prague fee market for blob gas

Signed-off-by: garyschulte <[email protected]>

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/MainnetProtocolSpecs.java

@@ -815,6 +815,18 @@ static ProtocolSpecBuilder pragueDefinition(
     final java.util.function.Supplier<GasCalculator> pragueGasCalcSupplier =
         () -> new PragueGasCalculator(pragueBlobSchedule.getTarget());
 
+    final BaseFeeMarket pragueFeeMarket;
+    if (genesisConfigOptions.isZeroBaseFee()) {
+      pragueFeeMarket = FeeMarket.zeroBaseFee(londonForkBlockNumber);
+    } else if (genesisConfigOptions.isFixedBaseFee()) {
+      pragueFeeMarket =
+          FeeMarket.fixedBaseFee(
+              londonForkBlockNumber, miningConfiguration.getMinTransactionGasPrice());
+    } else {
+      pragueFeeMarket =
+          FeeMarket.cancun(londonForkBlockNumber, genesisConfigOptions.getBaseFeePerGas());
+    }
+
     return cancunDefinition(
             chainId,
             enableRevertReason,
@@ -823,6 +835,7 @@ static ProtocolSpecBuilder pragueDefinition(
             miningConfiguration,
             isParallelTxProcessingEnabled,
             metricsSystem)
+        .feeMarket(pragueFeeMarket)
         .gasCalculator(pragueGasCalcSupplier)
         // EIP-7840 Blob schedule | EIP-7691 6/9 blob increase
         .gasLimitCalculatorBuilder(

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/feemarket/CancunFeeMarket.java

@@ -25,7 +25,7 @@
 
 public class CancunFeeMarket extends LondonFeeMarket {
   private static final Logger LOG = LoggerFactory.getLogger(CancunFeeMarket.class);
-  private static final BigInteger BLOB_GAS_PRICE = BigInteger.ONE;
+  protected static final BigInteger BLOB_GAS_PRICE = BigInteger.ONE;
   private static final BigInteger BLOB_GAS_PRICE_UPDATE_FRACTION = BigInteger.valueOf(3338477);
 
   public CancunFeeMarket(
@@ -53,7 +53,7 @@ public Wei blobGasPricePerGas(final BlobGas excessBlobGas) {
     return blobGasPrice;
   }
 
-  private BigInteger fakeExponential(
+  protected BigInteger fakeExponential(
       final BigInteger factor, final BigInteger numerator, final BigInteger denominator) {
     int i = 1;
     BigInteger output = BigInteger.ZERO;

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/feemarket/FeeMarket.java

@@ -49,6 +49,11 @@ static BaseFeeMarket cancun(
     return new CancunFeeMarket(londonForkBlockNumber, baseFeePerGasOverride);
   }
 
+  static BaseFeeMarket prague(
+      final long londonForkBlockNumber, final Optional<Wei> baseFeePerGasOverride) {
+    return new PragueFeeMarket(londonForkBlockNumber, baseFeePerGasOverride);
+  }
+
   static BaseFeeMarket zeroBaseFee(final long londonForkBlockNumber) {
     return new ZeroBaseFeeMarket(londonForkBlockNumber);
   }

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/feemarket/PragueFeeMarket.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright contributors to Besu.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.ethereum.mainnet.feemarket;
+
+import org.hyperledger.besu.datatypes.BlobGas;
+import org.hyperledger.besu.datatypes.Wei;
+
+import java.math.BigInteger;
+import java.util.Optional;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class PragueFeeMarket extends CancunFeeMarket {
+  private static final BigInteger BLOB_BASE_FEE_UPDATE_FRACTION_ELECTRA =
+      BigInteger.valueOf(5007716);
+  private static final Logger LOG = LoggerFactory.getLogger(PragueFeeMarket.class);
+
+  public PragueFeeMarket(
+      final long londonForkBlockNumber, final Optional<Wei> baseFeePerGasOverride) {
+    super(londonForkBlockNumber, baseFeePerGasOverride);
+  }
+
+  @Override
+  public Wei blobGasPricePerGas(final BlobGas excessBlobGas) {
+    final var blobGasPrice =
+        Wei.of(
+            fakeExponential(
+                BLOB_GAS_PRICE,
+                excessBlobGas.toBigInteger(),
+                BLOB_BASE_FEE_UPDATE_FRACTION_ELECTRA));
+    LOG.atTrace()
+        .setMessage("parentExcessBlobGas: {} blobGasPrice: {}")
+        .addArgument(excessBlobGas::toShortHexString)
+        .addArgument(blobGasPrice::toHexString)
+        .log();
+
+    return blobGasPrice;
+  }
+}

ethereum/core/src/test/java/org/hyperledger/besu/ethereum/mainnet/feemarket/PragueFeeMarketTest.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright contributors to Hyperledger Besu.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.ethereum.mainnet.feemarket;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.hyperledger.besu.datatypes.BlobGas;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+import org.junit.jupiter.api.Test;
+
+class PragueFeeMarketTest {
+
+  private static final int BLOB_GAS_PER_BLOB = 131072;
+
+  /**
+   * from: https://eips.ethereum.org/EIPS/eip-7691 The BLOB_BASE_FEE_UPDATE_FRACTION_PRAGUE value in
+   * this EIP is chosen as the mid-point between keeping the responsiveness to full blobs and no
+   * blobs constant:
+   *
+   * <p>full blobs: basefee increases by ~8.2% no blobs: basefee decreases by ~14.5%
+   */
+  @Test
+  void dataPricePerGas() {
+    PragueFeeMarket pragueFeeMarket = new PragueFeeMarket(0, Optional.empty());
+    // when no excess blob gas, data price per gas is 1
+    assertEquals(1, pragueFeeMarket.blobGasPricePerGas(BlobGas.ZERO).getAsBigInteger().intValue());
+
+    record BlobGasPricing(long excess, long price) {}
+    List<BlobGasPricing> testVector = new ArrayList<>();
+
+    int numBlobs = 1;
+    long price = 1;
+    while (price <= 1000) {
+      price = blobGasPrice(BlobGas.of(numBlobs * BLOB_GAS_PER_BLOB));
+      var testCase = new BlobGasPricing(numBlobs * BLOB_GAS_PER_BLOB, price);
+      testVector.add(testCase);
+      numBlobs++;
+    }
+
+    testVector.stream()
+        .forEach(
+            blobGasPricing -> {
+              assertEquals(
+                  blobGasPricing.price,
+                  pragueFeeMarket
+                      .blobGasPricePerGas(BlobGas.of(blobGasPricing.excess))
+                      .getAsBigInteger()
+                      .intValue());
+            });
+  }
+
+  private long blobGasPrice(final BlobGas excess) {
+    double dgufDenominator = 5007716;
+    double fakeExpo = excess.getValue().longValue() / dgufDenominator;
+    return (long) (1 * Math.exp(fakeExpo));
+  }
+}