Ensure Subscriptions do not yield same values (#2196)

* fix: only yield response when it differs from previous one

* chore: changeset file

* fix: add logic to ensure we only yield values if they differ from the previous ones

.changeset/rotten-falcons-fix.md

@@ -0,0 +1,5 @@
+---
+"@kadena/graph": patch
+---
+
+Added validations to ensure that we do not yield same events on subscriptions

packages/apps/graph/src/graph/subscription/transaction.ts

@@ -40,6 +40,9 @@ async function* iteratorFn(
   context: IContext,
   chainId?: string,
 ): AsyncGenerator<Transaction | undefined, void, unknown> {
+  let previousTransaction: Transaction | undefined;
+  let eventYielded: boolean = false;
+
   while (!context.req.socket.destroyed) {
     const transaction = await prismaClient.transaction.findFirst({
       where: {
@@ -57,10 +60,17 @@ async function* iteratorFn(
         chainId,
       );
 
-      if (mempoolResponse) {
+      if (
+        mempoolResponse &&
+        JSON.stringify(mempoolResponse) !== JSON.stringify(previousTransaction)
+      ) {
+        previousTransaction = { ...mempoolResponse };
         yield mempoolResponse;
       } else {
-        yield undefined;
+        if (!eventYielded) {
+          yield undefined;
+          eventYielded = true;
+        }
       }
     }