feat: compute base-fee on l1 (#9986)

l1-contracts/src/core/libraries/FeeMath.sol

@@ -28,6 +28,13 @@ library FeeMath {
   uint256 internal constant MAX_FEE_ASSET_PRICE_MODIFIER = 1000000000;
   uint256 internal constant FEE_ASSET_PRICE_UPDATE_FRACTION = 100000000000;
 
+  uint256 internal constant L1_GAS_PER_BLOCK_PROPOSED = 150000;
+  uint256 internal constant L1_GAS_PER_EPOCH_VERIFIED = 1000000;
+
+  uint256 internal constant MINIMUM_CONGESTION_MULTIPLIER = 1000000000;
+  uint256 internal constant MANA_TARGET = 100000000;
+  uint256 internal constant CONGESTION_UPDATE_FRACTION = 854700854;
+
   function assertValid(OracleInput memory _self) internal pure returns (bool) {
     require(
       SignedMath.abs(_self.provingCostModifier) <= MAX_PROVING_COST_MODIFIER,
@@ -70,6 +77,10 @@ library FeeMath {
     return fakeExponential(MINIMUM_FEE_ASSET_PRICE, _numerator, FEE_ASSET_PRICE_UPDATE_FRACTION);
   }
 
+  function congestionMultiplier(uint256 _numerator) internal pure returns (uint256) {
+    return fakeExponential(MINIMUM_CONGESTION_MULTIPLIER, _numerator, CONGESTION_UPDATE_FRACTION);
+  }
+
   /**
    * @notice An approximation of the exponential function: factor * e ** (numerator / denominator)
    *

l1-contracts/test/base/Base.sol

@@ -147,6 +147,15 @@ contract TestBase is Test {
     }
   }
 
+  function assertEq(uint256 a, Slot b) internal {
+    if (Slot.wrap(a) != b) {
+      emit log("Error: a == b not satisfied [Slot]");
+      emit log_named_uint("      Left", a);
+      emit log_named_uint("     Right", b.unwrap());
+      fail();
+    }
+  }
+
   function assertEq(Slot a, uint256 b) internal {
     if (a != Slot.wrap(b)) {
       emit log("Error: a == b not satisfied [Slot]");
@@ -163,6 +172,13 @@ contract TestBase is Test {
     }
   }
 
+  function assertEq(uint256 a, Slot b, string memory err) internal {
+    if (Slot.wrap(a) != b) {
+      emit log_named_string("Error", err);
+      assertEq(a, b);
+    }
+  }
+
   function assertEq(Slot a, uint256 b, string memory err) internal {
     if (a != Slot.wrap(b)) {
       emit log_named_string("Error", err);

l1-contracts/test/fees/FeeModelTestPoints.t.sol

@@ -4,6 +4,7 @@
 pragma solidity >=0.8.27;
 
 import {TestBase} from "../base/Base.sol";
+import {OracleInput as FeeMathOracleInput} from "@aztec/core/libraries/FeeMath.sol";
 
