Dev/test option for short BFT block periods (#7588)

* Dev mode for short BFT block periods

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

* Refactoring

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

* Fix comment

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

* Refactor to make BFT block milliseconds an experimental QBFT config option

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

* Update Json BFT config options

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

---------

Signed-off-by: Matthew Whitehead <matthew1001@gmail.com>

besu/src/main/java/org/hyperledger/besu/controller/IbftBesuControllerBuilder.java

@@ -74,6 +74,7 @@ import org.hyperledger.besu.ethereum.worldstate.WorldStateArchive;
 import org.hyperledger.besu.plugin.services.BesuEvents;
 import org.hyperledger.besu.util.Subscribers;
 
+import java.time.Duration;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -182,7 +183,10 @@ public class IbftBesuControllerBuilder extends BftBesuControllerBuilder {
             Util.publicKeyToAddress(nodeKey.getPublicKey()),
             proposerSelector,
             uniqueMessageMulticaster,
-            new RoundTimer(bftEventQueue, bftConfig.getRequestTimeoutSeconds(), bftExecutors),
+            new RoundTimer(
+                bftEventQueue,
+                Duration.ofSeconds(bftConfig.getRequestTimeoutSeconds()),
+                bftExecutors),
             new BlockTimer(bftEventQueue, forksSchedule, bftExecutors, clock),
             blockCreatorFactory,
             clock);

besu/src/main/java/org/hyperledger/besu/controller/QbftBesuControllerBuilder.java

@@ -84,6 +84,7 @@ import org.hyperledger.besu.ethereum.worldstate.WorldStateArchive;
 import org.hyperledger.besu.plugin.services.BesuEvents;
 import org.hyperledger.besu.util.Subscribers;
 
+import java.time.Duration;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -222,7 +223,10 @@ public class QbftBesuControllerBuilder extends BftBesuControllerBuilder {
             Util.publicKeyToAddress(nodeKey.getPublicKey()),
             proposerSelector,
             uniqueMessageMulticaster,
-            new RoundTimer(bftEventQueue, qbftConfig.getRequestTimeoutSeconds(), bftExecutors),
+            new RoundTimer(
+                bftEventQueue,
+                Duration.ofSeconds(qbftConfig.getRequestTimeoutSeconds()),
+                bftExecutors),
             new BlockTimer(bftEventQueue, qbftForksSchedule, bftExecutors, clock),
             blockCreatorFactory,
             clock);

config/src/main/java/org/hyperledger/besu/config/BftConfigOptions.java

@@ -37,6 +37,13 @@ public interface BftConfigOptions {
    */
   int getBlockPeriodSeconds();
 
+  /**
+   * Gets block period milliseconds. For TESTING only. If set then blockperiodseconds is ignored.
+   *
+   * @return the block period milliseconds
+   */
+  long getBlockPeriodMilliseconds();
+
   /**
    * Gets request timeout seconds.
    *

config/src/main/java/org/hyperledger/besu/config/BftFork.java

@@ -21,6 +21,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Optional;
 import java.util.OptionalInt;
+import java.util.OptionalLong;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.databind.node.ArrayNode;
@@ -40,6 +41,9 @@ public class BftFork implements Fork {
   /** The constant BLOCK_PERIOD_SECONDS_KEY. */
   public static final String BLOCK_PERIOD_SECONDS_KEY = "blockperiodseconds";
 
+  /** The constant BLOCK_PERIOD_MILLISECONDS_KEY. */
+  public static final String BLOCK_PERIOD_MILLISECONDS_KEY = "xblockperiodmilliseconds";
+
   /** The constant BLOCK_REWARD_KEY. */
   public static final String BLOCK_REWARD_KEY = "blockreward";
 
@@ -82,6 +86,15 @@ public class BftFork implements Fork {
     return JsonUtil.getPositiveInt(forkConfigRoot, BLOCK_PERIOD_SECONDS_KEY);
   }
 
