[staking] add stake subsidies

crates/sui-config/tests/snapshots/snapshot_tests__populated_genesis_snapshot_matches-4.snap

@@ -445,4 +445,5 @@ parameters:
 reference_gas_price: 0
 validator_report_records:
   contents: []
+next_epoch_stake_subsidy: 1000000
 

crates/sui-config/tests/snapshots/snapshot_tests__populated_genesis_snapshot_matches-5.snap

@@ -441,4 +441,5 @@ parameters:
 reference_gas_price: 0
 validator_report_records:
   contents: []
+next_epoch_stake_subsidy: 1000000
 

crates/sui-cost/tests/snapshots/empirical_transaction_cost__good_snapshot-2.snap

@@ -4,13 +4,13 @@ expression: common_costs_estimate
 ---
 {
   "MergeCoin": {
-    "computation_cost": 6134,
-    "storage_cost": 9057,
+    "computation_cost": 6166,
+    "storage_cost": 9104,
     "storage_rebate": 0
   },
   "Publish": {
-    "computation_cost": 6927,
-    "storage_cost": 10161,
+    "computation_cost": 6958,
+    "storage_cost": 10208,
     "storage_rebate": 0
   },
   "SharedCounterAssertValue": {
@@ -29,8 +29,8 @@ expression: common_costs_estimate
     "storage_rebate": 0
   },
   "SplitCoin": {
-    "computation_cost": 6112,
-    "storage_cost": 9024,
+    "computation_cost": 6144,
+    "storage_cost": 9071,
     "storage_rebate": 0
   },
   "TransferPortionSuiCoin": {

crates/sui-framework/docs/genesis.md

@@ -45,6 +45,16 @@ Initial value of the lower-bound on the amount of stake required to become a val
 
 
 
+<a name="0x2_genesis_INIT_STAKE_SUBSIDY_AMOUNT"></a>
+
+Stake subisidy to be given out in the very first epoch. Placeholder value.
+
+
+<pre><code><b>const</b> <a href="genesis.md#0x2_genesis_INIT_STAKE_SUBSIDY_AMOUNT">INIT_STAKE_SUBSIDY_AMOUNT</a>: u64 = 1000000;
+</code></pre>
+
+
+
 <a name="0x2_genesis_INIT_STORAGE_FUND"></a>
 
 The initial amount of SUI locked in the storage fund.
@@ -152,6 +162,7 @@ all the information we need in the system.
         <a href="genesis.md#0x2_genesis_INIT_MAX_VALIDATOR_COUNT">INIT_MAX_VALIDATOR_COUNT</a>,
         <a href="genesis.md#0x2_genesis_INIT_MIN_VALIDATOR_STAKE">INIT_MIN_VALIDATOR_STAKE</a>,
         <a href="genesis.md#0x2_genesis_INIT_STORAGE_GAS_PRICE">INIT_STORAGE_GAS_PRICE</a>,
+        <a href="genesis.md#0x2_genesis_INIT_STAKE_SUBSIDY_AMOUNT">INIT_STAKE_SUBSIDY_AMOUNT</a>,
     );
 }
 </code></pre>

crates/sui-framework/docs/sui_system.md

@@ -23,6 +23,7 @@
 -  [Function `report_validator`](#0x2_sui_system_report_validator)
 -  [Function `undo_report_validator`](#0x2_sui_system_undo_report_validator)
 -  [Function `advance_epoch`](#0x2_sui_system_advance_epoch)
+-  [Function `update_stake_subsidy_amount`](#0x2_sui_system_update_stake_subsidy_amount)
 -  [Function `epoch`](#0x2_sui_system_epoch)
 -  [Function `validator_delegate_amount`](#0x2_sui_system_validator_delegate_amount)
 -  [Function `validator_stake_amount`](#0x2_sui_system_validator_stake_amount)
@@ -164,6 +165,13 @@ The top-level object containing all information of the Sui system.
  them. If a validator has never been reported they don't have an entry in this map.
  This map resets every epoch.
 </dd>
+<dt>
+<code>next_epoch_stake_subsidy: u64</code>
+</dt>
+<dd>
+ The amount of stake subsidies to be given out in the next epoch, updated at
+ epoch boundaries.
+</dd>
 </dl>
 
 
@@ -228,6 +236,24 @@ The top-level object containing all information of the Sui system.
 