 // Remember that foundry json parsing is alphabetically done, so you MUST
 // sort the struct fields alphabetically or prepare for a headache.
@@ -96,4 +97,48 @@ contract FeeModelTestPoints is TestBase {
       points.push(data.points[i]);
     }
   }
+
+  function assertEq(L1Fees memory a, L1Fees memory b) internal pure {
+    assertEq(a.base_fee, b.base_fee, "base_fee mismatch");
+    assertEq(a.blob_fee, b.blob_fee, "blob_fee mismatch");
+  }
+
+  function assertEq(L1Fees memory a, L1Fees memory b, string memory _message) internal pure {
+    assertEq(a.base_fee, b.base_fee, string.concat(_message, "base_fee mismatch"));
+    assertEq(a.blob_fee, b.blob_fee, string.concat(_message, "blob_fee mismatch"));
+  }
+
+  function assertEq(L1GasOracleValues memory a, L1GasOracleValues memory b) internal pure {
+    assertEq(a.post, b.post, "post ");
+    assertEq(a.pre, b.pre, "pre ");
+    assertEq(a.slot_of_change, b.slot_of_change, "slot_of_change mismatch");
+  }
+
+  function assertEq(OracleInput memory a, FeeMathOracleInput memory b) internal pure {
+    assertEq(
+      a.fee_asset_price_modifier, b.feeAssetPriceModifier, "fee_asset_price_modifier mismatch"
+    );
+    assertEq(a.proving_cost_modifier, b.provingCostModifier, "proving_cost_modifier mismatch");
+  }
+
+  function assertEq(FeeHeader memory a, FeeHeader memory b) internal pure {
+    assertEq(a.excess_mana, b.excess_mana, "excess_mana mismatch");
+    assertEq(
+      a.fee_asset_price_numerator, b.fee_asset_price_numerator, "fee_asset_price_numerator mismatch"
+    );
+    assertEq(a.mana_used, b.mana_used, "mana_used mismatch");
+    assertEq(
+      a.proving_cost_per_mana_numerator,
+      b.proving_cost_per_mana_numerator,
+      "proving_cost_per_mana_numerator mismatch"
+    );
+  }
+
+  function assertEq(ManaBaseFeeComponents memory a, ManaBaseFeeComponents memory b) internal pure {
+    assertEq(a.congestion_cost, b.congestion_cost, "congestion_cost mismatch");
+    assertEq(a.congestion_multiplier, b.congestion_multiplier, "congestion_multiplier mismatch");
+    assertEq(a.data_cost, b.data_cost, "data_cost mismatch");
+    assertEq(a.gas_cost, b.gas_cost, "gas_cost mismatch");
+    assertEq(a.proving_cost, b.proving_cost, "proving_cost mismatch");
+  }
 }

l1-contracts/test/fees/MinimalFeeModel.sol

@@ -3,63 +3,118 @@
 pragma solidity >=0.8.27;
 
 import {FeeMath, OracleInput} from "@aztec/core/libraries/FeeMath.sol";
-import {Timestamp, TimeFns, Slot} from "@aztec/core/libraries/TimeMath.sol";
+import {Timestamp, TimeFns, Slot, SlotLib} from "@aztec/core/libraries/TimeMath.sol";
 import {Vm} from "forge-std/Vm.sol";
+import {
+  ManaBaseFeeComponents, L1Fees, L1GasOracleValues, FeeHeader
+} from "./FeeModelTestPoints.t.sol";
+import {Math} from "@oz/utils/math/Math.sol";
 
-struct BaseFees {
-  uint256 baseFee;
-  uint256 blobFee;
-}
-
-// This actually behaves pretty close to the slow updates.
-struct L1BaseFees {
-  BaseFees pre;
-  BaseFees post;
-  Slot slotOfChange;
-}
-
-struct DataPoint {
-  uint256 provingCostNumerator;
-  uint256 feeAssetPriceNumerator;
-}
+// The data types are slightly messed up here, the reason is that
+// we just want to use the same structs from the test points making
+// is simpler to compare etc.
 
 contract MinimalFeeModel is TimeFns {
   using FeeMath for OracleInput;
   using FeeMath for uint256;
+  using SlotLib for Slot;
 
   // This is to allow us to use the cheatcodes for blobbasefee as foundry does not play nice
   // with the block.blobbasefee value if using cheatcodes to alter it.
   Vm internal constant VM = Vm(address(uint160(uint256(keccak256("hevm cheat code")))));
 
+  uint256 internal constant BLOB_GAS_PER_BLOB = 2 ** 17;
+  uint256 internal constant GAS_PER_BLOB_POINT_EVALUATION = 50_000;
+
   Slot public constant LIFETIME = Slot.wrap(5);
   Slot public constant LAG = Slot.wrap(2);
   Timestamp public immutable GENESIS_TIMESTAMP;
 
   uint256 public populatedThrough = 0;
-  mapping(uint256 _slotNumber => DataPoint _dataPoint) public dataPoints;
+  mapping(uint256 slotNumber => FeeHeader feeHeader) public feeHeaders;
 