+  /**
+   * Gets block period milliseconds. Experimental for test scenarios only.
+   *
+   * @return the block period milliseconds
+   */
+  public OptionalLong getBlockPeriodMilliseconds() {
+    return JsonUtil.getLong(forkConfigRoot, BLOCK_PERIOD_MILLISECONDS_KEY);
+  }
+
   /**
    * Gets block reward wei.
    *

config/src/main/java/org/hyperledger/besu/config/JsonBftConfigOptions.java

@@ -34,6 +34,7 @@ public class JsonBftConfigOptions implements BftConfigOptions {
 
   private static final long DEFAULT_EPOCH_LENGTH = 30_000;
   private static final int DEFAULT_BLOCK_PERIOD_SECONDS = 1;
+  private static final int DEFAULT_BLOCK_PERIOD_MILLISECONDS = 0; // Experimental for test only
   private static final int DEFAULT_ROUND_EXPIRY_SECONDS = 1;
   // In a healthy network this can be very small. This default limit will allow for suitable
   // protection for on a typical 20 node validator network with multiple rounds
@@ -66,6 +67,12 @@ public class JsonBftConfigOptions implements BftConfigOptions {
         bftConfigRoot, "blockperiodseconds", DEFAULT_BLOCK_PERIOD_SECONDS);
   }
 
+  @Override
+  public long getBlockPeriodMilliseconds() {
+    return JsonUtil.getLong(
+        bftConfigRoot, "xblockperiodmilliseconds", DEFAULT_BLOCK_PERIOD_MILLISECONDS);
+  }
+
   @Override
   public int getRequestTimeoutSeconds() {
     return JsonUtil.getInt(bftConfigRoot, "requesttimeoutseconds", DEFAULT_ROUND_EXPIRY_SECONDS);
@@ -133,6 +140,9 @@ public class JsonBftConfigOptions implements BftConfigOptions {
     if (bftConfigRoot.has("blockperiodseconds")) {
       builder.put("blockPeriodSeconds", getBlockPeriodSeconds());
     }
+    if (bftConfigRoot.has("xblockperiodmilliseconds")) {
+      builder.put("xBlockPeriodMilliSeconds", getBlockPeriodMilliseconds());
+    }
     if (bftConfigRoot.has("requesttimeoutseconds")) {
       builder.put("requestTimeoutSeconds", getRequestTimeoutSeconds());
     }

consensus/common/src/main/java/org/hyperledger/besu/consensus/common/bft/BlockTimer.java

@@ -24,9 +24,14 @@ import java.util.Optional;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /** Class for starting and keeping organised block timers */
 public class BlockTimer {
 
+  private static final Logger LOG = LoggerFactory.getLogger(BlockTimer.class);
+
   private final ForksSchedule<? extends BftConfigOptions> forksSchedule;
   private final BftExecutors bftExecutors;
   private Optional<ScheduledFuture<?>> currentTimerTask;
@@ -79,12 +84,26 @@ public class BlockTimer {
     cancelTimer();
 
     final long now = clock.millis();
+    final long expiryTime;
+
+    // Experimental option for test scenarios only. Not for production use.
+    final long blockPeriodMilliseconds =
+        forksSchedule.getFork(round.getSequenceNumber()).getValue().getBlockPeriodMilliseconds();
 
-    // absolute time when the timer is supposed to expire
-    final int blockPeriodSeconds =
-        forksSchedule.getFork(round.getSequenceNumber()).getValue().getBlockPeriodSeconds();
-    final long minimumTimeBetweenBlocksMillis = blockPeriodSeconds * 1000L;
-    final long expiryTime = chainHeadHeader.getTimestamp() * 1_000 + minimumTimeBetweenBlocksMillis;
+    if (blockPeriodMilliseconds > 0) {
+      // Experimental mode for setting < 1 second block periods e.g. for CI/CD pipelines
+      // running tests against Besu
+      expiryTime = clock.millis() + blockPeriodMilliseconds;
+      LOG.warn(
+          "Test-mode only xblockperiodmilliseconds has been set to {} millisecond blocks. Do not use in a production system.",
+          blockPeriodMilliseconds);
+    } else {
+      // absolute time when the timer is supposed to expire
+      final int blockPeriodSeconds =
+          forksSchedule.getFork(round.getSequenceNumber()).getValue().getBlockPeriodSeconds();
+      final long minimumTimeBetweenBlocksMillis = blockPeriodSeconds * 1000L;
+      expiryTime = chainHeadHeader.getTimestamp() * 1_000 + minimumTimeBetweenBlocksMillis;
+    }
 
     if (expiryTime > now) {
       final long delay = expiryTime - now;

consensus/common/src/main/java/org/hyperledger/besu/consensus/common/bft/MutableBftConfigOptions.java

