Token con interessi

Che cos'è un Mint con Interessi?

L'estensione del mint InterestBearingConfig del Token Extensions Program consente a un mint di memorizzare un tasso di interesse annualizzato direttamente onchain.

I token con interessi non aggiungono più token ai token account nel tempo. L'importo dei token memorizzato in ogni token account rimane lo stesso finché un'istruzione del programma token non lo modifica, come coniazione, trasferimento o distruzione.

Con il passare del tempo, l'importo UI calcolato con gli interessi può aumentare anche se l'importo dei token e la token supply rimangono invariati.

Come Vengono Calcolate le Modifiche Storiche del Tasso

  • InterestBearingConfig memorizza initialization_timestamp, pre_update_average_rate, last_update_timestamp e current_rate.
  • amount_to_ui_amount calcola l'importo UI in due passaggi: prima calcola gli interessi dall'inizializzazione a last_update_timestamp usando pre_update_average_rate, poi calcola gli interessi da last_update_timestamp al timestamp corrente usando current_rate.
  • Quando UpdateRate viene eseguito, process_update_rate chiama time_weighted_average_rate e aggiorna pre_update_average_rate a una nuova media storica ponderata per tempo, quindi registra un nuovo last_update_timestamp e current_rate.
  • Dopo le modifiche del tasso nel tempo, le modifiche precedenti sono rappresentate da pre_update_average_rate, mentre il periodo da last_update_timestamp al tempo corrente viene calcolato con current_rate.

Come Creare e Utilizzare Token con Interessi

Per creare e utilizzare token con interessi:

  1. Calcola la dimensione del mint account e il rent necessario per il mint e l'estensione InterestBearingConfig.
  2. Crea il mint account con CreateAccount, inizializza InterestBearingConfig e inizializza il mint con InitializeMint.
  3. Conia i token come al solito.
  4. Usa UpdateRate per modificare il tasso corrente del mint nel tempo.
  5. Converti gli importi dei token in un importo UI con interessi con AmountToUiAmount o metodi helper che recuperano il mint account e il clock sysvar, quindi calcolano l'importo UI senza inviare una transazione.

Conversione dell'importo UI Offchain e Onchain

Il percorso helper offchain recupera il mint account e il clock sysvar, quindi calcola l'importo UI localmente senza inviare una transazione. Il percorso onchain utilizza AmountToUiAmount, che viene eseguito nel Token Program e restituisce l'importo UI nei dati di ritorno della transazione. AmountToUiAmount può essere inviato in una transazione o simulato.

Calcola la dimensione dell'account

Calcola la dimensione del mint account per il mint di base più l'estensione InterestBearingConfig. Questa è la dimensione utilizzata in CreateAccount.

Calcola il rent

Calcola il rent utilizzando la dimensione necessaria per il mint più l'estensione InterestBearingConfig.

Crea il mint account

Crea il mint account con lo spazio e i lamport calcolati.

Inizializza InterestBearingConfig

Inizializza l'estensione InterestBearingConfig sul mint.

Inizializza il mint

Inizializza il mint con InitializeMint nella stessa transazione.

Crea un token account e conia token

Crea un token account per il mint, quindi conia token in quel token account.

Calcola l'importo UI con l'helper offchain

Recupera il mint account e il sysvar dell'orologio, quindi calcola l'importo UI senza inviare una transazione.

Calcola la dimensione dell'account

Calcola la dimensione del mint account per il mint di base più l'estensione InterestBearingConfig. Questa è la dimensione utilizzata in CreateAccount.

Calcola il rent

Calcola il rent utilizzando la dimensione necessaria per il mint più l'estensione InterestBearingConfig.

Crea il mint account

Crea il mint account con lo spazio e i lamport calcolati.

Inizializza InterestBearingConfig

Inizializza l'estensione InterestBearingConfig sul mint.

Inizializza il mint

Inizializza il mint con InitializeMint nella stessa transazione.

Crea un token account e conia token

Crea un token account per il mint, quindi conia token in quel token account.

Calcola l'importo UI con l'helper offchain

Recupera il mint account e il sysvar dell'orologio, quindi calcola l'importo UI senza inviare una transazione.

