChildReference(
provider.provide(RefState.ACTIVE_STATE, concern, context),
path, addr.uri.hash.substring(1), concern, context, provider, child);
}
reselect(path, context) {
this._cache[path] = null;
return this.select(path, context);
}
}
export default ChildReferenceProvider