Blueshift | Anchor Escrow

Take

我們現在可以移至 take 指令，該指令位於 take.rs，並將執行以下操作：

關閉托管記錄，將其租金 lamports 返回給創建者。
將 Token A 從保管庫移至接受者，然後關閉保管庫。
將商定數量的 Token B 從接受者移至創建者。

帳戶

在此情境中需要的帳戶包括：

taker：接受 maker 條款並進行交換的用戶
maker：最初設定條款的用戶
escrow：存放此交換所有條款的帳戶
mint_a：maker 存入的代幣
mint_b：maker 想要交換的代幣
vault：與 escrow 和 mint_a 關聯的代幣帳戶，將代幣發送給 taker
taker_ata_a：與 taker 和 mint_a 關聯的代幣帳戶，將從 vault 接收代幣
taker_ata_b：與 taker 和 mint_b 關聯的代幣帳戶，將代幣發送給 maker
maker_ata_b：與 maker 和 mint_b 關聯的代幣帳戶，將接收來自 taker 的代幣
associated_token_program：用於創建關聯代幣帳戶的關聯代幣程式
token_program：用於 CPI 傳輸的代幣程式
system_program：用於創建 Escrow 的系統程式

結合所有約束條件後，它看起來會像這樣：

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>,
}

邏輯

在邏輯部分，我們首先將代幣從taker_ata_b轉移到maker_ata_b；接著，我們將代幣從vault轉移到taker_ata_a，然後像這樣關閉現在已經空的保管庫：

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(())
    }
}

我們現在創建handler函數，這次幸運的是我們不需要執行任何額外的檢查，因此它將如下所示：

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(())
}