Example
const client = await createLocalClient();
const mint = await generateKeyPairSigner();
const interestBearingExtension = extension("InterestBearingConfig", {
rateAuthority: client.payer.address,
initializationTimestamp: BigInt(Math.floor(Date.now() / 1000)),
lastUpdateTimestamp: BigInt(Math.floor(Date.now() / 1000)),
preUpdateAverageRate: 30000,
currentRate: 30000
});
const mintSpace = BigInt(getMintSize([interestBearingExtension]));

Ordine delle istruzioni

InterestBearingMintInstruction::Initialize deve precedere InitializeMint. CreateAccount, InterestBearingMintInstruction::Initialize e InitializeMint devono essere inclusi nella stessa transazione.

Riferimento sorgente

ElementoDescrizioneSorgente
InterestBearingConfigEstensione del mint che memorizza l'autorità del tasso di interesse, i timestamp e i tassi correnti e storici.Sorgente
InterestBearingMintInstruction::InitializeIstruzione che inizializza la configurazione fruttante prima di InitializeMint.Sorgente
InterestBearingMintInstruction::UpdateRateIstruzione che modifica il tasso di interesse corrente del mint.Sorgente
AmountToUiAmountIstruzione che restituisce la stringa dell'importo UI corrente per un importo di token utilizzando la configurazione attiva del mint.Sorgente
InterestBearingConfig::amount_to_ui_amountHelper che converte un importo di token in un importo UI con interessi per un timestamp.Sorgente
process_initializeLogica del processore che inizializza InterestBearingConfig e registra i timestamp e il tasso iniziali.Sorgente
process_update_rateLogica del processore che aggiorna il tasso corrente, ricalcola il tasso medio ponderato nel tempo e registra il timestamp di aggiornamento.Sorgente
process_amount_to_ui_amountLogica del processore che restituisce la stringa dell'importo UI utilizzando la configurazione fruttante attiva del mint.Sorgente

Typescript

L'esempio Kit di seguito utilizza le istruzioni generate direttamente. Gli esempi legacy che usano @solana/web3.js e @solana/spl-token sono inclusi per riferimento.

