Add fix to prevent the node from stopping downloading blocks (#2213)

Signed-off-by: Karim TAAM <karim.t2am@gmail.com>

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/task/GetBlockFromPeerTask.java

@@ -24,24 +24,26 @@ import org.hyperledger.besu.ethereum.mainnet.ProtocolSchedule;
 import org.hyperledger.besu.plugin.services.MetricsSystem;
 
 import java.util.List;
+import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.apache.tuweni.bytes.Bytes;
 
 /** Downloads a block from a peer. Will complete exceptionally if block cannot be downloaded. */
 public class GetBlockFromPeerTask extends AbstractPeerTask<Block> {
   private static final Logger LOG = LogManager.getLogger();
 
   private final ProtocolSchedule protocolSchedule;
-  private final Hash hash;
+  private final Optional<Hash> hash;
   private final long blockNumber;
   private final MetricsSystem metricsSystem;
 
   protected GetBlockFromPeerTask(
       final ProtocolSchedule protocolSchedule,
       final EthContext ethContext,
-      final Hash hash,
+      final Optional<Hash> hash,
       final long blockNumber,
       final MetricsSystem metricsSystem) {
     super(ethContext, metricsSystem);
@@ -54,7 +56,7 @@ public class GetBlockFromPeerTask extends AbstractPeerTask<Block> {
   public static GetBlockFromPeerTask create(
       final ProtocolSchedule protocolSchedule,
       final EthContext ethContext,
-      final Hash hash,
+      final Optional<Hash> hash,
       final long blockNumber,
       final MetricsSystem metricsSystem) {
     return new GetBlockFromPeerTask(protocolSchedule, ethContext, hash, blockNumber, metricsSystem);
@@ -62,9 +64,10 @@ public class GetBlockFromPeerTask extends AbstractPeerTask<Block> {
 
   @Override
   protected void executeTask() {
+    final String blockIdentifier = hash.map(Bytes::toHexString).orElse(Long.toString(blockNumber));
     LOG.debug(
         "Downloading block {} from peer {}.",
-        hash,
+        blockIdentifier,
         assignedPeer.map(EthPeer::toString).orElse("<any>"));
     downloadHeader()
         .thenCompose(this::completeBlock)
@@ -73,14 +76,15 @@ public class GetBlockFromPeerTask extends AbstractPeerTask<Block> {
               if (t != null) {
                 LOG.info(
                     "Failed to download block {} from peer {}.",
-                    hash,
+                    blockIdentifier,
                     assignedPeer.map(EthPeer::toString).orElse("<any>"));
                 result.completeExceptionally(t);
               } else if (r.getResult().isEmpty()) {
-                LOG.info("Failed to download block {} from peer {}.", hash, r.getPeer());
+                LOG.info("Failed to download block {} from peer {}.", blockIdentifier, r.getPeer());
                 result.completeExceptionally(new IncompleteResultsException());
               } else {
-                LOG.debug("Successfully downloaded block {} from peer {}.", hash, r.getPeer());
+                LOG.debug(
+                    "Successfully downloaded block {} from peer {}.", blockIdentifier, r.getPeer());
                 result.complete(new PeerTaskResult<>(r.getPeer(), r.getResult().get(0)));
               }
             });
@@ -89,9 +93,16 @@ public class GetBlockFromPeerTask extends AbstractPeerTask<Block> {
   private CompletableFuture<PeerTaskResult<List<BlockHeader>>> downloadHeader() {
     return executeSubTask(
         () -> {
-          final AbstractGetHeadersFromPeerTask task =
-              GetHeadersFromPeerByHashTask.forSingleHash(
-                  protocolSchedule, ethContext, hash, blockNumber, metricsSystem);
+          final AbstractGetHeadersFromPeerTask task;
+          task =
+              hash.map(
+                      value ->
+                          GetHeadersFromPeerByHashTask.forSingleHash(
+                              protocolSchedule, ethContext, value, blockNumber, metricsSystem))
+                  .orElseGet(
+                      () ->
+                          GetHeadersFromPeerByNumberTask.forSingleNumber(
+                              protocolSchedule, ethContext, blockNumber, metricsSystem));
           assignedPeer.ifPresent(task::assignPeer);
           return task.run();
         });