 
 
+<a name="0x2_sui_system_STAKE_SUBSIDY_DECREASE_RATE"></a>
+
+
+
+<pre><code><b>const</b> <a href="sui_system.md#0x2_sui_system_STAKE_SUBSIDY_DECREASE_RATE">STAKE_SUBSIDY_DECREASE_RATE</a>: u128 = 1000;
+</code></pre>
+
+
+
+<a name="0x2_sui_system_STAKE_SUBSIDY_PERIOD_LENGTH"></a>
+
+
+
+<pre><code><b>const</b> <a href="sui_system.md#0x2_sui_system_STAKE_SUBSIDY_PERIOD_LENGTH">STAKE_SUBSIDY_PERIOD_LENGTH</a>: u64 = 30;
+</code></pre>
+
+
+
 <a name="0x2_sui_system_create"></a>
 
 ## Function `create`
@@ -236,7 +262,7 @@ Create a new SuiSystemState object and make it shared.
 This function will be called only once in genesis.
 
 
-<pre><code><b>public</b>(<b>friend</b>) <b>fun</b> <a href="sui_system.md#0x2_sui_system_create">create</a>(chain_id: u8, validators: <a href="">vector</a>&lt;<a href="validator.md#0x2_validator_Validator">validator::Validator</a>&gt;, sui_supply: <a href="balance.md#0x2_balance_Supply">balance::Supply</a>&lt;<a href="sui.md#0x2_sui_SUI">sui::SUI</a>&gt;, storage_fund: <a href="balance.md#0x2_balance_Balance">balance::Balance</a>&lt;<a href="sui.md#0x2_sui_SUI">sui::SUI</a>&gt;, max_validator_candidate_count: u64, min_validator_stake: u64, storage_gas_price: u64)
+<pre><code><b>public</b>(<b>friend</b>) <b>fun</b> <a href="sui_system.md#0x2_sui_system_create">create</a>(chain_id: u8, validators: <a href="">vector</a>&lt;<a href="validator.md#0x2_validator_Validator">validator::Validator</a>&gt;, sui_supply: <a href="balance.md#0x2_balance_Supply">balance::Supply</a>&lt;<a href="sui.md#0x2_sui_SUI">sui::SUI</a>&gt;, storage_fund: <a href="balance.md#0x2_balance_Balance">balance::Balance</a>&lt;<a href="sui.md#0x2_sui_SUI">sui::SUI</a>&gt;, max_validator_candidate_count: u64, min_validator_stake: u64, storage_gas_price: u64, next_epoch_stake_subsidy: u64)
 </code></pre>
 
 
@@ -253,6 +279,7 @@ This function will be called only once in genesis.
     max_validator_candidate_count: u64,
     min_validator_stake: u64,
     storage_gas_price: u64,
+    next_epoch_stake_subsidy: u64,
 ) {
     <b>assert</b>!(chain_id &gt;= 1 && chain_id &lt;= 127, 1);
     <b>let</b> validators = <a href="validator_set.md#0x2_validator_set_new">validator_set::new</a>(validators);
@@ -272,6 +299,7 @@ This function will be called only once in genesis.
         },
         reference_gas_price,
         validator_report_records: <a href="vec_map.md#0x2_vec_map_empty">vec_map::empty</a>(),
+        next_epoch_stake_subsidy,
     };
     <a href="transfer.md#0x2_transfer_share_object">transfer::share_object</a>(state);
 }
@@ -811,6 +839,10 @@ gas coins.
     <b>let</b> storage_reward = <a href="balance.md#0x2_balance_create_staking_rewards">balance::create_staking_rewards</a>(storage_charge);
     <b>let</b> computation_reward = <a href="balance.md#0x2_balance_create_staking_rewards">balance::create_staking_rewards</a>(computation_charge);
 
+    // Include <a href="stake.md#0x2_stake">stake</a> subsidy in the rewards given out <b>to</b> validators and delegators.
+    <b>let</b> stake_subsidy = <a href="balance.md#0x2_balance_increase_supply">balance::increase_supply</a>(&<b>mut</b> self.sui_supply, self.next_epoch_stake_subsidy);
+    <a href="balance.md#0x2_balance_join">balance::join</a>(&<b>mut</b> computation_reward, stake_subsidy);
+
     <b>let</b> delegation_stake = <a href="validator_set.md#0x2_validator_set_total_delegation_stake">validator_set::total_delegation_stake</a>(&self.validators);
     <b>let</b> validator_stake = <a href="validator_set.md#0x2_validator_set_total_validator_stake">validator_set::total_validator_stake</a>(&self.validators);
     <b>let</b> storage_fund_balance = <a href="balance.md#0x2_balance_value">balance::value</a>(&self.storage_fund);
@@ -856,6 +888,9 @@ gas coins.
     <b>assert</b>!(<a href="balance.md#0x2_balance_value">balance::value</a>(&self.storage_fund) &gt;= storage_rebate, 0);
     <a href="balance.md#0x2_balance_destroy_storage_rebates">balance::destroy_storage_rebates</a>(<a href="balance.md#0x2_balance_split">balance::split</a>(&<b>mut</b> self.storage_fund, storage_rebate));
 
