Nour/improved rotation (#290)

* improved rotation

* fix bugs

* only parse slot if necessary

* add metrics for ws source

* add select by recent slot to utils

* fix solana web3.js version

---------

Co-authored-by: wphan <william@drift.trade>

src/utils/utils.ts

@@ -472,3 +472,18 @@ export type SubscriberLookup = {
 		openbook?: OpenbookV2Subscriber;
 	};
 };
+
+export const selectMostRecentBySlot = (responses: any[]): any => {
+	const parsedResponses = responses
+		.map((response) => {
+			try {
+				return JSON.parse(response);
+			} catch {
+				return null;
+			}
+		})
+		.filter((parsed) => parsed && typeof parsed.slot === 'number');
+	return parsedResponses.reduce((mostRecent, current) => {
+		return !mostRecent || current.slot > mostRecent.slot ? current : mostRecent;
+	}, null);
+};