Enable the pipeline chain downloader by default (#1344)

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

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

@@ -374,10 +374,10 @@ public class SynchronizerConfiguration {
     @CommandLine.Option(
         names = "--Xsynchronizer-pipeline-full-sync-enabled",
         hidden = true,
-        defaultValue = "false",
+        defaultValue = "true",
         paramLabel = "<BOOLEAN>",
         description = "Enable the pipeline based chain downloader during full synchronization")
-    private Boolean piplineDownloaderForFullSyncEnabled = false;
+    private Boolean piplineDownloaderForFullSyncEnabled = true;
 
     public Builder fastSyncPivotDistance(final int distance) {
       fastSyncPivotDistance = distance;

ethereum/eth/src/main/java/tech/pegasys/pantheon/ethereum/eth/sync/fullsync/FullSyncChainDownloader.java

@@ -54,6 +54,7 @@ public class FullSyncChainDownloader {
           metricsSystem);
     }
 
+    LOG.info("Using EthTaskChainDownloader");
     return new EthTaskChainDownloader<>(
         config,
         ethContext,

ethereum/eth/src/test/java/tech/pegasys/pantheon/ethereum/eth/sync/fullsync/IncrementerTest.java

@@ -94,7 +94,10 @@ public class IncrementerTest {
         RespondingEthPeer.blockchainResponder(otherBlockchain);
 
     final SynchronizerConfiguration syncConfig =
-        SynchronizerConfiguration.builder().downloaderChainSegmentSize(10).build();
+        SynchronizerConfiguration.builder()
+            .piplineDownloaderForFullSyncEnabled(false)
+            .downloaderChainSegmentSize(10)
+            .build();
     final ChainDownloader downloader = downloader(syncConfig);
     downloader.start();