Blueshift | Anchor 托管

Take

我们现在可以转到 take 指令，该指令位于 take.rs 中，并将执行以下操作：

关闭托管记录，将其租金 lamports 返还给创建者。
将 Token A 从保管库转移到接受者，然后关闭保管库。
将约定数量的 Token B 从接受者转移到创建者。

账户

在此上下文中需要的账户包括：

taker：接受 maker 条款并进行交换的用户
maker：最初设定条款的用户
escrow：存储此交换所有条款的账户
mint_a：maker 存入的代币
mint_b：maker 希望交换的代币
vault：与 escrow 和 mint_a 关联的代币账户，将代币发送给 taker
taker_ata_a：与 taker 和 mint_a 关联的代币账户，将从 vault 接收代币
taker_ata_b：与 taker 和 mint_b 关联的代币账户，将代币发送给 maker
maker_ata_b：与 maker 和 mint_b 关联的代币账户，将接收来自 taker 的代币
associated_token_program：用于创建关联代币账户的关联代币程序
token_program：用于 CPI 转账的代币程序
system_program：用于创建 Escrow 的系统程序

结合所有约束条件，它看起来会是这样的：

rust
#[derive(Accounts)]
pub struct Take<'info> {
  #[account(mut)]
  pub taker: Signer<'info>,
  #[account(mut)]
  pub maker: SystemAccount<'info>,
  #[account(
      mut,
      close = maker,
      seeds = [b"escrow", maker.key().as_ref(), escrow.seed.to_le_bytes().as_ref()],
      bump = escrow.bump,
      has_one = maker @ EscrowError::InvalidMaker,
      has_one = mint_a @ EscrowError::InvalidMintA,
      has_one = mint_b @ EscrowError::InvalidMintB,
  )]
  pub escrow: Box<Account<'info, Escrow>>,

  /// Token Accounts
  pub mint_a: Box<InterfaceAccount<'info, Mint>>,
  pub mint_b: Box<InterfaceAccount<'info, Mint>>,
  #[account(
      mut,
      associated_token::mint = mint_a,
      associated_token::authority = escrow,
      associated_token::token_program = token_program
  )]
  pub vault: Box<InterfaceAccount<'info, TokenAccount>>,
  #[account(
      init_if_needed,
      payer = taker,
      associated_token::mint = mint_a,
      associated_token::authority = taker,
      associated_token::token_program = token_program
  )]
  pub taker_ata_a: Box<InterfaceAccount<'info, TokenAccount>>,
  #[account(
      mut,
      associated_token::mint = mint_b,
      associated_token::authority = taker,
      associated_token::token_program = token_program
  )]
  pub taker_ata_b: Box<InterfaceAccount<'info, TokenAccount>>,
  #[account(
      init_if_needed,
      payer = taker,
      associated_token::mint = mint_b,
      associated_token::authority = maker,
      associated_token::token_program = token_program
  )]
  pub maker_ata_b: Box<InterfaceAccount<'info, TokenAccount>>,

  /// Programs
  pub associated_token_program: Program<'info, AssociatedToken>,
  pub token_program: Interface<'info, TokenInterface>,
  pub system_program: Program<'info, System>,
}

逻辑

在逻辑部分，我们首先将代币从taker_ata_b转移到maker_ata_b；然后将代币从vault转移到taker_ata_a，最后像这样关闭现在已空的保险库：

rust
impl<'info> Take<'info> {
    fn transfer_to_maker(&mut self) -> Result<()> {
        transfer_checked(
            CpiContext::new(
                self.token_program.to_account_info(),
                TransferChecked {
                    from: self.taker_ata_b.to_account_info(),
                    to: self.maker_ata_b.to_account_info(),
                    mint: self.mint_b.to_account_info(),
                    authority: self.taker.to_account_info(),
                },
            ),
            self.escrow.receive,
            self.mint_b.decimals,
        )?;

        Ok(())
    }

    fn withdraw_and_close_vault(&mut self) -> Result<()> {
        // Create the signer seeds for the Vault
        let signer_seeds: [&[&[u8]]; 1] = [&[
            b"escrow",
            self.maker.to_account_info().key.as_ref(),
            &self.escrow.seed.to_le_bytes()[..],
            &[self.escrow.bump],
        ]];

        // Transfer Token A (Vault -> Taker)
        transfer_checked(
            CpiContext::new_with_signer(
                self.token_program.to_account_info(),
                TransferChecked {
                    from: self.vault.to_account_info(),
                    to: self.taker_ata_a.to_account_info(),
                    mint: self.mint_a.to_account_info(),
                    authority: self.escrow.to_account_info(),
                },
                &signer_seeds,
            ),
            self.vault.amount,
            self.mint_a.decimals,
        )?;

        // Close the Vault
        close_account(CpiContext::new_with_signer(
            self.token_program.to_account_info(),
            CloseAccount {
                account: self.vault.to_account_info(),
                authority: self.escrow.to_account_info(),
                destination: self.maker.to_account_info(),
            },
            &signer_seeds,
        ))?;

        Ok(())
    }
}

我们现在创建handler函数，这次幸运的是我们不需要执行任何额外的检查，因此它将如下所示：

rust
pub fn handler(ctx: Context<Take>) -> Result<()> {
    // Transfer Token B to Maker
    ctx.accounts.transfer_to_maker()?;

    // Withdraw and close the Vault
    ctx.accounts.withdraw_and_close_vault()?;

    Ok(())
}