add max supply

src/consts.rs

@@ -11,10 +11,10 @@ pub const INITIAL_TOLERANCE: i64 = 5;
 /// The minimum difficulty required of all submitted hashes.
 pub const MIN_DIFFICULTY: u32 = 12;
 
-/// The decimal precision of the ORE token.
+/// The decimal precision of the Ore token (100 billion indivisible units per Ore).
 pub const TOKEN_DECIMALS: u8 = 11;
 
-/// One ORE token, denominated in indivisible units.
+/// One Ore token, denominated in indivisible units.
 pub const ONE_ORE: u64 = 10u64.pow(TOKEN_DECIMALS as u32);
 
 /// The duration of one minute, in seconds.
@@ -23,6 +23,9 @@ pub const ONE_MINUTE: i64 = 60;
 /// The duration of two years, in minutes.
 pub const TWO_YEARS: u64 = 60 * 24 * 365 * 2;
 
+/// The maximum token supply (100 million).
+pub const MAX_SUPPLY: u64 = ONE_ORE.saturating_mul(100_000_000);
+
 /// The target quantity of ORE to be mined per epoch.
 /// Inflation rate ≈ 1 ORE / epoch (min 0, max 2)
 pub const TARGET_EPOCH_REWARDS: u64 = ONE_ORE;

src/error.rs

@@ -19,6 +19,8 @@ pub enum OreError {
     TransactionInvalid = 5,
     #[error("The tolerance cannot exceed i64 max value")]
     ToleranceOverflow = 6,
+    #[error("The maximum supply has been reached")]
+    MaxSupply = 7,
 }
 
 impl From<OreError> for ProgramError {

src/processor/reset.rs

@@ -1,7 +1,8 @@
 use solana_program::{
     account_info::AccountInfo, clock::Clock, entrypoint::ProgramResult,
-    program_error::ProgramError, pubkey::Pubkey, sysvar::Sysvar,
+    program_error::ProgramError, program_pack::Pack, pubkey::Pubkey, sysvar::Sysvar,
 };
+use spl_token::state::Mint;
 
 use crate::{
     error::OreError,
@@ -11,8 +12,8 @@ use crate::{
     },
     state::{Bus, Config},
     utils::AccountDeserialize,
-    BUS_COUNT, BUS_EPOCH_REWARDS, MAX_EPOCH_REWARDS, MINT_ADDRESS, ONE_MINUTE, SMOOTHING_FACTOR,
-    TARGET_EPOCH_REWARDS, TREASURY, TREASURY_BUMP,
+    BUS_COUNT, BUS_EPOCH_REWARDS, MAX_EPOCH_REWARDS, MAX_SUPPLY, MINT_ADDRESS, ONE_MINUTE,
+    SMOOTHING_FACTOR, TARGET_EPOCH_REWARDS, TREASURY, TREASURY_BUMP,
 };
 
 /// Reset sets up the Ore program for the next epoch. Its responsibilities include:
@@ -104,6 +105,15 @@ pub fn process_reset<'a, 'info>(
     config.base_reward_rate =
         calculate_new_reward_rate(config.base_reward_rate, total_theoretical_rewards);
 
+    // Load mint
+    let mint = Mint::unpack(&mint_info.data.borrow()).expect("Failed to parse mint");
+    let amount = MAX_SUPPLY
+        .saturating_sub(mint.supply)
+        .min(total_epoch_rewards);
+    if amount.eq(&0) {
+        return Err(OreError::MaxSupply.into());
+    }
+
     // Fund treasury token account
     solana_program::program::invoke_signed(
         &spl_token::instruction::mint_to(
@@ -112,7 +122,7 @@ pub fn process_reset<'a, 'info>(
             treasury_tokens_info.key,
             treasury_info.key,
             &[treasury_info.key],
-            total_epoch_rewards,
+            amount,
         )?,
         &[
             token_program.clone(),