Bump version to 1.5.2

This specifies the maximum number of trades to be used when calculating the price. Default: 10

pom.xml

@@ -3,12 +3,12 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>1.5.1</version>
+	<version>1.5.2</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>
 		<altcoinj.version>bf9fb80</altcoinj.version>
-		<bitcoinj.version>0.15.6</bitcoinj.version>
+		<bitcoinj.version>0.15.10</bitcoinj.version>
 		<bouncycastle.version>1.64</bouncycastle.version>
 		<build.timestamp>${maven.build.timestamp}</build.timestamp>
 		<ciyam-at.version>1.3.8</ciyam-at.version>
@@ -439,6 +439,11 @@
 			<artifactId>json-simple</artifactId>
 			<version>1.1.1</version>
 		</dependency>
+		<dependency>
+			<groupId>org.json</groupId>
+			<artifactId>json</artifactId>
+			<version>20210307</version>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.commons</groupId>
 			<artifactId>commons-text</artifactId>

src/main/java/org/qortal/api/model/BlockMintingInfo.java

@@ -0,0 +1,23 @@
+package org.qortal.api.model;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class BlockMintingInfo {
+
+	public byte[] minterPublicKey;
+	public int minterLevel;
+	public int onlineAccountsCount;
+	public BigDecimal maxDistance;
+	public BigInteger keyDistance;
+	public double keyDistanceRatio;
+	public long timestamp;
+	public long timeDelta;
+
+	public BlockMintingInfo() {
+	}
+
+}

src/main/java/org/qortal/api/resource/AdminResource.java

@@ -542,19 +542,8 @@ public class AdminResource {
 		Security.checkApiCallAllowed(request);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+			repository.exportNodeLocalData();
-
+			return "true";
-			blockchainLock.lockInterruptibly();
-
-			try {
-				repository.exportNodeLocalData(true);
-				return "true";
-			} finally {
-				blockchainLock.unlock();
-			}
-		} catch (InterruptedException e) {
-			// We couldn't lock blockchain to perform export
-			return "false";
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -564,7 +553,7 @@ public class AdminResource {
 	@Path("/repository/data")
 	@Operation(
 		summary = "Import data into repository.",
-		description = "Imports data from file on local machine. Filename is forced to 'import.script' if apiKey is not set.",
+		description = "Imports data from file on local machine. Filename is forced to 'import.json' if apiKey is not set.",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(
@@ -588,7 +577,7 @@ public class AdminResource {
 
 		// Hard-coded because it's too dangerous to allow user-supplied filenames in weaker security contexts
 		if (Settings.getInstance().getApiKey() == null)
-			filename = "import.script";
+			filename = "import.json";
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();

src/main/java/org/qortal/api/resource/BlocksResource.java

@@ -8,6 +8,9 @@ import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.math.RoundingMode;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -20,10 +23,13 @@ import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
+import org.qortal.account.Account;
 import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrors;
 import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.model.BlockMintingInfo;
 import org.qortal.api.model.BlockSignerSummary;
+import org.qortal.block.Block;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
@@ -328,6 +334,59 @@ public class BlocksResource {
 		}
 	}
 
+	@GET
+	@Path("/byheight/{height}/mintinginfo")
+	@Operation(
+			summary = "Fetch block minter info using block height",
+			description = "Returns the minter info for the block with given height",
+			responses = {
+					@ApiResponse(
+							description = "the block",
+							content = @Content(
+									schema = @Schema(
+											implementation = BlockData.class
+									)
+							)
+					)
+			}
+	)
+	@ApiErrors({
+			ApiError.BLOCK_UNKNOWN, ApiError.REPOSITORY_ISSUE
+	})
+	public BlockMintingInfo getBlockMintingInfoByHeight(@PathParam("height") int height) {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			BlockData blockData = repository.getBlockRepository().fromHeight(height);
+			if (blockData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+
+			Block block = new Block(repository, blockData);
+			BlockData parentBlockData = repository.getBlockRepository().fromSignature(blockData.getReference());
+			int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, blockData.getMinterPublicKey());
+			if (minterLevel == 0)
+				// This may be unavailable when requesting a trimmed block
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+			BigInteger distance = block.calcKeyDistance(parentBlockData.getHeight(), parentBlockData.getSignature(), blockData.getMinterPublicKey(), minterLevel);
+			double ratio = new BigDecimal(distance).divide(new BigDecimal(block.MAX_DISTANCE), 40, RoundingMode.DOWN).doubleValue();
+			long timestamp = block.calcTimestamp(parentBlockData, blockData.getMinterPublicKey(), minterLevel);
+			long timeDelta = timestamp - parentBlockData.getTimestamp();
+
+			BlockMintingInfo blockMintingInfo = new BlockMintingInfo();
+			blockMintingInfo.minterPublicKey = blockData.getMinterPublicKey();
+			blockMintingInfo.minterLevel = minterLevel;
+			blockMintingInfo.onlineAccountsCount = blockData.getOnlineAccountsCount();
+			blockMintingInfo.maxDistance = new BigDecimal(block.MAX_DISTANCE);
+			blockMintingInfo.keyDistance = distance;
+			blockMintingInfo.keyDistanceRatio = ratio;
+			blockMintingInfo.timestamp = timestamp;
+			blockMintingInfo.timeDelta = timeDelta;
+
+			return blockMintingInfo;
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 	@GET
 	@Path("/timestamp/{timestamp}")
 	@Operation(

src/main/java/org/qortal/api/resource/CrossChainResource.java

@@ -255,13 +255,19 @@ public class CrossChainResource {
 					description = "foreign blockchain",
 					example = "LITECOIN",
 					schema = @Schema(implementation = SupportedBlockchain.class)
-				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain) {
+				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain,
+			@Parameter(
+					description = "Maximum number of trades to include in price calculation",
+					example = "10",
+					schema = @Schema(type = "integer", defaultValue = "10")
+			) @QueryParam("maxtrades") Integer maxtrades) {
 		// foreignBlockchain is required
 		if (foreignBlockchain == null)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 		// We want both a minimum of 5 trades and enough trades to span at least 4 hours
 		int minimumCount = 5;
+		int maximumCount = maxtrades != null ? maxtrades : 10;
 		long minimumPeriod = 4 * 60 * 60 * 1000L; // ms
 		Boolean isFinished = Boolean.TRUE;
 
