From 45c70c29e572de3e9ca24d993f0616fd31f05029 Mon Sep 17 00:00:00 2001
From: Alex Dima <alexdima@microsoft.com>
Date: Fri, 4 Sep 2020 01:19:38 +0200
Subject: [PATCH] Fixes #83672

---
 src/vs/base/parts/ipc/common/ipc.net.ts | 73 ++++++++++++++++++++++---
 1 file changed, 65 insertions(+), 8 deletions(-)

diff --git a/src/vs/base/parts/ipc/common/ipc.net.ts b/src/vs/base/parts/ipc/common/ipc.net.ts
index c3fede90bf31e..bc8e97c269cce 100644
--- a/src/vs/base/parts/ipc/common/ipc.net.ts
+++ b/src/vs/base/parts/ipc/common/ipc.net.ts
@@ -533,6 +533,53 @@ class Queue<T> {
 	}
 }
 
+class LoadEstimator {
+
+	private static _HISTORY_LENGTH = 10;
+	private static _INSTANCE: LoadEstimator | null = null;
+	public static getInstance(): LoadEstimator {
+		if (!LoadEstimator._INSTANCE) {
+			LoadEstimator._INSTANCE = new LoadEstimator();
+		}
+		return LoadEstimator._INSTANCE;
+	}
+
+	private lastRuns: number[];
+
+	constructor() {
+		this.lastRuns = [];
+		const now = Date.now();
+		for (let i = 0; i < LoadEstimator._HISTORY_LENGTH; i++) {
+			this.lastRuns[i] = now - 1000 * i;
+		}
+		setInterval(() => {
+			for (let i = LoadEstimator._HISTORY_LENGTH; i >= 1; i--) {
+				this.lastRuns[i] = this.lastRuns[i - 1];
+			}
+			this.lastRuns[0] = Date.now();
+		}, 1000);
+	}
+
+	/**
+	 * returns an estimative number, from 0 (low load) to 1 (high load)
+	 */
+	public load(): number {
+		const now = Date.now();
+		const historyLimit = (1 + LoadEstimator._HISTORY_LENGTH) * 1000;
+		let score = 0;
+		for (let i = 0; i < LoadEstimator._HISTORY_LENGTH; i++) {
+			if (now - this.lastRuns[i] <= historyLimit) {
+				score++;
+			}
+		}
+		return 1 - score / LoadEstimator._HISTORY_LENGTH;
+	}
+
+	public hasHighLoad(): boolean {
+		return this.load() >= 0.5;
+	}
+}
+
 /**
  * Same as Protocol, but will actually track messages and acks.
  * Moreover, it will ensure no messages are lost if there are no event listeners.
@@ -559,6 +606,8 @@ export class PersistentProtocol implements IMessagePassingProtocol {
 	private _socketReader: ProtocolReader;
 	private _socketDisposables: IDisposable[];
 
+	private readonly _loadEstimator = LoadEstimator.getInstance();
+
 	private readonly _onControlMessage = new BufferedEmitter<VSBuffer>();
 	readonly onControlMessage: Event<VSBuffer> = this._onControlMessage.event;
 
@@ -670,15 +719,19 @@ export class PersistentProtocol implements IMessagePassingProtocol {
 
 		const timeSinceLastIncomingMsg = Date.now() - this._socketReader.lastReadTime;
 		if (timeSinceLastIncomingMsg >= ProtocolConstants.KeepAliveTimeoutTime) {
-			// Trash the socket
-			this._onSocketTimeout.fire(undefined);
-			return;
+			// It's been a long time since we received a server message
+			// But this might be caused by the event loop being busy and failing to read messages
+			if (!this._loadEstimator.hasHighLoad()) {
+				// Trash the socket
+				this._onSocketTimeout.fire(undefined);
+				return;
+			}
 		}
 
 		this._incomingKeepAliveTimeout = setTimeout(() => {
 			this._incomingKeepAliveTimeout = null;
 			this._recvKeepAliveCheck();
-		}, ProtocolConstants.KeepAliveTimeoutTime - timeSinceLastIncomingMsg + 5);
+		}, Math.max(ProtocolConstants.KeepAliveTimeoutTime - timeSinceLastIncomingMsg, 0) + 5);
 	}
 
 	public getSocket(): ISocket {
@@ -821,15 +874,19 @@ export class PersistentProtocol implements IMessagePassingProtocol {
 		const oldestUnacknowledgedMsg = this._outgoingUnackMsg.peek()!;
 		const timeSinceOldestUnacknowledgedMsg = Date.now() - oldestUnacknowledgedMsg.writtenTime;
 		if (timeSinceOldestUnacknowledgedMsg >= ProtocolConstants.AcknowledgeTimeoutTime) {
-			// Trash the socket
-			this._onSocketTimeout.fire(undefined);
-			return;
+			// It's been a long time since our sent message was acknowledged
+			// But this might be caused by the event loop being busy and failing to read messages
+			if (!this._loadEstimator.hasHighLoad()) {
+				// Trash the socket
+				this._onSocketTimeout.fire(undefined);
+				return;
+			}
 		}
 
 		this._outgoingAckTimeout = setTimeout(() => {
 			this._outgoingAckTimeout = null;
 			this._recvAckCheck();
-		}, ProtocolConstants.AcknowledgeTimeoutTime - timeSinceOldestUnacknowledgedMsg + 5);
+		}, Math.max(ProtocolConstants.AcknowledgeTimeoutTime - timeSinceOldestUnacknowledgedMsg, 0) + 5);
 	}
 
 	private _sendAck(): void {