Add totalDiffculty to BlockPropagated events. (#97)

* Add totalDiffculty to BlockPropagated events.
The chain head block can be contentious with many fork blocks (ommers) propagating on the network.  We should add a totalDifficulty to make it easier to see which block is most likely the current head.
- added `BlockPropagated` interface in `plugin-api`.
- updated `BesuEvents.onBlockPropagated` method to take a `BlockPropagated` instead of a `BlockHeader`.
- created `BlockPropagatedSubscriber` in `BlockBroadcaster`.
- changed type of `BlockBroadcaster.blockPropagatedSubscribers` from `Consumer<Block>` to `BlockPropagatedSubscriber`.
- updated unit tests accordingly to all changes.
- updated known hash in `build.gradle` file of `plugin-api`: new value is `4SAeaZIJMsDvUK5Wp2RzU8TlHacslALnM/4yvVhsMtY=`

Signed-off-by: Abdelhamid Bakhta <abdelhamid.bakhta@consensys.net>

besu/src/main/java/org/hyperledger/besu/services/BesuEventsImpl.java

@@ -17,8 +17,13 @@ package org.hyperledger.besu.services;
 import org.hyperledger.besu.ethereum.eth.sync.BlockBroadcaster;
 import org.hyperledger.besu.ethereum.eth.sync.state.SyncState;
 import org.hyperledger.besu.ethereum.eth.transactions.TransactionPool;
+import org.hyperledger.besu.plugin.data.BlockHeader;
+import org.hyperledger.besu.plugin.data.PropagatedBlockContext;
+import org.hyperledger.besu.plugin.data.Quantity;
 import org.hyperledger.besu.plugin.services.BesuEvents;
 
+import java.util.function.Supplier;
+
 public class BesuEventsImpl implements BesuEvents {
   private final BlockBroadcaster blockBroadcaster;
   private final TransactionPool transactionPool;
@@ -36,7 +41,9 @@ public class BesuEventsImpl implements BesuEvents {
   @Override
   public long addBlockPropagatedListener(final BlockPropagatedListener listener) {
     return blockBroadcaster.subscribePropagateNewBlocks(
-        block -> listener.onBlockPropagated(block.getHeader()));
+        (block, totalDifficulty) ->
+            listener.onBlockPropagated(
+                blockPropagatedContext(block::getHeader, () -> totalDifficulty)));
   }
 
   @Override
@@ -75,4 +82,20 @@ public class BesuEventsImpl implements BesuEvents {
   public void removeSyncStatusListener(final long listenerIdentifier) {
     syncState.removeSyncStatusListener(listenerIdentifier);
   }
+
+  private static PropagatedBlockContext blockPropagatedContext(
+      final Supplier<BlockHeader> blockHeaderSupplier,
+      final Supplier<Quantity> totalDifficultySupplier) {
+    return new PropagatedBlockContext() {
+      @Override
+      public BlockHeader getBlockHeader() {
+        return blockHeaderSupplier.get();
+      }
+
+      @Override
+      public Quantity getTotalDifficulty() {
+        return totalDifficultySupplier.get();
+      }
+    };
+  }
 }

besu/src/test/java/org/hyperledger/besu/plugins/TestBesuEventsPlugin.java

@@ -17,6 +17,7 @@ package org.hyperledger.besu.plugins;
 import org.hyperledger.besu.plugin.BesuContext;
 import org.hyperledger.besu.plugin.BesuPlugin;
 import org.hyperledger.besu.plugin.data.BlockHeader;
+import org.hyperledger.besu.plugin.data.PropagatedBlockContext;
 import org.hyperledger.besu.plugin.services.BesuEvents;
 
 import java.io.File;
@@ -66,7 +67,8 @@ public class TestBesuEventsPlugin implements BesuPlugin {
     LOG.info("No longer listening with ID#" + subscriptionId);
   }
 
