Mailspring/internal_packages/worker-sync/lib/delta-streaming-connection.es6
Juan Tejada 3dccb374b3 fix(search/long-conn): Process results buffer before ending connection (#750)
NylasLongConnection ends the connection when the 'end' event is emitted
by the `request` object. When this happens, the global connection buffer is cleared.
Also, the global buffer holds the data we've received from the connection, and
whenever we receive new data, we accumulate it in the buffer and call a processBuffer function
which is throttled to 400ms.

Given that the buffer is global state, and processing occurs
asynchronously with a delay of up to 400ms, if the 'end' event on the connection is
fired before we actually get to process the buffer, we would clear it and show no results.

This scenario currently only affected search because if we accidentally
threw away some data when streaming deltas, we will get that data again
when we reopen the delta streaming connection.
2016-09-22 12:08:59 -07:00

77 lines
2.1 KiB
JavaScript

import _ from 'underscore'
import {NylasLongConnection, DatabaseStore} from 'nylas-exports'
const {Status} = NylasLongConnection
class DeltaStreamingConnection extends NylasLongConnection {
constructor(api, accountId, opts = {}) {
opts.debounceResultsInterval = 1000
opts.closeIfDataStopsInterval = 15 * 1000
super(api, accountId, opts)
const {isReady, getCursor, setCursor} = opts
this._isReady = isReady
this._getCursor = getCursor
this._setCursor = setCursor
// Update cursor when deltas received
this.onDeltas((deltas) => {
const last = _.last(deltas)
this._setCursor(last.cursor)
})
}
deltaStreamingPath(cursor) {
return `/delta/streaming?cursor=${cursor}&exclude_folders=false&exclude_metadata=false&exclude_account=false`
}
hasCursor() {
return !!this._getCursor()
}
onError(err) {
if (err.message.indexOf('Invalid cursor') > 0) {
const error = new Error('Delta Connection: Cursor is invalid. Need to blow away local cache.')
NylasEnv.config.unset(`nylas.${this._accountId}.cursor`)
DatabaseStore._handleSetupError(error)
}
}
latestCursor() {
const cursor = this._getCursor()
if (cursor) { return Promise.resolve(cursor) }
return this._api.makeRequest({
path: "/delta/latest_cursor",
accountId: this._accountId,
method: 'POST',
})
.then((result) => {
console.log(`Obtained stream cursor ${result.cursor}.`)
this._setCursor(result.cursor)
return Promise.resolve(result.cursor)
})
}
onDeltas(callback) {
return this.onResults(callback)
}
start() {
if (!this._isReady()) { return }
if (!this.canStart()) { return }
if (this._req != null) { return }
this.latestCursor().then((cursor) => {
if (this._status === Status.Ended) { return }
this._path = this.deltaStreamingPath(cursor)
super.start()
})
.catch((error) => {
console.error(`Can't establish DeltaStreamingConnection: Error fetching latest cursor`, error)
})
}
}
export default DeltaStreamingConnection