Block summaries (repository/data/message/synchronizer) + BlockGenerator

Also refactored some tests.

Original commit was 06fe8fc, with commit message:
Initial implementation of random block generator, etc.

src/main/java/org/qora/block/BlockGenerator.java

@@ -66,6 +66,15 @@ public class BlockGenerator extends Thread {
 			List<Block> newBlocks = new ArrayList<>();
 
 			while (running) {
+				// Sleep for a while
+				try {
+					repository.discardChanges(); // Free repository locks, if any
+					Thread.sleep(1000); // No point sleeping less than this as block timestamp millisecond values must be the same
+				} catch (InterruptedException e) {
+					// We've been interrupted - time to exit
+					return;
+				}
+
 				// Check blockchain hasn't changed
 				BlockData lastBlockData = blockRepository.getLastBlock();
 				if (previousBlock == null || !Arrays.equals(previousBlock.getSignature(), lastBlockData.getSignature())) {
@@ -155,15 +164,6 @@ public class BlockGenerator extends Thread {
 					} finally {
 						blockchainLock.unlock();
 					}
-
-				// Sleep for a while
-				try {
-					repository.discardChanges(); // Free repository locks, if any
-					Thread.sleep(1000); // No point sleeping less than this as block timestamp millisecond values must be the same
-				} catch (InterruptedException e) {
-					// We've been interrupted - time to exit
-					return;
-				}
 			}
 		} catch (DataException e) {
 			LOGGER.warn("Repository issue while running block generator", e);

src/main/java/org/qora/controller/Synchronizer.java

@@ -11,9 +11,12 @@ import org.qora.block.Block;
 import org.qora.block.Block.ValidationResult;
 import org.qora.block.GenesisBlock;
 import org.qora.data.block.BlockData;
+import org.qora.data.network.BlockSummaryData;
 import org.qora.network.Peer;
 import org.qora.network.message.BlockMessage;
+import org.qora.network.message.BlockSummariesMessage;
 import org.qora.network.message.GetBlockMessage;
+import org.qora.network.message.GetBlockSummariesMessage;
 import org.qora.network.message.GetSignaturesMessage;
 import org.qora.network.message.Message;
 import org.qora.network.message.Message.MessageType;
@@ -264,6 +267,18 @@ public class Synchronizer {
 		return blockSignatures;
 	}
 
+	private List<BlockSummaryData> getBlockSummaries(Peer peer, byte[] parentSignature, int numberRequested) {
+		Message getBlockSummariesMessage = new GetBlockSummariesMessage(parentSignature, numberRequested);
+
+		Message message = peer.getResponse(getBlockSummariesMessage);
+		if (message == null || message.getType() != MessageType.BLOCK_SUMMARIES)
+			return null;
+
+		BlockSummariesMessage blockSummariesMessage = (BlockSummariesMessage) message;
+
+		return blockSummariesMessage.getBlockSummaries();
+	}
+
 	private List<byte[]> getBlockSignatures(Peer peer, byte[] parentSignature, int numberRequested) {
 		// TODO numberRequested is v2+ feature
 		Message getSignaturesMessage = new GetSignaturesMessage(parentSignature);

src/main/java/org/qora/data/network/BlockSummaryData.java

@@ -0,0 +1,37 @@
+package org.qora.data.network;
+
+import org.qora.data.block.BlockData;
+
+public class BlockSummaryData {
+
+	// Properties
+	private int height;
+	private byte[] signature;
+	private byte[] generatorPublicKey;
+
+	// Constructors
+	public BlockSummaryData(int height, byte[] signature, byte[] generatorPublicKey) {
+		this.height = height;
+		this.signature = signature;
+		this.generatorPublicKey = generatorPublicKey;
+	}
+
+	public BlockSummaryData(BlockData blockData) {
+		this(blockData.getHeight(), blockData.getSignature(), blockData.getGeneratorPublicKey());
+	}
+
+	// Getters / setters
+
+	public int getHeight() {
+		return this.height;
+	}
+
+	public byte[] getSignature() {
+		return this.signature;
+	}
+
+	public byte[] getGeneratorPublicKey() {
+		return this.generatorPublicKey;
+	}
+
+}