@@ -276,7 +282,7 @@ public class CrossChainResource {
 				ACCT acct = acctInfo.getValue().get();
 
 				List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStatesQuorum(codeHash,
-						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, minimumPeriod);
+						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, maximumCount, minimumPeriod);
 
 				for (ATStateData atState : atStates) {
 					CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);

src/main/java/org/qortal/api/resource/PeersResource.java

@@ -321,7 +321,7 @@ public class PeersResource {
 				boolean force = true;
 				List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
 
-				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries);
+				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries, true);
 				if (findCommonBlockResult != SynchronizationResult.OK)
 					return null;
 

src/main/java/org/qortal/block/Block.java

@@ -232,7 +232,7 @@ public class Block {
 
 	// Other useful constants
 
-	private static final BigInteger MAX_DISTANCE;
+	public static final BigInteger MAX_DISTANCE;
 	static {
 		byte[] maxValue = new byte[Transformer.PUBLIC_KEY_LENGTH];
 		Arrays.fill(maxValue, (byte) 0xFF);
@@ -831,7 +831,7 @@ public class Block {
 			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp() && parentHeight >= maxHeight)
 				break;
 		}
-		LOGGER.debug(String.format("Chain weight calculation was based on %d blocks", blockCount));
+		LOGGER.trace(String.format("Chain weight calculation was based on %d blocks", blockCount));
 
 		return cumulativeWeight;
 	}
@@ -1998,6 +1998,10 @@ public class Block {
 
 	private void logDebugInfo() {
 		try {
+			// Avoid calculations if possible. We have to check against INFO here, since Level.isMoreSpecificThan() confusingly uses <= rather than just <
+			if (LOGGER.getLevel().isMoreSpecificThan(Level.INFO))
+				return;
+
 			if (this.repository == null || this.getMinter() == null || this.getBlockData() == null)
 				return;
 
@@ -2007,9 +2011,10 @@ public class Block {
 			LOGGER.debug(String.format("Timestamp: %d", this.getBlockData().getTimestamp()));
 			LOGGER.debug(String.format("Minter level: %d", minterLevel));
 			LOGGER.debug(String.format("Online accounts: %d", this.getBlockData().getOnlineAccountsCount()));
+			LOGGER.debug(String.format("AT count: %d", this.getBlockData().getATCount()));
 
 			BlockSummaryData blockSummaryData = new BlockSummaryData(this.getBlockData());
-			if (this.getParent() == null || this.getParent().getSignature() == null || blockSummaryData == null)
+			if (this.getParent() == null || this.getParent().getSignature() == null || blockSummaryData == null || minterLevel == 0)
 				return;
 
 			blockSummaryData.setMinterLevel(minterLevel);

src/main/java/org/qortal/controller/Controller.java

@@ -623,6 +623,11 @@ public class Controller extends Thread {
 		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(new ByteArray(peerChainTipData.getLastBlockSignature()));
 	};
 
+	public static final Predicate<Peer> hasOldVersion = peer -> {
+		final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
+		return peer.isAtLeastVersion(minPeerVersion) == false;
+	};
+
 	private void potentiallySynchronize() throws InterruptedException {
 		// Already synchronizing via another thread?
 		if (this.isSynchronizing)
@@ -639,11 +644,15 @@ public class Controller extends Thread {
 		// Disregard peers that don't have a recent block
 		peers.removeIf(hasNoRecentBlock);
 
+		// Disregard peers that are on an old version
+		peers.removeIf(hasOldVersion);
+
 		checkRecoveryModeForPeers(peers);
 		if (recoveryMode) {
 			peers = Network.getInstance().getHandshakedPeers();
 			peers.removeIf(hasOnlyGenesisBlock);
 			peers.removeIf(hasMisbehaved);
+			peers.removeIf(hasOldVersion);
 		}
 
 		// Check we have enough peers to potentially synchronize
@@ -668,7 +677,7 @@ public class Controller extends Thread {
 		peers.removeIf(hasInferiorChainTip);
 
 		final int peersRemoved = peersBeforeComparison - peers.size();
-		if (peersRemoved > 0)
+		if (peersRemoved > 0 && peers.size() > 0)
 			LOGGER.info(String.format("Ignoring %d peers on inferior chains. Peers remaining: %d", peersRemoved, peers.size()));
 
 		if (peers.isEmpty())

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

@@ -35,6 +35,7 @@ import org.qortal.network.message.Message.MessageType;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
 import org.qortal.transaction.Transaction;
 import org.qortal.utils.Base58;
 import org.qortal.utils.NTP;
@@ -57,9 +58,6 @@ public class Synchronizer {
 	/** Maximum number of block signatures we ask from peer in one go */
 	private static final int MAXIMUM_REQUEST_SIZE = 200; // XXX move to Settings?
 
-	/** Number of retry attempts if a peer fails to respond with the requested data */
-	private static final int MAXIMUM_RETRIES = 2; // XXX move to Settings?
-
 
 	private static Synchronizer instance;
 
@@ -113,6 +111,7 @@ public class Synchronizer {
 				LOGGER.debug(String.format("Searching for common blocks with %d peers...", peers.size()));
 				final long startTime = System.currentTimeMillis();
 				int commonBlocksFound = 0;
+				boolean wereNewRequestsMade = false;
 
 				for (Peer peer : peers) {
 					// Are we shutting down?
@@ -133,10 +132,15 @@ public class Synchronizer {
 					Synchronizer.getInstance().findCommonBlockWithPeer(peer, repository);
 					if (peer.getCommonBlockData() != null)
 						commonBlocksFound++;
+
+					// This round wasn't served entirely from the cache, so we may want to log the results
+					wereNewRequestsMade = true;
 				}
 
