Spaces:
Build error
Build error
File size: 4,358 Bytes
30c32c8 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 |
const SharedDispatch = require('./shared-dispatch');
const log = require('../util/log');
const {centralDispatchService} = require('../extension-support/tw-extension-worker-context');
/**
* This class provides a Worker with the means to participate in the message dispatch system managed by CentralDispatch.
* From any context in the messaging system, the dispatcher's "call" method can call any method on any "service"
* provided in any participating context. The dispatch system will forward function arguments and return values across
* worker boundaries as needed.
* @see {CentralDispatch}
*/
class WorkerDispatch extends SharedDispatch {
constructor () {
super();
/**
* This promise will be resolved when we have successfully connected to central dispatch.
* @type {Promise}
* @see {waitForConnection}
* @private
*/
this._connectionPromise = new Promise(resolve => {
this._onConnect = resolve;
});
/**
* Map of service name to local service provider.
* If a service is not listed here, it is assumed to be provided by another context (another Worker or the main
* thread).
* @see {setService}
* @type {object}
*/
this.services = {};
this._onMessage = this._onMessage.bind(this, centralDispatchService);
if (typeof self !== 'undefined') {
self.onmessage = this._onMessage;
}
}
/**
* @returns {Promise} a promise which will resolve upon connection to central dispatch. If you need to make a call
* immediately on "startup" you can attach a 'then' to this promise.
* @example
* dispatch.waitForConnection.then(() => {
* dispatch.call('myService', 'hello');
* })
*/
get waitForConnection () {
return this._connectionPromise;
}
/**
* Set a local object as the global provider of the specified service.
* WARNING: Any method on the provider can be called from any worker within the dispatch system.
* @param {string} service - a globally unique string identifying this service. Examples: 'vm', 'gui', 'extension9'.
* @param {object} provider - a local object which provides this service.
* @returns {Promise} - a promise which will resolve once the service is registered.
*/
setService (service, provider) {
if (this.services.hasOwnProperty(service)) {
log.warn(`Worker dispatch replacing existing service provider for ${service}`);
}
this.services[service] = provider;
return this.waitForConnection.then(() => (
this._remoteCall(centralDispatchService, 'dispatch', 'setService', service)
));
}
/**
* Fetch the service provider object for a particular service name.
* @override
* @param {string} service - the name of the service to look up
* @returns {{provider:(object|Worker), isRemote:boolean}} - the means to contact the service, if found
* @protected
*/
_getServiceProvider (service) {
// if we don't have a local service by this name, contact central dispatch by calling `postMessage` on self
const provider = this.services[service];
return {
provider: provider || centralDispatchService,
isRemote: !provider
};
}
/**
* Handle a call message sent to the dispatch service itself
* @override
* @param {Worker} worker - the worker which sent the message.
* @param {DispatchCallMessage} message - the message to be handled.
* @returns {Promise|undefined} - a promise for the results of this operation, if appropriate
* @protected
*/
_onDispatchMessage (worker, message) {
let promise;
switch (message.method) {
case 'handshake':
promise = this._onConnect();
break;
case 'terminate':
// Don't close until next tick, after sending confirmation back
setTimeout(() => self.close(), 0);
promise = Promise.resolve();
break;
default:
log.error(`Worker dispatch received message for unknown method: ${message.method}`);
}
return promise;
}
}
module.exports = new WorkerDispatch();
|