Synchronized LatestATStates, to make rebuildLatestAtStates() thread safe.

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

@@ -604,28 +604,34 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public void rebuildLatestAtStates() throws DataException {
-		// Rebuild cache of latest AT states that we can't trim
+		// latestATStatesLock is to prevent concurrent updates on LatestATStates
-		String deleteSql = "DELETE FROM LatestATStates";
+		// that could result in one process using a partial or empty dataset
-		try {
+		// because it was in the process of being rebuilt by another thread
-			this.repository.executeCheckedUpdate(deleteSql);
+		synchronized (this.repository.latestATStatesLock) {
-		} catch (SQLException e) {
-			repository.examineException(e);
-			throw new DataException("Unable to delete temporary latest AT states cache from repository", e);
-		}
 
-		String insertSql = "INSERT INTO LatestATStates ("
+			// Rebuild cache of latest AT states that we can't trim
-				+ "SELECT AT_address, height FROM ATs "
+			String deleteSql = "DELETE FROM LatestATStates";
-				+ "CROSS JOIN LATERAL("
+			try {
-				+ "SELECT height FROM ATStates "
+				this.repository.executeCheckedUpdate(deleteSql);
-				+ "WHERE ATStates.AT_address = ATs.AT_address "
+			} catch (SQLException e) {
-				+ "ORDER BY AT_address DESC, height DESC LIMIT 1"
+				repository.examineException(e);
-				+ ") "
+				throw new DataException("Unable to delete temporary latest AT states cache from repository", e);
-				+ ")";
+			}
-		try {
+
-			this.repository.executeCheckedUpdate(insertSql);
+			String insertSql = "INSERT INTO LatestATStates ("
-		} catch (SQLException e) {
+					+ "SELECT AT_address, height FROM ATs "
-			repository.examineException(e);
+					+ "CROSS JOIN LATERAL("
-			throw new DataException("Unable to populate temporary latest AT states cache in repository", e);
+					+ "SELECT height FROM ATStates "
+					+ "WHERE ATStates.AT_address = ATs.AT_address "
+					+ "ORDER BY AT_address DESC, height DESC LIMIT 1"
+					+ ") "
+					+ ")";
+			try {
+				this.repository.executeCheckedUpdate(insertSql);
+			} catch (SQLException e) {
+				repository.examineException(e);
+				throw new DataException("Unable to populate temporary latest AT states cache in repository", e);
+			}
 		}
 	}
 
@@ -666,22 +672,28 @@ public class HSQLDBATRepository implements ATRepository {
 		if (minHeight >= maxHeight)
 			return 0;
 
-		// We're often called so no need to trim all states in one go.
+		// latestATStatesLock is to prevent concurrent updates on LatestATStates
-		// Limit updates to reduce CPU and memory load.
+		// that could result in one process using a partial or empty dataset
-		String sql = "DELETE FROM ATStatesData "
+		// because it was in the process of being rebuilt by another thread
-				+ "WHERE height BETWEEN ? AND ? "
+		synchronized (this.repository.latestATStatesLock) {
-				+ "AND NOT EXISTS("
+
+			// We're often called so no need to trim all states in one go.
+			// Limit updates to reduce CPU and memory load.
+			String sql = "DELETE FROM ATStatesData "
+					+ "WHERE height BETWEEN ? AND ? "
+					+ "AND NOT EXISTS("
 					+ "SELECT TRUE FROM LatestATStates "
 					+ "WHERE LatestATStates.AT_address = ATStatesData.AT_address "
 					+ "AND LatestATStates.height = ATStatesData.height"
-				+ ") "
+					+ ") "
-				+ "LIMIT ?";
+					+ "LIMIT ?";
 
-		try {
+			try {
-			return this.repository.executeCheckedUpdate(sql, minHeight, maxHeight, limit);
+				return this.repository.executeCheckedUpdate(sql, minHeight, maxHeight, limit);
-		} catch (SQLException e) {
+			} catch (SQLException e) {
-			repository.examineException(e);
+				repository.examineException(e);
-			throw new DataException("Unable to trim AT states in repository", e);
+				throw new DataException("Unable to trim AT states in repository", e);
+			}
 		}
 	}
 
