Only compare same number of blocks when comparing peer chains

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

@@ -822,10 +822,9 @@ public class Block {
 			parentHeight = blockSummaryData.getHeight();
 			parentBlockSignature = blockSummaryData.getSignature();
 
-			/* Potential future consensus change: only comparing the same number of blocks.
+			// After this timestamp, we only compare the same number of blocks
-			if (parentHeight >= maxHeight)
+			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp() && parentHeight >= maxHeight)
 				break;
-			*/
 		}
 
 		return cumulativeWeight;

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

@@ -70,7 +70,8 @@ public class BlockChain {
 	private GenesisBlock.GenesisInfo genesisInfo;
 
 	public enum FeatureTrigger {
-		atFindNextTransactionFix;
+		atFindNextTransactionFix,
+		calcChainWeightTimestamp;
 	}
 
 	/** Map of which blockchain features are enabled when (height/timestamp) */
@@ -376,6 +377,10 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.atFindNextTransactionFix.name()).intValue();
 	}
 
+	public long getCalcChainWeightTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.calcChainWeightTimestamp.name()).longValue();
+	}
+
 	// More complex getters for aspects that change by height or timestamp
 
 	public long getRewardAtHeight(int ourHeight) {

src/main/resources/blockchain.json

@@ -48,7 +48,8 @@
 		"minutesPerBlock": 1
 	},
 	"featureTriggers": {
-		"atFindNextTransactionFix": 275000
+		"atFindNextTransactionFix": 275000,
+		"calcChainWeightTimestamp": 1616000000000,
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/java/org/qortal/test/ChainWeightTests.java

@@ -11,6 +11,7 @@ import java.util.Random;
 
 import org.qortal.account.Account;
 import org.qortal.block.Block;
+import org.qortal.block.BlockChain;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
@@ -19,7 +20,9 @@ import org.qortal.test.common.Common;
 import org.qortal.test.common.TestAccount;
 import org.qortal.transform.Transformer;
 import org.qortal.transform.block.BlockTransformer;
+import org.qortal.utils.NTP;
 import org.junit.Before;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 public class ChainWeightTests extends Common {
@@ -27,6 +30,12 @@ public class ChainWeightTests extends Common {
 	private static final Random RANDOM = new Random();
 	private static final NumberFormat FORMATTER = new DecimalFormat("0.###E0");
 
+	@BeforeClass
+	public static void beforeClass() {
+		// We need this so that NTP.getTime() in Block.calcChainWeight() doesn't return null, causing NPE
+		NTP.setFixedOffset(0L);
+	}
+
 	@Before
 	public void beforeTest() throws DataException {
 		Common.useSettings("test-settings-v2-minting.json");
@@ -182,7 +191,7 @@ public class ChainWeightTests extends Common {
 		return BigInteger.valueOf(blockSummaryData.getOnlineAccountsCount()).shiftLeft(accountsCountShift).add(keyDistance);
 	}
 
-	// Check that a longer chain beats a shorter chain
+	// Check that a longer chain has same weight as shorter/truncated chain
 	@Test
 	public void testLongerChain() throws DataException {
 		try (final Repository repository = RepositoryManager.getRepository()) {
@@ -190,17 +199,19 @@ public class ChainWeightTests extends Common {
 			BlockSummaryData commonBlockSummary = genBlockSummary(repository, commonBlockHeight);
 			byte[] commonBlockGeneratorKey = commonBlockSummary.getMinterPublicKey();
 
-			List<BlockSummaryData> shorterChain = genBlockSummaries(repository, 3, commonBlockSummary);
+			List<BlockSummaryData> longerChain = genBlockSummaries(repository, 6, commonBlockSummary);
-			List<BlockSummaryData> longerChain = genBlockSummaries(repository, shorterChain.size() + 1, commonBlockSummary);
-
-			populateBlockSummariesMinterLevels(repository, shorterChain);
 			populateBlockSummariesMinterLevels(repository, longerChain);
 
+			List<BlockSummaryData> shorterChain = longerChain.subList(0, longerChain.size() / 2);
+
 			final int mutualHeight = commonBlockHeight - 1 + Math.min(shorterChain.size(), longerChain.size());
 
 			BigInteger shorterChainWeight = Block.calcChainWeight(commonBlockHeight, commonBlockGeneratorKey, shorterChain, mutualHeight);
 			BigInteger longerChainWeight = Block.calcChainWeight(commonBlockHeight, commonBlockGeneratorKey, longerChain, mutualHeight);
 
+			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp())
+				assertEquals("longer chain should have same weight", 0, longerChainWeight.compareTo(shorterChainWeight));
+			else
 				assertEquals("longer chain should have greater weight", 1, longerChainWeight.compareTo(shorterChainWeight));
 		}
 	}

src/test/resources/test-chain-v2-founder-rewards.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-leftover-reward.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-minting.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-qora-holder-extremes.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-qora-holder.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-reward-scaling.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2.json

@@ -44,7 +44,9 @@
 		"powfixTimestamp": 0,
 		"qortalTimestamp": 0,
 		"newAssetPricingTimestamp": 0,
-		"groupApprovalTimestamp": 0
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,