How to use the Reallocate instruction

To enable additional extensions on existing Token Accounts created via the Token Extension program, additional space must first be reallocated to accommodate the extra data required by these extensions. This can be done using the reallocate instruction.

For example, this allows existing Token Accounts can be updated to enable the MemoTransfer and CpiGuard extensions.

In this guide, we'll walk through an example of using Solana Playground. Here is the final script.

Getting Started

Start by opening this Solana Playground link with the following starter code.

// Client
console.log("My address:", pg.wallet.publicKey.toString());
const balance = await pg.connection.getBalance(pg.wallet.publicKey);
console.log(`My balance: ${balance / web3.LAMPORTS_PER_SOL} SOL`);

If it is your first time using Solana Playground, you'll first need to create a Playground Wallet and fund the wallet with devnet SOL.

If you do not have a Playground wallet, you may see a type error within the editor on all declarations of pg.wallet.publicKey. This type error will clear after you create a Playground wallet.

To get devnet SOL, run the solana airdrop command in the Playground's terminal, or visit this devnet faucet.

solana airdrop 5

Once you've created and funded the Playground wallet, click the "Run" button to run the starter code.

Add Dependencies

Let's start by setting up our script. We'll be using the @solana/web3.js and @solana/spl-token libraries.

Replace the starter code with the following:

import {
  Connection,
  Transaction,
  clusterApiUrl,
  sendAndConfirmTransaction,
} from "@solana/web3.js";
import {
  ExtensionType,
  TOKEN_2022_PROGRAM_ID,
  createAccount,
  createMint,
  createReallocateInstruction,
  createEnableRequiredMemoTransfersInstruction,
} from "@solana/spl-token";

// Playground wallet
const payer = pg.wallet.keypair;

// Connection to devnet cluster
const connection = new Connection(clusterApiUrl("devnet"), "confirmed");

// Transaction signature returned from sent transaction
let transactionSignature: string;

Create Mint and Token Account

First, we'll need to create a new Mint Account.

// Authority that can mint new tokens
const mintAuthority = pg.wallet.publicKey;
// Decimals for Mint Account
const decimals = 2;

// Create Mint Account
const mint = await createMint(
  connection,
  payer, // Payer of the transaction and initialization fees
  mintAuthority, // Mint Authority
  null, // Optional Freeze Authority
  decimals, // Decimals of Mint
  undefined, // Optional keypair
  undefined, // Options for confirming the transaction
  TOKEN_2022_PROGRAM_ID, // Token Extension Program ID
);

Next, let's create a Token Account with no extensions enabled.

// Create Token Account for Playground wallet
const tokenAccount = await createAccount(
  connection,
  payer, // Payer to create Token Account
  mint, // Mint Account address
  payer.publicKey, // Token Account owner
  undefined, // Optional keypair, default to Associated Token Account
  undefined, // Confirmation options
  TOKEN_2022_PROGRAM_ID, // Token Extension Program ID
);

Build Instructions

Next, let's build a transaction to enable the MemoTransfer extensions for an existing Token Account.

First, build the instruction to reallocate the Token Account with enough space for the specified extension. The Token Extensions Program includes a reallocate instruction that automatically calculates the space and lamports required.

// Extensions to reallocate data for
const extensions = [ExtensionType.MemoTransfer];
// Instruction to reallocate Token Account data
const reallocateInstruction = createReallocateInstruction(
  tokenAccount, // Token Account address
  payer.publicKey, // Payer to reallocate data
  extensions, // Extensions to reallocate for
  payer.publicKey, // Token Account owner
  undefined, // Additional signers
  TOKEN_2022_PROGRAM_ID, // Token Extension Program ID
);

Next, build the instruction to enable the MemoTransfer extension for the Token Account.

// Instruction to initialize the MemoTransfer Extension
const enableRequiredMemoTransfersInstruction =
  createEnableRequiredMemoTransfersInstruction(
    tokenAccount, // Token Account address
    payer.publicKey, // Token Account Owner
    undefined, // Additional signers
    TOKEN_2022_PROGRAM_ID, // Token Extension Program ID
  );

Send Transaction

Next, let's add the instructions to a new transaction and send it to the network. This will update the Token Account with the MemoTransfer extension enabled.

// Add instructions to new transaction
const transaction = new Transaction().add(
  reallocateInstruction,
  enableRequiredMemoTransfersInstruction,
);

// Send Transaction
transactionSignature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [payer],
);

console.log(
  "\nReallocate:",
  `https://solana.fm/tx/${transactionSignature}?cluster=devnet-solana`,
);

Run the script by clicking the Run button. You can then inspect the transaction details on SolanaFM.

Conclusion

The reallocate instruction on the Token Extensions program offers a flexible way to update existing Token Accounts with additional functionalities. This instruction is useful for token owners who may not have foreseen the need for certain extensions initially, but find themselves requiring these additional features at a later time.