From 615381ca5aac8218a18218f46c681d21e4fe81d7 Mon Sep 17 00:00:00 2001
From: catbref <misc-github@talk2dom.com>
Date: Wed, 5 Aug 2020 10:03:08 +0100
Subject: [PATCH] Fix BTC spend txn building to be less aggressive about
 caching/checking spent keys

---
 src/main/java/org/qortal/crosschain/BTC.java  | 13 ++++++------
 .../org/qortal/test/btcacct/BtcTests.java     | 20 ++++++++++++++++++-
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/qortal/crosschain/BTC.java b/src/main/java/org/qortal/crosschain/BTC.java
index 0f2920a7..5e5a3639 100644
--- a/src/main/java/org/qortal/crosschain/BTC.java
+++ b/src/main/java/org/qortal/crosschain/BTC.java
@@ -277,12 +277,6 @@ public class BTC {
 				for (; ki < keys.size(); ++ki) {
 					ECKey key = keys.get(ki);
 
-					if (btc.spentKeys.contains(key)) {
-						wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
-						areAllKeysUnspent = false;
-						continue;
-					}
-
 					Address address = Address.fromKey(btc.params, key, ScriptType.P2PKH);
 					byte[] script = ScriptBuilder.createOutputScript(address).getProgram();
 
@@ -299,6 +293,13 @@ public class BTC {
 					 */
 
 					if (unspentOutputs.isEmpty()) {
+						// If this is a known key that has been spent before, then we can skip asking for transaction history
+						if (btc.spentKeys.contains(key)) {
+							wallet.getActiveKeyChain().markKeyAsUsed((DeterministicKey) key);
+							areAllKeysUnspent = false;
+							continue;
+						}
+
 						// Ask for transaction history - if it's empty then key has never been used
 						List<byte[]> historicTransactionHashes = btc.electrumX.getAddressTransactions(script);
 						if (historicTransactionHashes == null)
diff --git a/src/test/java/org/qortal/test/btcacct/BtcTests.java b/src/test/java/org/qortal/test/btcacct/BtcTests.java
index f5829be8..a00e54f6 100644
--- a/src/test/java/org/qortal/test/btcacct/BtcTests.java
+++ b/src/test/java/org/qortal/test/btcacct/BtcTests.java
@@ -5,6 +5,7 @@ import static org.junit.Assert.*;
 import java.util.Arrays;
 import java.util.List;
 
+import org.bitcoinj.core.Transaction;
 import org.bitcoinj.store.BlockStoreException;
 import org.junit.After;
 import org.junit.Before;
@@ -67,10 +68,17 @@ public class BtcTests extends Common {
 		BTC btc = BTC.getInstance();
 
 		String xprv58 = "tprv8ZgxMBicQKsPdahhFSrCdvC1bsWyzHHZfTneTVqUXN6s1wEtZLwAkZXzFP6TYLg2aQMecZLXLre5bTVGajEB55L1HYJcawpdFG66STVAWPJ";
+
 		String recipient = "2N8WCg52ULCtDSMjkgVTm5mtPdCsUptkHWE";
 		long amount = 1000L;
 
-		btc.buildSpend(xprv58, recipient, amount);
+		Transaction transaction = btc.buildSpend(xprv58, recipient, amount);
+		assertNotNull(transaction);
+
+		// Check spent key caching doesn't affect outcome
+
+		transaction = btc.buildSpend(xprv58, recipient, amount);
+		assertNotNull(transaction);
 	}
 
 	@Test
@@ -84,6 +92,16 @@ public class BtcTests extends Common {
 		assertNotNull(balance);
 
 		System.out.println(BTC.format(balance));
+
+		// Check spent key caching doesn't affect outcome
+
+		Long repeatBalance = btc.getWalletBalance(xprv58);
+
+		assertNotNull(repeatBalance);
+
+		System.out.println(BTC.format(repeatBalance));
+
+		assertEquals(balance, repeatBalance);
 	}
 
 }