-				final long totalTimeTaken = System.currentTimeMillis() - startTime;
+				if (wereNewRequestsMade) {
-				LOGGER.info(String.format("Finished searching for common blocks with %d peer%s. Found: %d. Total time taken: %d ms", peers.size(), (peers.size() != 1 ? "s" : ""), commonBlocksFound, totalTimeTaken));
+					final long totalTimeTaken = System.currentTimeMillis() - startTime;
+					LOGGER.info(String.format("Finished searching for common blocks with %d peer%s. Found: %d. Total time taken: %d ms", peers.size(), (peers.size() != 1 ? "s" : ""), commonBlocksFound, totalTimeTaken));
+				}
 
 				return SynchronizationResult.OK;
 			} finally {
@@ -174,7 +178,7 @@ public class Synchronizer {
 					ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
 
 			List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
-			SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, false, peerBlockSummaries);
+			SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, false, peerBlockSummaries, false);
 			if (findCommonBlockResult != SynchronizationResult.OK) {
 				// Logging performed by fetchSummariesFromCommonBlock() above
 				peer.setCommonBlockData(null);
@@ -284,7 +288,9 @@ public class Synchronizer {
 							return peers;
 
 						// Count the number of blocks this peer has beyond our common block
-						final int peerHeight = peer.getChainTipData().getLastHeight();
+						final PeerChainTipData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getLastHeight();
+						final byte[] peerLastBlockSignature = peerChainTipData.getLastBlockSignature();
 						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
 						// Limit the number of blocks we are comparing. FUTURE: we could request more in batches, but there may not be a case when this is needed
 						int summariesRequired = Math.min(peerAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
@@ -294,7 +300,7 @@ public class Synchronizer {
 						if (peer.canUseCachedCommonBlockData()) {
 							if (peer.getCommonBlockData().getBlockSummariesAfterCommonBlock() != null) {
 								if (peer.getCommonBlockData().getBlockSummariesAfterCommonBlock().size() == summariesRequired) {
-									LOGGER.debug(String.format("Using cached block summaries for peer %s", peer));
+									LOGGER.trace(String.format("Using cached block summaries for peer %s", peer));
 									useCachedSummaries = true;
 								}
 							}
@@ -304,15 +310,23 @@ public class Synchronizer {
 							if (summariesRequired > 0) {
 								LOGGER.trace(String.format("Requesting %d block summar%s from peer %s after common block %.8s. Peer height: %d", summariesRequired, (summariesRequired != 1 ? "ies" : "y"), peer, Base58.encode(commonBlockSummary.getSignature()), peerHeight));
 
-								List<BlockSummaryData> blockSummaries = this.getBlockSummaries(peer, commonBlockSummary.getSignature(), summariesRequired);
+								// Forget any cached summaries
-								peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(blockSummaries);
+								peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(null);
 
+								// Request new block summaries
+								List<BlockSummaryData> blockSummaries = this.getBlockSummaries(peer, commonBlockSummary.getSignature(), summariesRequired);
 								if (blockSummaries != null) {
 									LOGGER.trace(String.format("Peer %s returned %d block summar%s", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y")));
 
 									if (blockSummaries.size() < summariesRequired)
-										// This could mean that the peer has re-orged. But we still have the same common block, so it's safe to proceed with this set of signatures instead.
+										// This could mean that the peer has re-orged. Exclude this peer until they return the summaries we expect.
-										LOGGER.debug(String.format("Peer %s returned %d block summar%s instead of expected %d", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"), summariesRequired));
+										LOGGER.debug(String.format("Peer %s returned %d block summar%s instead of expected %d - excluding them from this round", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"), summariesRequired));
+									else if (blockSummaryWithSignature(peerLastBlockSignature, blockSummaries) == null)
+										// We don't have a block summary for the peer's reported chain tip, so should exclude it
+										LOGGER.debug(String.format("Peer %s didn't return a block summary with signature %.8s - excluding them from this round", peer, Base58.encode(peerLastBlockSignature)));
+									else
+										// All looks good, so store the retrieved block summaries in the peer's cache
+										peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(blockSummaries);
 								}
 							} else {
 								// There are no block summaries after this common block
@@ -385,8 +399,8 @@ public class Synchronizer {
 							peers.remove(peer);
 						}
 						else {
-							// Our chain is inferior
+							// Our chain is inferior or equal
-							LOGGER.debug(String.format("Peer %s is on a better chain to us. We will compare the other peers sharing this common block against each other, and drop all peers sharing higher common blocks.", peer));
+							LOGGER.debug(String.format("Peer %s is on an equal or better chain to us. We will compare the other peers sharing this common block against each other, and drop all peers sharing higher common blocks.", peer));
 							dropPeersAfterCommonBlockHeight = commonBlockSummary.getHeight();
 							superiorPeersForComparison.add(peer);
 						}
@@ -408,6 +422,9 @@ public class Synchronizer {
 								peers.remove(peer);
 							}
 						}
+						// FUTURE: we may want to prefer peers with additional blocks, and compare the additional blocks against each other.
+						// This would fast track us to the best candidate for the latest block.
+						// Right now, peers with the exact same chain as us are treated equally to those with an additional block.
 					}
 				}
 
@@ -426,14 +443,14 @@ public class Synchronizer {
 
 		for (Peer peer : peers) {
 			if (peer.getCommonBlockData() != null && peer.getCommonBlockData().getCommonBlockSummary() != null) {
-				LOGGER.debug(String.format("Peer %s has common block %.8s", peer, Base58.encode(peer.getCommonBlockData().getCommonBlockSummary().getSignature())));
+				LOGGER.trace(String.format("Peer %s has common block %.8s", peer, Base58.encode(peer.getCommonBlockData().getCommonBlockSummary().getSignature())));
 
 				BlockSummaryData commonBlockSummary = peer.getCommonBlockData().getCommonBlockSummary();
 				if (!commonBlocks.contains(commonBlockSummary))
 					commonBlocks.add(commonBlockSummary);
 			}
 			else {
-				LOGGER.debug(String.format("Peer %s has no common block data. Skipping...", peer));
+				LOGGER.trace(String.format("Peer %s has no common block data. Skipping...", peer));
 			}
 		}
 
