From 96b459d21653ef08162192e7fd7089a25baf929d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emanuel=20Tesa=C5=99?= <e.tesarr@gmail.com>
Date: Thu, 19 Oct 2023 13:22:00 +0200
Subject: [PATCH] Persist derived airnode wallet in state

---
 packages/pusher/src/api-requests/signed-api.ts | 6 +++---
 packages/pusher/src/sign-template-data.ts      | 6 +++---
 packages/pusher/src/state.ts                   | 4 ++++
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/packages/pusher/src/api-requests/signed-api.ts b/packages/pusher/src/api-requests/signed-api.ts
index c586ef41..581dce9c 100644
--- a/packages/pusher/src/api-requests/signed-api.ts
+++ b/packages/pusher/src/api-requests/signed-api.ts
@@ -1,7 +1,6 @@
 import { deriveBeaconId } from '@api3/airnode-node';
 import { go } from '@api3/promise-utils';
 import axios, { type AxiosError } from 'axios';
-import { ethers } from 'ethers';
 import { isEmpty, isNil, pick } from 'lodash';
 
 import { logger } from '../logger';
@@ -11,13 +10,14 @@ import { type SignedApiPayload, signedApiResponseSchema } from '../validation/sc
 
 export const postSignedApiData = async (group: SignedApiNameUpdateDelayGroup) => {
   const {
-    config: { signedApis, airnodeWalletMnemonic },
+    config: { signedApis },
     templateValues,
+    airnodeWallet,
   } = getState();
   const { signedApiName, templateIds, updateDelay } = group;
   const logContext = { signedApiName, updateDelay };
 
-  const airnode = ethers.Wallet.fromMnemonic(airnodeWalletMnemonic).address;
+  const airnode = airnodeWallet.address;
   const batchPayloadOrNull = templateIds.map((templateId): SignedApiPayload | null => {
     // Calculate the reference timestamp based on the current time and update delay.
     const referenceTimestamp = Date.now() / 1000 - updateDelay;
diff --git a/packages/pusher/src/sign-template-data.ts b/packages/pusher/src/sign-template-data.ts
index 7415a017..de75004b 100644
--- a/packages/pusher/src/sign-template-data.ts
+++ b/packages/pusher/src/sign-template-data.ts
@@ -1,6 +1,5 @@
 import type { ExtractedAndEncodedResponse } from '@api3/airnode-adapter';
 import { go } from '@api3/promise-utils';
-import { ethers } from 'ethers';
 import { isNil } from 'lodash';
 
 import { logger } from './logger';
@@ -19,8 +18,9 @@ export const signTemplateResponses = async (templateResponses: TemplateResponse[
     const { encodedValue } = response;
     const timestamp = Math.floor(Date.now() / 1000).toString();
 
-    const wallet = ethers.Wallet.fromMnemonic(getState().config.airnodeWalletMnemonic);
-    const goSignWithTemplateId = await go(async () => signWithTemplateId(wallet, templateId, timestamp, encodedValue));
+    const goSignWithTemplateId = await go(async () =>
+      signWithTemplateId(getState().airnodeWallet, templateId, timestamp, encodedValue)
+    );
     if (!goSignWithTemplateId.success) {
       const message = `Failed to sign response. Error: "${goSignWithTemplateId.error.message}"`;
       logger.warn(message, {
diff --git a/packages/pusher/src/state.ts b/packages/pusher/src/state.ts
index 283b0d43..5d41c4f2 100644
--- a/packages/pusher/src/state.ts
+++ b/packages/pusher/src/state.ts
@@ -1,4 +1,5 @@
 import Bottleneck from 'bottleneck';
+import { ethers } from 'ethers';
 import { last } from 'lodash';
 
 import { OIS_MAX_CONCURRENCY_DEFAULT, OIS_MIN_TIME_DEFAULT_MS } from './constants';
@@ -11,6 +12,8 @@ export interface State {
   config: Config;
   templateValues: TemplateValueStorage;
   apiLimiters: Record<string, Bottleneck | undefined>;
+  // We persist the derived Airnode wallet in memory as a performance optimization.
+  airnodeWallet: ethers.Wallet;
 }
 
 let state: State;
@@ -81,6 +84,7 @@ export const getInitialState = (config: Config): State => {
     config,
     templateValues: buildTemplateStorages(config),
     apiLimiters: buildApiLimiters(config),
+    airnodeWallet: ethers.Wallet.fromMnemonic(config.airnodeWalletMnemonic),
   };
 };