Use @vercel/kv to persist nonces as new NonceManagerSource

[amilcarrey]

Hi team,

I’ve implemented a solution for managing nonces while running tasks in parallel. To ensure robustness and avoid transaction failures due to memory loss (e.g., during downtime), I’ve decided to persist the nonces in Redis.

This allows us to recover nonces and prevent failures caused by missing or reset state.

I’ve written a simple NonceManagerSource to handle this, and here’s a snippet of the implementation. If everyone is on board with this approach, I’ll proceed with the full PR.

Let me know your thoughts!

Code:

import { kv } from "@vercel/kv";
import { Address, Client, NonceManagerSource } from "viem";
import { getTransactionCount } from "viem/actions";

type FunctionParameters = {
  address: Address;
  chainId: number;
};

/**
 * Nonce source that persists nonces in Vercel KV.
 * If the nonce is not found in Vercel KV, it fetches the next nonce from the blockchain.
 *
 * - Docs: https://viem.sh/docs/accounts/local/createNonceManager#source
 *  @link https://github.com/wevm/viem/blob/0f83248faf93ccab82f768c04eafb230d3d5bbc4/src/utils/nonceManager.ts
 *  @implements NonceManagerSource
 */
export function kvNonceSource(): NonceManagerSource {
  return {
    async get(
      parameters: FunctionParameters & { client: Client },
    ): Promise<number> {
      const { address, chainId, client } = parameters;

      // Try to get the nonce from Vercel KV
      const nonce = await kv.get<number>(`nonce:${address}:${chainId}`);
      if (nonce !== null) {
        return nonce + 1; // Return the stored nonce if it exists
      }

      // If no nonce is found, get the current transaction count from the blockchain.
      return getTransactionCount(client, {
        address,
        blockTag: "pending",
      });
    },

    async set(parameters: FunctionParameters, nonce: number): Promise<void> {
      const { address, chainId } = parameters;

      // Save the updated nonce in Vercel KV
      await kv.set(`nonce:${address}:${chainId}`, nonce);
    },
  };
}