cleanup old sessionData_ localStorage values (#120)

## Summary

Duplicate tabs would not clean up their old localStorage values, leading
to issues where we would
exceed localStorage quota.

## How did you test this change?

local deploy
https://www.loom.com/share/9c351101df184660a24433325f82bba4

## Are there any deployment considerations?

changeset

Author: Vadman97

.changeset/swift-dodos-watch.md

@@ -0,0 +1,7 @@
+---
+'highlight.run': patch
+'@launchdarkly/observability': patch
+'@launchdarkly/session-replay': patch
+---
+
+delete sessionData\_ localstorage values to avoid overfilling quota

sdk/highlight-run/src/client/utils/sessionStorage/highlightSession.ts

@@ -1,6 +1,13 @@
 import { SESSION_PUSH_THRESHOLD } from '../../constants/sessions'
-import { cookieStorage, getItem, removeItem, setItem } from '../storage'
+import {
+	cookieStorage,
+	getItem,
+	removeItem,
+	setItem,
+	getPersistentStorage,
+} from '../storage'
 import { SESSION_STORAGE_KEYS } from './sessionStorageKeys'
+import { internalLogOnce } from '../../../sdk/util'
 
 export type SessionData = {
 	sessionSecureID: string
@@ -76,7 +83,10 @@ export const setSessionData = function (sessionData?: SessionData) {
 	if (!sessionData?.sessionSecureID) return
 	const secureID = sessionData.sessionSecureID!
 	setPersistentSessionSecureID(secureID)
-	setItem(getSessionDataKey(secureID), JSON.stringify(sessionData))
+	const key = getSessionDataKey(secureID)
+	setItem(key, JSON.stringify(sessionData))
+	// delete old session data
+	pruneSessionData(key)
 }
 
 export const loadCookieSessionData = function () {
@@ -90,3 +100,46 @@ export const loadCookieSessionData = function () {
 		setSessionData(JSON.parse(sessionDataStr) as SessionData)
 	} catch (e) {}
 }
+
+function pruneSessionData(keepKey: string): void {
+	const prefix = `${SESSION_STORAGE_KEYS.SESSION_DATA}_`
+
+	// Walk backwards so index order isn’t upset by removals.
+	for (let i = getPersistentStorage().length - 1; i >= 0; i--) {
+		const key = getPersistentStorage().key(i)
+		if (key && key.startsWith(prefix) && key !== keepKey) {
+			try {
+				const sessionData = JSON.parse(
+					getItem(key) || '{}',
+				) as SessionData
+				if (sessionData.lastPushTime === undefined) {
+					internalLogOnce(
+						'highlightSession',
+						'pruneSessionData',
+						'error',
+						`data for key ${key} is not session data`,
+					)
+				} else if (
+					Date.now() - sessionData.lastPushTime >=
+					SESSION_PUSH_THRESHOLD
+				) {
+					internalLogOnce(
+						'highlightSession',
+						'pruneSessionData',
+						'debug',
+						`removing session data for stale key ${key}`,
+					)
+					removeItem(key)
+				}
+			} catch (e) {
+				internalLogOnce(
+					'highlightSession',
+					'pruneSessionData',
+					'error',
+					`failed to parse session data for key ${key}`,
+					e,
+				)
+			}
+		}
+	}
+}

sdk/highlight-run/src/client/utils/storage.ts

@@ -13,6 +13,16 @@ let cookieWriteEnabled: boolean = true
 
 class Storage {
 	private storage: { [key: string]: string } = {}
+
+	public get length(): number {
+		return Object.keys(this.storage).length
+	}
+
+	public key(index: number): string | null {
+		const keys = Object.keys(this.storage)
+		return keys[index] ?? null
+	}
+
 	public getItem(key: string) {
 		return this.storage[key] ?? ''
 	}
@@ -49,7 +59,7 @@ export class CookieStorage {
 export const globalStorage = new Storage()
 export const cookieStorage = new CookieStorage()
 
-const getPersistentStorage = () => {
+export const getPersistentStorage = () => {
 	let storage:
 		| Storage
 		| typeof window.localStorage