@@ -453,6 +470,12 @@ public class Synchronizer {
 		return minChainLength;
 	}
 
+	private BlockSummaryData blockSummaryWithSignature(byte[] signature, List<BlockSummaryData> blockSummaries) {
+		if (blockSummaries != null)
+			return blockSummaries.stream().filter(blockSummary -> Arrays.equals(blockSummary.getSignature(), signature)).findAny().orElse(null);
+		return null;
+	}
+
 
 	/**
 	 * Attempt to synchronize blockchain with peer.
@@ -488,7 +511,7 @@ public class Synchronizer {
 							ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
 
 					List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
-					SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries);
+					SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries, true);
 					if (findCommonBlockResult != SynchronizationResult.OK) {
 						// Logging performed by fetchSummariesFromCommonBlock() above
 						// Clear our common block cache for this peer
@@ -570,7 +593,7 @@ public class Synchronizer {
 	 * @throws DataException
 	 * @throws InterruptedException
 	 */
-	public SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon) throws DataException, InterruptedException {
+	public SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon, boolean infoLogWhenNotFound) throws DataException, InterruptedException {
 		// Start by asking for a few recent block hashes as this will cover a majority of reorgs
 		// Failing that, back off exponentially
 		int step = INITIAL_BLOCK_STEP;
@@ -599,8 +622,12 @@ public class Synchronizer {
 			blockSummariesBatch = this.getBlockSummaries(peer, testSignature, step);
 
 			if (blockSummariesBatch == null) {
+				if (infoLogWhenNotFound)
+					LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
+				else
+					LOGGER.debug(String.format("Error while trying to find common block with peer %s", peer));
+				
 				// No response - give up this time
-				LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
 				return SynchronizationResult.NO_REPLY;
 			}
 
@@ -748,6 +775,7 @@ public class Synchronizer {
 
 		LOGGER.debug(() -> String.format("Fetching peer %s chain from height %d, sig %.8s", peer, commonBlockHeight, commonBlockSig58));
 
+		final int maxRetries = Settings.getInstance().getMaxRetries();
 
 		// Overall plan: fetch peer's blocks first, then orphan, then apply
 
@@ -786,19 +814,13 @@ public class Synchronizer {
 					if (cachedCommonBlockData != null)
 						cachedCommonBlockData.setBlockSummariesAfterCommonBlock(null);
 
-                    // If we have already received recent or newer blocks from this peer, go ahead and apply them
+                    // If we have already received newer blocks from this peer that what we have already, go ahead and apply them
                     if (peerBlocks.size() > 0) {
 						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
                     	final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
 						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
 						if (ourLatestBlockData != null && peerLatestBlock != null && minLatestBlockTimestamp != null) {
 
-							// If we have received at least one recent block, we can apply them
-							if (peerLatestBlock.getBlockData().getTimestamp() > minLatestBlockTimestamp) {
-								LOGGER.debug("Newly received blocks are recent, so we will apply them");
-								break;
-							}
-
 							// If our latest block is very old....
 							if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
 								// ... and we have received a block that is more recent than our latest block ...
@@ -814,7 +836,7 @@ public class Synchronizer {
 							}
 						}
                     }
-                    // Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated state
+					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated or incomplete state
                     return SynchronizationResult.NO_REPLY;
                 }
 
@@ -837,21 +859,14 @@ public class Synchronizer {
 				LOGGER.info(String.format("Peer %s failed to respond with block for height %d, sig %.8s", peer,
 						nextHeight, Base58.encode(nextPeerSignature)));
 
-				if (retryCount >= MAXIMUM_RETRIES) {
+				if (retryCount >= maxRetries) {
-
+					// If we have already received newer blocks from this peer that what we have already, go ahead and apply them
-					// If we have already received recent or newer blocks from this peer, go ahead and apply them
 					if (peerBlocks.size() > 0) {
 						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 						final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
 						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
 						if (ourLatestBlockData != null && peerLatestBlock != null && minLatestBlockTimestamp != null) {
 
-							// If we have received at least one recent block, we can apply them
-							if (peerLatestBlock.getBlockData().getTimestamp() > minLatestBlockTimestamp) {
-								LOGGER.debug("Newly received blocks are recent, so we will apply them");
-								break;
-							}
-
 							// If our latest block is very old....
 							if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
 								// ... and we have received a block that is more recent than our latest block ...
@@ -867,7 +882,7 @@ public class Synchronizer {
 							}
 						}
 					}
-					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated state
+					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated or incomplete state
 					return SynchronizationResult.NO_REPLY;
 
 				} else {
@@ -875,9 +890,9 @@ public class Synchronizer {
 					peerBlockSignatures.clear();
 					numberSignaturesRequired = peerHeight - height;
 
-					// Retry until retryCount reaches MAXIMUM_RETRIES
+					// Retry until retryCount reaches maxRetries
 					retryCount++;
-					int triesRemaining = MAXIMUM_RETRIES - retryCount;
+					int triesRemaining = maxRetries - retryCount;
 					LOGGER.info(String.format("Re-issuing request to peer %s (%d attempt%s remaining)", peer, triesRemaining, (triesRemaining != 1 ? "s" : "")));
 					continue;
 				}

src/main/java/org/qortal/controller/tradebot/TradeBot.java

@@ -272,15 +272,9 @@ public class TradeBot implements Listener {
 		// Attempt to backup the trade bot data. This an optional step and doesn't impact trading, so don't throw an exception on failure
 		try {
 			LOGGER.info("About to backup trade bot data...");
-			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
+			repository.exportNodeLocalData();
-			blockchainLock.lockInterruptibly();
+		} catch (DataException e) {
-			try {
+			LOGGER.info(String.format("Repository issue when exporting trade bot data: %s", e.getMessage()));
-				repository.exportNodeLocalData(true);
-			} finally {
-				blockchainLock.unlock();
-			}
-		} catch (InterruptedException | DataException e) {
-			LOGGER.info(String.format("Failed to obtain blockchain lock when exporting trade bot data: %s", e.getMessage()));
 		}
 	}
 

src/main/java/org/qortal/data/crosschain/TradeBotData.java

@@ -6,6 +6,9 @@ import javax.xml.bind.annotation.XmlTransient;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 import io.swagger.v3.oas.annotations.media.Schema;
+import org.json.JSONObject;
+
+import org.qortal.utils.Base58;
 