@@ -31,6 +31,7 @@ import java.util.Optional;
 public class MutableBftConfigOptions implements BftConfigOptions {
   private long epochLength;
   private int blockPeriodSeconds;
+  private long blockPeriodMilliseconds;
   private int requestTimeoutSeconds;
   private int gossipedHistoryLimit;
   private int messageQueueLimit;
@@ -48,6 +49,7 @@ public class MutableBftConfigOptions implements BftConfigOptions {
   public MutableBftConfigOptions(final BftConfigOptions bftConfigOptions) {
     this.epochLength = bftConfigOptions.getEpochLength();
     this.blockPeriodSeconds = bftConfigOptions.getBlockPeriodSeconds();
+    this.blockPeriodMilliseconds = bftConfigOptions.getBlockPeriodMilliseconds();
     this.requestTimeoutSeconds = bftConfigOptions.getRequestTimeoutSeconds();
     this.gossipedHistoryLimit = bftConfigOptions.getGossipedHistoryLimit();
     this.messageQueueLimit = bftConfigOptions.getMessageQueueLimit();
@@ -68,6 +70,11 @@ public class MutableBftConfigOptions implements BftConfigOptions {
     return blockPeriodSeconds;
   }
 
+  @Override
+  public long getBlockPeriodMilliseconds() {
+    return blockPeriodMilliseconds;
+  }
+
   @Override
   public int getRequestTimeoutSeconds() {
     return requestTimeoutSeconds;
@@ -131,6 +138,16 @@ public class MutableBftConfigOptions implements BftConfigOptions {
     this.blockPeriodSeconds = blockPeriodSeconds;
   }
 
+  /**
+   * Sets block period milliseconds. Experimental for test scenarios. Not for use on production
+   * systems.
+   *
+   * @param blockPeriodMilliseconds the block period milliseconds
+   */
+  public void setBlockPeriodMilliseconds(final long blockPeriodMilliseconds) {
+    this.blockPeriodMilliseconds = blockPeriodMilliseconds;
+  }
+
   /**
    * Sets request timeout seconds.
    *

consensus/common/src/main/java/org/hyperledger/besu/consensus/common/bft/RoundTimer.java

@@ -16,6 +16,7 @@ package org.hyperledger.besu.consensus.common.bft;
 
 import org.hyperledger.besu.consensus.common.bft.events.RoundExpiry;
 
+import java.time.Duration;
 import java.util.Optional;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
@@ -31,21 +32,21 @@ public class RoundTimer {
   private final BftExecutors bftExecutors;
   private Optional<ScheduledFuture<?>> currentTimerTask;
   private final BftEventQueue queue;
-  private final long baseExpiryMillis;
+  private final Duration baseExpiryPeriod;
 
   /**
    * Construct a RoundTimer with primed executor service ready to start timers
    *
    * @param queue The queue in which to put round expiry events
-   * @param baseExpirySeconds The initial round length for round 0
+   * @param baseExpiryPeriod The initial round length for round 0
    * @param bftExecutors executor service that timers can be scheduled with
    */
   public RoundTimer(
-      final BftEventQueue queue, final long baseExpirySeconds, final BftExecutors bftExecutors) {
+      final BftEventQueue queue, final Duration baseExpiryPeriod, final BftExecutors bftExecutors) {
     this.queue = queue;
     this.bftExecutors = bftExecutors;
     this.currentTimerTask = Optional.empty();
-    this.baseExpiryMillis = baseExpirySeconds * 1000;
+    this.baseExpiryPeriod = baseExpiryPeriod;
   }
 
   /** Cancels the current running round timer if there is one */
@@ -71,7 +72,8 @@ public class RoundTimer {
   public synchronized void startTimer(final ConsensusRoundIdentifier round) {
     cancelTimer();
 
-    final long expiryTime = baseExpiryMillis * (long) Math.pow(2, round.getRoundNumber());
+    final long expiryTime =
+        baseExpiryPeriod.toMillis() * (long) Math.pow(2, round.getRoundNumber());
 
     final Runnable newTimerRunnable = () -> queue.add(new RoundExpiry(round));
 

consensus/common/src/test/java/org/hyperledger/besu/consensus/common/bft/RoundTimerTest.java

@@ -25,6 +25,7 @@ import static org.mockito.Mockito.when;
 
 import org.hyperledger.besu.consensus.common.bft.events.RoundExpiry;
 