-  private void onBlockAnnounce(final BlockHeader header) {
+  private void onBlockAnnounce(final PropagatedBlockContext propagatedBlockContext) {
+    final BlockHeader header = propagatedBlockContext.getBlockHeader();
     final int blockCount = blockCounter.incrementAndGet();
     LOG.info("I got a new block! (I've seen {}) - {}", blockCount, header);
     try {

besu/src/test/java/org/hyperledger/besu/services/BesuEventsImplTest.java

@@ -43,7 +43,7 @@ import org.hyperledger.besu.ethereum.mainnet.TransactionValidator;
 import org.hyperledger.besu.ethereum.mainnet.ValidationResult;
 import org.hyperledger.besu.ethereum.worldstate.WorldStateArchive;
 import org.hyperledger.besu.metrics.noop.NoOpMetricsSystem;
-import org.hyperledger.besu.plugin.data.BlockHeader;
+import org.hyperledger.besu.plugin.data.PropagatedBlockContext;
 import org.hyperledger.besu.plugin.data.SyncStatus;
 import org.hyperledger.besu.plugin.data.Transaction;
 import org.hyperledger.besu.testutil.TestClock;
@@ -144,24 +144,29 @@ public class BesuEventsImplTest {
 
   @Test
   public void newBlockEventFiresAfterSubscribe() {
-    final AtomicReference<BlockHeader> result = new AtomicReference<>();
+    final AtomicReference<PropagatedBlockContext> result = new AtomicReference<>();
     serviceImpl.addBlockPropagatedListener(result::set);
-
+    final Block block = generateBlock();
     assertThat(result.get()).isNull();
-    blockBroadcaster.propagate(generateBlock(), UInt256.of(1));
+    blockBroadcaster.propagate(block, UInt256.of(1));
 
     assertThat(result.get()).isNotNull();
+    assertThat(result.get().getBlockHeader()).isEqualTo(block.getHeader());
+    assertThat(result.get().getTotalDifficulty()).isEqualTo(UInt256.of(1));
   }
 
   @Test
   public void newBlockEventDoesNotFireAfterUnsubscribe() {
-    final AtomicReference<BlockHeader> result = new AtomicReference<>();
+    final AtomicReference<PropagatedBlockContext> result = new AtomicReference<>();
     final long id = serviceImpl.addBlockPropagatedListener(result::set);
 
     assertThat(result.get()).isNull();
-    blockBroadcaster.propagate(generateBlock(), UInt256.of(1));
+    final Block block = generateBlock();
+    blockBroadcaster.propagate(block, UInt256.of(2));
 
     assertThat(result.get()).isNotNull();
+    assertThat(result.get().getBlockHeader()).isEqualTo(block.getHeader());
+    assertThat(result.get().getTotalDifficulty()).isEqualTo(UInt256.of(2));
     serviceImpl.removeBlockPropagatedListener(id);
     result.set(null);
 

build.gradle

@@ -268,7 +268,7 @@ allprojects {
 
 task deploy() {}
 
-task checkMavenCoordianteCollisions {
+task checkMavenCoordinateCollisions {
   doLast {
     def coordinates = [:]
     getAllprojects().forEach {
@@ -276,8 +276,8 @@ task checkMavenCoordianteCollisions {
         def coordinate = it.publishing?.publications[0].coordinates
         if (coordinates.containsKey(coordinate)) {
           throw new GradleException("Duplicate maven coordinates detected, ${coordinate} is used by " +
-              "both ${coordinates[coordinate]} and ${it.path}.\n" +
+          "both ${coordinates[coordinate]} and ${it.path}.\n" +
-              "Please add a `publishing` script block to one or both subprojects.")
+          "Please add a `publishing` script block to one or both subprojects.")
         }
         coordinates[coordinate] = it.path
       }
@@ -287,7 +287,7 @@ task checkMavenCoordianteCollisions {
 
 tasks.register('checkPluginAPIChanges', DefaultTask) { }
 checkPluginAPIChanges.dependsOn(':plugin-api:checkAPIChanges')
-check.dependsOn('checkPluginAPIChanges', 'checkMavenCoordianteCollisions')
+check.dependsOn('checkPluginAPIChanges', 'checkMavenCoordinateCollisions')
 
 subprojects {
 

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/BlockBroadcaster.java

@@ -21,8 +21,6 @@ import org.hyperledger.besu.ethereum.p2p.rlpx.connections.PeerConnection;
 import org.hyperledger.besu.util.Subscribers;
 import org.hyperledger.besu.util.uint.UInt256;
 