Kit

Instructions
import {
appendTransactionMessageInstructions,
createTransactionMessage,
generateKeyPairSigner,
getBase64EncodedWireTransaction,
pipe,
setTransactionMessageFeePayerSigner,
setTransactionMessageLifetimeUsingBlockhash,
signTransactionMessageWithSigners,
unwrapOption
} from "@solana/kit";
import { createLocalClient } from "@solana/kit-client-rpc";
import { getCreateAccountInstruction } from "@solana-program/system";
import {
amountToUiAmountForMintWithoutSimulation,
extension,
fetchMint,
findAssociatedTokenPda,
getAmountToUiAmountInstruction,
getCreateAssociatedTokenInstructionAsync,
getInitializeInterestBearingMintInstruction,
getInitializeMintInstruction,
getMintSize,
getMintToCheckedInstruction,
getUpdateRateInterestBearingMintInstruction,
isExtension,
TOKEN_2022_PROGRAM_ADDRESS
} from "@solana-program/token-2022";
const client = await createLocalClient();
const mint = await generateKeyPairSigner();
const recipient = await generateKeyPairSigner();
const tokenAmount = 1_000_000_000_000n;
const interestBearingExtension = extension("InterestBearingConfig", {
rateAuthority: client.payer.address,
initializationTimestamp: BigInt(Math.floor(Date.now() / 1000)),
lastUpdateTimestamp: BigInt(Math.floor(Date.now() / 1000)),
preUpdateAverageRate: 30000,
currentRate: 30000
});
const mintSpace = BigInt(getMintSize([interestBearingExtension]));
const mintRent = await client.rpc
.getMinimumBalanceForRentExemption(mintSpace)
.send();
const [tokenAccount] = await findAssociatedTokenPda({
mint: mint.address,
owner: recipient.address,
tokenProgram: TOKEN_2022_PROGRAM_ADDRESS
});
await client.sendTransaction([
getCreateAccountInstruction({
payer: client.payer, // Account funding the new mint account.
newAccount: mint, // New mint account to create.
lamports: mintRent, // Lamports funding the mint account rent.
space: mintSpace, // Account size in bytes for the mint plus InterestBearingConfig.
programAddress: TOKEN_2022_PROGRAM_ADDRESS // Program that owns the mint account.
}),
getInitializeInterestBearingMintInstruction({
mint: mint.address, // Mint account that stores the InterestBearingConfig extension.
rateAuthority: client.payer.address, // Authority allowed to update the interest rate later.
rate: 30000 // Interest rate in basis points.
}),
getInitializeMintInstruction({
mint: mint.address, // Mint account to initialize.
decimals: 0, // Number of decimals for the token.
mintAuthority: client.payer.address, // Authority allowed to mint new tokens.
freezeAuthority: client.payer.address // Authority allowed to freeze token accounts.
})
]);
await client.sendTransaction([
await getCreateAssociatedTokenInstructionAsync({
payer: client.payer, // Account funding the associated token account creation.
mint: mint.address, // Mint for the associated token account.
owner: recipient.address // Owner of the token account.
}),
getMintToCheckedInstruction({
mint: mint.address, // Mint account that issues the tokens.
token: tokenAccount, // Token account receiving the newly minted tokens.
mintAuthority: client.payer, // Signer authorized to mint new tokens.
amount: tokenAmount, // Token amount in base units.
decimals: 0 // Decimals defined on the mint.
})
]);
await new Promise((resolve) => setTimeout(resolve, 2_000));
const calculatedUiAmount = await amountToUiAmountForMintWithoutSimulation(
client.rpc,
mint.address,
tokenAmount
);
const amountToUiInstruction = getAmountToUiAmountInstruction({
mint: mint.address, // Mint whose UI amount conversion is being simulated.
amount: tokenAmount // Token amount in base units.
});
const { value: latestBlockhash } = await client.rpc.getLatestBlockhash().send();
const amountToUiMessage = pipe(
createTransactionMessage({ version: 0 }),
(tx) => setTransactionMessageFeePayerSigner(client.payer, tx),
(tx) => setTransactionMessageLifetimeUsingBlockhash(latestBlockhash, tx),
(tx) => appendTransactionMessageInstructions([amountToUiInstruction], tx)
);
const signedAmountToUiMessage =
await signTransactionMessageWithSigners(amountToUiMessage);
const simulation = await client.rpc
.simulateTransaction(
getBase64EncodedWireTransaction(signedAmountToUiMessage),
{
encoding: "base64"
}
)
.send();
const simulatedUiAmount = Buffer.from(
simulation.value.returnData?.data?.[0] ?? "",
"base64"
).toString("utf8");
const updateRateInstruction = getUpdateRateInterestBearingMintInstruction({
mint: mint.address, // Mint account that stores the InterestBearingConfig extension.
rateAuthority: client.payer, // Signer authorized to update the interest rate.
rate: 15000 // New interest rate in basis points.
});
await client.sendTransaction([updateRateInstruction]);
const mintAccount = await fetchMint(client.rpc, mint.address);
const interestBearingConfig = (
unwrapOption(mintAccount.data.extensions) ?? []
).find((item) => isExtension("InterestBearingConfig", item));
console.log("Mint Address:", mint.address);
console.log("Token Account:", tokenAccount);
console.log("Calculated UI Amount:", calculatedUiAmount);
console.log("Simulated UI Amount:", simulatedUiAmount);
console.log("InterestBearingConfig:", interestBearingConfig);
Console
Click to execute the code.