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/task/GetBlockFromPeersTask.java

@@ -23,6 +23,7 @@ import org.hyperledger.besu.ethereum.mainnet.ProtocolSchedule;
 import org.hyperledger.besu.plugin.services.MetricsSystem;
 
 import java.util.List;
+import java.util.Optional;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -34,7 +35,7 @@ public class GetBlockFromPeersTask extends AbstractEthTask<AbstractPeerTask.Peer
   private final List<EthPeer> peers;
   private final EthContext ethContext;
   private final ProtocolSchedule protocolSchedule;
-  private final Hash hash;
+  private final Optional<Hash> hash;
   private final long blockNumber;
   private final MetricsSystem metricsSystem;
 
@@ -42,7 +43,7 @@ public class GetBlockFromPeersTask extends AbstractEthTask<AbstractPeerTask.Peer
       final List<EthPeer> peers,
       final ProtocolSchedule protocolSchedule,
       final EthContext ethContext,
-      final Hash hash,
+      final Optional<Hash> hash,
       final long blockNumber,
       final MetricsSystem metricsSystem) {
     super(metricsSystem);
@@ -58,7 +59,7 @@ public class GetBlockFromPeersTask extends AbstractEthTask<AbstractPeerTask.Peer
       final List<EthPeer> peers,
       final ProtocolSchedule protocolSchedule,
       final EthContext ethContext,
-      final Hash hash,
+      final Optional<Hash> hash,
       final long blockNumber,
       final MetricsSystem metricsSystem) {
     return new GetBlockFromPeersTask(

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

@@ -23,6 +23,7 @@ import org.hyperledger.besu.ethereum.core.Block;
 import org.hyperledger.besu.ethereum.core.BlockHeader;
 import org.hyperledger.besu.ethereum.core.Difficulty;
 import org.hyperledger.besu.ethereum.core.Hash;
+import org.hyperledger.besu.ethereum.core.ProcessableBlockHeader;
 import org.hyperledger.besu.ethereum.eth.manager.EthContext;
 import org.hyperledger.besu.ethereum.eth.manager.EthMessage;
 import org.hyperledger.besu.ethereum.eth.manager.EthPeer;
@@ -45,6 +46,7 @@ import org.hyperledger.besu.plugin.services.MetricsSystem;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
@@ -143,6 +145,20 @@ public class BlockPropagationManager {
                   LOG.info("Imported {} pending blocks", r.size());
                 }
               });
+    } else {
+      pendingBlocksManager
+          .lowestAnnouncedBlock()
+          .map(ProcessableBlockHeader::getNumber)
+          .ifPresent(
+              minAnnouncedBlockNumber -> {
+                long distance =
+                    minAnnouncedBlockNumber
+                        - protocolContext.getBlockchain().getChainHeadBlockNumber();
+                if (distance < config.getBlockPropagationRange().upperEndpoint()
+                    && minAnnouncedBlockNumber > newBlock.getHeader().getNumber()) {
+                  retrieveMissingAnnouncedBlock(newBlock.getHeader().getNumber() + 1);
+                }
+              });
     }
 
     if (blockAddedEvent.getEventType().equals(EventType.HEAD_ADVANCED)) {
@@ -245,11 +261,28 @@ public class BlockPropagationManager {
     }
   }
 
+  private CompletableFuture<Block> retrieveMissingAnnouncedBlock(final long blockNumber) {
+    LOG.debug("Retrieve missing announced block {} from peer", blockNumber);
+    final List<EthPeer> peers =
+        ethContext.getEthPeers().streamBestPeers().collect(Collectors.toList());
+    final GetBlockFromPeersTask getBlockTask =
+        GetBlockFromPeersTask.create(
+            peers, protocolSchedule, ethContext, Optional.empty(), blockNumber, metricsSystem);
+    return getBlockTask
+        .run()
+        .thenCompose((r) -> importOrSavePendingBlock(r.getResult(), r.getPeer().nodeId()));
+  }
+
   private CompletableFuture<Block> processAnnouncedBlock(
       final List<EthPeer> peers, final NewBlockHash newBlock) {
     final GetBlockFromPeersTask getBlockTask =
         GetBlockFromPeersTask.create(
-            peers, protocolSchedule, ethContext, newBlock.hash(), newBlock.number(), metricsSystem);
+            peers,
+            protocolSchedule,
+            ethContext,
+            Optional.of(newBlock.hash()),
+            newBlock.number(),
+            metricsSystem);
     return getBlockTask
         .run()
         .thenCompose((r) -> importOrSavePendingBlock(r.getResult(), r.getPeer().nodeId()));

