Base and Quote Rebates

packages/deepbook/sources/state/balances.move

@@ -1,8 +1,8 @@
 // Copyright (c) Mysten Labs, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
-/// `Balances` represents the three assets make up a pool: base, quote, and deep.
-/// Whenever funds are moved, they are moved in the form of `Balances`.
+/// `Balances` represents the three assets make up a pool: base, quote, and
+/// deep. Whenever funds are moved, they are moved in the form of `Balances`.
 module deepbook::balances;
 
 use deepbook::math;

packages/deepbook/sources/state/history.move

@@ -2,8 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0
 
 /// History module tracks the volume data for the current epoch and past epochs.
-/// It also tracks past trade params. Past maker fees are used to calculate fills for
-/// old orders. The historic median is used to calculate rebates and burns.
+/// It also tracks past trade params. Past maker fees are used to calculate
+/// fills for old orders. The historic median is used to calculate rebates and
+/// burns.
 module deepbook::history;
 
 use deepbook::balances::{Self, Balances};
@@ -20,7 +21,8 @@ const EHistoricVolumesNotFound: u64 = 0;
 /// `Volumes` represents volume data for a single epoch.
 /// Using flashloans on a whitelisted pool, assuming 1_000_000 * 1_000_000_000
 /// in volume per trade, at 1 trade per millisecond, the total volume can reach
-/// 1_000_000 * 1_000_000_000 * 1000 * 60 * 60 * 24 * 365 = 8.64e22 in one epoch.
+/// 1_000_000 * 1_000_000_000 * 1000 * 60 * 60 * 24 * 365 = 8.64e22 in one
+/// epoch.
 public struct Volumes has store, copy, drop {
     total_volume: u128,
     total_staked_volume: u128,
@@ -39,8 +41,8 @@ public struct History has store {
 }
 
 // === Public-Package Functions ===
-/// Create a new `History` instance. Called once upon pool creation. A single blank
-/// `Volumes` instance is created and added to the historic_volumes table.
+/// Create a new `History` instance. Called once upon pool creation. A single
+/// blank `Volumes` instance is created and added to the historic_volumes table.
 public(package) fun empty(
     trade_params: TradeParams,
     epoch_created: u64,
@@ -129,21 +131,20 @@ public(package) fun calculate_rebate_amount(
     };
     let maker_rebate_percentage = maker_rebate_percentage as u64;
     let maker_volume_proportion = if (volumes.total_staked_volume > 0) {
-        math::div_u128(maker_volume, volumes.total_staked_volume)
+        (math::div_u128(maker_volume, volumes.total_staked_volume)) as u64
     } else {
         0
     };
-    let maker_fee_proportion =
-        math::mul_u128(
-            maker_volume_proportion,
-            volumes.total_fees_collected.deep() as u128,
-        ) as u64;
-    let maker_rebate = math::mul(maker_rebate_percentage, maker_fee_proportion);
-    let maker_burn = maker_fee_proportion - maker_rebate;
+    let mut max_rebates = volumes.total_fees_collected;
+    max_rebates.mul(maker_volume_proportion); // Maximum rebates possible
+    let mut rebates = max_rebates;
+    rebates.mul(maker_rebate_percentage); // Actual rebates
+
+    let maker_burn = max_rebates.deep() - rebates.deep();
 
     self.balance_to_burn = self.balance_to_burn + maker_burn;
 
-    balances::new(0, 0, maker_rebate)
+    rebates
 }
 
 /// Updates the historic_median for past 28 epochs.

packages/deepbook/tests/state/history_tests.move

@@ -43,7 +43,7 @@ fun test_rebate_amount() {
     history.set_current_volumes(
         10 * FLOAT_SCALING,
         5 * FLOAT_SCALING,
-        balances::new(0, 0, 1_000_000_000),
+        balances::new(500_000, 2_500_000, 1_000_000_000),
     );
 
     // epoch 30
@@ -55,6 +55,8 @@ fun test_rebate_amount() {
         (3 * FLOAT_SCALING) as u128,
         1_000_000,
     );
+    assert!(rebate.base() == 90_000, EWrongRebateAmount);
+    assert!(rebate.quote() == 450_000, EWrongRebateAmount);
     assert!(rebate.deep() == 180_000_000, EWrongRebateAmount);
 
     test_utils::destroy(history);
@@ -79,7 +81,7 @@ fun test_epoch_skipped() {
         history.set_current_volumes(
             10 * FLOAT_SCALING,
             5 * FLOAT_SCALING,
-            balances::new(0, 0, 500_000_000),
+            balances::new(500_000, 2_500_000, 500_000_000),
         );
         epochs_to_advance = epochs_to_advance - 1;
     };
@@ -91,7 +93,7 @@ fun test_epoch_skipped() {
     history.set_current_volumes(
         10 * FLOAT_SCALING,
         5 * FLOAT_SCALING,
-        balances::new(0, 0, 1_000_000_000),
+        balances::new(500_000, 2_500_000, 1_000_000_000),
     );
 
