Add cache to eth_getBlockByNumber (#930)

* Add cache

Signed-off-by: nikolay <[email protected]>

* Add test

Signed-off-by: nikolay <[email protected]>

* Edit test

Signed-off-by: nikolay <[email protected]>

---------

Signed-off-by: nikolay <[email protected]>

Author: natanasow

packages/relay/src/lib/eth.ts

@@ -770,15 +770,27 @@ export class EthImpl implements Eth {
 
   /**
    * Gets the block by its block number.
-   * @param blockNumOrTag
+   * @param blockNumOrTag Possible values are earliest/pending/latest or hex, and can't be null (validator check).
    * @param showDetails
    */
   async getBlockByNumber(blockNumOrTag: string, showDetails: boolean, requestId?: string): Promise<Block | null> {
     const requestIdPrefix = formatRequestIdMessage(requestId);
     this.logger.trace(`${requestIdPrefix} getBlockByNumber(blockNum=${blockNumOrTag}, showDetails=${showDetails})`);
-    return this.getBlock(blockNumOrTag, showDetails, requestId).catch((e: any) => {
-      throw this.genericErrorHandler(e, `${requestIdPrefix} Failed to retrieve block for blockNum ${blockNumOrTag}`);
-    });
+
+    const cacheKey = `eth_getBlockByNumber_${blockNumOrTag}_${showDetails}`;
+    let block = this.cache.get(cacheKey);
+    if (!block) {
+      block = await this.getBlock(blockNumOrTag, showDetails, requestId).catch((e: any) => {
+        throw this.genericErrorHandler(e, `${requestIdPrefix} Failed to retrieve block for blockNum ${blockNumOrTag}`);
+      });
+
+      if (blockNumOrTag != EthImpl.blockLatest && blockNumOrTag != EthImpl.blockPending) {
+        this.logger.trace(`${requestIdPrefix} caching ${cacheKey} for ${constants.CACHE_TTL.ONE_HOUR} ms`);
+        this.cache.set(cacheKey, block);
+      }
+    }
+
+    return block;
   }
 
   /**

packages/relay/tests/lib/eth.spec.ts

@@ -677,6 +677,21 @@ describe('Eth calls using MirrorNode', async function () {
     verifyBlockConstants(result);
   });
 
+  it('eth_getBlockByNumber should return cached result', async function() {
+    // mirror node request mocks
+    restMock.onGet(`blocks/${blockNumber}`).reply(200, defaultBlock);
+    restMock.onGet(`contracts/results?timestamp=gte:${defaultBlock.timestamp.from}&timestamp=lte:${defaultBlock.timestamp.to}&limit=100&order=asc`).reply(200, defaultContractResults);
+    restMock.onGet(`contracts/${contractAddress1}/results/${contractTimestamp1}`).reply(200, defaultDetailedContractResults);
+    restMock.onGet(`contracts/${contractAddress2}/results/${contractTimestamp2}`).reply(200, defaultDetailedContractResults);
+    restMock.onGet('network/fees').reply(200, defaultNetworkFees);
+    const resBeforeCache = await ethImpl.getBlockByNumber(EthImpl.numberTo0x(blockNumber), false);
+
+    restMock.onGet(`blocks/${blockNumber}`).reply(404);
+    const resAfterCache = await ethImpl.getBlockByNumber(EthImpl.numberTo0x(blockNumber), false);
+
+    expect(resBeforeCache).to.eq(resAfterCache);
+  });
+
   it('eth_getBlockByNumber with zero transactions', async function () {
     // mirror node request mocks
     restMock.onGet(`blocks/${blockNumber}`).reply(200, {...defaultBlock, gas_used: 0});