Add synchronization around updating trim heights to prevent deadlock/rollback

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

@@ -415,6 +415,9 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public void setAtTrimHeight(int trimHeight) throws DataException {
+		// trimHeightsLock is to prevent concurrent update on DatabaseInfo
+		// that could result in "transaction rollback: serialization failure"
+		synchronized (this.repository.trimHeightsLock) {
 			String updateSql = "UPDATE DatabaseInfo SET AT_trim_height = ?";
 
 			try {
@@ -424,6 +427,7 @@ public class HSQLDBATRepository implements ATRepository {
 				throw new DataException("Unable to set AT state trim height in repository", e);
 			}
 		}
+	}
 
 	@Override
 	public void prepareForAtStateTrimming() throws DataException {

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

@@ -477,6 +477,9 @@ public class HSQLDBBlockRepository implements BlockRepository {
 
 	@Override
 	public void setOnlineAccountsSignaturesTrimHeight(int trimHeight) throws DataException {
+		// trimHeightsLock is to prevent concurrent update on DatabaseInfo
+		// that could result in "transaction rollback: serialization failure"
+		synchronized (this.repository.trimHeightsLock) {
 			String updateSql = "UPDATE DatabaseInfo SET online_signatures_trim_height = ?";
 
 			try {
@@ -486,6 +489,7 @@ public class HSQLDBBlockRepository implements BlockRepository {
 				throw new DataException("Unable to set online accounts signatures trim height in repository", e);
 			}
 		}
+	}
 
 	@Override
 	public int trimOldOnlineAccountsSignatures(int minHeight, int maxHeight) throws DataException {

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

@@ -60,6 +60,7 @@ public class HSQLDBRepository implements Repository {
 	protected List<String> sqlStatements;
 	protected long sessionId;
 	protected final Map<String, PreparedStatement> preparedStatementCache = new HashMap<>();
+	protected final Object trimHeightsLock = new Object();
 
 	private final ATRepository atRepository = new HSQLDBATRepository(this);
 	private final AccountRepository accountRepository = new HSQLDBAccountRepository(this);