获取时钟（即当前时间）可以通过两种方式完成：
- 传递SYSVAR_CLOCK_PUBKEY指令
- 在指令内部直接访问时钟。
了解这两种方法是很有好处的，因为一些遗留程序仍然需要将其SYSVAR_CLOCK_PUBKEY作为一个帐户。
在指令中将 Clock 作为账户传递
让我们创建一个接收初始化帐户和 sysvar 公钥的指令
use borsh::{BorshDeserialize, BorshSerialize};
use solana_program::{
account_info::{next_account_info, AccountInfo},
clock::Clock,
entrypoint,
entrypoint::ProgramResult,
msg,
pubkey::Pubkey,
sysvar::Sysvar,
};
entrypoint!(process_instruction);
#[derive(BorshSerialize, BorshDeserialize, Debug)]
pub struct HelloState {
is_initialized: bool,
}
// Accounts required
/// 1. [signer, writable] Payer
/// 2. [writable] Hello state account
/// 3. [] Clock sys var
pub fn process_instruction(
_program_id: &Pubkey,
accounts: &[AccountInfo],
_instruction_data: &[u8],
) -> ProgramResult {
let accounts_iter = &mut accounts.iter();
// Payer account
let _payer_account = next_account_info(accounts_iter)?;
// Hello state account
let hello_state_account = next_account_info(accounts_iter)?;
// Clock sysvar
let sysvar_clock_pubkey = next_account_info(accounts_iter)?;
let mut hello_state = HelloState::try_from_slice(&hello_state_account.data.borrow())?;
hello_state.is_initialized = true;
hello_state.serialize(&mut &mut hello_state_account.data.borrow_mut()[..])?;
msg!("Account initialized :)");
// Type casting [AccountInfo] to [Clock]
let clock = Clock::from_account_info(&sysvar_clock_pubkey)?;
// Getting timestamp
let current_timestamp = clock.unix_timestamp;
msg!("Current Timestamp: {}", current_timestamp);
Ok(())
}现在我们通过客户端传递时钟的 sysvar 公共地址
import {
clusterApiUrl,
Connection,
Keypair,
LAMPORTS_PER_SOL,
PublicKey,
SystemProgram,
SYSVAR_CLOCK_PUBKEY,
Transaction,
TransactionInstruction,
sendAndConfirmTransaction,
} from "@solana/web3.js";
(async () => {
const programId = new PublicKey(
"77ezihTV6mTh2Uf3ggwbYF2NyGJJ5HHah1GrdowWJVD3",
);
const connection = new Connection(clusterApiUrl("devnet"), "confirmed");
const latestBlockHash = await connection.getLatestBlockhash();
// Airdropping 1 SOL
const feePayer = Keypair.generate();
await connection.confirmTransaction(
{
blockhash: latestBlockHash.blockhash,
lastValidBlockHeight: latestBlockHash.lastValidBlockHeight,
signature: await connection.requestAirdrop(
feePayer.publicKey,
LAMPORTS_PER_SOL,
),
},
"confirmed",
);
// Hello state account
const helloAccount = Keypair.generate();
const accountSpace = 1; // because there exists just one boolean variable
const rentRequired =
await connection.getMinimumBalanceForRentExemption(accountSpace);
// Allocating space for hello state account
const allocateHelloAccountIx = SystemProgram.createAccount({
fromPubkey: feePayer.publicKey,
lamports: rentRequired,
newAccountPubkey: helloAccount.publicKey,
programId: programId,
space: accountSpace,
});
// Passing Clock Sys Var
const passClockIx = new TransactionInstruction({
programId: programId,
keys: [
{
isSigner: true,
isWritable: true,
pubkey: feePayer.publicKey,
},
{
isSigner: false,
isWritable: true,
pubkey: helloAccount.publicKey,
},
{
isSigner: false,
isWritable: false,
pubkey: SYSVAR_CLOCK_PUBKEY,
},
],
});
const transaction = new Transaction();
transaction.add(allocateHelloAccountIx, passClockIx);
const txHash = await sendAndConfirmTransaction(connection, transaction, [
feePayer,
helloAccount,
]);
console.log(`Transaction succeeded. TxHash: ${txHash}`);
})();直接在指令内部访问时钟
让我们创建相同的指令，但不期望 SYSVAR_CLOCK_PUBKEY来自客户端。
use borsh::{BorshDeserialize, BorshSerialize};
use solana_program::{
account_info::{next_account_info, AccountInfo},
clock::Clock,
entrypoint,
entrypoint::ProgramResult,
msg,
pubkey::Pubkey,
sysvar::Sysvar,
};
entrypoint!(process_instruction);
#[derive(BorshSerialize, BorshDeserialize, Debug)]
pub struct HelloState {
is_initialized: bool,
}
// Accounts required
/// 1. [signer, writable] Payer
/// 2. [writable] Hello state account
pub fn process_instruction(
_program_id: &Pubkey,
accounts: &[AccountInfo],
_instruction_data: &[u8],
) -> ProgramResult {
let accounts_iter = &mut accounts.iter();
// Payer account
let _payer_account = next_account_info(accounts_iter)?;
// Hello state account
let hello_state_account = next_account_info(accounts_iter)?;
// Getting clock directly
let clock = Clock::get()?;
let mut hello_state = HelloState::try_from_slice(&hello_state_account.data.borrow())?;
hello_state.is_initialized = true;
hello_state.serialize(&mut &mut hello_state_account.data.borrow_mut()[..])?;
msg!("Account initialized :)");
// Getting timestamp
let current_timestamp = clock.unix_timestamp;
msg!("Current Timestamp: {}", current_timestamp);
Ok(())
}客户端指令现在只需要传递州和付款人账户。
import {
clusterApiUrl,
Connection,
Keypair,
LAMPORTS_PER_SOL,
PublicKey,
SystemProgram,
Transaction,
TransactionInstruction,
} from "@solana/web3.js";
(async () => {
const programId = new PublicKey(
"4ZEdbCtb5UyCSiAMHV5eSHfyjq3QwbG3yXb6oHD7RYjk",
);
const connection = new Connection(clusterApiUrl("devnet"), "confirmed");
const latestBlockHash = await connection.getLatestBlockhash();
// Airdropping 1 SOL
const feePayer = Keypair.generate();
await connection.confirmTransaction(
{
blockhash: latestBlockHash.blockhash,
lastValidBlockHeight: latestBlockHash.lastValidBlockHeight,
signature: await connection.requestAirdrop(
feePayer.publicKey,
LAMPORTS_PER_SOL,
),
},
"confirmed",
);
// Hello state account
const helloAccount = Keypair.generate();
const accountSpace = 1; // because there exists just one boolean variable
const rentRequired =
await connection.getMinimumBalanceForRentExemption(accountSpace);
// Allocating space for hello state account
const allocateHelloAccountIx = SystemProgram.createAccount({
fromPubkey: feePayer.publicKey,
lamports: rentRequired,
newAccountPubkey: helloAccount.publicKey,
programId: programId,
space: accountSpace,
});
const initIx = new TransactionInstruction({
programId: programId,
keys: [
{
isSigner: true,
isWritable: true,
pubkey: feePayer.publicKey,
},
{
isSigner: false,
isWritable: true,
pubkey: helloAccount.publicKey,
},
],
});
const transaction = new Transaction();
transaction.add(allocateHelloAccountIx, initIx);
const txHash = await sendAndConfirmTransaction(connection, transaction, [
feePayer,
helloAccount,
]);
console.log(`Transaction succeeded. TxHash: ${txHash}`);
})();