Fix to increment/decrement gas-limit in block production (#6425)

Signed-off-by: Matt Nelson <85905982+non-fungible-nelson@users.noreply.github.com>
Co-authored-by: Stefan Pingel <16143240+pinges@users.noreply.github.com>
Co-authored-by: Simon Dudley <simon.dudley@consensys.net>
Co-authored-by: Sally MacFarlane <macfarla.github@gmail.com>
Signed-off-by: Simon Dudley <simon.dudley@consensys.net>

CHANGELOG.md

@@ -26,6 +26,7 @@
 - Fix Besu Docker images with `openjdk-latest` tags since 23.10.3 using UID 1001 instead of 1000 for the `besu` user [#6360](https://github.com/hyperledger/besu/pull/6360)
 - Fluent EVM API definition for Tangerine Whistle had incorrect code size validation configured [#6382](https://github.com/hyperledger/besu/pull/6382)
 - Correct mining beneficiary for Clique networks in TraceServiceImpl [#6390](https://github.com/hyperledger/besu/pull/6390)
+- Fix to gas limit delta calculations used in block production. Besu should now increment or decrement the block gas limit towards its target correctly (thanks @arbora) #6425
 
 ### Download Links
 

acceptance-tests/tests/src/test/resources/jsonrpc/engine/cancun/test-cases/block-production/12_cancun_get_built_block.json

@@ -10,7 +10,7 @@
         "stateRoot" : "0x8d9115d9211932d4a3a1f068fb8fe262b0b2ab0bfd74eaece1a572efe6336677",
         "logsBloom" : "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
         "prevRandao" : "0xc13da06dc53836ca0766057413b9683eb9a8773bbb8fcc5691e41c25b56dda1d",
-        "gasLimit" : "0x2ff3d8",
+        "gasLimit" : "0x2ffbd2",
         "gasUsed" : "0xf618",
         "timestamp" : "0x1236",
         "extraData" : "0x",
@@ -70,7 +70,7 @@
           "amount" : "0x64"
         } ],
         "blockNumber" : "0x1",
-        "blockHash" : "0xf1e35607932349e87f29e1053a4fb2666782e09fde21ded74c1f7e4a57d3fa2b",
+        "blockHash" : "0x736bdddc2eca36fe8ed4ed515e5d295a08d7eaddc0d0fda2a35408127eb890d0",
         "receiptsRoot" : "0x9af165447e5b3193e9ac8389418648ee6d6cb1d37459fe65cfc245fc358721bd",
         "blobGasUsed" : "0x60000"
       },

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

@@ -19,7 +19,6 @@ import static com.google.common.base.Preconditions.checkArgument;
 /** Specification for the block gasLimit. */
 public abstract class AbstractGasLimitSpecification {
 
-  public static final long DEFAULT_MAX_CONSTANT_ADMUSTMENT_INCREMENT = 1024L;
   public static final long DEFAULT_MIN_GAS_LIMIT = 5000L;
   public static final long DEFAULT_MAX_GAS_LIMIT = Long.MAX_VALUE;
 

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

@@ -23,16 +23,13 @@ public class FrontierTargetingGasLimitCalculator extends AbstractGasLimitSpecifi
     implements GasLimitCalculator {
   private static final Logger LOG =
       LoggerFactory.getLogger(FrontierTargetingGasLimitCalculator.class);
-  private final long maxConstantAdjustmentIncrement;
 
   public FrontierTargetingGasLimitCalculator() {
-    this(DEFAULT_MAX_CONSTANT_ADMUSTMENT_INCREMENT, DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT);
+    this(DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT);
   }
 
-  public FrontierTargetingGasLimitCalculator(
-      final long maxConstantAdjustmentIncrement, final long minGasLimit, final long maxGasLimit) {
+  public FrontierTargetingGasLimitCalculator(final long minGasLimit, final long maxGasLimit) {
     super(minGasLimit, maxGasLimit);
-    this.maxConstantAdjustmentIncrement = maxConstantAdjustmentIncrement;
   }
 