+    // Update the amount of subsidy <b>to</b> be given out in the next epoch.
+    <a href="sui_system.md#0x2_sui_system_update_stake_subsidy_amount">update_stake_subsidy_amount</a>(self, new_epoch);
+
     // Validator reports are only valid for the epoch.
     // TODO: or do we want <b>to</b> make it persistent and validators have <b>to</b> explicitly change their scores?
     self.validator_report_records = <a href="vec_map.md#0x2_vec_map_empty">vec_map::empty</a>();
@@ -879,6 +914,35 @@ Total supply of SUI shouldn't change.
 
 
 
+</details>
+
+<a name="0x2_sui_system_update_stake_subsidy_amount"></a>
+
+## Function `update_stake_subsidy_amount`
+
+
+
+<pre><code><b>fun</b> <a href="sui_system.md#0x2_sui_system_update_stake_subsidy_amount">update_stake_subsidy_amount</a>(self: &<b>mut</b> <a href="sui_system.md#0x2_sui_system_SuiSystemState">sui_system::SuiSystemState</a>, new_epoch: u64)
+</code></pre>
+
+
+
+<details>
+<summary>Implementation</summary>
+
+
+<pre><code><b>fun</b> <a href="sui_system.md#0x2_sui_system_update_stake_subsidy_amount">update_stake_subsidy_amount</a>(self: &<b>mut</b> <a href="sui_system.md#0x2_sui_system_SuiSystemState">SuiSystemState</a>, new_epoch: u64) {
+    // Decrease the subsidy amount only when the current period ends.
+    <b>if</b> (new_epoch % <a href="sui_system.md#0x2_sui_system_STAKE_SUBSIDY_PERIOD_LENGTH">STAKE_SUBSIDY_PERIOD_LENGTH</a> == 0) {
+        <b>let</b> decrease_amount = (self.next_epoch_stake_subsidy <b>as</b> u128)
+            * <a href="sui_system.md#0x2_sui_system_STAKE_SUBSIDY_DECREASE_RATE">STAKE_SUBSIDY_DECREASE_RATE</a> / <a href="sui_system.md#0x2_sui_system_BASIS_POINT_DENOMINATOR">BASIS_POINT_DENOMINATOR</a>;
+        self.next_epoch_stake_subsidy = self.next_epoch_stake_subsidy - (decrease_amount <b>as</b> u64)
+    };
+}
+</code></pre>
+
+
+
 </details>
 
 <a name="0x2_sui_system_epoch"></a>

crates/sui-framework/sources/governance/genesis.move

@@ -24,6 +24,9 @@ module sui::genesis {
     /// Initial storage gas price
     const INIT_STORAGE_GAS_PRICE: u64 = 1;
 
+    /// Stake subisidy to be given out in the very first epoch. Placeholder value.
+    const INIT_STAKE_SUBSIDY_AMOUNT: u64 = 1000000;
+
     /// This function will be explicitly called once at genesis.
     /// It will create a singleton SuiSystemState object, which contains
     /// all the information we need in the system.
@@ -95,6 +98,7 @@ module sui::genesis {
             INIT_MAX_VALIDATOR_COUNT,
             INIT_MIN_VALIDATOR_STAKE,
             INIT_STORAGE_GAS_PRICE,
+            INIT_STAKE_SUBSIDY_AMOUNT,
         );
     }
 }

crates/sui-framework/sources/governance/sui_system.move

@@ -61,6 +61,9 @@ module sui::sui_system {
         /// them. If a validator has never been reported they don't have an entry in this map.
         /// This map resets every epoch.
         validator_report_records: VecMap<address, VecSet<address>>,
+        /// The amount of stake subsidies to be given out in the next epoch, updated at
+        /// epoch boundaries.
+        next_epoch_stake_subsidy: u64,
     }
 
     // Errors
@@ -72,6 +75,10 @@ module sui::sui_system {
 
     const BASIS_POINT_DENOMINATOR: u128 = 10000;
 
+    // Placeholder numbers for stake subsidies.
+    const STAKE_SUBSIDY_DECREASE_RATE: u128 = 1000; // in basis point
+    const STAKE_SUBSIDY_PERIOD_LENGTH: u64 = 30; // in number of epochs
+
     // ==== functions that can only be called by genesis ====
 