     // epoch 31
@@ -104,20 +106,26 @@ fun test_epoch_skipped() {
         0,
         1_000_000,
     );
+    assert!(rebate_epoch_0_alice.base() == 0, EWrongRebateAmount);
+    assert!(rebate_epoch_0_alice.quote() == 0, EWrongRebateAmount);
     assert!(rebate_epoch_0_alice.deep() == 0, EWrongRebateAmount);
 
     let rebate_epoch_1_alice = history.calculate_rebate_amount(
         28,
         0,
         1_000_000,
     );
+    assert!(rebate_epoch_1_alice.base() == 0, EWrongRebateAmount);
+    assert!(rebate_epoch_1_alice.quote() == 0, EWrongRebateAmount);
     assert!(rebate_epoch_1_alice.deep() == 0, EWrongRebateAmount);
 
     let rebate_epoch_1_bob = history.calculate_rebate_amount(
         29,
         (3 * FLOAT_SCALING) as u128,
         1_000_000,
     );
+    assert!(rebate_epoch_1_bob.base() == 90_000, EWrongRebateAmount);
+    assert!(rebate_epoch_1_bob.quote() == 450_000, EWrongRebateAmount);
     assert!(rebate_epoch_1_bob.deep() == 180_000_000, EWrongRebateAmount);
 
     test_utils::destroy(history);
@@ -141,7 +149,7 @@ fun test_other_maker_volume_above_phase_out() {
         history.set_current_volumes(
             10 * FLOAT_SCALING,
             5 * FLOAT_SCALING,
-            balances::new(0, 0, 500_000_000),
+            balances::new(500_000, 2_500_000, 500_000_000),
         );
         epochs_to_advance = epochs_to_advance - 1;
     };
@@ -153,7 +161,7 @@ fun test_other_maker_volume_above_phase_out() {
     history.set_current_volumes(
         15 * FLOAT_SCALING,
         5 * FLOAT_SCALING,
-        balances::new(0, 0, 1_000_000_000),
+        balances::new(500_000, 2_500_000, 1_000_000_000),
     );
 
     // epoch 30
@@ -165,14 +173,17 @@ fun test_other_maker_volume_above_phase_out() {
         (3 * FLOAT_SCALING) as u128,
         1_000_000,
     );
+    assert!(rebate.base() == 0, EWrongRebateAmount);
+    assert!(rebate.quote() == 0, EWrongRebateAmount);
     assert!(rebate.deep() == 0, EWrongRebateAmount);
 
     test_utils::destroy(history);
     end(test);
 }
 
 #[test]
-/// Pool is created on epoch 0, up till epoch 27 should still grant close to the maximum rebate.
+/// Pool is created on epoch 0,
+/// up till epoch 27 should still grant close to the maximum rebate.
 /// Epoch 28 should return the normal rebate.
 fun test_rebate_edge_epoch_ok() {
     let owner: address = @0x1;
@@ -185,7 +196,7 @@ fun test_rebate_edge_epoch_ok() {
     history.set_current_volumes(
         10 * FLOAT_SCALING,
         5 * FLOAT_SCALING,
-        balances::new(0, 0, 500_000_000),
+        balances::new(500_000, 2_500_000, 500_000_000),
     );
     let mut epochs_to_advance = constants::phase_out_epochs() - 1;
 
@@ -195,13 +206,15 @@ fun test_rebate_edge_epoch_ok() {
         history.set_current_volumes(
             10 * FLOAT_SCALING,
             5 * FLOAT_SCALING,
-            balances::new(0, 0, 500_000_000),
+            balances::new(500_000, 2_500_000, 500_000_000),
         );
         let rebate = history.calculate_rebate_amount(
             0,
             (3 * FLOAT_SCALING) as u128,
             1_000_000,
         );
+        assert!(rebate.base() == 300_000, EWrongRebateAmount);
+        assert!(rebate.quote() == 1_500_000, EWrongRebateAmount);
         assert!(rebate.deep() == 300_000_000, EWrongRebateAmount);
         epochs_to_advance = epochs_to_advance - 1;
     };
@@ -213,7 +226,7 @@ fun test_rebate_edge_epoch_ok() {
     history.set_current_volumes(
         10 * FLOAT_SCALING,
         5 * FLOAT_SCALING,
-        balances::new(0, 0, 1_000_000_000),
+        balances::new(500_000, 1_000_000, 1_000_000_000),
     );
 
     // epoch 29
@@ -225,6 +238,8 @@ fun test_rebate_edge_epoch_ok() {
         (3 * FLOAT_SCALING) as u128,
         1_000_000,
     );
+    assert!(rebate.base() == 90_000, EWrongRebateAmount);
+    assert!(rebate.quote() == 180_000, EWrongRebateAmount);
     assert!(rebate.deep() == 180_000_000, EWrongRebateAmount);
 
     test_utils::destroy(history);