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/state/PendingBlocksManager.java

@@ -17,15 +17,18 @@ package org.hyperledger.besu.ethereum.eth.sync.state;
 import static java.util.Collections.newSetFromMap;
 
 import org.hyperledger.besu.ethereum.core.Block;
+import org.hyperledger.besu.ethereum.core.BlockHeader;
 import org.hyperledger.besu.ethereum.core.Hash;
 import org.hyperledger.besu.ethereum.eth.sync.SynchronizerConfiguration;
 import org.hyperledger.besu.ethereum.eth.sync.state.cache.ImmutablePendingBlock;
 import org.hyperledger.besu.ethereum.eth.sync.state.cache.PendingBlockCache;
 
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
@@ -116,4 +119,11 @@ public class PendingBlocksManager {
         .map(ImmutablePendingBlock::block)
         .collect(Collectors.toList());
   }
+
+  public Optional<BlockHeader> lowestAnnouncedBlock() {
+    return pendingBlocks.values().stream()
+        .map(ImmutablePendingBlock::block)
+        .map(Block::getHeader)
+        .min(Comparator.comparing(BlockHeader::getNumber));
+  }
 }

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/tasks/DownloadHeaderSequenceTask.java

@@ -212,7 +212,7 @@ public class DownloadHeaderSequenceTask extends AbstractRetryingPeerTask<List<Bl
                   GetBlockFromPeerTask.create(
                           protocolSchedule,
                           ethContext,
-                          child.getHash(),
+                          Optional.of(child.getHash()),
                           child.getNumber(),
                           metricsSystem)
                       .assignPeer(headersResult.getPeer());

ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/manager/task/GetBlockFromPeerTaskTest.java

@@ -26,6 +26,7 @@ import org.hyperledger.besu.ethereum.eth.manager.ethtaskutils.AbstractMessageTas
 import org.hyperledger.besu.ethereum.eth.manager.exceptions.EthTaskException;
 import org.hyperledger.besu.util.ExceptionUtils;
 
+import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicReference;
@@ -47,7 +48,11 @@ public class GetBlockFromPeerTaskTest
   @Override
   protected EthTask<AbstractPeerTask.PeerTaskResult<Block>> createTask(final Block requestedData) {
     return GetBlockFromPeerTask.create(
-        protocolSchedule, ethContext, requestedData.getHash(), BLOCK_NUMBER, metricsSystem);
+        protocolSchedule,
+        ethContext,
+        Optional.of(requestedData.getHash()),
+        BLOCK_NUMBER,
+        metricsSystem);
   }
 
   @Override

ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/sync/state/PendingBlocksManagerTest.java

@@ -245,4 +245,18 @@ public class PendingBlocksManagerTest {
     }
     assertThat(pendingBlocksManager.contains(reorgBlock.getHash())).isTrue();
   }
+
+  @Test
+  public void shouldReturnLowestBlockByNumber() {
+    final BlockDataGenerator gen = new BlockDataGenerator();
+    final Block parentBlock = gen.block();
+    final Block childBlock = gen.nextBlock(parentBlock);
+    final Block childBlock2 = gen.nextBlock(parentBlock);
+
+    pendingBlocksManager.registerPendingBlock(parentBlock, NODE_ID_1);
+    pendingBlocksManager.registerPendingBlock(childBlock, NODE_ID_1);
+    pendingBlocksManager.registerPendingBlock(childBlock2, NODE_ID_1);
+
+    assertThat(pendingBlocksManager.lowestAnnouncedBlock()).contains(parentBlock.getHeader());
+  }
 }