 // All properties to be converted to JSON via JAXB
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -205,6 +208,58 @@ public class TradeBotData {
 		return this.receivingAccountInfo;
 	}
 
+	public JSONObject toJson() {
+		JSONObject jsonObject = new JSONObject();
+		jsonObject.put("tradePrivateKey", Base58.encode(this.getTradePrivateKey()));
+		jsonObject.put("acctName", this.getAcctName());
+		jsonObject.put("tradeState", this.getState());
+		jsonObject.put("tradeStateValue", this.getStateValue());
+		jsonObject.put("creatorAddress", this.getCreatorAddress());
+		jsonObject.put("atAddress", this.getAtAddress());
+		jsonObject.put("timestamp", this.getTimestamp());
+		jsonObject.put("qortAmount", this.getQortAmount());
+		if (this.getTradeNativePublicKey() != null) jsonObject.put("tradeNativePublicKey", Base58.encode(this.getTradeNativePublicKey()));
+		if (this.getTradeNativePublicKeyHash() != null) jsonObject.put("tradeNativePublicKeyHash", Base58.encode(this.getTradeNativePublicKeyHash()));
+		jsonObject.put("tradeNativeAddress", this.getTradeNativeAddress());
+		if (this.getSecret() != null) jsonObject.put("secret", Base58.encode(this.getSecret()));
+		if (this.getHashOfSecret() != null) jsonObject.put("hashOfSecret", Base58.encode(this.getHashOfSecret()));
+		jsonObject.put("foreignBlockchain", this.getForeignBlockchain());
+		if (this.getTradeForeignPublicKey() != null) jsonObject.put("tradeForeignPublicKey", Base58.encode(this.getTradeForeignPublicKey()));
+		if (this.getTradeForeignPublicKeyHash() != null) jsonObject.put("tradeForeignPublicKeyHash", Base58.encode(this.getTradeForeignPublicKeyHash()));
+		jsonObject.put("foreignKey", this.getForeignKey());
+        jsonObject.put("foreignAmount", this.getForeignAmount());
+		if (this.getLastTransactionSignature() != null) jsonObject.put("lastTransactionSignature", Base58.encode(this.getLastTransactionSignature()));
+        jsonObject.put("lockTimeA", this.getLockTimeA());
+		if (this.getReceivingAccountInfo() != null) jsonObject.put("receivingAccountInfo", Base58.encode(this.getReceivingAccountInfo()));
+		return jsonObject;
+	}
+
+	public static TradeBotData fromJson(JSONObject json) {
+		return new TradeBotData(
+				json.isNull("tradePrivateKey") ? null : Base58.decode(json.getString("tradePrivateKey")),
+				json.isNull("acctName") ? null : json.getString("acctName"),
+				json.isNull("tradeState") ? null : json.getString("tradeState"),
+				json.isNull("tradeStateValue") ? null : json.getInt("tradeStateValue"),
+				json.isNull("creatorAddress") ? null : json.getString("creatorAddress"),
+				json.isNull("atAddress") ? null : json.getString("atAddress"),
+				json.isNull("timestamp") ? null : json.getLong("timestamp"),
+				json.isNull("qortAmount") ? null : json.getLong("qortAmount"),
+				json.isNull("tradeNativePublicKey") ? null : Base58.decode(json.getString("tradeNativePublicKey")),
+				json.isNull("tradeNativePublicKeyHash") ? null : Base58.decode(json.getString("tradeNativePublicKeyHash")),
+				json.isNull("tradeNativeAddress") ? null : json.getString("tradeNativeAddress"),
+				json.isNull("secret") ? null : Base58.decode(json.getString("secret")),
+				json.isNull("hashOfSecret") ? null : Base58.decode(json.getString("hashOfSecret")),
+				json.isNull("foreignBlockchain") ? null : json.getString("foreignBlockchain"),
+				json.isNull("tradeForeignPublicKey") ? null : Base58.decode(json.getString("tradeForeignPublicKey")),
+				json.isNull("tradeForeignPublicKeyHash") ? null : Base58.decode(json.getString("tradeForeignPublicKeyHash")),
+				json.isNull("foreignAmount") ? null : json.getLong("foreignAmount"),
+				json.isNull("foreignKey") ? null : json.getString("foreignKey"),
+				json.isNull("lastTransactionSignature") ? null : Base58.decode(json.getString("lastTransactionSignature")),
+				json.isNull("lockTimeA") ? null : json.getInt("lockTimeA"),
+				json.isNull("receivingAccountInfo") ? null : Base58.decode(json.getString("receivingAccountInfo"))
+		);
+	}
+
 	// Mostly for debugging
 	public String toString() {
 		return String.format("%s: %s (%d)", this.atAddress, this.tradeState, this.tradeStateValue);

src/main/java/org/qortal/network/Handshake.java

@@ -4,7 +4,6 @@ import java.util.Arrays;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -51,7 +50,7 @@ public enum Handshake {
 
 			String versionString = helloMessage.getVersionString();
 
-			Matcher matcher = VERSION_PATTERN.matcher(versionString);
+			Matcher matcher = peer.VERSION_PATTERN.matcher(versionString);
 			if (!matcher.lookingAt()) {
 				LOGGER.debug(() -> String.format("Peer %s sent invalid HELLO version string '%s'", peer, versionString));
 				return null;
@@ -72,6 +71,15 @@ public enum Handshake {
 			peer.setPeersConnectionTimestamp(peersConnectionTimestamp);
 			peer.setPeersVersion(versionString, version);
 
+			if (Settings.getInstance().getAllowConnectionsWithOlderPeerVersions() == false) {
+				// Ensure the peer is running at least the minimum version allowed for connections
+				final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
+				if (peer.isAtLeastVersion(minPeerVersion) == false) {
+					LOGGER.debug(String.format("Ignoring peer %s because it is on an old version (%s)", peer, versionString));
+					return null;
+				}
+			}
+
 			return CHALLENGE;
 		}
 