Web3.js

Instructions
import {
Connection,
Keypair,
sendAndConfirmTransaction,
SystemProgram,
Transaction,
LAMPORTS_PER_SOL
} from "@solana/web3.js";
import {
ASSOCIATED_TOKEN_PROGRAM_ID,
amountToUiAmountForMintWithoutSimulation,
createAmountToUiAmountInstruction,
createAssociatedTokenAccountInstruction,
createInitializeMintInstruction,
createInitializeInterestBearingMintInstruction,
createMintToCheckedInstruction,
createUpdateRateInterestBearingMintInstruction,
ExtensionType,
getAssociatedTokenAddressSync,
getInterestBearingMintConfigState,
getMint,
getMintLen,
TOKEN_2022_PROGRAM_ID
} from "@solana/spl-token";
const connection = new Connection("http://localhost:8899", "confirmed");
const latestBlockhash = await connection.getLatestBlockhash();
const feePayer = Keypair.generate();
const recipient = Keypair.generate();
const tokenAmount = 1_000_000_000_000n;
const airdropSignature = await connection.requestAirdrop(
feePayer.publicKey,
5 * LAMPORTS_PER_SOL
);
await connection.confirmTransaction({
blockhash: latestBlockhash.blockhash,
lastValidBlockHeight: latestBlockhash.lastValidBlockHeight,
signature: airdropSignature
});
const extensions = [ExtensionType.InterestBearingConfig];
const mint = Keypair.generate();
const mintLength = getMintLen(extensions);
const mintRent = await connection.getMinimumBalanceForRentExemption(mintLength);
const tokenAccount = getAssociatedTokenAddressSync(
mint.publicKey,
recipient.publicKey,
false,
TOKEN_2022_PROGRAM_ID,
ASSOCIATED_TOKEN_PROGRAM_ID
);
const createMintAccountInstruction = SystemProgram.createAccount({
fromPubkey: feePayer.publicKey, // Account funding the new mint account.
newAccountPubkey: mint.publicKey, // New mint account to create.
space: mintLength, // Account size in bytes for the mint plus InterestBearingConfig.
lamports: mintRent, // Lamports funding the mint account rent.
programId: TOKEN_2022_PROGRAM_ID // Program that owns the mint account.
});
const initializeInterestBearingInstruction =
createInitializeInterestBearingMintInstruction(
mint.publicKey, // Mint account that stores the InterestBearingConfig extension.
feePayer.publicKey, // Authority allowed to update the interest rate later.
30000, // Interest rate in basis points.
TOKEN_2022_PROGRAM_ID // Token program that owns the mint.
);
const initializeMintInstruction = createInitializeMintInstruction(
mint.publicKey, // Mint account to initialize.
0, // Number of decimals for the token.
feePayer.publicKey, // Authority allowed to mint new tokens.
feePayer.publicKey, // Authority allowed to freeze token accounts.
TOKEN_2022_PROGRAM_ID // Program that owns the mint account.
);
const createTokenAccountInstruction = createAssociatedTokenAccountInstruction(
feePayer.publicKey, // Account funding the associated token account creation.
tokenAccount, // Associated token account address to create.
recipient.publicKey, // Owner of the token account.
mint.publicKey, // Mint for the associated token account.
TOKEN_2022_PROGRAM_ID, // Token program that owns the token account.
ASSOCIATED_TOKEN_PROGRAM_ID // Associated Token Program that creates the account.
);
const mintToTokenAccountInstruction = createMintToCheckedInstruction(
mint.publicKey, // Mint account that issues the tokens.
tokenAccount, // Token account receiving the newly minted tokens.
feePayer.publicKey, // Signer authorized to mint new tokens.
tokenAmount, // Token amount in base units.
0, // Decimals defined on the mint.
[], // Additional multisig signers.
TOKEN_2022_PROGRAM_ID // Token program that owns the mint and token account.
);
await sendAndConfirmTransaction(
connection,
new Transaction({
feePayer: feePayer.publicKey,
blockhash: latestBlockhash.blockhash,
lastValidBlockHeight: latestBlockhash.lastValidBlockHeight
}).add(
createMintAccountInstruction,
initializeInterestBearingInstruction,
initializeMintInstruction
),
[feePayer, mint]
);
await sendAndConfirmTransaction(
connection,
new Transaction().add(
createTokenAccountInstruction,
mintToTokenAccountInstruction
),
[feePayer]
);
await new Promise((resolve) => setTimeout(resolve, 2_000));
const calculatedUiAmount = await amountToUiAmountForMintWithoutSimulation(
connection,
mint.publicKey,
tokenAmount
);
const amountToUiInstruction = createAmountToUiAmountInstruction(
mint.publicKey, // Mint whose UI amount conversion is being simulated.
tokenAmount, // Token amount in base units.
TOKEN_2022_PROGRAM_ID // Token program that owns the mint.
);
const amountToUiSimulation = await connection.simulateTransaction(
new Transaction().add(amountToUiInstruction),
[feePayer],
false
);
const simulatedUiAmount = Buffer.from(
amountToUiSimulation.value.returnData?.data?.[0] ?? "",
"base64"
).toString("utf8");
const updateRateInstruction = createUpdateRateInterestBearingMintInstruction(
mint.publicKey, // Mint account that stores the InterestBearingConfig extension.
feePayer.publicKey, // Signer authorized to update the interest rate.
15000, // New interest rate in basis points.
[], // Additional multisig signers.
TOKEN_2022_PROGRAM_ID // Token program that owns the mint.
);
await sendAndConfirmTransaction(
connection,
new Transaction().add(updateRateInstruction),
[feePayer]
);
const mintAccount = await getMint(
connection,
mint.publicKey,
"confirmed",
TOKEN_2022_PROGRAM_ID
);
const interestBearingConfig = getInterestBearingMintConfigState(mintAccount);
console.log("Mint Address:", mint.publicKey.toBase58());
console.log("Token Account:", tokenAccount.toBase58());
console.log("Calculated UI Amount:", calculatedUiAmount);
console.log("Simulated UI Amount:", simulatedUiAmount);
console.log("InterestBearingConfig:", interestBearingConfig);
Console
Click to execute the code.

