rent: Deprecate the concept of paying rent, prep for SIMD-0194

rent/src/lib.rs

@@ -32,16 +32,28 @@ static_assertions::const_assert_eq!(
 #[derive(PartialEq, CloneZeroed, Debug)]
 pub struct Rent {
     /// Rental rate in lamports/byte-year.
+    #[deprecated(
+        since = "3.1.0",
+        note = "Field will be renamed to `lamports_per_byte` in v4, use `Rent::new_with_lamports_per_byte` to create, and `Rent::minimum_balance` or `Rent::is_exempt`"
+    )]
     pub lamports_per_byte_year: u64,
 
     /// Amount of time (in years) a balance must include rent for the account to
     /// be rent exempt.
+    #[deprecated(
+        since = "3.1.0",
+        note = "Exemption threshold will be set to 1f64 with SIMD-0194 and should no longer be used"
+    )]
     pub exemption_threshold: f64,
 
     /// The percentage of collected rent that is burned.
     ///
     /// Valid values are in the range [0, 100]. The remaining percentage is
     /// distributed to validators.
+    #[deprecated(
+        since = "3.1.0",
+        note = "The concept of rent no longer exists, only rent-exemption"
+    )]
     pub burn_percent: u8,
 }
 
@@ -71,6 +83,7 @@ pub const DEFAULT_BURN_PERCENT: u8 = 50;
 pub const ACCOUNT_STORAGE_OVERHEAD: u64 = 128;
 
 impl Default for Rent {
+    #[allow(deprecated)]
     fn default() -> Self {
         Self {
             lamports_per_byte_year: DEFAULT_LAMPORTS_PER_BYTE_YEAR,
@@ -85,12 +98,18 @@ impl Rent {
     ///
     /// The first value returned is the amount burned. The second is the amount
     /// to distribute to validators.
+    #[deprecated(
+        since = "3.1.0",
+        note = "The concept of rent no longer exists, only rent-exemption"
+    )]
+    #[allow(deprecated)]
     pub fn calculate_burn(&self, rent_collected: u64) -> (u64, u64) {
         let burned_portion = (rent_collected * u64::from(self.burn_percent)) / 100;
         (burned_portion, rent_collected - burned_portion)
     }
 
     /// Minimum balance due for rent-exemption of a given account data size.
+    #[allow(deprecated)]
     pub fn minimum_balance(&self, data_len: usize) -> u64 {
         let bytes = data_len as u64;
         (((ACCOUNT_STORAGE_OVERHEAD + bytes) * self.lamports_per_byte_year) as f64
@@ -103,6 +122,11 @@ impl Rent {
     }
 
     /// Rent due on account's data length with balance.
+    #[deprecated(
+        since = "3.1.0",
+        note = "The concept of rent no longer exists, only rent-exemption"
+    )]
+    #[allow(deprecated)]
     pub fn due(&self, balance: u64, data_len: usize, years_elapsed: f64) -> RentDue {
         if self.is_exempt(balance, data_len) {
             RentDue::Exempt
@@ -112,6 +136,11 @@ impl Rent {
     }
 
     /// Rent due for account that is known to be not exempt.
+    #[deprecated(
+        since = "3.1.0",
+        note = "The concept of rent no longer exists, only rent-exemption"
+    )]
+    #[allow(deprecated)]
     pub fn due_amount(&self, data_len: usize, years_elapsed: f64) -> u64 {
         let actual_data_len = data_len as u64 + ACCOUNT_STORAGE_OVERHEAD;
         let lamports_per_year = self.lamports_per_byte_year * actual_data_len;
@@ -121,6 +150,7 @@ impl Rent {
     /// Creates a `Rent` that charges no lamports.
     ///
     /// This is used for testing.
+    #[allow(deprecated)]
     pub fn free() -> Self {
         Self {
             lamports_per_byte_year: 0,
@@ -131,6 +161,11 @@ impl Rent {
     /// Creates a `Rent` that is scaled based on the number of slots in an epoch.
     ///
     /// This is used for testing.
+    #[deprecated(
+        since = "3.1.0",
+        note = "The concept of rent no longer exists, only rent-exemption, use `Rent::with_lamports_per_byte`"
+    )]
+    #[allow(deprecated)]
     pub fn with_slots_per_epoch(slots_per_epoch: u64) -> Self {
         let ratio = slots_per_epoch as f64 / DEFAULT_SLOTS_PER_EPOCH as f64;
         let exemption_threshold = DEFAULT_EXEMPTION_THRESHOLD * ratio;
@@ -141,9 +176,22 @@ impl Rent {
             ..Self::default()
         }
     }
+
+    /// Creates a `Rent` with lamports per byte
+    #[allow(deprecated)]
+    pub fn with_lamports_per_byte(lamports_per_byte: u64) -> Self {
+        Self {
+            lamports_per_byte_year: lamports_per_byte,
+            ..Self::default()
+        }
+    }
 }
 
 /// The return value of [`Rent::due`].
+#[deprecated(
+    since = "3.1.0",
+    note = "The concept of rent no longer exists, only rent-exemption"
+)]
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum RentDue {
     /// Used to indicate the account is rent exempt.
@@ -152,6 +200,7 @@ pub enum RentDue {
     Paying(u64),
 }
 
+#[allow(deprecated)]
 impl RentDue {
     /// Return the lamports due for rent.
     pub fn lamports(&self) -> u64 {
@@ -175,6 +224,7 @@ mod tests {
     use super::*;
 
     #[test]
+    #[allow(deprecated)]
     fn test_due() {
         let default_rent = Rent::default();
 
@@ -221,6 +271,7 @@ mod tests {
     }
 
     #[test]
+    #[allow(deprecated)]
     fn test_rent_due_lamports() {
         assert_eq!(RentDue::Exempt.lamports(), 0);
 
@@ -229,12 +280,14 @@ mod tests {
     }
 
     #[test]
+    #[allow(deprecated)]
     fn test_rent_due_is_exempt() {
         assert!(RentDue::Exempt.is_exempt());
         assert!(!RentDue::Paying(0).is_exempt());
     }
 
     #[test]
+    #[allow(deprecated)]
     fn test_clone() {
         let rent = Rent {
             lamports_per_byte_year: 1,