     /// Create a new SuiSystemState object and make it shared.
@@ -84,6 +91,7 @@ module sui::sui_system {
         max_validator_candidate_count: u64,
         min_validator_stake: u64,
         storage_gas_price: u64,
+        next_epoch_stake_subsidy: u64,
     ) {
         assert!(chain_id >= 1 && chain_id <= 127, 1);
         let validators = validator_set::new(validators);
@@ -103,6 +111,7 @@ module sui::sui_system {
             },
             reference_gas_price,
             validator_report_records: vec_map::empty(),
+            next_epoch_stake_subsidy,
         };
         transfer::share_object(state);
     }
@@ -367,6 +376,10 @@ module sui::sui_system {
         let storage_reward = balance::create_staking_rewards(storage_charge);
         let computation_reward = balance::create_staking_rewards(computation_charge);
 
+        // Include stake subsidy in the rewards given out to validators and delegators.
+        let stake_subsidy = balance::increase_supply(&mut self.sui_supply, self.next_epoch_stake_subsidy);
+        balance::join(&mut computation_reward, stake_subsidy);
+
         let delegation_stake = validator_set::total_delegation_stake(&self.validators);
         let validator_stake = validator_set::total_validator_stake(&self.validators);
         let storage_fund_balance = balance::value(&self.storage_fund);
@@ -412,6 +425,9 @@ module sui::sui_system {
         assert!(balance::value(&self.storage_fund) >= storage_rebate, 0);
         balance::destroy_storage_rebates(balance::split(&mut self.storage_fund, storage_rebate));
 
+        // Update the amount of subsidy to be given out in the next epoch.
+        update_stake_subsidy_amount(self, new_epoch);
+
         // Validator reports are only valid for the epoch.
         // TODO: or do we want to make it persistent and validators have to explicitly change their scores?
         self.validator_report_records = vec_map::empty();
@@ -423,6 +439,15 @@ module sui::sui_system {
             == old(balance::supply_value(self.sui_supply));
     }
 
+    fun update_stake_subsidy_amount(self: &mut SuiSystemState, new_epoch: u64) {
+        // Decrease the subsidy amount only when the current period ends.
+        if (new_epoch % STAKE_SUBSIDY_PERIOD_LENGTH == 0) {
+            let decrease_amount = (self.next_epoch_stake_subsidy as u128)
+                * STAKE_SUBSIDY_DECREASE_RATE / BASIS_POINT_DENOMINATOR;
+            self.next_epoch_stake_subsidy = self.next_epoch_stake_subsidy - (decrease_amount as u64)
+        };
+    }
+
     /// Return the current epoch number. Useful for applications that need a coarse-grained concept of time,
     /// since epochs are ever-increasing and epoch changes are intended to happen every 24 hours.
     public fun epoch(self: &SuiSystemState): u64 {

crates/sui-framework/tests/governance_test_utils.move

@@ -46,7 +46,8 @@ module sui::governance_test_utils {
             balance::create_for_testing<SUI>(storage_fund_amount), // storage_fund
             1024, // max_validator_candidate_count
             0, // min_validator_stake
-            1, //storage_gas_price
+            1, // storage_gas_price
+            0, // stake subsidy
         )
     }
 

crates/sui-open-rpc/spec/openrpc.json

@@ -5082,6 +5082,7 @@
           "chain_id",
           "epoch",
           "info",
+          "next_epoch_stake_subsidy",
           "parameters",
           "reference_gas_price",
           "storage_fund",
@@ -5101,6 +5102,11 @@
           "info": {
             "$ref": "#/components/schemas/UID"
           },
+          "next_epoch_stake_subsidy": {
+            "type": "integer",
+            "format": "uint64",
+            "minimum": 0.0
+          },
           "parameters": {
             "$ref": "#/components/schemas/SystemParameters"
           },

crates/sui-types/src/sui_system_state.rs

@@ -150,6 +150,7 @@ pub struct SuiSystemState {
     pub parameters: SystemParameters,
     pub reference_gas_price: u64,
     pub validator_report_records: VecMap<SuiAddress, VecSet<SuiAddress>>,
+    pub next_epoch_stake_subsidy: u64,
     // TODO: Use getters instead of all pub.
 }
 

crates/test-utils/src/sui_system_state.rs

@@ -94,5 +94,6 @@ pub fn test_sui_system_state(epoch: EpochId, validators: Vec<Validator>) -> SuiS
         },
         reference_gas_price: 1,
         validator_report_records: VecMap { contents: vec![] },
+        next_epoch_stake_subsidy: 0,
     }
 }