feat(cardano-services): blockfrost utxo provider now caches utxos locally

Author: AngelCastilloB

packages/cardano-services-client/src/UtxoProvider/BlockfrostUtxoProvider.ts

@@ -3,6 +3,8 @@ import { Cardano, Serialization, UtxoByAddressesArgs, UtxoProvider } from '@card
 import type { Responses } from '@blockfrost/blockfrost-js';
 
 export class BlockfrostUtxoProvider extends BlockfrostProvider implements UtxoProvider {
+  private readonly cache: Map<string, Cardano.Tx> = new Map();
+
   protected async fetchUtxos(addr: Cardano.PaymentAddress, paginationQueryString: string): Promise<Cardano.Utxo[]> {
     const queryString = `addresses/${addr.toString()}/utxos?${paginationQueryString}`;
     const utxos = await this.request<Responses['address_utxo_content']>(queryString);
@@ -27,7 +29,11 @@ export class BlockfrostUtxoProvider extends BlockfrostProvider implements UtxoPr
       });
   }
   protected async fetchDetailsFromCBOR(hash: string) {
-    return this.fetchCBOR(hash)
+    if (this.cache.has(hash)) {
+      return this.cache.get(hash);
+    }
+
+    const result = await this.fetchCBOR(hash)
       .then((cbor) => {
         const tx = Serialization.Transaction.fromCbor(Serialization.TxCBOR(cbor)).toCore();
         this.logger.info('Fetched details from CBOR for tx', hash);
@@ -37,7 +43,15 @@ export class BlockfrostUtxoProvider extends BlockfrostProvider implements UtxoPr
         this.logger.warn('Failed to fetch details from CBOR for tx', hash, error);
         return null;
       });
+
+    if (!result) {
+      return null;
+    }
+
+    this.cache.set(hash, result);
+    return result;
   }
+
   public async utxoByAddresses({ addresses }: UtxoByAddressesArgs): Promise<Cardano.Utxo[]> {
     try {
       const utxoResults = await Promise.all(

packages/cardano-services-client/test/Utxo/BlockfrostUtxoProvider.test.ts

@@ -79,5 +79,29 @@ describe('blockfrostUtxoProvider', () => {
         }
       });
     });
+
+    test('does not call txs/${hash}/cbor when data is cached', async () => {
+      const txHash = '0f3abbc8fc19c2e61bab6059bf8a466e6e754833a08a62a6c56fe0e78f19d9d5';
+
+      mockResponses(request, [
+        [`txs/${txHash}/cbor`, 'mockedCBORData'],
+        [`addresses/${address.toString()}/utxos?page=1&count=100`, generateUtxoResponseMock(1)],
+        [`addresses/${address.toString()}/utxos?page=2&count=100`, generateUtxoResponseMock(0)]
+      ]);
+
+      const firstResponse = await provider.utxoByAddresses({ addresses: [address] });
+
+      expect(firstResponse).toBeTruthy();
+      expect(firstResponse.length).toBe(1);
+
+      expect(request).toHaveBeenCalled();
+      request.mockClear();
+
+      const secondResponse = await provider.utxoByAddresses({ addresses: [address] });
+
+      expect(secondResponse).toEqual(firstResponse);
+
+      expect(request).not.toHaveBeenCalledWith(`txs/${txHash}/cbor`);
+    });
   });
 });