feat: use a nanotimer in socket child for ack'ing

src/lib/atemSocketChild.ts

@@ -3,12 +3,14 @@ import { EventEmitter } from 'events'
 import { format } from 'util'
 import { Util } from './atemUtil'
 import { ConnectionState, IPCMessageType, PacketFlag } from '../enums'
+import * as NanoTimer from 'nanotimer'
 
 export class AtemSocketChild extends EventEmitter {
 	private _connectionState = ConnectionState.Closed
 	private _debug = false
 	private _reconnectTimer: NodeJS.Timer | undefined
-	private _retransmitTimer: NodeJS.Timer | undefined
+	// private _retransmitTimer: NodeJS.Timer | undefined
+	private _retransmitTimer = new NanoTimer()
 
 	private _localPacketId = 1
 	private _maxPacketID = (1 << 15) - 1 // Atem expects 15 not 16 bits before wrapping
@@ -19,12 +21,15 @@ export class AtemSocketChild extends EventEmitter {
 	private _socket: Socket
 	private _reconnectInterval = 5000
 
-	private _inFlightTimeout = 100
+	// private _inFlightTimeout = 100
+	private _inFlightTimeout = 30
 	private _maxRetries = 5
 	private _lastReceivedAt: number = Date.now()
 	private _lastReceivedPacketId = 0
 	private _inFlight: Array<{packetId: number, trackingId: number, lastSent: number, packet: Buffer, resent: number}> = []
-	// private _ackTimer: NodeJS.Timer | null
+	private _ackTimer = new NanoTimer()
+	private _hasTimeout = false
+	private _receivedWithoutAck = 0
 
 	constructor (options: { address?: string, port?: number } = {}) {
 		super()
@@ -51,7 +56,8 @@ export class AtemSocketChild extends EventEmitter {
 			}, this._reconnectInterval)
 		}
 		if (!this._retransmitTimer) {
-			this._retransmitTimer = setInterval(() => this._checkForRetransmit(), 50)
+			// this._retransmitTimer = setInterval(() => this._checkForRetransmit(), 50)
+			this._retransmitTimer.setInterval(() => this._checkForRetransmit(), '', 10)
 		}
 
 		if (address) {
@@ -149,7 +155,7 @@ export class AtemSocketChild extends EventEmitter {
 		if (flags & PacketFlag.AckRequest) {
 			if (this._connectionState === ConnectionState.Established) {
 				if (remotePacketId === (this._lastReceivedPacketId + 1) % this._maxPacketID) {
-					this._sendAck(remotePacketId)
+					this._attemptAck(remotePacketId)
 					this._lastReceivedPacketId = remotePacketId
 				} else {
 					return
@@ -184,21 +190,23 @@ export class AtemSocketChild extends EventEmitter {
 		this._socket.send(packet, 0, packet.length, this._port, this._address)
 	}
 
-	// private _attemptAck (packetId: number) {
-	// 	if (this._lastReceivedPacketId && packetId !== (this._lastReceivedPacketId + 1) % this._maxPacketID) return false
-	// 	this._lastReceivedPacketId = packetId
-	// 	this._receivedWithoutAck++
-	// 	if (this._receivedWithoutAck === 16) {
-	// 		this._receivedWithoutAck = 0
-	// 		this._ackTimer = null
-	// 		this._sendAck(this._lastReceivedPacketId)
-	// 	} else if (!this._ackTimer) this._ackTimer = setTimeout(() => {
-	// 		this._receivedWithoutAck = 0
-	// 		this._ackTimer = null
-	// 		this._sendAck(this._lastReceivedPacketId)
-	// 	}, 0)
-	// 	return true
-	// }
+	private _attemptAck (packetId: number) {
+		this._lastReceivedPacketId = packetId
+		this._receivedWithoutAck++
+		if (this._receivedWithoutAck === 16) {
+			this._receivedWithoutAck = 0
+			this._hasTimeout = false
+			this._ackTimer.clearTimeout()
+			this._sendAck(this._lastReceivedPacketId)
+		} else if (!this._hasTimeout) {
+			this._hasTimeout = true
+			this._ackTimer.setTimeout(() => {
+				this._receivedWithoutAck = 0
+				this._hasTimeout = false
+				this._sendAck(this._lastReceivedPacketId)
+			}, '', '5ms')
+		}
+	}
 
 	private _sendAck (packetId: number) {
 		const buffer = new Buffer(12)