From 06d1c0992dc66d7f2b73bfbbcbae0138c574880a Mon Sep 17 00:00:00 2001
From: Quinn Slack <quinn@slack.org>
Date: Sun, 15 Sep 2024 16:22:19 -0700
Subject: [PATCH] reduce background network access (#5566)

Skip the UpstreamHealthProviderCheck if the window is not focused, and
try again when the window becomes focused again. Some users have OS
firewalls that make periodic background network access annoying for
users. See
https://linear.app/sourcegraph/issue/CODY-3745/codys-background-periodic-network-access-causes-2fa.

This check is used to gather latency information to properly measure
actual latency for autocomplete. As long as the user has VS Code focused
for slightly more than 10 seconds, it will still gather the necessary
latency information for these calculations.

Fixes
https://linear.app/sourcegraph/issue/CODY-3745/codys-background-periodic-network-access-causes-2fa



## Test plan

Open VS Code and check logs for the UpstreamHealthProvider call. Ensure
that it does not trigger when the window is not focused, and then it
triggers within 10 seconds of being focused after that.

## Changelog

Suppressed Cody's background process for monitoring latency to the
Sourcegraph endpoint, which was used to calculate autocomplete latency
for performance tracking purposes. For users with OS firewalls that
notify on background network access, this will reduce notification
annoyance.
---
 vscode/src/services/UpstreamHealthProvider.ts | 40 ++++++++++++++++---
 vscode/src/testutils/mocks.ts                 |  2 +
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/vscode/src/services/UpstreamHealthProvider.ts b/vscode/src/services/UpstreamHealthProvider.ts
index 2f44b9518edf..4ddc79ff8338 100644
--- a/vscode/src/services/UpstreamHealthProvider.ts
+++ b/vscode/src/services/UpstreamHealthProvider.ts
@@ -10,7 +10,7 @@ import {
     wrapInActiveSpan,
 } from '@sourcegraph/cody-shared'
 import { fetch } from '@sourcegraph/cody-shared'
-import type * as vscode from 'vscode'
+import * as vscode from 'vscode'
 
 // We choose an interval that gives us a reasonable aggregate without causing
 // too many requests
@@ -27,12 +27,25 @@ class UpstreamHealthProvider implements vscode.Disposable {
     private lastUpstreamLatency?: number
     private lastGatewayLatency?: number
 
+    private disposables: vscode.Disposable[] = []
+
     private config: Pick<
         ClientConfigurationWithAccessToken,
         'serverEndpoint' | 'customHeaders' | 'accessToken'
     > | null = null
     private nextTimeoutId: NodeJS.Timeout | null = null
 
+    constructor() {
+        this.disposables.push(
+            vscode.window.onDidChangeWindowState(state => {
+                if (state.focused && this.lastMeasurementSkippedBecauseNotFocused) {
+                    this.lastMeasurementSkippedBecauseNotFocused = false
+                    this.enqueue(INITIAL_PING_DELAY_MS)
+                }
+            })
+        )
+    }
+
     public getUpstreamLatency(): number | undefined {
         if (!this.config) {
             return undefined
@@ -60,12 +73,18 @@ class UpstreamHealthProvider implements vscode.Disposable {
         // Enqueue the initial ping after a config change in 10 seconds. This
         // avoids running the test while the extension is still initializing and
         // competing with many other network requests.
+        this.enqueue(INITIAL_PING_DELAY_MS)
+    }
+
+    private enqueue(delay: number): void {
         if (this.nextTimeoutId) {
             clearTimeout(this.nextTimeoutId)
         }
-        this.nextTimeoutId = setTimeout(this.measure.bind(this), INITIAL_PING_DELAY_MS)
+        this.nextTimeoutId = setTimeout(this.measure.bind(this), delay)
     }
 
+    private lastMeasurementSkippedBecauseNotFocused = false
+
     private async measure() {
         if (this.nextTimeoutId) {
             clearTimeout(this.nextTimeoutId)
@@ -76,6 +95,15 @@ class UpstreamHealthProvider implements vscode.Disposable {
                 return
             }
 
+            if (!vscode.window.state.focused) {
+                // Skip if the window is not focused, and try again when the window becomes focused
+                // again. Some users have OS firewalls that make periodic background network access
+                // annoying for users, and this eliminates that annoyance. See
+                // https://linear.app/sourcegraph/issue/CODY-3745/codys-background-periodic-network-access-causes-2fa.
+                this.lastMeasurementSkippedBecauseNotFocused = true
+                return
+            }
+
             if (!this.config) {
                 throw new Error('UpstreamHealthProvider not initialized')
             }
@@ -140,10 +168,7 @@ class UpstreamHealthProvider implements vscode.Disposable {
             // We don't care about errors here, we just want to measure the latency
         } finally {
             // Enqueue a new ping
-            if (this.nextTimeoutId) {
-                clearTimeout(this.nextTimeoutId)
-            }
-            this.nextTimeoutId = setTimeout(this.measure.bind(this), PING_INTERVAL_MS)
+            this.enqueue(PING_INTERVAL_MS)
         }
     }
 
@@ -151,6 +176,9 @@ class UpstreamHealthProvider implements vscode.Disposable {
         if (this.nextTimeoutId) {
             clearTimeout(this.nextTimeoutId)
         }
+        for (const disposable of this.disposables) {
+            disposable.dispose()
+        }
     }
 }
 
diff --git a/vscode/src/testutils/mocks.ts b/vscode/src/testutils/mocks.ts
index 8179ee4dacbc..57d276706c74 100644
--- a/vscode/src/testutils/mocks.ts
+++ b/vscode/src/testutils/mocks.ts
@@ -803,6 +803,8 @@ export const vsCodeMocks = {
         },
         onDidChangeActiveTextEditor() {},
         onDidChangeTextEditorSelection() {},
+        onDidChangeWindowState() {},
+        state: { focused: false },
         createTextEditorDecorationType: () => ({
             key: 'foo',
             dispose: () => {},