   @Override
@@ -55,8 +52,7 @@ public class FrontierTargetingGasLimitCalculator extends AbstractGasLimitSpecifi
   }
 
   private long adjustAmount(final long currentGasLimit) {
-    final long maxProportionalAdjustmentLimit = Math.max(deltaBound(currentGasLimit) - 1, 0);
-    return Math.min(maxConstantAdjustmentIncrement, maxProportionalAdjustmentLimit);
+    return Math.max(deltaBound(currentGasLimit) - 1, 0);
   }
 
   protected long safeAddAtMost(final long gasLimit) {

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

@@ -27,21 +27,15 @@ public class LondonTargetingGasLimitCalculator extends FrontierTargetingGasLimit
 
   public LondonTargetingGasLimitCalculator(
       final long londonForkBlock, final BaseFeeMarket feeMarket) {
-    this(
-        DEFAULT_MAX_CONSTANT_ADMUSTMENT_INCREMENT,
-        DEFAULT_MIN_GAS_LIMIT,
-        DEFAULT_MAX_GAS_LIMIT,
-        londonForkBlock,
-        feeMarket);
+    this(DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT, londonForkBlock, feeMarket);
   }
 
   public LondonTargetingGasLimitCalculator(
-      final long maxConstantAdjustmentIncrement,
       final long minGasLimit,
       final long maxGasLimit,
       final long londonForkBlock,
       final BaseFeeMarket feeMarket) {
-    super(maxConstantAdjustmentIncrement, minGasLimit, maxGasLimit);
+    super(minGasLimit, maxGasLimit);
     this.londonForkBlock = londonForkBlock;
     this.feeMarket = feeMarket;
   }

ethereum/core/src/test/java/org/hyperledger/besu/ethereum/mainnet/TargetingGasLimitCalculatorTest.java

@@ -27,22 +27,6 @@ import org.junit.jupiter.api.Test;
 public class TargetingGasLimitCalculatorTest {
   private static final long ADJUSTMENT_FACTOR = 1024L;
 
-  @Test
-  public void verifyGasLimitIsIncreasedWithinLimits() {
-    FrontierTargetingGasLimitCalculator targetingGasLimitCalculator =
-        new FrontierTargetingGasLimitCalculator();
-    assertThat(targetingGasLimitCalculator.nextGasLimit(8_000_000L, 10_000_000L, 1L))
-        .isEqualTo(8_000_000L + ADJUSTMENT_FACTOR);
-  }
-
-  @Test
-  public void verifyGasLimitIsDecreasedWithinLimits() {
-    FrontierTargetingGasLimitCalculator targetingGasLimitCalculator =
-        new FrontierTargetingGasLimitCalculator();
-    assertThat(targetingGasLimitCalculator.nextGasLimit(12_000_000L, 10_000_000L, 1L))
-        .isEqualTo(12_000_000L - ADJUSTMENT_FACTOR);
-  }
-
   @Test
   public void verifyGasLimitReachesTarget() {
     final long target = 10_000_000L;
@@ -55,6 +39,33 @@ public class TargetingGasLimitCalculatorTest {
         .isEqualTo(target);
   }
 
+  @Test
+  public void verifyAdjustmentDeltas() {
+    assertDeltas(20000000L, 20019530L, 19980470L);
+    assertDeltas(40000000L, 40039061L, 39960939L);
+  }
+
+  private void assertDeltas(
+      final long gasLimit, final long expectedIncrease, final long expectedDecrease) {
+    FrontierTargetingGasLimitCalculator targetingGasLimitCalculator =
+        new FrontierTargetingGasLimitCalculator();
+    // increase
+    assertThat(targetingGasLimitCalculator.nextGasLimit(gasLimit, gasLimit * 2, 1L))
+        .isEqualTo(expectedIncrease);
+    // decrease
+    assertThat(targetingGasLimitCalculator.nextGasLimit(gasLimit, 0, 1L))
+        .isEqualTo(expectedDecrease);
+    // small decrease
+    assertThat(targetingGasLimitCalculator.nextGasLimit(gasLimit, gasLimit - 1, 1L))
+        .isEqualTo(gasLimit - 1);
+    // small increase
+    assertThat(targetingGasLimitCalculator.nextGasLimit(gasLimit, gasLimit + 1, 1L))
+        .isEqualTo(gasLimit + 1);
+    // no change
+    assertThat(targetingGasLimitCalculator.nextGasLimit(gasLimit, gasLimit, 1L))
+        .isEqualTo(gasLimit);
+  }
+
   @Test
   public void verifyMinGasLimit() {
     assertThat(AbstractGasLimitSpecification.isValidTargetGasLimit(DEFAULT_MIN_GAS_LIMIT - 1))