+import java.time.Duration;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 
@@ -46,7 +47,7 @@ public class RoundTimerTest {
     bftExecutors = mock(BftExecutors.class);
     queue = new BftEventQueue(1000);
     queue.start();
-    timer = new RoundTimer(queue, 1, bftExecutors);
+    timer = new RoundTimer(queue, Duration.ofSeconds(1), bftExecutors);
   }
 
   @Test

consensus/ibft/src/integration-test/java/org/hyperledger/besu/consensus/ibft/support/TestContextBuilder.java

@@ -100,6 +100,7 @@ import org.hyperledger.besu.testutil.TestClock;
 import org.hyperledger.besu.util.Subscribers;
 
 import java.time.Clock;
+import java.time.Duration;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.util.ArrayList;
@@ -403,7 +404,7 @@ public class TestContextBuilder {
             Util.publicKeyToAddress(nodeKey.getPublicKey()),
             proposerSelector,
             multicaster,
-            new RoundTimer(bftEventQueue, ROUND_TIMER_SEC, bftExecutors),
+            new RoundTimer(bftEventQueue, Duration.ofSeconds(ROUND_TIMER_SEC), bftExecutors),
             new BlockTimer(bftEventQueue, forksSchedule, bftExecutors, TestClock.fixed()),
             blockCreatorFactory,
             clock);

consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/IbftBlockHeaderValidationRulesetFactory.java

@@ -32,6 +32,7 @@ import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.GasUsageValid
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.TimestampBoundedByFutureParameter;
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.TimestampMoreRecentThanParent;
 
+import java.time.Duration;
 import java.util.Optional;
 
 import org.apache.tuweni.units.bigints.UInt256;
@@ -45,32 +46,43 @@ public class IbftBlockHeaderValidationRulesetFactory {
    * Produces a BlockHeaderValidator configured for assessing bft block headers which are to form
    * part of the BlockChain (i.e. not proposed blocks, which do not contain commit seals)
    *
-   * @param secondsBetweenBlocks the minimum number of seconds which must elapse between blocks.
+   * @param minimumTimeBetweenBlocks the minimum time which must elapse between blocks.
    * @param baseFeeMarket an {@link Optional} wrapping {@link BaseFeeMarket} class if appropriate.
    * @return BlockHeaderValidator configured for assessing bft block headers
    */
   public static BlockHeaderValidator.Builder blockHeaderValidator(
-      final long secondsBetweenBlocks, final Optional<BaseFeeMarket> baseFeeMarket) {
-    return new BlockHeaderValidator.Builder()
-        .addRule(new AncestryValidationRule())
-        .addRule(new GasUsageValidationRule())
-        .addRule(
-            new GasLimitRangeAndDeltaValidationRule(
-                DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT, baseFeeMarket))
-        .addRule(new TimestampBoundedByFutureParameter(1))
-        .addRule(new TimestampMoreRecentThanParent(secondsBetweenBlocks))
-        .addRule(
-            new ConstantFieldValidationRule<>(
-                "MixHash", BlockHeader::getMixHash, BftHelpers.EXPECTED_MIX_HASH))
-        .addRule(
-            new ConstantFieldValidationRule<>(
-                "OmmersHash", BlockHeader::getOmmersHash, Hash.EMPTY_LIST_HASH))
-        .addRule(
-            new ConstantFieldValidationRule<>(
-                "Difficulty", BlockHeader::getDifficulty, UInt256.ONE))
-        .addRule(new ConstantFieldValidationRule<>("Nonce", BlockHeader::getNonce, 0L))
-        .addRule(new BftValidatorsValidationRule())
-        .addRule(new BftCoinbaseValidationRule())
-        .addRule(new BftCommitSealsValidationRule());
+      final Duration minimumTimeBetweenBlocks, final Optional<BaseFeeMarket> baseFeeMarket) {
+    final BlockHeaderValidator.Builder ruleBuilder =
+        new BlockHeaderValidator.Builder()
+            .addRule(new AncestryValidationRule())
+            .addRule(new GasUsageValidationRule())
+            .addRule(
+                new GasLimitRangeAndDeltaValidationRule(
+                    DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT, baseFeeMarket))
+            .addRule(new TimestampBoundedByFutureParameter(1))
+            .addRule(
+                new ConstantFieldValidationRule<>(
+                    "MixHash", BlockHeader::getMixHash, BftHelpers.EXPECTED_MIX_HASH))
+            .addRule(
+                new ConstantFieldValidationRule<>(
+                    "OmmersHash", BlockHeader::getOmmersHash, Hash.EMPTY_LIST_HASH))
+            .addRule(
+                new ConstantFieldValidationRule<>(
+                    "Difficulty", BlockHeader::getDifficulty, UInt256.ONE))
+            .addRule(new ConstantFieldValidationRule<>("Nonce", BlockHeader::getNonce, 0L))
+            .addRule(new BftValidatorsValidationRule())
+            .addRule(new BftCoinbaseValidationRule())
+            .addRule(new BftCommitSealsValidationRule());
+
+    // Currently the minimum acceptable time between blocks is 1 second. The timestamp of an
+    // Ethereum header is stored as seconds since Unix epoch so blocks being produced more
+    // frequently than once a second cannot pass this validator. For non-production scenarios
+    // (e.g. for testing block production much more frequently than once a second) Besu has
+    // an experimental 'xblockperiodmilliseconds' option for BFT chains. If this is enabled
+    // we cannot apply the TimestampMoreRecentThanParent validation rule so we do not add it
+    if (minimumTimeBetweenBlocks.compareTo(Duration.ofSeconds(1)) >= 0) {
+      ruleBuilder.addRule(new TimestampMoreRecentThanParent(minimumTimeBetweenBlocks.getSeconds()));
+    }
+    return ruleBuilder;
   }
 }