@@ -719,57 +731,63 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public int pruneAtStates(int minHeight, int maxHeight) throws DataException {
-		int deletedCount = 0;
+		// latestATStatesLock is to prevent concurrent updates on LatestATStates
+		// that could result in one process using a partial or empty dataset
+		// because it was in the process of being rebuilt by another thread
+		synchronized (this.repository.latestATStatesLock) {
 
-		for (int height=minHeight; height<maxHeight; height++) {
+			int deletedCount = 0;
 
-			// Give up if we're stopping
+			for (int height = minHeight; height < maxHeight; height++) {
-			if (Controller.isStopping()) {
-				return deletedCount;
-			}
-
-			// Get latest AT states for this height
-			List<String> atAddresses = new ArrayList<>();
-			String updateSql = "SELECT AT_address FROM LatestATStates WHERE height = ?";
-			try (ResultSet resultSet = this.repository.checkedExecute(updateSql, height)) {
-				if (resultSet != null) {
-					do {
-						String atAddress = resultSet.getString(1);
-						atAddresses.add(atAddress);
-
-					} while (resultSet.next());
-				}
-			} catch (SQLException e) {
-				throw new DataException("Unable to fetch flagged accounts from repository", e);
-			}
-
-			List<ATStateData> atStates = this.getBlockATStatesAtHeight(height);
-			for (ATStateData atState : atStates) {
-				//LOGGER.info("Found atState {} at height {}", atState.getATAddress(), atState.getHeight());
 
 				// Give up if we're stopping
 				if (Controller.isStopping()) {
 					return deletedCount;
 				}
 
-				if (atAddresses.contains(atState.getATAddress())) {
+				// Get latest AT states for this height
-					// We don't want to delete this AT state because it is still active
+				List<String> atAddresses = new ArrayList<>();
-					LOGGER.info("Skipping atState {} at height {}", atState.getATAddress(), atState.getHeight());
+				String updateSql = "SELECT AT_address FROM LatestATStates WHERE height = ?";
-					continue;
+				try (ResultSet resultSet = this.repository.checkedExecute(updateSql, height)) {
+					if (resultSet != null) {
+						do {
+							String atAddress = resultSet.getString(1);
+							atAddresses.add(atAddress);
+
+						} while (resultSet.next());
+					}
+				} catch (SQLException e) {
+					throw new DataException("Unable to fetch flagged accounts from repository", e);
 				}
 
-				// Safe to delete everything else for this height
+				List<ATStateData> atStates = this.getBlockATStatesAtHeight(height);
-				try {
+				for (ATStateData atState : atStates) {
-					this.repository.delete("ATStates", "AT_address = ? AND height = ?",
+					//LOGGER.info("Found atState {} at height {}", atState.getATAddress(), atState.getHeight());
-							atState.getATAddress(), atState.getHeight());
+
-					deletedCount++;
+					// Give up if we're stopping
-				} catch (SQLException e) {
+					if (Controller.isStopping()) {
-					throw new DataException("Unable to delete AT state data from repository", e);
+						return deletedCount;
+					}
+
+					if (atAddresses.contains(atState.getATAddress())) {
+						// We don't want to delete this AT state because it is still active
+						LOGGER.info("Skipping atState {} at height {}", atState.getATAddress(), atState.getHeight());
+						continue;
+					}
+
+					// Safe to delete everything else for this height
+					try {
+						this.repository.delete("ATStates", "AT_address = ? AND height = ?",
+								atState.getATAddress(), atState.getHeight());
+						deletedCount++;
+					} catch (SQLException e) {
+						throw new DataException("Unable to delete AT state data from repository", e);
+					}
 				}
 			}
-		}
 
-		return deletedCount;
+			return deletedCount;
+		}
 	}
 
 

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

@@ -69,6 +69,7 @@ public class HSQLDBRepository implements Repository {
 	protected final Map<String, PreparedStatement> preparedStatementCache = new HashMap<>();
 	// We want the same object corresponding to the actual DB
 	protected final Object trimHeightsLock = RepositoryManager.getRepositoryFactory();
+	protected final Object latestATStatesLock = RepositoryManager.getRepositoryFactory();
 
 	private final ATRepository atRepository = new HSQLDBATRepository(this);
 	private final AccountRepository accountRepository = new HSQLDBAccountRepository(this);