feat: add timestamp to indexed events (#42)

Currently, the indexer does not store the timestamp associated with blockchain events. As part of [ACT-612](https://linear.app/valora/issue/ACT-612/add-time-field-to-valora-transfer-events), this PR adds this functionality and updates the database schema as required.

src/indexer/index.ts

@@ -82,6 +82,21 @@ const contracts: { [contract in Contract]: ContractInfo } = {
   },
 }
 
+// Exported to allow for testing
+export async function getBlockTimestamps(events: EventLog[], kit: ContractKit) {
+  const blockNumberToTimestamp: Record<number, number> = {}
+  const uniqueBlockNumbers = new Set(
+    events.map(({ blockNumber }) => blockNumber),
+  )
+  await Promise.all(
+    Array.from(uniqueBlockNumbers).map(async (blockNumber) => {
+      const block = await kit.web3.eth.getBlock(blockNumber)
+      blockNumberToTimestamp[blockNumber] = Number(block.timestamp)
+    }),
+  )
+  return blockNumberToTimestamp
+}
+
 export async function indexEvents(
   contractKey: Contract,
   contractEvent: Event,
@@ -111,6 +126,7 @@ export async function indexEvents(
           `${key} - Got ${events.length} events between blocks [${fromBlock}, ${toBlock}]`,
         )
       }
+      const blockNumberToTimestamp = await getBlockTimestamps(events, kit)
       fromBlock = toBlock + 1
       // Wrap write to event table and block index in a transaction so that the
       // update is atomic.
@@ -123,6 +139,7 @@ export async function indexEvents(
               logIndex,
               blockNumber,
               blockHash,
+              blockTimestamp: blockNumberToTimestamp[blockNumber],
               ...payloadMapper(event),
             })
             .transacting(trx)

src/migrations/20230221212034_CreateTimestamp.ts

@@ -0,0 +1,30 @@
+import { Knex } from 'knex'
+
+const TABLE_NAMES = [
+  'account_wallet_mappings',
+  'attestations_completed',
+  'escrow',
+  'transfers',
+]
+
+export async function up(knex: Knex): Promise<void> {
+  await Promise.all(
+    TABLE_NAMES.map(
+      async (tableName) =>
+        await knex.schema.alterTable(tableName, (table) =>
+          table.bigInteger('blockTimestamp'),
+        ),
+    ),
+  )
+}
+
+export async function down(knex: Knex): Promise<void> {
+  await Promise.all(
+    TABLE_NAMES.map(
+      async (tableName) =>
+        await knex.schema.alterTable(tableName, (table) =>
+          table.dropColumn('blockTimestamp'),
+        ),
+    ),
+  )
+}

test/indexer.test.ts

@@ -1,16 +1,19 @@
-import { Contract, Event, indexEvents } from '../src/indexer'
+import { Contract, Event, indexEvents, getBlockTimestamps } from '../src/indexer'
 import { database, initDatabase } from '../src/database/db'
 import { partialEventLog } from '../src/util/testing'
 import { getLastBlock } from '../src/indexer/blocks'
+import { getContractKit } from '../src/util/utils'
 
 const getLastBlockNumberMock = jest.fn()
 const getAccountEventsMock = jest.fn()
+const getBlockMock = jest.fn()
 
 jest.mock('../src/util/utils', () => ({
   getContractKit: jest.fn(() => ({
     web3: {
       eth: {
         getBlockNumber: getLastBlockNumberMock,
+        getBlock: getBlockMock
       },
     },
     contracts: {
@@ -47,6 +50,7 @@ describe('Indexer', () => {
     getAccountEventsMock
       .mockImplementationOnce(() => [partialEventLog({ transactionHash: firstTxHash })])
       .mockImplementationOnce(() => [partialEventLog({ transactionHash: secondTxHash })])
+    getBlockMock.mockImplementation((blockNumber) => ({timestamp: blockNumber}))
   }
 
   it('indexes account events', async () => {
@@ -88,4 +92,23 @@ describe('Indexer', () => {
     const key = `${Contract.Accounts}_${Event.AccountWalletAddressSet}`
     expect(await getLastBlock(key)).toEqual(0)
   })
+
+  it('getBlockTimestamps returns a mapping from blockNumber to timestamp', async () => {
+    const blockNumber1 = 1234
+    const blockNumber2 = 1235
+    const kit = await getContractKit()
+    const blockNumberToTimestamp = await getBlockTimestamps([partialEventLog({blockNumber: blockNumber1}), partialEventLog({blockNumber: blockNumber2})], kit)
+
+    expect(blockNumberToTimestamp).toEqual({[blockNumber1]: blockNumber1, [blockNumber2]: blockNumber2})
+    expect(getBlockMock).toHaveBeenCalledTimes(2)
+  })
+
+  it('getBlockTimestamps calls getBlock once if multiple events are in one block', async () => {
+    const blockNumber = 1234
+    const kit = await getContractKit()
+    const blockNumberToTimestamp = await getBlockTimestamps([partialEventLog({blockNumber}), partialEventLog({blockNumber})], kit)
+
+    expect(blockNumberToTimestamp).toEqual({[blockNumber]: blockNumber})
+    expect(getBlockMock).toHaveBeenCalledTimes(1)
+  })
 })