consensus/ibft/src/main/java/org/hyperledger/besu/consensus/ibft/IbftProtocolScheduleBuilder.java

@@ -29,6 +29,7 @@ import org.hyperledger.besu.ethereum.mainnet.feemarket.FeeMarket;
 import org.hyperledger.besu.evm.internal.EvmConfiguration;
 import org.hyperledger.besu.plugin.services.MetricsSystem;
 
+import java.time.Duration;
 import java.util.Optional;
 
 /** Defines the protocol behaviours for a blockchain using a BFT consensus mechanism. */
@@ -120,6 +121,9 @@ public class IbftProtocolScheduleBuilder extends BaseBftProtocolScheduleBuilder
         Optional.of(feeMarket).filter(FeeMarket::implementsBaseFee).map(BaseFeeMarket.class::cast);
 
     return IbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
-        config.getBlockPeriodSeconds(), baseFeeMarket);
+        config.getBlockPeriodMilliseconds() > 0
+            ? Duration.ofMillis(config.getBlockPeriodMilliseconds())
+            : Duration.ofSeconds(config.getBlockPeriodSeconds()),
+        baseFeeMarket);
   }
 }

consensus/ibft/src/test/java/org/hyperledger/besu/consensus/ibft/IbftBlockHeaderValidationRulesetFactoryTest.java

@@ -38,6 +38,7 @@ import org.hyperledger.besu.ethereum.mainnet.BlockHeaderValidator;
 import org.hyperledger.besu.ethereum.mainnet.HeaderValidationMode;
 import org.hyperledger.besu.ethereum.mainnet.feemarket.FeeMarket;
 
+import java.time.Duration;
 import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
@@ -93,7 +94,7 @@ public class IbftBlockHeaderValidationRulesetFactoryTest {
 
     final BlockHeaderValidator validator =
         IbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
-                5, Optional.of(FeeMarket.london(1)))
+                Duration.ofSeconds(5), Optional.of(FeeMarket.london(1)))
             .build();
 
     assertThat(
@@ -372,7 +373,8 @@ public class IbftBlockHeaderValidationRulesetFactoryTest {
   }
 
   public BlockHeaderValidator getBlockHeaderValidator() {
-    return IbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(5, Optional.empty())
+    return IbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
+            Duration.ofSeconds(5), Optional.empty())
         .build();
   }
 }

consensus/ibft/src/test/java/org/hyperledger/besu/consensus/ibft/blockcreation/BftBlockCreatorTest.java

@@ -64,6 +64,7 @@ import org.hyperledger.besu.plugin.services.MetricsSystem;
 import org.hyperledger.besu.testutil.DeterministicEthScheduler;
 import org.hyperledger.besu.testutil.TestClock;
 
+import java.time.Duration;
 import java.time.ZoneId;
 import java.util.Collections;
 import java.util.List;
@@ -105,7 +106,7 @@ public class BftBlockCreatorTest {
           public BlockHeaderValidator.Builder createBlockHeaderRuleset(
               final BftConfigOptions config, final FeeMarket feeMarket) {
             return IbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
-                5, Optional.empty());
+                Duration.ofSeconds(5), Optional.empty());
           }
         };
     final GenesisConfigOptions configOptions =
@@ -200,7 +201,7 @@ public class BftBlockCreatorTest {
 
     final BlockHeaderValidator rules =
         IbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
-                secondsBetweenBlocks, Optional.empty())
+                Duration.ofSeconds(secondsBetweenBlocks), Optional.empty())
             .build();
 
