🐛 [RUMF-876] Improve proxy behavior for xhr reuse

[amortemousque]

Detected issues

• We can have a max stack size error when using a single instance of XMLHTTPRequest.

Changes

• Ensure to attach our listeners only once per request.

Testing

Unit, Locally

---

I have gone over the contributing documentation.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.84%. Comparing base (8f24278) to head (185cb70).
Report is 1696 commits behind head on main.

❗ Current head 185cb70 differs from pull request most recent head 00a48fe

Please upload reports for the commit 00a48fe to get more accurate results.

Files with missing lines	Patch %	Lines
packages/core/src/browser/xhrProxy.ts	97.82%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #865      +/-   ##
==========================================
- Coverage   89.13%   88.84%   -0.30%     
==========================================
  Files          81       81              
  Lines        3791     3764      -27     
  Branches      848      834      -14     
==========================================
- Hits         3379     3344      -35     
- Misses        412      420       +8     

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[BenoitZugmeyer]

LGTM

[bcaudan]

what is the reasoning for not retrieving the context from xhr anymore?

[amortemousque]

Yes, I can simplify

[bcaudan]

what about reinforcing the design by having something like:

Suggested change

	function reportXhr(xhr: BrowserXHR<XhrStartContext>, pendingContext: XhrStartContext) {
	const xhrCompleteContext: XhrCompleteContext = {
	...pendingContext,
	duration: elapsed(pendingContext.startClocks.timeStamp, timeStampNow()),
	response: xhr.response as string | undefined,
	status: xhr.status,
	}
	function reportXhr(xhr: BrowserXHR<XhrCompleteContext>) {
	xhr._datadog_xhr!.duration = elapsed(pendingContext.startClocks.timeStamp, timeStampNow())
	...

[amortemousque]

Good point.
On thing I see, by doing this, is that I have to cast like so reportXhr(this as BrowserXHR<XhrCompleteContext>) in sendXhr()
What do you think?

[bcaudan]

it seems good enough to me