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import logger from "./logger"
// Responsible for ensuring the cable connection is in good health by validating the heartbeat pings sent from the server, and attempting
// revival reconnections if things go astray. Internal class, not intended for direct user manipulation.
const now = () => new Date().getTime()
const secondsSince = time => (now() - time) / 1000
const clamp = (number, min, max) => Math.max(min, Math.min(max, number))
class ConnectionMonitor {
constructor(connection) {
this.visibilityDidChange = this.visibilityDidChange.bind(this)
this.connection = connection
this.reconnectAttempts = 0
}
start() {
if (!this.isRunning()) {
this.startedAt = now()
delete this.stoppedAt
this.startPolling()
addEventListener("visibilitychange", this.visibilityDidChange)
logger.log(`ConnectionMonitor started. pollInterval = ${this.getPollInterval()} ms`)
}
}
stop() {
if (this.isRunning()) {
this.stoppedAt = now()
this.stopPolling()
removeEventListener("visibilitychange", this.visibilityDidChange)
logger.log("ConnectionMonitor stopped")
}
}
isRunning() {
return this.startedAt && !this.stoppedAt
}
recordPing() {
this.pingedAt = now()
}
recordConnect() {
this.reconnectAttempts = 0
this.recordPing()
delete this.disconnectedAt
logger.log("ConnectionMonitor recorded connect")
}
recordDisconnect() {
this.disconnectedAt = now()
logger.log("ConnectionMonitor recorded disconnect")
}
// Private
startPolling() {
this.stopPolling()
this.poll()
}
stopPolling() {
clearTimeout(this.pollTimeout)
}
poll() {
this.pollTimeout = setTimeout(() => {
this.reconnectIfStale()
this.poll()
}
, this.getPollInterval())
}
getPollInterval() {
const {min, max, multiplier} = this.constructor.pollInterval
const interval = multiplier * Math.log(this.reconnectAttempts + 1)
return Math.round(clamp(interval, min, max) * 1000)
}
reconnectIfStale() {
if (this.connectionIsStale()) {
logger.log(`ConnectionMonitor detected stale connection. reconnectAttempts = ${this.reconnectAttempts}, pollInterval = ${this.getPollInterval()} ms, time disconnected = ${secondsSince(this.disconnectedAt)} s, stale threshold = ${this.constructor.staleThreshold} s`)
this.reconnectAttempts++
if (this.disconnectedRecently()) {
logger.log("ConnectionMonitor skipping reopening recent disconnect")
} else {
logger.log("ConnectionMonitor reopening")
this.connection.reopen()
}
}
}
connectionIsStale() {
return secondsSince(this.pingedAt ? this.pingedAt : this.startedAt) > this.constructor.staleThreshold
}
disconnectedRecently() {
return this.disconnectedAt && (secondsSince(this.disconnectedAt) < this.constructor.staleThreshold)
}
visibilityDidChange() {
if (document.visibilityState === "visible") {
setTimeout(() => {
if (this.connectionIsStale() || !this.connection.isOpen()) {
logger.log(`ConnectionMonitor reopening stale connection on visibilitychange. visbilityState = ${document.visibilityState}`)
this.connection.reopen()
}
}
, 200)
}
}
}
ConnectionMonitor.pollInterval = {
min: 3,
max: 30,
multiplier: 5
}
ConnectionMonitor.staleThreshold = 6 // Server::Connections::BEAT_INTERVAL * 2 (missed two pings)
export default ConnectionMonitor
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