     // NOTE: The header will not contain commit seals, so can only do light validation on header.

consensus/qbft/src/integration-test/java/org/hyperledger/besu/consensus/qbft/support/TestContextBuilder.java

@@ -118,6 +118,7 @@ import org.hyperledger.besu.util.Subscribers;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.time.Clock;
+import java.time.Duration;
 import java.time.Instant;
 import java.time.ZoneId;
 import java.util.ArrayList;
@@ -512,7 +513,7 @@ public class TestContextBuilder {
             Util.publicKeyToAddress(nodeKey.getPublicKey()),
             proposerSelector,
             multicaster,
-            new RoundTimer(bftEventQueue, ROUND_TIMER_SEC, bftExecutors),
+            new RoundTimer(bftEventQueue, Duration.ofSeconds(ROUND_TIMER_SEC), bftExecutors),
             new BlockTimer(bftEventQueue, forksSchedule, bftExecutors, TestClock.fixed()),
             blockCreatorFactory,
             clock);

consensus/qbft/src/main/java/org/hyperledger/besu/consensus/qbft/QbftBlockHeaderValidationRulesetFactory.java

@@ -31,6 +31,7 @@ import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.GasUsageValid
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.TimestampBoundedByFutureParameter;
 import org.hyperledger.besu.ethereum.mainnet.headervalidationrules.TimestampMoreRecentThanParent;
 
+import java.time.Duration;
 import java.util.Optional;
 
 import org.apache.tuweni.units.bigints.UInt256;
@@ -44,31 +45,42 @@ public class QbftBlockHeaderValidationRulesetFactory {
    * Produces a BlockHeaderValidator configured for assessing bft block headers which are to form
    * part of the BlockChain (i.e. not proposed blocks, which do not contain commit seals)
    *
-   * @param secondsBetweenBlocks the minimum number of seconds which must elapse between blocks.
+   * @param minimumTimeBetweenBlocks the minimum amount of time that must elapse between blocks.
    * @param useValidatorContract whether validator selection is using a validator contract
    * @param baseFeeMarket an {@link Optional} wrapping {@link BaseFeeMarket} class if appropriate.
    * @return BlockHeaderValidator configured for assessing bft block headers
    */
   public static BlockHeaderValidator.Builder blockHeaderValidator(
-      final long secondsBetweenBlocks,
+      final Duration minimumTimeBetweenBlocks,
       final boolean useValidatorContract,
       final Optional<BaseFeeMarket> baseFeeMarket) {
-    return new BlockHeaderValidator.Builder()
-        .addRule(new AncestryValidationRule())
-        .addRule(new GasUsageValidationRule())
-        .addRule(
-            new GasLimitRangeAndDeltaValidationRule(
-                DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT, baseFeeMarket))
-        .addRule(new TimestampBoundedByFutureParameter(1))
-        .addRule(new TimestampMoreRecentThanParent(secondsBetweenBlocks))
-        .addRule(
-            new ConstantFieldValidationRule<>(
-                "MixHash", BlockHeader::getMixHash, BftHelpers.EXPECTED_MIX_HASH))
-        .addRule(
-            new ConstantFieldValidationRule<>(
-                "Difficulty", BlockHeader::getDifficulty, UInt256.ONE))
-        .addRule(new QbftValidatorsValidationRule(useValidatorContract))
-        .addRule(new BftCoinbaseValidationRule())
-        .addRule(new BftCommitSealsValidationRule());
+    BlockHeaderValidator.Builder ruleBuilder =
+        new BlockHeaderValidator.Builder()
+            .addRule(new AncestryValidationRule())
+            .addRule(new GasUsageValidationRule())
+            .addRule(
+                new GasLimitRangeAndDeltaValidationRule(
+                    DEFAULT_MIN_GAS_LIMIT, DEFAULT_MAX_GAS_LIMIT, baseFeeMarket))
+            .addRule(new TimestampBoundedByFutureParameter(1))
+            .addRule(
+                new ConstantFieldValidationRule<>(
+                    "MixHash", BlockHeader::getMixHash, BftHelpers.EXPECTED_MIX_HASH))
+            .addRule(
+                new ConstantFieldValidationRule<>(
+                    "Difficulty", BlockHeader::getDifficulty, UInt256.ONE))
+            .addRule(new QbftValidatorsValidationRule(useValidatorContract))
+            .addRule(new BftCoinbaseValidationRule())
+            .addRule(new BftCommitSealsValidationRule());
+
+    // Currently the minimum acceptable time between blocks is 1 second. The timestamp of an
+    // Ethereum header is stored as seconds since Unix epoch so blocks being produced more
+    // frequently than once a second cannot pass this validator. For non-production scenarios
+    // (e.g. for testing block production much more frequently than once a second) Besu has
+    // an experimental 'xblockperiodmilliseconds' option for BFT chains. If this is enabled
+    // we cannot apply the TimestampMoreRecentThanParent validation rule so we do not add it
+    if (minimumTimeBetweenBlocks.compareTo(Duration.ofSeconds(1)) >= 0) {
+      ruleBuilder.addRule(new TimestampMoreRecentThanParent(minimumTimeBetweenBlocks.getSeconds()));
+    }
+    return ruleBuilder;
   }
 }