-import java.util.function.Consumer;
-
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -30,13 +28,14 @@ public class BlockBroadcaster {
   private static final Logger LOG = LogManager.getLogger();
 
   private final EthContext ethContext;
-  private final Subscribers<Consumer<Block>> blockPropagatedSubscribers = Subscribers.create();
+  private final Subscribers<BlockPropagatedSubscriber> blockPropagatedSubscribers =
+      Subscribers.create();
 
   public BlockBroadcaster(final EthContext ethContext) {
     this.ethContext = ethContext;
   }
 
-  public long subscribePropagateNewBlocks(final Consumer<Block> callback) {
+  public long subscribePropagateNewBlocks(final BlockPropagatedSubscriber callback) {
     return blockPropagatedSubscribers.subscribe(callback);
   }
 
@@ -45,7 +44,7 @@ public class BlockBroadcaster {
   }
 
   public void propagate(final Block block, final UInt256 totalDifficulty) {
-    blockPropagatedSubscribers.forEach(listener -> listener.accept(block));
+    blockPropagatedSubscribers.forEach(listener -> listener.accept(block, totalDifficulty));
     final NewBlockMessage newBlockMessage = NewBlockMessage.create(block, totalDifficulty);
     ethContext
         .getEthPeers()
@@ -61,4 +60,9 @@ public class BlockBroadcaster {
               }
             });
   }
+
+  @FunctionalInterface
+  public interface BlockPropagatedSubscriber {
+    void accept(Block block, UInt256 totalDifficulty);
+  }
 }

plugin-api/build.gradle

@@ -56,7 +56,7 @@ Calculated : ${currentHash}
 tasks.register('checkAPIChanges', FileStateChecker) {
   description = "Checks that the API for the Plugin-API project does not change without deliberate thought"
   files = sourceSets.main.allJava.files
-  knownHash = 'b8BCiNvy9vSYsTtS1NfszsVT0EMV8tiNc7igzXzTrak='
+  knownHash = 'XMBMdVNS2VAa+WN3lyEAKmXznu4ExSIHA2arYUeo0eo='
 }
 check.dependsOn('checkAPIChanges')
 

plugin-api/src/main/java/org/hyperledger/besu/plugin/data/PropagatedBlockContext.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright ConsenSys AG.
+ *
+ * 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.plugin.data;
+
+import org.hyperledger.besu.plugin.Unstable;
+
+/** The minimum set of data for a PropagatedBlockContext. */
+@Unstable
+public interface PropagatedBlockContext {
+
+  /**
+   * A {@link BlockHeader} object.
+   *
+   * @return A {@link BlockHeader}
+   */
+  BlockHeader getBlockHeader();
+
+  /**
+   * A scalar value corresponding to the total difficulty.
+   *
+   * @return A scalar value corresponding to the total difficulty.
+   */
+  Quantity getTotalDifficulty();
+}

plugin-api/src/main/java/org/hyperledger/besu/plugin/services/BesuEvents.java

@@ -15,7 +15,7 @@
 package org.hyperledger.besu.plugin.services;
 
 import org.hyperledger.besu.plugin.Unstable;
-import org.hyperledger.besu.plugin.data.BlockHeader;
+import org.hyperledger.besu.plugin.data.PropagatedBlockContext;
 import org.hyperledger.besu.plugin.data.SyncStatus;
 import org.hyperledger.besu.plugin.data.Transaction;
 
@@ -109,9 +109,9 @@ public interface BesuEvents {
      * <p>The block may not have been imported to the local chain yet and may fail later
      * validations.
      *
-     * @param blockHeader the new block header.
+     * @param propagatedBlockContext block being propagated.
      */
-    void onBlockPropagated(BlockHeader blockHeader);
+    void onBlockPropagated(PropagatedBlockContext propagatedBlockContext);
   }
 
   /** The listener interface for receiving new transaction added events. */