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import jsonrpc from 'jsonrpc-lite';
import uuid from 'uuid';
import log from 'electron-log';
export default class Ipc {
constructor(connectionString) {
this._connectionString = connectionString;
this._onConnect = [];
this._unansweredRequests = {};
this._subscriptions = {};
this._backoff = new ReconnectionBackoff();
this._reconnect();
}
on(event, listener) {
// We're currently not actually using the event parameter.
// This is because we aren't sure if the backend will use
// one subscription per event or one subscription per
// event source.
log.info('Adding a listener to', event);
this.send('event_subscribe')
.then(subscriptionId => this._subscriptions[subscriptionId] = listener);
}
send(action, ...data) {
return this._getWebSocket()
.then(ws => this._send(ws, action, data))
.catch(e => {
log.error('Failed sending RPC message "' + action + '":', e);
throw e;
});
}
_getWebSocket() {
return new Promise(resolve => {
if (this._websocket.readyState === 1) { // Connected
resolve(this._websocket);
} else {
log.debug('Waiting for websocket to connect');
this._onConnect.push({
resolve: () => resolve(this._websocket),
});
}
});
}
_send(websocket, action, data) {
return new Promise((resolve, reject) => {
const id = uuid.v4();
const jsonrpcMessage = jsonrpc.request(id, action, data);
this._unansweredRequests[id] = {resolve: resolve, reject: reject};
log.debug('Sending message', id, action);
websocket.send(jsonrpcMessage);
});
}
_onMessage(message) {
const json = JSON.parse(message);
const c = jsonrpc.parseObject(json);
if (c.type === 'notification') {
this._onNotification(c);
} else {
this._onReply(c);
}
}
_onNotification(message) {
const subscriptionId = message.payload.params.subscription;
const listener = this._subscriptions[subscriptionId];
if (listener) {
log.debug('Got notification', message.payload.method, message.payload.params.result);
listener(message.payload.params.result);
} else {
log.warn('Got notification for', message.payload.method, 'but no one is listening for it');
}
}
_onReply(message) {
const id = message.payload.id;
const request = this._unansweredRequests[id];
delete this._unansweredRequests[id];
if (!request) {
log.warn('Got reply to', id, 'but no one was waiting for it');
return;
}
log.debug('Got answer to', id, message.type);
if (message.type === 'error') {
request.reject(message.payload.error.message);
} else {
const reply = message.payload.result;
request.resolve(reply);
}
}
_reconnect() {
if (!this._connectionString) return;
log.info('Connecting to websocket', this._connectionString);
this._websocket = new WebSocket(this._connectionString);
this._websocket.onopen = () => {
log.debug('Websocket is connected');
this._backoff.successfullyConnected();
while(this._onConnect.length > 0) {
this._onConnect.pop().resolve();
}
};
this._websocket.onmessage = (evt) => {
this._onMessage(evt.data);
};
this._websocket.onclose = () => {
const delay = this._backoff.getIncreasedBackoff();
log.warn('The websocket connetion closed, attempting to reconnect it in', delay, 'milliseconds');
setTimeout(() => this._reconnect(), delay);
};
}
}
/*
* Used to calculate the time to wait before reconnecting
* the websocket.
*
* It uses a linear backoff function that goes from 500ms
* to 3000ms
*/
class ReconnectionBackoff {
constructor() {
this._attempt = 0;
}
successfullyConnected() {
this._attempt = 0;
}
getIncreasedBackoff() {
if (this._attempt < 6) {
this._attempt++;
}
return this._attempt * 500;
}
}
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