@@ -244,8 +252,6 @@ public enum Handshake {
 	/** Maximum allowed difference between peer's reported timestamp and when they connected, in milliseconds. */
 	private static final long MAX_TIMESTAMP_DELTA = 30 * 1000L; // ms
 
-	private static final Pattern VERSION_PATTERN = Pattern.compile(Controller.VERSION_PREFIX + "(\\d{1,3})\\.(\\d{1,5})\\.(\\d{1,5})");
-
 	private static final long PEER_VERSION_131 = 0x0100030001L;
 
 	private static final int POW_BUFFER_SIZE_PRE_131 = 8 * 1024 * 1024; // bytes

src/main/java/org/qortal/network/Peer.java

@@ -20,9 +20,12 @@ import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
 import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
@@ -87,6 +90,9 @@ public class Peer {
 
 	byte[] ourChallenge;
 
+	// Versioning
+	public static final Pattern VERSION_PATTERN = Pattern.compile(Controller.VERSION_PREFIX + "(\\d{1,3})\\.(\\d{1,5})\\.(\\d{1,5})");
+
 	// Peer info
 
 	private final Object peerInfoLock = new Object();
@@ -634,6 +640,35 @@ public class Peer {
 	}
 
 
+	// Minimum version
+
+	public boolean isAtLeastVersion(String minVersionString) {
+		if (minVersionString == null)
+			return false;
+
+		// Add the version prefix
+		minVersionString = Controller.VERSION_PREFIX + minVersionString;
+
+		Matcher matcher = VERSION_PATTERN.matcher(minVersionString);
+		if (!matcher.lookingAt())
+			return false;
+
+		// We're expecting 3 positive shorts, so we can convert 1.2.3 into 0x0100020003
+		long minVersion = 0;
+		for (int g = 1; g <= 3; ++g) {
+			long value = Long.parseLong(matcher.group(g));
+
+			if (value < 0 || value > Short.MAX_VALUE)
+				return false;
+
+			minVersion <<= 16;
+			minVersion |= value;
+		}
+
+		return this.getPeersVersion() >= minVersion;
+	}
+
+
 	// Common block data
 
 	public boolean canUseCachedCommonBlockData() {

src/main/java/org/qortal/repository/ATRepository.java

@@ -98,7 +98,7 @@ public interface ATRepository {
 	 */
 	public List<ATStateData> getMatchingFinalATStatesQuorum(byte[] codeHash, Boolean isFinished,
 			Integer dataByteOffset, Long expectedValue,
-			int minimumCount, long minimumPeriod) throws DataException;
+			int minimumCount, int maximumCount, long minimumPeriod) throws DataException;
 
 	/**
 	 * Returns all ATStateData for a given block height.

src/main/java/org/qortal/repository/Repository.java

@@ -49,7 +49,7 @@ public interface Repository extends AutoCloseable {
 
 	public void performPeriodicMaintenance() throws DataException;
 
-	public void exportNodeLocalData(boolean keepArchivedCopy) throws DataException;
+	public void exportNodeLocalData() throws DataException;
 
 	public void importDataFromFile(String filename) throws DataException;
 

src/main/java/org/qortal/repository/hsqldb/HSQLDBATRepository.java

@@ -454,7 +454,7 @@ public class HSQLDBATRepository implements ATRepository {
 	@Override
 	public List<ATStateData> getMatchingFinalATStatesQuorum(byte[] codeHash, Boolean isFinished,
 			Integer dataByteOffset, Long expectedValue,
-			int minimumCount, long minimumPeriod) throws DataException {
+			int minimumCount, int maximumCount, long minimumPeriod) throws DataException {
 		// We need most recent entry first so we can use its timestamp to slice further results
 		List<ATStateData> mostRecentStates = this.getMatchingFinalATStates(codeHash, isFinished,
 				dataByteOffset, expectedValue, null,
@@ -510,7 +510,8 @@ public class HSQLDBATRepository implements ATRepository {
 		bindParams.add(minimumHeight);
 		bindParams.add(minimumCount);
 
-		sql.append("ORDER BY FinalATStates.height DESC");
+		sql.append("ORDER BY FinalATStates.height DESC LIMIT ?");
+		bindParams.add(maximumCount);
 
 		List<ATStateData> atStates = new ArrayList<>();
 

src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java

@@ -2,6 +2,7 @@ package org.qortal.repository.hsqldb;
 
 import java.awt.TrayIcon.MessageType;
 import java.io.File;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.math.BigDecimal;
 import java.nio.file.Files;
@@ -15,23 +16,19 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Savepoint;
 import java.sql.Statement;
-import java.util.ArrayDeque;
+import java.util.*;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.Deque;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
+import org.json.JSONArray;
+import org.json.JSONObject;
+
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.account.PrivateKeyAccount;
 import org.qortal.crypto.Crypto;
+import org.qortal.data.crosschain.TradeBotData;
 import org.qortal.globalization.Translator;
 import org.qortal.gui.SysTray;
 import org.qortal.repository.ATRepository;
@@ -52,7 +49,7 @@ import org.qortal.repository.TransactionRepository;
 import org.qortal.repository.VotingRepository;
 import org.qortal.repository.hsqldb.transaction.HSQLDBTransactionRepository;
 import org.qortal.settings.Settings;
-import org.qortal.utils.NTP;
+import org.qortal.utils.Base58;
 
 public class HSQLDBRepository implements Repository {
 
@@ -460,8 +457,7 @@ public class HSQLDBRepository implements Repository {
 	}
 
 	@Override
-	public void exportNodeLocalData(boolean keepArchivedCopy) throws DataException {
+	public void exportNodeLocalData() throws DataException {
-
 		// Create the qortal-backup folder if it doesn't exist
 		Path backupPath = Paths.get("qortal-backup");
 		try {
@@ -471,52 +467,59 @@ public class HSQLDBRepository implements Repository {
 			throw new DataException("Unable to create backup folder");
 		}
 