src/main/java/org/qora/network/message/BlockSummariesMessage.java

@@ -0,0 +1,81 @@
+package org.qora.network.message;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.qora.data.block.BlockData;
+import org.qora.data.network.BlockSummaryData;
+import org.qora.transform.Transformer;
+import org.qora.transform.block.BlockTransformer;
+
+import com.google.common.primitives.Ints;
+
+public class BlockSummariesMessage extends Message {
+
+	private static final int BLOCK_SUMMARY_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH + Transformer.INT_LENGTH + Transformer.PUBLIC_KEY_LENGTH;
+
+	private List<BlockSummaryData> blockSummaries;
+
+	public BlockSummariesMessage(List<BlockData> blocksData) {
+		// Extract what we need from block data
+		this(-1, blocksData.stream().map(blockData -> new BlockSummaryData(blockData)).collect(Collectors.toList()));
+	}
+
+	private BlockSummariesMessage(int id, List<BlockSummaryData> blockSummaries) {
+		super(id, MessageType.BLOCK_SUMMARIES);
+
+		this.blockSummaries = blockSummaries;
+	}
+
+	public List<BlockSummaryData> getBlockSummaries() {
+		return this.blockSummaries;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+		int count = bytes.getInt();
+
+		if (bytes.remaining() != count * BLOCK_SUMMARY_LENGTH)
+			return null;
+
+		List<BlockSummaryData> blockSummaries = new ArrayList<>();
+		for (int i = 0; i < count; ++i) {
+			int height = bytes.getInt();
+
+			byte[] signature = new byte[BlockTransformer.BLOCK_SIGNATURE_LENGTH];
+			bytes.get(signature);
+
+			byte[] generatorPublicKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+			bytes.get(generatorPublicKey);
+
+			BlockSummaryData blockSummary = new BlockSummaryData(height, signature, generatorPublicKey);
+			blockSummaries.add(blockSummary);
+		}
+
+		return new BlockSummariesMessage(id, blockSummaries);
+	}
+
+	@Override
+	protected byte[] toData() {
+		try {
+			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+			bytes.write(Ints.toByteArray(this.blockSummaries.size()));
+
+			for (BlockSummaryData blockSummary : this.blockSummaries) {
+				bytes.write(blockSummary.getHeight());
+				bytes.write(blockSummary.getSignature());
+				bytes.write(blockSummary.getGeneratorPublicKey());
+			}
+
+			return bytes.toByteArray();
+		} catch (IOException e) {
+			return null;
+		}
+	}
+
+}

src/main/java/org/qora/network/message/GetBlockSummariesMessage.java

@@ -0,0 +1,64 @@
+package org.qora.network.message;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+
+import org.qora.transform.Transformer;
+import org.qora.transform.block.BlockTransformer;
+
+public class GetBlockSummariesMessage extends Message {
+
+	private static final int BLOCK_SIGNATURE_LENGTH = BlockTransformer.BLOCK_SIGNATURE_LENGTH;
+
+	private byte[] parentSignature;
+	private int numberRequested;
+
+	public GetBlockSummariesMessage(byte[] parentSignature, int numberRequested) {
+		this(-1, parentSignature, numberRequested);
+	}
+
+	private GetBlockSummariesMessage(int id, byte[] parentSignature, int numberRequested) {
+		super(id, MessageType.GET_BLOCK_SUMMARIES);
+
+		this.parentSignature = parentSignature;
+		this.numberRequested = numberRequested;
+	}
+
+	public byte[] getParentSignature() {
+		return this.parentSignature;
+	}
+
+	public int getNumberRequested() {
+		return this.numberRequested;
+	}
+
+	public static Message fromByteBuffer(int id, ByteBuffer bytes) throws UnsupportedEncodingException {
+		if (bytes.remaining() != BLOCK_SIGNATURE_LENGTH + Transformer.INT_LENGTH)
+			return null;
+
+		byte[] parentSignature = new byte[BLOCK_SIGNATURE_LENGTH];
+		bytes.get(parentSignature);
+
+		int numberRequested = bytes.getInt();
+
+		return new GetBlockSummariesMessage(id, parentSignature, numberRequested);
+	}
+
+	@Override
+	protected byte[] toData() {
+		try {
+			ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+
+			bytes.write(this.parentSignature);
+
+			bytes.write(this.numberRequested);
+
+			return bytes.toByteArray();
+		} catch (IOException e) {
+			return null;
+		}
+	}
+
+}

src/main/java/org/qora/network/message/Message.java

@@ -40,7 +40,9 @@ public abstract class Message {
 		VERSION(10),
 		PEER_ID(11),
 		PROOF(12),
-		PEERS_V2(13);
+		PEERS_V2(13),
+		GET_BLOCK_SUMMARIES(14),
+		BLOCK_SUMMARIES(15);
 
 		public final int value;
 		public final Method fromByteBuffer;

src/main/java/org/qora/repository/BlockRepository.java

@@ -112,6 +112,11 @@ public interface BlockRepository {
 	 */
 	public List<BlockData> getBlocksWithGenerator(byte[] generatorPublicKey, Integer limit, Integer offset, Boolean reverse) throws DataException;
 
+	/**
+	 * Returns blocks within height range.
+	 */
+	public List<BlockData> getBlocks(int firstBlockHeight, int lastBlockHeight) throws DataException;
+
 	/**
 	 * Saves block into repository.
 	 * 

src/main/java/org/qora/repository/hsqldb/HSQLDBBlockRepository.java

@@ -215,6 +215,26 @@ public class HSQLDBBlockRepository implements BlockRepository {
 		}
 	}
 
+	@Override
+	public List<BlockData> getBlocks(int firstBlockHeight, int lastBlockHeight) throws DataException {
+		String sql = "SELECT " + BLOCK_DB_COLUMNS + " FROM Blocks WHERE height BETWEEN ? AND ?";
+
+		List<BlockData> blockData = new ArrayList<>();
+
+		try (ResultSet resultSet = this.repository.checkedExecute(sql, firstBlockHeight, lastBlockHeight)) {
+			if (resultSet == null)
+				return blockData;
+
+			do {
+				blockData.add(getBlockFromResultSet(resultSet));
+			} while (resultSet.next());
+
+			return blockData;
+		} catch (SQLException e) {
+			throw new DataException("Unable to fetch height-ranged blocks from repository", e);
+		}
+	}
+
 	@Override
 	public void save(BlockData blockData) throws DataException {
 		HSQLDBSaver saveHelper = new HSQLDBSaver("Blocks");