chore: improve perf of parseEventLogs

.changeset/gorgeous-dryers-act.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Improved performance of `parseEventLogs`

src/utils/abi/decodeEventLog.test.ts

@@ -882,6 +882,17 @@ test("errors: event doesn't exist", () => {
           name: 'Bar',
           type: 'event',
         },
+        {
+          inputs: [
+            {
+              indexed: true,
+              name: 'message',
+              type: 'string',
+            },
+          ],
+          name: 'Baz',
+          type: 'event',
+        },
       ],
       topics: [
         '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',

src/utils/abi/decodeEventLog.ts

@@ -116,11 +116,15 @@ export function decodeEventLog<
   const [signature, ...argTopics] = topics
   if (!signature) throw new AbiEventSignatureEmptyTopicsError({ docsPath })
 
-  const abiItem = abi.find(
-    (x) =>
-      x.type === 'event' &&
-      signature === toEventSelector(formatAbiItem(x) as EventDefinition),
-  )
+  const abiItem = (() => {
+    if (abi.length === 1) return abi[0]
+    return abi.find(
+      (x) =>
+        x.type === 'event' &&
+        signature === toEventSelector(formatAbiItem(x) as EventDefinition),
+    )
+  })()
+
   if (!(abiItem && 'name' in abiItem) || abiItem.type !== 'event')
     throw new AbiEventSignatureNotFoundError(signature, { docsPath })
 

src/utils/abi/parseEventLogs.bench.ts

@@ -0,0 +1,81 @@
+import { bench } from 'vitest'
+
+import { anvilMainnet } from '../../../test/src/anvil.js'
+import { getLogs } from '../../actions/public/getLogs.js'
+import { mainnet } from '../../chains/index.js'
+import { createClient } from '../../clients/createClient.js'
+import { http } from '../../clients/transports/http.js'
+import { parseEventLogs } from './parseEventLogs.js'
+
+const client = createClient({
+  chain: mainnet,
+  transport: http(),
+})
+
+const abi = [
+  {
+    name: 'Transfer',
+    type: 'event',
+    inputs: [
+      {
+        indexed: true,
+        name: 'from',
+        type: 'address',
+      },
+      {
+        indexed: true,
+        name: 'to',
+        type: 'address',
+      },
+      {
+        indexed: false,
+        name: 'value',
+        type: 'uint256',
+      },
+    ],
+  },
+  {
+    type: 'event',
+    name: 'Approval',
+    inputs: [
+      {
+        indexed: true,
+        name: 'owner',
+        type: 'address',
+      },
+      {
+        indexed: true,
+        name: 'spender',
+        type: 'address',
+      },
+      {
+        indexed: false,
+        name: 'value',
+        type: 'uint256',
+      },
+    ],
+  },
+  {
+    inputs: [
+      {
+        indexed: true,
+        name: 'message',
+        type: 'string',
+      },
+    ],
+    name: 'Foo',
+    type: 'event',
+  },
+] as const
+
+const logs = await getLogs(client, {
+  fromBlock: anvilMainnet.forkBlockNumber - 5n,
+  toBlock: anvilMainnet.forkBlockNumber,
+})
+
+bench('parseEventLogs', async () => {
+  parseEventLogs({
+    abi,
+    logs,
+  })
+})

src/utils/abi/parseEventLogs.ts

@@ -13,11 +13,11 @@ import type { RpcLog } from '../../types/rpc.js'
 import { isAddressEqual } from '../address/isAddressEqual.js'
 import { toBytes } from '../encoding/toBytes.js'
 import { keccak256 } from '../hash/keccak256.js'
+import { toEventSelector } from '../hash/toEventSelector.js'
 import {
   type DecodeEventLogErrorType,
   decodeEventLog,
 } from './decodeEventLog.js'
-import { getAbiItem } from './getAbiItem.js'
 
 export type ParseEventLogsParameters<
   abi extends Abi | readonly unknown[] = Abi,
@@ -116,10 +116,11 @@ export function parseEventLogs<
   return logs
     .map((log) => {
       try {
-        const abiItem = getAbiItem({
-          abi: abi as Abi,
-          name: log.topics[0] as string,
-        }) as AbiEvent
+        const abiItem = (abi as Abi).find(
+          (abiItem) =>
+            abiItem.type === 'event' &&
+            log.topics[0] === toEventSelector(abiItem),
+        ) as AbiEvent
         if (!abiItem) return null
 
         const event = decodeEventLog({