fix: ensure we don't send multiple flag requests in parallel

[frankh]

Problem

currently if we call e.g. getFeatureFlags() 100 times straight away after initialisation we will send 100 fetch requests before the first one returns

this is even worse if e.g. we are erroring so never setting loadedSuccessfullyOnce

Changes

add logic to check if we have an inflight request already and block on the existing one instead of starting a new one

Release info Sub-libraries affected

Bump level

• Major
• Minor
• Patch

Libraries affected

• All of them
• posthog-web
• posthog-node
• posthog-ai
• posthog-react-native

Changelog notes

• Fix: don't send multiple feature flag fetch requests in parallel.

[greptile-apps]

PR Summary

This PR implements request deduplication for feature flag fetches to prevent flooding the API with parallel requests when getFeatureFlags() is called multiple times in quick succession.

• Added inflightRequest property to track and reuse in-progress feature flag fetch requests
• Modified _loadFeatureFlags() to check for existing requests before initiating new ones
• Added guard in loadFeatureFlags() to wait for inflight requests to complete before returning
• Properly cleans up inflightRequest reference after request completion or failure
• Fixes potential rate limiting issues by preventing duplicate API calls during initialization

_{2 file(s) reviewed, 2 comment(s)
Edit PR Review Bot Settings | Greptile}

[greptile-apps]

syntax: Missing type declaration for inflightRequest class property

Suggested change

	this.inflightRequest = undefined
	inflightRequest?: Promise<PostHogFetchResponse>
	this.inflightRequest = undefined

[greptile-apps]

style: Consider adding error handling around the await to ensure inflightRequest is always cleared, even if the request fails

Suggested change

	const res = await this.inflightRequest
	this.inflightRequest = undefined
	try {
	const res = await this.inflightRequest
	return res
	} finally {
	this.inflightRequest = undefined
	}

[havenbarnes]

Nice, makes sense and posthog-js does this already