doc: compressible config

Author: ananas-block

sdk-libs/ctoken-sdk/src/ctoken/close.rs

@@ -73,6 +73,7 @@ impl CloseCTokenAccount {
 /// # let account: AccountInfo = todo!();
 /// # let destination: AccountInfo = todo!();
 /// # let owner: AccountInfo = todo!();
+/// // Use ctoken::RENT_SPONSOR or ctoken::rent_sponsor_pda() to get the protocol rent sponsor.
 /// # let rent_sponsor: AccountInfo = todo!();
 /// CloseCTokenAccountCpi {
 ///     token_program,

sdk-libs/ctoken-sdk/src/ctoken/compressible.rs

@@ -6,10 +6,30 @@ use solana_pubkey::Pubkey;
 
 use crate::ctoken::{COMPRESSIBLE_CONFIG_V1, RENT_SPONSOR};
 
+/// Parameters for creating compressible ctoken accounts.
+///
+/// Compressible accounts have sponsored rent and can be compressed to compressed
+/// token accounts when their lamports balance is insufficient.
+///
+/// Default values are:
+/// - 24 hours rent
+/// - lamports for 3 hours rent (paid on transfer when account rent is insufficient to cover the next 2 epochs)
+/// - Protocol rent sponsor
+/// - TokenDataVersion::ShaFlat token data hashing (only sha is supported for compressible accounts)
+///
+/// # Example
+/// ```rust
+/// use light_ctoken_sdk::ctoken::CompressibleParams;
+///
+/// let params = CompressibleParams::new();
+/// ```
 #[derive(Debug, Clone)]
 pub struct CompressibleParams {
     pub token_account_version: TokenDataVersion,
     pub pre_pay_num_epochs: u8,
+    /// Number of lamports transferred on a write operation (eg transfer) when account rent is insufficient to cover the next 2 rent-epochs.
+    /// Default: 766 lamports for 3 hours rent.
+    /// These lamports keep the ctoken account perpetually funded when used.
     pub lamports_per_write: Option<u32>,
     pub compress_to_account_pubkey: Option<CompressToPubkey>,
     pub compressible_config: Pubkey,
@@ -31,9 +51,10 @@ impl Default for CompressibleParams {
 
 impl CompressibleParams {
     /// Creates a new `CompressibleParams` with default values.
-    ///
-    /// Use builder methods to customize:
-    /// - [`compress_to_pubkey`](Self::compress_to_pubkey) - set the destination for compression
+    /// - 24 hours rent
+    /// - 3 hours top up (paid on transfer when account rent is insufficient to cover the next 2 epochs)
+    /// - Protocol rent sponsor
+    /// - TokenDataVersion::ShaFlat token data hashing (only sha is supported for compressible accounts)
     pub fn new() -> Self {
         Self::default()
     }
@@ -45,7 +66,23 @@ impl CompressibleParams {
     }
 }
 
-/// Account infos for compressible token accounts in CPI operations.
+/// Parameters for creating compressible ctoken accounts via CPI.
+///
+/// # Example
+/// ```rust,no_run
+/// # use light_ctoken_sdk::ctoken::CompressibleParamsCpi;
+/// # use solana_account_info::AccountInfo;
+/// // Use ctoken::COMPRESSIBLE_CONFIG_V1 or ctoken::config_pda() to get the protocol config.
+/// // Use ctoken::RENT_SPONSOR or ctoken::rent_sponsor_pda() to get the protocol rent sponsor.
+/// # let compressible_config: AccountInfo = todo!();
+/// # let rent_sponsor: AccountInfo = todo!();
+/// # let system_program: AccountInfo = todo!();
+/// let params = CompressibleParamsCpi::new(
+///     compressible_config,
+///     rent_sponsor,
+///     system_program,
+/// );
+/// ```
 pub struct CompressibleParamsCpi<'info> {
     pub compressible_config: AccountInfo<'info>,
     pub rent_sponsor: AccountInfo<'info>,

sdk-libs/ctoken-sdk/src/lib.rs

@@ -12,6 +12,7 @@
 //!     - rent is 388 lamports per rent epoch (1.5 hours).
 //!     - once the account's lamports balance is insufficient, it is compressed to a compressed token account.
 //!     - compressed tokens can be decompressed to a cToken account.
+//!     - configurable lamports per write (eg transfer) keep the cToken account perpetually funded when used. So you don't have to worry about funding rent.
 //!
 //! ## Compressed Token Accounts
 //! - are on Solana mainnet.