-  L1BaseFees public l1BaseFees;
+  L1GasOracleValues public l1BaseFees;
 
   constructor(uint256 _slotDuration, uint256 _epochDuration) TimeFns(_slotDuration, _epochDuration) {
     GENESIS_TIMESTAMP = Timestamp.wrap(block.timestamp);
-    dataPoints[0] = DataPoint({provingCostNumerator: 0, feeAssetPriceNumerator: 0});
+    feeHeaders[0] = FeeHeader({
+      excess_mana: 0,
+      fee_asset_price_numerator: 0,
+      mana_used: 0,
+      proving_cost_per_mana_numerator: 0
+    });
 
-    l1BaseFees.pre = BaseFees({baseFee: 1 gwei, blobFee: 1});
-    l1BaseFees.post = BaseFees({baseFee: block.basefee, blobFee: _getBlobBaseFee()});
-    l1BaseFees.slotOfChange = LIFETIME;
+    l1BaseFees.pre = L1Fees({base_fee: 1 gwei, blob_fee: 1});
+    l1BaseFees.post = L1Fees({base_fee: block.basefee, blob_fee: _getBlobBaseFee()});
+    l1BaseFees.slot_of_change = LIFETIME.unwrap();
+  }
+
+  function getL1GasOracleValues() public view returns (L1GasOracleValues memory) {
+    return l1BaseFees;
+  }
+
+  // For all of the estimations we have been using `3` blobs.
+  function manaBaseFeeComponents(uint256 _blobsUsed, bool _inFeeAsset)
+    public
+    view
+    returns (ManaBaseFeeComponents memory)
+  {
+    L1Fees memory fees = getCurrentL1Fees();
+    uint256 dataCost = Math.mulDiv(
+      _blobsUsed * BLOB_GAS_PER_BLOB, fees.blob_fee, FeeMath.MANA_TARGET, Math.Rounding.Ceil
+    );
+    uint256 gasUsed = FeeMath.L1_GAS_PER_BLOCK_PROPOSED + _blobsUsed * GAS_PER_BLOB_POINT_EVALUATION
+      + FeeMath.L1_GAS_PER_EPOCH_VERIFIED / EPOCH_DURATION;
+    uint256 gasCost = Math.mulDiv(gasUsed, fees.base_fee, FeeMath.MANA_TARGET, Math.Rounding.Ceil);
+    uint256 provingCost = getProvingCost();
+
+    uint256 congestionMultiplier = FeeMath.congestionMultiplier(calcExcessMana());
+
+    uint256 total = dataCost + gasCost + provingCost;
+    uint256 congestionCost =
+      (total * congestionMultiplier / FeeMath.MINIMUM_CONGESTION_MULTIPLIER) - total;
+
+    uint256 feeAssetPrice = _inFeeAsset ? getFeeAssetPrice() : 1e9;
+
+    return ManaBaseFeeComponents({
+      data_cost: Math.mulDiv(dataCost, feeAssetPrice, 1e9, Math.Rounding.Ceil),
+      gas_cost: Math.mulDiv(gasCost, feeAssetPrice, 1e9, Math.Rounding.Ceil),
+      proving_cost: Math.mulDiv(provingCost, feeAssetPrice, 1e9, Math.Rounding.Ceil),
+      congestion_cost: Math.mulDiv(congestionCost, feeAssetPrice, 1e9, Math.Rounding.Ceil),
+      congestion_multiplier: congestionMultiplier
+    });
+  }
+
+  function getFeeHeader(uint256 _slotNumber) public view returns (FeeHeader memory) {
+    return feeHeaders[_slotNumber];
+  }
+
+  function calcExcessMana() internal view returns (uint256) {
+    FeeHeader storage parent = feeHeaders[populatedThrough];
+    return (parent.excess_mana + parent.mana_used).clampedAdd(-int256(FeeMath.MANA_TARGET));
   }
 
