> ## Documentation Index > Fetch the complete documentation index at: https://docs.magicblock.gg/llms.txt > Use this file to discover all available pages before exploring further. # Ephemeral Accounts > 创建、调整大小并关闭完全存在于 Ephemeral Rollup 中的账户。 Ephemeral accounts 是只存在于 Ephemeral Rollup 内部的账户。一个 **sponsor** 账户（已委托到 ER）会以 **32 lamports/byte** 的成本为 ephemeral accounts 代付租金，这比 Solana 基础租金便宜约 109 倍。 **关键特性：** * 完全在 ER 中创建、存在并销毁 * 归调用它的程序所有（从 CPI 上下文推断） * 由 sponsor 账户的 lamports 提供资金 * 可以被创建、调整大小和关闭 *** ## `#[ephemeral_accounts]` Macro 这个 proc-macro attribute 用于 Anchor 的 `Accounts` struct。它会识别 `#[account(...)]` 中的两个自定义标记： | 标记 | 作用 | | --------- | ------------------------------ | | `sponsor` | 标记为 ephemeral accounts 支付租金的账户 | | `eph` | 将账户标记为 ephemeral（仅存在于 ER） | ### 校验规则 * 如果存在 `eph` 字段，则至少需要一个 `sponsor` * 每个 struct 只允许 **一个** `sponsor` * `eph` 不能与 `init` 或 `init_if_needed` 一起使用（请改用生成的方法） * 如果 sponsor 是 PDA（而不是 `Signer`），则必须提供用于 PDA 签名的 `seeds` ### 生成的方法 对于名为 `conversation` 的字段，macro 会生成： | 方法 | 签名 | 说明 | | --------------------------------------- | ----------------------------------- | ---------------------- | | `create_ephemeral_conversation` | `(data_len: u32) -> Result<()>` | 创建 ephemeral account | | `init_if_needed_ephemeral_conversation` | `(data_len: u32) -> Result<()>` | 仅在 `data_len == 0` 时创建 | | `resize_ephemeral_conversation` | `(new_data_len: u32) -> Result<()>` | 扩大或缩小账户 | | `close_ephemeral_conversation` | `() -> Result<()>` | 关闭账户，并将租金退还给 sponsor | *** ## 签名要求 * **Sponsor**：在所有操作（create、resize、close）中都必须是 signer * **Ephemeral**：**仅在 create 时** 必须是 signer（防止 pubkey 抢注）。resize 或 close 时不要求。 * 对于 PDA 账户，macro 会通过 `find_program_address` 自动推导 signer seeds *** ## 租金模型 ```rust theme={null} pub const EPHEMERAL_RENT_PER_BYTE: u64 = 32; const ACCOUNT_OVERHEAD: u32 = 60; // rent = (data_len + 60) * 32 pub const fn rent(data_len: u32) -> u64 { (data_len as u64 + ACCOUNT_OVERHEAD as u64) * EPHEMERAL_RENT_PER_BYTE } ``` * **扩容**：sponsor 向 vault 支付额外租金 * **缩容**：vault 将多余租金退还给 sponsor * **关闭**：所有租金都从 vault 退还给 sponsor *** ## 创建一个 Ephemeral Account ```rust theme={null} use ephemeral_rollups_sdk::anchor::ephemeral_accounts; pub fn create_conversation(ctx: Context) -> Result<()> { ctx.accounts .create_ephemeral_conversation((8 + Conversation::space_for_message_count(0)) as u32)?; let conversation = Conversation { handle_owner: ctx.accounts.profile_owner.handle.clone(), handle_other: ctx.accounts.profile_other.handle.clone(), bump: ctx.bumps.conversation, messages: Vec::new(), }; let mut data = ctx.accounts.conversation.try_borrow_mut_data()?; conversation.try_serialize(&mut &mut data[..])?; Ok(()) } #[ephemeral_accounts] #[derive(Accounts)] pub struct CreateConversation<'info> { #[account(mut)] pub authority: Signer<'info>, #[account( mut, sponsor, seeds = [b"profile", profile_owner.handle.as_bytes()], bump = profile_owner.bump, has_one = authority )] pub profile_owner: Account<'info, Profile>, #[account( seeds = [b"profile", profile_other.handle.as_bytes()], bump = profile_other.bump, )] pub profile_other: Account<'info, Profile>, /// CHECK: Ephemeral conversation PDA sponsored by the profile. #[account( mut, eph, seeds = [b"conversation", profile_owner.handle.as_bytes(), profile_other.handle.as_bytes()], bump )] pub conversation: AccountInfo<'info>, // vault and magic_program are auto-injected by the macro } ``` 在调用 `create_ephemeral_*` 之后，你必须手动将数据 struct 序列化到原始账户数据中。该 macro 只会分配空间，并不会初始化数据。 *** ## 调整 Ephemeral Account 大小 ```rust theme={null} pub fn extend_conversation( ctx: Context, additional_messages: u32, ) -> Result<()> { let current_capacity = Conversation::message_capacity(ctx.accounts.conversation.to_account_info().data_len()); let new_capacity = current_capacity + additional_messages as usize; ctx.accounts.resize_ephemeral_conversation( (8 + Conversation::space_for_message_count(new_capacity)) as u32, )?; Ok(()) } #[ephemeral_accounts] #[derive(Accounts)] pub struct ExtendConversation<'info> { #[account(mut)] pub authority: Signer<'info>, #[account(mut, sponsor, seeds = [...], bump = ..., has_one = authority)] pub profile_sender: Account<'info, Profile>, #[account(seeds = [...], bump = ...)] pub profile_other: Account<'info, Profile>, /// CHECK: Ephemeral conversation PDA #[account(mut, eph, seeds = [...], bump)] pub conversation: AccountInfo<'info>, } ``` *** ## 关闭一个 Ephemeral Account ```rust theme={null} pub fn close_conversation(ctx: Context) -> Result<()> { let profile = &mut ctx.accounts.profile_owner; profile.active_conversation_count = profile .active_conversation_count .checked_sub(1) .ok_or(ChatError::ConversationCountUnderflow)?; ctx.accounts.close_ephemeral_conversation()?; Ok(()) } #[ephemeral_accounts] #[derive(Accounts)] pub struct CloseConversation<'info> { #[account(mut)] pub authority: Signer<'info>, #[account(mut, sponsor, seeds = [...], bump = ..., has_one = authority)] pub profile_owner: Account<'info, Profile>, #[account(seeds = [...], bump = ...)] pub profile_other: Account<'info, Profile>, /// CHECK: Ephemeral conversation PDA #[account(mut, eph, seeds = [...], bump)] pub conversation: AccountInfo<'info>, } ``` *** ## 使用钱包作为 Sponsor 可以直接使用 `Signer` 作为 sponsor，而不是 PDA： ```rust theme={null} #[ephemeral_accounts] #[derive(Accounts)] pub struct CreateGame<'info> { #[account(mut, sponsor)] pub payer: Signer<'info>, /// CHECK: Ephemeral PDA #[account(mut, eph, seeds = [b"game", payer.key().as_ref()], bump)] pub game_state: AccountInfo<'info>, } ``` *** ## TypeScript 客户端用法 所有 ephemeral account 操作都发送到 **ER connection**，而不是 base layer： ```typescript theme={null} // Create await erProgram.methods .createConversation() .accounts({ authority: userA.publicKey, profileOwner: profileAPda, profileOther: profileBPda, conversation: conversationPda, systemProgram: SystemProgram.programId, }) .rpc(); // Resize await erProgram.methods .extendConversation(5) .accounts({ authority: userA.publicKey, profileSender: profileAPda, profileOther: profileBPda, }) .rpc(); // Close await erProgram.methods .closeConversation() .accounts({ authority: userA.publicKey, profileOwner: profileAPda, profileOther: profileBPda, conversation: conversationPda, }) .rpc(); ``` *** ## 常见坑点 `eph` fields must use `AccountInfo<'info>`, not `Account<'info, T>`. The account doesn't exist yet at validation time, so Anchor cannot deserialize it. After calling `create_ephemeral_*`, you must serialize your data struct into the raw account data yourself. The macro allocates space but does not write any data. The macro enforces this at compile time. Use the generated `create_ephemeral_*` method instead of Anchor's `init` constraint. The sponsor account needs lamports on the ER to pay ephemeral rent. It must be delegated before creating ephemeral accounts. Transfer extra SOL to the sponsor account before delegating it, so it has enough lamports to fund ephemeral accounts on the ER. You don't need to declare them in your struct, but they appear in the IDL and must be passed from the client. Anchor resolves them automatically if named correctly. *** ## Learn More Full example program on GitHub How delegation and state synchronization work Build your first program with Ephemeral Rollups