-		// We need to rename or delete an existing TradeBotStates backup before creating a new one
+		try {
-		File tradeBotStatesBackupFile = new File("qortal-backup/TradeBotStates.script");
+			// Load trade bot data
-		if (tradeBotStatesBackupFile.exists()) {
+			List<TradeBotData> allTradeBotData = this.getCrossChainRepository().getAllTradeBotData();
-			if (keepArchivedCopy) {
+			JSONArray allTradeBotDataJson = new JSONArray();
-				// Rename existing TradeBotStates backup, to make sure that we're not overwriting any keys
+			for (TradeBotData tradeBotData : allTradeBotData) {
-				File archivedBackupFile = new File(String.format("qortal-backup/TradeBotStates-archive-%d.script", NTP.getTime()));
+				JSONObject tradeBotDataJson = tradeBotData.toJson();
-				if (tradeBotStatesBackupFile.renameTo(archivedBackupFile))
+				allTradeBotDataJson.put(tradeBotDataJson);
-					LOGGER.info(String.format("Moved existing TradeBotStates backup file to %s", archivedBackupFile.getPath()));
-				else
-					throw new DataException("Unable to rename existing TradeBotStates backup");
-			} else {
-				// Delete existing copy
-				LOGGER.info("Deleting existing TradeBotStates backup because it is being replaced with a new one");
-				tradeBotStatesBackupFile.delete();
 			}
-		}
 
-		// There's currently no need to take an archived copy of the MintingAccounts data - just delete the old one if it exists
+			// We need to combine existing TradeBotStates data before overwriting
-		File mintingAccountsBackupFile = new File("qortal-backup/MintingAccounts.script");
+			String fileName = "qortal-backup/TradeBotStates.json";
-		if (mintingAccountsBackupFile.exists()) {
+			File tradeBotStatesBackupFile = new File(fileName);
-			LOGGER.info("Deleting existing MintingAccounts backup because it is being replaced with a new one");
+			if (tradeBotStatesBackupFile.exists()) {
-			mintingAccountsBackupFile.delete();
+				String jsonString = new String(Files.readAllBytes(Paths.get(fileName)));
-		}
+				JSONArray allExistingTradeBotData = new JSONArray(jsonString);
+				Iterator<Object> iterator = allExistingTradeBotData.iterator();
+				while(iterator.hasNext()) {
+					JSONObject existingTradeBotData = (JSONObject)iterator.next();
+					String existingTradePrivateKey = (String) existingTradeBotData.get("tradePrivateKey");
+						// Check if we already have an entry for this trade
+						boolean found = allTradeBotData.stream().anyMatch(tradeBotData -> Base58.encode(tradeBotData.getTradePrivateKey()).equals(existingTradePrivateKey));
+						if (found == false)
+							// We need to add this to our list
+							allTradeBotDataJson.put(existingTradeBotData);
+				}
+			}
 
-		try (Statement stmt = this.connection.createStatement()) {
+			FileWriter writer = new FileWriter(fileName);
-			stmt.execute("PERFORM EXPORT SCRIPT FOR TABLE MintingAccounts DATA TO 'qortal-backup/MintingAccounts.script'");
+			writer.write(allTradeBotDataJson.toString());
-			stmt.execute("PERFORM EXPORT SCRIPT FOR TABLE TradeBotStates DATA TO 'qortal-backup/TradeBotStates.script'");
+			writer.close();
-			LOGGER.info("Exported sensitive/node-local data: minting keys and trade bot states");
+			LOGGER.info("Exported sensitive/node-local data: trade bot states");
-		} catch (SQLException e) {
+
-			throw new DataException("Unable to export sensitive/node-local data from repository");
+		} catch (DataException | IOException e) {
+			throw new DataException("Unable to export trade bot states from repository");
 		}
 	}
 
 	@Override
 	public void importDataFromFile(String filename) throws DataException {
-		try (Statement stmt = this.connection.createStatement()) {
+		LOGGER.info(() -> String.format("Importing data into repository from %s", filename));
-			LOGGER.info(() -> String.format("Importing data into repository from %s", filename));
+		try {
-
+			String jsonString = new String(Files.readAllBytes(Paths.get(filename)));
-			String escapedFilename = stmt.enquoteLiteral(filename);
+			JSONArray tradeBotDataToImport = new JSONArray(jsonString);
-			stmt.execute("PERFORM IMPORT SCRIPT DATA FROM " + escapedFilename + " CONTINUE ON ERROR");
+			Iterator<Object> iterator = tradeBotDataToImport.iterator();
-
+			while(iterator.hasNext()) {
-			LOGGER.info(() -> String.format("Imported data into repository from %s", filename));
+				JSONObject tradeBotDataJson = (JSONObject)iterator.next();
-		} catch (SQLException e) {
+				TradeBotData tradeBotData = TradeBotData.fromJson(tradeBotDataJson);
-			LOGGER.info(() -> String.format("Failed to import data into repository from %s: %s", filename, e.getMessage()));
+				this.getCrossChainRepository().save(tradeBotData);
-			throw new DataException("Unable to import sensitive/node-local data to repository: " + e.getMessage());
+			}
+		} catch (IOException e) {
+			throw new DataException("Unable to import sensitive/node-local trade bot states to repository: " + e.getMessage());
 		}
+		LOGGER.info(() -> String.format("Imported trade bot states into repository from %s", filename));
 	}
 
 	@Override

src/main/java/org/qortal/settings/Settings.java

@@ -122,6 +122,15 @@ public class Settings {
 	private int maxNetworkThreadPoolSize = 20;
 	/** Maximum number of threads for network proof-of-work compute, used during handshaking. */
 	private int networkPoWComputePoolSize = 2;
+	/** Maximum number of retry attempts if a peer fails to respond with the requested data */
+	private int maxRetries = 2;
+
+	/** Minimum peer version number required in order to sync with them */
+	private String minPeerVersion = "1.5.0";
+	/** Whether to allow connections with peers below minPeerVersion
+	 * If true, we won't sync with them but they can still sync with us, and will show in the peers list
+	 * If false, sync will be blocked both ways, and they will not appear in the peers list */
+	private boolean allowConnectionsWithOlderPeerVersions = true;
 