-  // See the `add_slot` function in the `fee-model.ipynb` notebook for more context.
   function addSlot(OracleInput memory _oracleInput) public {
+    addSlot(_oracleInput, 0);
+  }
+
+  // The `_manaUsed` is all the data we needed to know to calculate the excess mana.
+  function addSlot(OracleInput memory _oracleInput, uint256 _manaUsed) public {
     _oracleInput.assertValid();
 
-    DataPoint memory parent = dataPoints[populatedThrough];
+    FeeHeader memory parent = feeHeaders[populatedThrough];
+
+    uint256 excessMana = calcExcessMana();
 
-    dataPoints[++populatedThrough] = DataPoint({
-      provingCostNumerator: parent.provingCostNumerator.clampedAdd(_oracleInput.provingCostModifier),
-      feeAssetPriceNumerator: parent.feeAssetPriceNumerator.clampedAdd(
+    feeHeaders[++populatedThrough] = FeeHeader({
+      proving_cost_per_mana_numerator: parent.proving_cost_per_mana_numerator.clampedAdd(
+        _oracleInput.provingCostModifier
+      ),
+      fee_asset_price_numerator: parent.fee_asset_price_numerator.clampedAdd(
         _oracleInput.feeAssetPriceModifier
-      )
+      ),
+      mana_used: _manaUsed,
+      excess_mana: excessMana
     });
   }
 
@@ -72,29 +127,29 @@ contract MinimalFeeModel is TimeFns {
   function photograph() public {
     Slot slot = getCurrentSlot();
     // The slot where we find a new queued value acceptable
-    Slot acceptableSlot = l1BaseFees.slotOfChange + (LIFETIME - LAG);
+    Slot acceptableSlot = Slot.wrap(l1BaseFees.slot_of_change) + (LIFETIME - LAG);
 
     if (slot < acceptableSlot) {
       return;
     }
 
     // If we are at or beyond the scheduled change, we need to update the "current" value
     l1BaseFees.pre = l1BaseFees.post;
-    l1BaseFees.post = BaseFees({baseFee: block.basefee, blobFee: _getBlobBaseFee()});
-    l1BaseFees.slotOfChange = slot + LAG;
+    l1BaseFees.post = L1Fees({base_fee: block.basefee, blob_fee: _getBlobBaseFee()});
+    l1BaseFees.slot_of_change = (slot + LAG).unwrap();
   }
 
-  function getFeeAssetPrice(uint256 _slotNumber) public view returns (uint256) {
-    return FeeMath.feeAssetPriceModifier(dataPoints[_slotNumber].feeAssetPriceNumerator);
+  function getFeeAssetPrice() public view returns (uint256) {
+    return FeeMath.feeAssetPriceModifier(feeHeaders[populatedThrough].fee_asset_price_numerator);
   }
 
-  function getProvingCost(uint256 _slotNumber) public view returns (uint256) {
-    return FeeMath.provingCostPerMana(dataPoints[_slotNumber].provingCostNumerator);
+  function getProvingCost() public view returns (uint256) {
+    return FeeMath.provingCostPerMana(feeHeaders[populatedThrough].proving_cost_per_mana_numerator);
   }
 
-  function getCurrentL1Fees() public view returns (BaseFees memory) {
+  function getCurrentL1Fees() public view returns (L1Fees memory) {
     Slot slot = getCurrentSlot();
-    if (slot < l1BaseFees.slotOfChange) {
+    if (slot < Slot.wrap(l1BaseFees.slot_of_change)) {
       return l1BaseFees.pre;
     }
     return l1BaseFees.post;