Enforce ema price halving hyperparameter and add tests

Author: gztensor

pallets/admin-utils/src/tests/mod.rs

@@ -1669,3 +1669,32 @@ fn test_sudo_set_subnet_owner_hotkey() {
         );
     });
 }
+
+// cargo test --package pallet-admin-utils --lib -- tests::test_sudo_set_ema_halving --exact --show-output
+#[test]
+fn test_sudo_set_ema_halving() {
+    new_test_ext().execute_with(|| {
+        let netuid: u16 = 1;
+        let to_be_set: u64 = 10;
+        add_network(netuid, 10);
+
+        let value_before: u64 = pallet_subtensor::EMAPriceHalvingBlocks::<Test>::get(netuid);
+        assert_eq!(
+            AdminUtils::sudo_set_ema_price_halving_period(
+                <<Test as Config>::RuntimeOrigin>::signed(U256::from(1)),
+                netuid,
+                to_be_set
+            ),
+            Err(DispatchError::BadOrigin)
+        );
+        let value_after_1: u64 = pallet_subtensor::EMAPriceHalvingBlocks::<Test>::get(netuid);
+        assert_eq!(value_after_1, value_before);
+        assert_ok!(AdminUtils::sudo_set_ema_price_halving_period(
+            <<Test as Config>::RuntimeOrigin>::root(),
+            netuid,
+            to_be_set
+        ));
+        let value_after_2: u64 = pallet_subtensor::EMAPriceHalvingBlocks::<Test>::get(netuid);
+        assert_eq!(value_after_2, to_be_set);
+    });
+}

pallets/subtensor/src/staking/stake_utils.rs

@@ -60,10 +60,15 @@ impl<T: Config> Pallet<T> {
         let blocks_since_registration = I96F32::saturating_from_num(
             Self::get_current_block_as_u64().saturating_sub(NetworkRegisteredAt::<T>::get(netuid)),
         );
-        // 7200 * 14 = 100_800 is the halving time
+
+        // Use halving time hyperparameter. The meaning of this parameter can be best explained under
+        // the assumption of a constant price and SubnetMovingAlpha == 0.5: It is how many blocks it
+        // will take in order for the distance between current EMA of price and current price to shorten
+        // by half.
+        let halving_time = EMAPriceHalvingBlocks::<T>::get(netuid);
         let alpha: I96F32 =
             SubnetMovingAlpha::<T>::get().saturating_mul(blocks_since_registration.safe_div(
-                blocks_since_registration.saturating_add(I96F32::saturating_from_num(100_800)),
+                blocks_since_registration.saturating_add(I96F32::saturating_from_num(halving_time)),
             ));
         let minus_alpha: I96F32 = I96F32::saturating_from_num(1.0).saturating_sub(alpha);
         let current_price: I96F32 = alpha

pallets/subtensor/src/tests/coinbase.rs

@@ -218,8 +218,8 @@ fn test_coinbase_moving_prices() {
         SubnetMovingPrice::<Test>::insert(netuid, I96F32::from_num(0));
         SubnetMovingAlpha::<Test>::set(I96F32::from_num(0.1));
 
-        // EMA price 14 days after registration
-        System::set_block_number(7_200 * 14);
+        // EMA price 28 days after registration
+        System::set_block_number(7_200 * 28);
 
         // Run moving 14 times.
         for _ in 0..14 {
@@ -274,7 +274,7 @@ fn test_update_moving_price_after_time() {
         SubnetMovingPrice::<Test>::insert(netuid, I96F32::from_num(0));
 
         // Registered long time ago
-        System::set_block_number(72_000_500);
+        System::set_block_number(144_000_500);
         NetworkRegisteredAt::<Test>::insert(netuid, 500);
 
         SubtensorModule::update_moving_price(netuid);