Merge branch 'AT-sleep-until-message'

.gitignore

@@ -15,8 +15,8 @@
 /settings.json
 /testnet*
 /settings*.json
-/testchain.json
+/testchain*.json
-/run-testnet.sh
+/run-testnet*.sh
 /.idea
 /qortal.iml
 .DS_Store

src/main/java/org/qortal/at/AT.java

@@ -1,5 +1,7 @@
 package org.qortal.at;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.ciyam.at.MachineState;
@@ -56,12 +58,12 @@ public class AT {
 
 		this.atData = new ATData(atAddress, creatorPublicKey, creation, machineState.version, assetId, codeBytes, codeHash,
 				machineState.isSleeping(), machineState.getSleepUntilHeight(), machineState.isFinished(), machineState.hadFatalError(),
-				machineState.isFrozen(), machineState.getFrozenBalance());
+				machineState.isFrozen(), machineState.getFrozenBalance(), null);
 
 		byte[] stateData = machineState.toBytes();
 		byte[] stateHash = Crypto.digest(stateData);
 
-		this.atStateData = new ATStateData(atAddress, height, stateData, stateHash, 0L, true);
+		this.atStateData = new ATStateData(atAddress, height, stateData, stateHash, 0L, true, null);
 	}
 
 	// Getters / setters
@@ -84,13 +86,28 @@ public class AT {
 		this.repository.getATRepository().delete(this.atData.getATAddress());
 	}
 
+	/**
+	 * Potentially execute AT.
+	 * <p>
+	 * Note that sleep-until-message support might set/reset
+	 * sleep-related flags/values.
+	 * <p>
+	 * {@link #getATStateData()} will return null if nothing happened.
+	 * <p>
+	 * @param blockHeight
+	 * @param blockTimestamp
+	 * @return AT-generated transactions, possibly empty
+	 * @throws DataException
+	 */
 	public List<AtTransaction> run(int blockHeight, long blockTimestamp) throws DataException {
 		String atAddress = this.atData.getATAddress();
 
 		QortalATAPI api = new QortalATAPI(repository, this.atData, blockTimestamp);
 		QortalAtLoggerFactory loggerFactory = QortalAtLoggerFactory.getInstance();
 
-		byte[] codeBytes = this.atData.getCodeBytes();
+		if (!api.willExecute(blockHeight))
+			// this.atStateData will be null
+			return Collections.emptyList();
 
 		// Fetch latest ATStateData for this AT
 		ATStateData latestAtStateData = this.repository.getATRepository().getLatestATState(atAddress);
@@ -100,8 +117,10 @@ public class AT {
 			throw new IllegalStateException("No previous AT state data found");
 
 		// [Re]create AT machine state using AT state data or from scratch as applicable
+		byte[] codeBytes = this.atData.getCodeBytes();
 		MachineState state = MachineState.fromBytes(api, loggerFactory, latestAtStateData.getStateData(), codeBytes);
 		try {
+			api.preExecute(state);
 			state.execute();
 		} catch (Exception e) {
 			throw new DataException(String.format("Uncaught exception while running AT '%s'", atAddress), e);
@@ -109,9 +128,16 @@ public class AT {
 
 		byte[] stateData = state.toBytes();
 		byte[] stateHash = Crypto.digest(stateData);
-		long atFees = api.calcFinalFees(state);
 
-		this.atStateData = new ATStateData(atAddress, blockHeight, stateData, stateHash, atFees, false);
+		// Nothing happened?
+		if (state.getSteps() == 0 && Arrays.equals(stateHash, latestAtStateData.getStateHash()))
+			// this.atStateData will be null
+			return Collections.emptyList();
+
+		long atFees = api.calcFinalFees(state);
+		Long sleepUntilMessageTimestamp = this.atData.getSleepUntilMessageTimestamp();
+
+		this.atStateData = new ATStateData(atAddress, blockHeight, stateData, stateHash, atFees, false, sleepUntilMessageTimestamp);
 
 		return api.getTransactions();
 	}
@@ -130,6 +156,10 @@ public class AT {
 		this.atData.setHadFatalError(state.hadFatalError());
 		this.atData.setIsFrozen(state.isFrozen());
 		this.atData.setFrozenBalance(state.getFrozenBalance());
+
+		// Special sleep-until-message support
+		this.atData.setSleepUntilMessageTimestamp(this.atStateData.getSleepUntilMessageTimestamp());
+
 		this.repository.getATRepository().save(this.atData);
 	}
 