Rust

Rust
use anyhow::{anyhow, Result};
use base64::prelude::{Engine as _, BASE64_STANDARD};
use solana_client::nonblocking::rpc_client::RpcClient;
use solana_commitment_config::CommitmentConfig;
use solana_sdk::{
sysvar::clock::{self, Clock},
signature::{Keypair, Signer},
transaction::Transaction,
};
use solana_system_interface::instruction::create_account;
use spl_associated_token_account_interface::{
address::get_associated_token_address_with_program_id,
instruction::create_associated_token_account,
};
use spl_token_2022_interface::{
extension::{
interest_bearing_mint::{
instruction::{
initialize as initialize_interest_bearing_instruction, update_rate,
},
InterestBearingConfig,
},
BaseStateWithExtensions, ExtensionType, StateWithExtensions,
},
instruction::{amount_to_ui_amount, initialize_mint, mint_to_checked},
state::Mint,
ID as TOKEN_2022_PROGRAM_ID,
};
#[tokio::main]
async fn main() -> Result<()> {
let client = RpcClient::new_with_commitment(
String::from("http://localhost:8899"),
CommitmentConfig::confirmed(),
);
let fee_payer = Keypair::new();
let recipient = Keypair::new();
let token_amount = 1_000_000_000_000u64;
let airdrop_signature = client
.request_airdrop(&fee_payer.pubkey(), 5_000_000_000)
.await?;
loop {
let confirmed = client.confirm_transaction(&airdrop_signature).await?;
if confirmed {
break;
}
}
let mint = Keypair::new();
let mint_space =
ExtensionType::try_calculate_account_len::<Mint>(&[ExtensionType::InterestBearingConfig])?;
let mint_rent = client
.get_minimum_balance_for_rent_exemption(mint_space)
.await?;
let create_mint_account_instruction = create_account(
&fee_payer.pubkey(), // Account funding the new mint account.
&mint.pubkey(), // New mint account to create.
mint_rent, // Lamports funding the mint account rent.
mint_space as u64, // Account size in bytes for the mint plus InterestBearingConfig.
&TOKEN_2022_PROGRAM_ID, // Program that owns the mint account.
);
let initialize_interest_bearing_instruction = initialize_interest_bearing_instruction(
&TOKEN_2022_PROGRAM_ID, // Token program that owns the mint.
&mint.pubkey(), // Mint account that stores the InterestBearingConfig extension.
Some(fee_payer.pubkey()), // Authority allowed to update the interest rate later.
30000, // Interest rate in basis points.
)?;
let initialize_mint_instruction = initialize_mint(
&TOKEN_2022_PROGRAM_ID, // Program that owns the mint account.
&mint.pubkey(), // Mint account to initialize.
&fee_payer.pubkey(), // Authority allowed to mint new tokens.
Some(&fee_payer.pubkey()), // Authority allowed to freeze token accounts.
0, // Number of decimals for the token.
)?;
let create_mint_transaction = Transaction::new_signed_with_payer(
&[
create_mint_account_instruction,
initialize_interest_bearing_instruction,
initialize_mint_instruction,
],
Some(&fee_payer.pubkey()),
&[&fee_payer, &mint],
client.get_latest_blockhash().await?,
);
client
.send_and_confirm_transaction(&create_mint_transaction)
.await?;
let token_account = get_associated_token_address_with_program_id(
&recipient.pubkey(),
&mint.pubkey(),
&TOKEN_2022_PROGRAM_ID,
);
let create_token_account_instruction = create_associated_token_account(
&fee_payer.pubkey(), // Account funding the associated token account creation.
&recipient.pubkey(), // Owner of the token account.
&mint.pubkey(), // Mint for the associated token account.
