Improve logging of chain download errors in the pipeline chain downloader. (#1325)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

ethereum/eth/src/main/java/tech/pegasys/pantheon/ethereum/eth/sync/PipelineChainDownloader.java

@@ -17,8 +17,10 @@ import static tech.pegasys.pantheon.util.FutureUtils.completedExceptionally;
 import static tech.pegasys.pantheon.util.FutureUtils.exceptionallyCompose;
 
 import tech.pegasys.pantheon.ethereum.eth.manager.EthScheduler;
+import tech.pegasys.pantheon.ethereum.eth.manager.exceptions.EthTaskException;
 import tech.pegasys.pantheon.ethereum.eth.sync.state.SyncState;
 import tech.pegasys.pantheon.ethereum.eth.sync.state.SyncTarget;
+import tech.pegasys.pantheon.ethereum.eth.sync.tasks.exceptions.InvalidBlockException;
 import tech.pegasys.pantheon.metrics.Counter;
 import tech.pegasys.pantheon.metrics.LabelledMetric;
 import tech.pegasys.pantheon.metrics.MetricCategory;
@@ -112,19 +114,30 @@ public class PipelineChainDownloader<C> implements ChainDownloader {
 
   private CompletionStage<Void> handleFailedDownload(final Throwable error) {
     pipelineErrorCounter.inc();
-    final Throwable rootCause = ExceptionUtils.rootCause(error);
     if (!cancelled.get()
         && syncTargetManager.shouldContinueDownloading()
-        && !(rootCause instanceof CancellationException)) {
-      LOG.debug("Chain download failed. Restarting after short delay.", error);
+        && !(ExceptionUtils.rootCause(error) instanceof CancellationException)) {
+      logDownloadFailure("Chain download failed. Restarting after short delay.", error);
       // Allowing the normal looping logic to retry after a brief delay.
       return scheduler.scheduleFutureTask(() -> completedFuture(null), PAUSE_AFTER_ERROR_DURATION);
     }
-    LOG.debug("Chain download failed.", error);
+    logDownloadFailure("Chain download failed.", error);
     // Propagate the error out, terminating this chain download.
     return completedExceptionally(error);
   }
 
+  private void logDownloadFailure(final String message, final Throwable error) {
+    final Throwable rootCause = ExceptionUtils.rootCause(error);
+    if (rootCause instanceof CancellationException || rootCause instanceof InterruptedException) {
+      LOG.trace(message, error);
+    } else if (rootCause instanceof EthTaskException
+        || rootCause instanceof InvalidBlockException) {
+      LOG.debug(message, error);
+    } else {
+      LOG.error(message, error);
+    }
+  }
+
   private synchronized CompletionStage<Void> startDownloadForSyncTarget(final SyncTarget target) {
     if (cancelled.get()) {
       return completedExceptionally(new CancellationException("Chain download was cancelled"));