@@ -157,6 +187,10 @@ public class AT {
 		this.atData.setHadFatalError(state.hadFatalError());
 		this.atData.setIsFrozen(state.isFrozen());
 		this.atData.setFrozenBalance(state.getFrozenBalance());
+
+		// Special sleep-until-message support
+		this.atData.setSleepUntilMessageTimestamp(previousStateData.getSleepUntilMessageTimestamp());
+
 		this.repository.getATRepository().save(this.atData);
 	}
 

src/main/java/org/qortal/at/QortalATAPI.java

@@ -32,6 +32,7 @@ import org.qortal.group.Group;
 import org.qortal.repository.ATRepository;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
+import org.qortal.repository.ATRepository.NextTransactionInfo;
 import org.qortal.transaction.AtTransaction;
 import org.qortal.transaction.Transaction.TransactionType;
 import org.qortal.utils.Base58;
@@ -74,8 +75,45 @@ public class QortalATAPI extends API {
 		return this.transactions;
 	}
 
-	public long calcFinalFees(MachineState state) {
+	public boolean willExecute(int blockHeight) throws DataException {
-		return state.getSteps() * this.ciyamAtSettings.feePerStep;
+		// Sleep-until-message/height checking
+		Long sleepUntilMessageTimestamp = this.atData.getSleepUntilMessageTimestamp();
+
+		if (sleepUntilMessageTimestamp != null) {
+			// Quicker to check height, if sleep-until-height also active
+			Integer sleepUntilHeight = this.atData.getSleepUntilHeight();
+
+			boolean wakeDueToHeight = sleepUntilHeight != null && sleepUntilHeight != 0 && blockHeight >= sleepUntilHeight;
+
+			boolean wakeDueToMessage = false;
+			if (!wakeDueToHeight) {
+				// No avoiding asking repository
+				Timestamp previousTxTimestamp = new Timestamp(sleepUntilMessageTimestamp);
+				NextTransactionInfo nextTransactionInfo = this.repository.getATRepository().findNextTransaction(this.atData.getATAddress(),
+						previousTxTimestamp.blockHeight,
+						previousTxTimestamp.transactionSequence);
+
+				wakeDueToMessage = nextTransactionInfo != null;
+			}
+
+			// Can we skip?
+			if (!wakeDueToHeight && !wakeDueToMessage)
+				return false;
+		}
+
+		return true;
+	}
+
+	public void preExecute(MachineState state) {
+		// Sleep-until-message/height checking
+		Long sleepUntilMessageTimestamp = this.atData.getSleepUntilMessageTimestamp();
+
+		if (sleepUntilMessageTimestamp != null) {
+			// We've passed checks, so clear sleep-related flags/values
+			this.setIsSleeping(state, false);
+			this.setSleepUntilHeight(state, 0);
+			this.atData.setSleepUntilMessageTimestamp(null);
+		}
 	}
 
 	// Inherited methods from CIYAM AT API
@@ -412,6 +450,10 @@ public class QortalATAPI extends API {
 
 	// Utility methods
 
+	public long calcFinalFees(MachineState state) {
+		return state.getSteps() * this.ciyamAtSettings.feePerStep;
+	}
+
 	/** Returns partial transaction signature, used to verify we're operating on the same transaction and not naively using block height & sequence. */
 	public static byte[] partialSignature(byte[] fullSignature) {
 		return Arrays.copyOfRange(fullSignature, 8, 32);
@@ -460,6 +502,15 @@ public class QortalATAPI extends API {
 		}
 	}
 
+	/*package*/ void sleepUntilMessageOrHeight(MachineState state, long txTimestamp, Long sleepUntilHeight) {
+		this.setIsSleeping(state, true);
+
+		this.atData.setSleepUntilMessageTimestamp(txTimestamp);
+
+		if (sleepUntilHeight != null)
+			this.setSleepUntilHeight(state, sleepUntilHeight.intValue());
+	}
+
 	/** Returns AT's account */
 	/* package */ Account getATAccount() {
 		return new Account(this.repository, this.atData.getATAddress());

