NC-1815 Rinkeby import can stall with too many fragments (#255)

Add tests that hit the retry failure case

Move "complete what we just got" semantic into the
DownloadHeaderSequenceTask.  Previously it was completing everything
in the chunk it was assigned.

ethereum/eth/src/main/java/tech/pegasys/pantheon/ethereum/eth/sync/tasks/DownloadHeaderSequenceTask.java

@@ -114,7 +114,7 @@ public class DownloadHeaderSequenceTask<C> extends AbstractRetryingPeerTask<List
     return task.whenComplete(
         (r, t) -> {
           // We're done if we've filled all requested headers
-          if (r != null && r.size() == segmentLength) {
+          if (lastFilledHeaderIndex == 0) {
             LOG.debug(
                 "Finished downloading headers from {} to {}.",
                 startingBlockNumber,
@@ -162,6 +162,7 @@ public class DownloadHeaderSequenceTask<C> extends AbstractRetryingPeerTask<List
           final CompletableFuture<List<BlockHeader>> future = new CompletableFuture<>();
           BlockHeader child = null;
           boolean firstSkipped = false;
+          final int previousHeaderIndex = lastFilledHeaderIndex;
           for (final BlockHeader header : headersResult.getResult()) {
             final int headerIndex =
                 Ints.checkedCast(
@@ -191,7 +192,7 @@ public class DownloadHeaderSequenceTask<C> extends AbstractRetryingPeerTask<List
             lastFilledHeaderIndex = headerIndex;
             child = header;
           }
-          future.complete(asList(headers).subList(lastFilledHeaderIndex, segmentLength));
+          future.complete(asList(headers).subList(lastFilledHeaderIndex, previousHeaderIndex));
           return future;
         });
   }

ethereum/eth/src/test/java/tech/pegasys/pantheon/ethereum/eth/sync/tasks/DownloadHeaderSequenceTaskTest.java

@@ -12,12 +12,29 @@
  */
 package tech.pegasys.pantheon.ethereum.eth.sync.tasks;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
 import tech.pegasys.pantheon.ethereum.core.BlockHeader;
+import tech.pegasys.pantheon.ethereum.eth.manager.EthProtocolManagerTestUtil;
 import tech.pegasys.pantheon.ethereum.eth.manager.EthTask;
+import tech.pegasys.pantheon.ethereum.eth.manager.RespondingEthPeer;
+import tech.pegasys.pantheon.ethereum.eth.manager.RespondingEthPeer.Responder;
 import tech.pegasys.pantheon.ethereum.eth.manager.ethtaskutils.RetryingMessageTaskTest;
+import tech.pegasys.pantheon.ethereum.eth.manager.exceptions.MaxRetriesReachedException;
+import tech.pegasys.pantheon.ethereum.eth.messages.BlockHeadersMessage;
+import tech.pegasys.pantheon.ethereum.eth.messages.EthPV62;
+import tech.pegasys.pantheon.ethereum.p2p.api.MessageData;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
+
+import com.google.common.collect.Streams;
+import org.junit.Test;
 
 public class DownloadHeaderSequenceTaskTest extends RetryingMessageTaskTest<List<BlockHeader>> {
 
@@ -44,4 +61,62 @@ public class DownloadHeaderSequenceTaskTest extends RetryingMessageTaskTest<List
         requestedData.size(),
         maxRetries);
   }
+
+  @Test
+  public void failsWhenPeerReturnsOnlyReferenceHeader() {
+    final RespondingEthPeer respondingPeer =
+        EthProtocolManagerTestUtil.createPeer(ethProtocolManager);
+
+    // Execute task and wait for response
+    BlockHeader referenceHeader = blockchain.getChainHeadHeader();
+    final EthTask<List<BlockHeader>> task =
+        DownloadHeaderSequenceTask.endingAtHeader(
+            protocolSchedule, protocolContext, ethContext, referenceHeader, 10, maxRetries);
+    final CompletableFuture<List<BlockHeader>> future = task.run();
+
+    // Respond with only the reference header
+    final Responder responder =
+        (cap, message) ->
+            Optional.of(BlockHeadersMessage.create(Collections.singletonList(referenceHeader)));
+    respondingPeer.respondWhile(responder, () -> !future.isDone());
+
+    assertThat(future.isDone()).isTrue();
+    assertThat(future.isCompletedExceptionally()).isTrue();
+    assertThatThrownBy(future::get).hasCauseInstanceOf(MaxRetriesReachedException.class);
+  }
+
+  @Test
+  public void failsWhenPeerReturnsOnlySubsetOfHeaders() {
+    final RespondingEthPeer respondingPeer =
+        EthProtocolManagerTestUtil.createPeer(ethProtocolManager);
+
+    // Execute task and wait for response
+    BlockHeader referenceHeader = blockchain.getChainHeadHeader();
+    final EthTask<List<BlockHeader>> task =
+        DownloadHeaderSequenceTask.endingAtHeader(
+            protocolSchedule, protocolContext, ethContext, referenceHeader, 10, maxRetries);
+    final CompletableFuture<List<BlockHeader>> future = task.run();
+
+    // Filter response to include only reference header and previous header
+    final Responder fullResponder = RespondingEthPeer.blockchainResponder(blockchain);
+    final Responder responder =
+        (cap, message) -> {
+          Optional<MessageData> fullResponse = fullResponder.respond(cap, message);
+          if (!fullResponse.isPresent() || message.getCode() != EthPV62.GET_BLOCK_HEADERS) {
+            return fullResponse;
+          }
+          BlockHeadersMessage headersMessage = BlockHeadersMessage.readFrom(fullResponse.get());
+          // Filter for a subset of headers
+          List<BlockHeader> headerSubset =
+              Streams.stream(headersMessage.getHeaders(protocolSchedule))
+                  .filter(h -> h.getNumber() >= referenceHeader.getNumber() - 1L)
+                  .collect(Collectors.toList());
+          return Optional.of(BlockHeadersMessage.create(headerSubset));
+        };
+    respondingPeer.respondTimes(responder, 100);
+
+    assertThat(future.isDone()).isTrue();
+    assertThat(future.isCompletedExceptionally()).isTrue();
+    assertThatThrownBy(future::get).hasCauseInstanceOf(MaxRetriesReachedException.class);
+  }
 }

ethereum/eth/src/test/resources/log4j2.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration status="INFO">
+  <Properties>
+    <Property name="root.log.level">INFO</Property>
+  </Properties>
+
+  <Appenders>
+    <Console name="Console" target="SYSTEM_OUT">
+      <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSSZZZ} | %t | %-5level | %c{1} | %msg%n" />    </Console>
+  </Appenders>
+  <Loggers>
+    <Root level="${sys:root.log.level}">
+      <AppenderRef ref="Console" />
+    </Root>
+  </Loggers>
+</Configuration>