consensus/qbft/src/main/java/org/hyperledger/besu/consensus/qbft/QbftForksSchedulesFactory.java

@@ -49,6 +49,7 @@ public class QbftForksSchedulesFactory {
         new MutableQbftConfigOptions(lastSpec.getValue());
 
     fork.getBlockPeriodSeconds().ifPresent(bftConfigOptions::setBlockPeriodSeconds);
+    fork.getBlockPeriodMilliseconds().ifPresent(bftConfigOptions::setBlockPeriodMilliseconds);
     fork.getBlockRewardWei().ifPresent(bftConfigOptions::setBlockRewardWei);
 
     if (fork.isMiningBeneficiaryConfigured()) {

consensus/qbft/src/main/java/org/hyperledger/besu/consensus/qbft/QbftProtocolScheduleBuilder.java

@@ -33,6 +33,7 @@ import org.hyperledger.besu.ethereum.mainnet.feemarket.FeeMarket;
 import org.hyperledger.besu.evm.internal.EvmConfiguration;
 import org.hyperledger.besu.plugin.services.MetricsSystem;
 
+import java.time.Duration;
 import java.util.Optional;
 
 /** Defines the protocol behaviours for a blockchain using a QBFT consensus mechanism. */
@@ -164,7 +165,9 @@ public class QbftProtocolScheduleBuilder extends BaseBftProtocolScheduleBuilder
         Optional.of(feeMarket).filter(FeeMarket::implementsBaseFee).map(BaseFeeMarket.class::cast);
 
     return QbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
-        qbftConfigOptions.getBlockPeriodSeconds(),
+        qbftConfigOptions.getBlockPeriodMilliseconds() > 0
+            ? Duration.ofMillis(qbftConfigOptions.getBlockPeriodMilliseconds())
+            : Duration.ofSeconds(qbftConfigOptions.getBlockPeriodSeconds()),
         qbftConfigOptions.isValidatorContractMode(),
         baseFeeMarket);
   }

consensus/qbft/src/test/java/org/hyperledger/besu/consensus/qbft/QbftBlockHeaderValidationRulesetFactoryTest.java

@@ -34,6 +34,7 @@ import org.hyperledger.besu.ethereum.mainnet.BlockHeaderValidator;
 import org.hyperledger.besu.ethereum.mainnet.HeaderValidationMode;
 import org.hyperledger.besu.ethereum.mainnet.feemarket.FeeMarket;
 
+import java.time.Duration;
 import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
@@ -92,7 +93,7 @@ public class QbftBlockHeaderValidationRulesetFactoryTest {
 
     final BlockHeaderValidator validator =
         QbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
-                5, false, Optional.of(FeeMarket.london(1)))
+                Duration.ofSeconds(5), false, Optional.of(FeeMarket.london(1)))
             .build();
 
     assertThat(
@@ -366,7 +367,8 @@ public class QbftBlockHeaderValidationRulesetFactoryTest {
   }
 
   public BlockHeaderValidator getBlockHeaderValidator() {
-    return QbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(5, false, Optional.empty())
+    return QbftBlockHeaderValidationRulesetFactory.blockHeaderValidator(
+            Duration.ofSeconds(5), false, Optional.empty())
         .build();
   }
 }