 	// Which blockchains this node is running
 	private String blockchainConfig = null; // use default from resources
@@ -408,6 +417,12 @@ public class Settings {
 		return this.networkPoWComputePoolSize;
 	}
 
+	public int getMaxRetries() { return this.maxRetries; }
+
+	public String getMinPeerVersion() { return this.minPeerVersion; }
+
+	public boolean getAllowConnectionsWithOlderPeerVersions() { return this.allowConnectionsWithOlderPeerVersions; }
+
 	public String getBlockchainConfig() {
 		return this.blockchainConfig;
 	}

tools/block-timings.sh

@@ -0,0 +1,148 @@
+#!/usr/bin/env bash
+
+start_height=$1
+count=$2
+target=$3
+deviation=$4
+power=$5
+
+if [ -z "${start_height}" ]; then
+  echo
+  echo "Error: missing start height."
+  echo
+  echo "Usage:"
+  echo "block-timings.sh <startheight> [count] [target] [deviation] [power]"
+  echo
+  echo "startheight: a block height, preferably within the untrimmed range, to avoid data gaps"
+  echo "count: the number of blocks to request and analyse after the start height. Default: 100"
+  echo "target: the target block time in milliseconds. Originates from blockchain.json. Default: 60000"
+  echo "deviation: the allowed block time deviation in milliseconds. Originates from blockchain.json. Default: 30000"
+  echo "power: used when transforming key distance to a time offset. Originates from blockchain.json. Default: 0.2"
+  echo
+  exit
+fi
+
+count=${count:=100}
+target=${target:=60000}
+deviation=${deviation:=30000}
+power=${power:=0.2}
+
+finish_height=$((start_height + count - 1))
+height=$start_height
+
+echo "Settings:"
+echo "Target time offset: ${target}"
+echo "Deviation: ${deviation}"
+echo "Power transform: ${power}"
+echo
+
+function calculate_time_offset {
+  local key_distance_ratio=$1
+  local transformed=$( echo "" | awk "END {print ${key_distance_ratio} ^ ${power}}")
+  local time_offset=$(echo "${deviation}*2*${transformed}" | bc)
+  time_offset=${time_offset%.*}
+  echo $time_offset
+}
+
+
+function fetch_and_process_blocks {
+
+  echo "Fetching blocks from height ${start_height} to ${finish_height}..."
+  echo
+
+  total_time_offset=0
+  errors=0
+
+  while [ "${height}" -le "${finish_height}" ]; do
+    block_minting_info=$(curl -s "http://localhost:12391/blocks/byheight/${height}/mintinginfo")
+    error=$(echo "${block_minting_info}" | jq -r .error)
+    if [ "${error}" != "null" ]; then
+      echo "Error fetching minting info for block ${height}"
+      echo
+      errors=$((errors+1))
+      height=$((height+1))
+      continue;
+    fi
+
+    # Parse minting info
+    minter_level=$(echo "${block_minting_info}" | jq -r .minterLevel)
+    online_accounts_count=$(echo "${block_minting_info}" | jq -r .onlineAccountsCount)
+    key_distance_ratio=$(echo "${block_minting_info}" | jq -r .keyDistanceRatio)
+    time_delta=$(echo "${block_minting_info}" | jq -r .timeDelta)
+
+    time_offset=$(calculate_time_offset "${key_distance_ratio}")
+    block_time=$((target-deviation+time_offset))
+
+    echo "=== BLOCK ${height} ==="
+    echo "Minter level: ${minter_level}"
+    echo "Online accounts: ${online_accounts_count}"
+    echo "Key distance ratio: ${key_distance_ratio}"
+    echo "Time offset: ${time_offset}"
+    echo "Block time (real): ${time_delta}"
+    echo "Block time (calculated): ${block_time}"
+
+    if [ "${time_delta}" -ne "${block_time}" ]; then
+      echo "WARNING: Block time mismatch. This is to be expected when using custom settings."
+    fi
+    echo
+
+    total_time_offset=$((total_time_offset+block_time))
+
+    height=$((height+1))
+  done
+
+  adjusted_count=$((count-errors))
+  if [ "${adjusted_count}" -eq 0 ]; then
+    echo "No blocks were retrieved."
+    echo
+    exit;
+  fi
+
+  mean_time_offset=$((total_time_offset/adjusted_count))
+  time_offset_diff=$((mean_time_offset-target))
+
+  echo "==================="
+  echo "===== SUMMARY ====="
+  echo "==================="
+  echo "Total blocks retrieved: ${adjusted_count}"
+  echo "Total blocks failed: ${errors}"
+  echo "Mean time offset: ${mean_time_offset}ms"
+  echo "Target time offset: ${target}ms"
+  echo "Difference from target: ${time_offset_diff}ms"
+  echo
+
+}
+
+function estimate_key_distance_ratio_for_level {
+  local level=$1
+  local example_key_distance="0.5"
+  echo "(${example_key_distance}/${level})"
+}
+
+function estimate_block_timestamps {
+  min_block_time=9999999
+  max_block_time=0
+
+  echo "===== BLOCK TIME ESTIMATES ====="
+
+  for level in {1..10}; do
+    example_key_distance_ratio=$(estimate_key_distance_ratio_for_level "${level}")
+    time_offset=$(calculate_time_offset "${example_key_distance_ratio}")
+    block_time=$((target-deviation+time_offset))
+
+    if [ "${block_time}" -gt "${max_block_time}" ]; then
+      max_block_time=${block_time}
+    fi
+    if [ "${block_time}" -lt "${min_block_time}" ]; then
+      min_block_time=${block_time}
+    fi
+
+    echo "Level: ${level}, time offset: ${time_offset}, block time: ${block_time}"
+  done
+  block_time_range=$((max_block_time-min_block_time))
+  echo "Range: ${block_time_range}"
+  echo
+}
+
+fetch_and_process_blocks
+estimate_block_timestamps