&TOKEN_2022_PROGRAM_ID, // Token program that owns the token account.
);
let mint_to_token_account_instruction = mint_to_checked(
&TOKEN_2022_PROGRAM_ID, // Token program that owns the mint and token account.
&mint.pubkey(), // Mint account that issues the tokens.
&token_account, // Token account receiving the newly minted tokens.
&fee_payer.pubkey(), // Signer authorized to mint new tokens.
&[], // Additional multisig signers.
token_amount, // Token amount in base units.
0, // Decimals defined on the mint.
)?;
let create_token_account_transaction = Transaction::new_signed_with_payer(
&[
create_token_account_instruction,
mint_to_token_account_instruction,
],
Some(&fee_payer.pubkey()),
&[&fee_payer],
client.get_latest_blockhash().await?,
);
client
.send_and_confirm_transaction(&create_token_account_transaction)
.await?;
tokio::time::sleep(std::time::Duration::from_secs(2)).await;
let mint_account = client.get_account(&mint.pubkey()).await?;
let mint_state = StateWithExtensions::<Mint>::unpack(&mint_account.data)?;
let interest_bearing_config = mint_state.get_extension::<InterestBearingConfig>()?;
let clock_account = client.get_account(&clock::ID).await?;
let clock: Clock = clock_account.deserialize_data()?;
let calculated_ui_amount = interest_bearing_config
.amount_to_ui_amount(token_amount, mint_state.base.decimals, clock.unix_timestamp)
.ok_or_else(|| anyhow!("Failed to calculate UI amount"))?;
let amount_to_ui_instruction = amount_to_ui_amount(
&TOKEN_2022_PROGRAM_ID, // Token program that owns the mint.
&mint.pubkey(), // Mint whose UI amount conversion is being simulated.
token_amount, // Token amount in base units.
)?;
let amount_to_ui_blockhash = client.get_latest_blockhash().await?;
let amount_to_ui_transaction = Transaction::new_signed_with_payer(
&[amount_to_ui_instruction],
Some(&fee_payer.pubkey()),
&[&fee_payer],
amount_to_ui_blockhash,
);
let amount_to_ui_result = client.simulate_transaction(&amount_to_ui_transaction).await?;
let simulated_ui_amount = String::from_utf8(
BASE64_STANDARD.decode(
amount_to_ui_result
.value
.return_data
.ok_or_else(|| anyhow!("Expected AmountToUiAmount return data"))?
.data
.0,
)?,
)?;
let update_rate_instruction = update_rate(
&TOKEN_2022_PROGRAM_ID, // Token program that owns the mint.
&mint.pubkey(), // Mint account that stores the InterestBearingConfig extension.
&fee_payer.pubkey(), // Signer authorized to update the interest rate.
&[], // Additional multisig signers.
15000, // New interest rate in basis points.
)?;
let update_rate_transaction = Transaction::new_signed_with_payer(
&[update_rate_instruction],
Some(&fee_payer.pubkey()),
&[&fee_payer],
client.get_latest_blockhash().await?,
);
client
.send_and_confirm_transaction(&update_rate_transaction)
.await?;
let updated_mint_account = client.get_account(&mint.pubkey()).await?;
let updated_mint_state = StateWithExtensions::<Mint>::unpack(&updated_mint_account.data)?;
let interest_bearing_config = updated_mint_state.get_extension::<InterestBearingConfig>()?;
println!("Mint Address: {}", mint.pubkey());
println!("Token Account: {}", token_account);
println!("Calculated UI Amount: {}", calculated_ui_amount);
println!("Simulated UI Amount: {}", simulated_ui_amount);
println!("InterestBearingConfig: {:#?}", interest_bearing_config);
Ok(())
}
Console
Click to execute the code.

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