src/main/java/org/qortal/at/QortalFunctionCode.java

@@ -84,6 +84,43 @@ public enum QortalFunctionCode {
 			api.setB(state, bBytes);
 		}
 	},
+	/**
+	 * Sleep AT until a new message arrives after 'tx-timestamp'.<br>
+	 * <tt>0x0503 tx-timestamp</tt>
+	 */
+	SLEEP_UNTIL_MESSAGE(0x0503, 1, false) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			if (functionData.value1 <= 0)
+				return;
+
+			long txTimestamp = functionData.value1;
+
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+			api.sleepUntilMessageOrHeight(state, txTimestamp, null);
+		}
+	},
+	/**
+	 * Sleep AT until a new message arrives, after 'tx-timestamp', or height reached.<br>
+	 * <tt>0x0504 tx-timestamp height</tt>
+	 */
+	SLEEP_UNTIL_MESSAGE_OR_HEIGHT(0x0504, 2, false) {
+		@Override
+		protected void postCheckExecute(FunctionData functionData, MachineState state, short rawFunctionCode) throws ExecutionException {
+			if (functionData.value1 <= 0)
+				return;
+
+			long txTimestamp = functionData.value1;
+
+			if (functionData.value2 <= 0)
+				return;
+
+			long sleepUntilHeight = functionData.value2;
+
+			QortalATAPI api = (QortalATAPI) state.getAPI();
+			api.sleepUntilMessageOrHeight(state, txTimestamp, sleepUntilHeight);
+		}
+	},
 	/**
 	 * Convert address in B to 20-byte value in LSB of B1, and all of B2 & B3.<br>
 	 * <tt>0x0510</tt>

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

@@ -1247,12 +1247,13 @@ public class Block {
 		for (ATData atData : executableATs) {
 			AT at = new AT(this.repository, atData);
 			List<AtTransaction> atTransactions = at.run(this.blockData.getHeight(), this.blockData.getTimestamp());
+			ATStateData atStateData = at.getATStateData();
+			// Didn't execute? (e.g. sleeping)
+			if (atStateData == null)
+				continue;
 
 			allAtTransactions.addAll(atTransactions);
-
-			ATStateData atStateData = at.getATStateData();
 			this.ourAtStates.add(atStateData);
-
 			this.ourAtFees += atStateData.getFees();
 		}
 

src/main/java/org/qortal/data/at/ATData.java

@@ -23,6 +23,7 @@ public class ATData {
 	private boolean isFrozen;
 	@XmlJavaTypeAdapter(value = org.qortal.api.AmountTypeAdapter.class)
 	private Long frozenBalance;
+	private Long sleepUntilMessageTimestamp;
 
 	// Constructors
 
@@ -31,7 +32,8 @@ public class ATData {
 	}
 
 	public ATData(String ATAddress, byte[] creatorPublicKey, long creation, int version, long assetId, byte[] codeBytes, byte[] codeHash,
-			boolean isSleeping, Integer sleepUntilHeight, boolean isFinished, boolean hadFatalError, boolean isFrozen, Long frozenBalance) {
+			boolean isSleeping, Integer sleepUntilHeight, boolean isFinished, boolean hadFatalError, boolean isFrozen, Long frozenBalance,
+			Long sleepUntilMessageTimestamp) {
 		this.ATAddress = ATAddress;
 		this.creatorPublicKey = creatorPublicKey;
 		this.creation = creation;
@@ -45,6 +47,7 @@ public class ATData {
 		this.hadFatalError = hadFatalError;
 		this.isFrozen = isFrozen;
 		this.frozenBalance = frozenBalance;
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
 	}
 
 	/** For constructing skeleton ATData with bare minimum info. */
@@ -133,4 +136,12 @@ public class ATData {
 		this.frozenBalance = frozenBalance;
 	}
 
+	public Long getSleepUntilMessageTimestamp() {
+		return this.sleepUntilMessageTimestamp;
+	}
+
+	public void setSleepUntilMessageTimestamp(Long sleepUntilMessageTimestamp) {
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
+	}
+
 }

src/main/java/org/qortal/data/at/ATStateData.java

@@ -10,35 +10,32 @@ public class ATStateData {
 	private Long fees;
 	private boolean isInitial;
 
+	// Qortal-AT-specific
+	private Long sleepUntilMessageTimestamp;
+
 	// Constructors
 
 	/** Create new ATStateData */
-	public ATStateData(String ATAddress, Integer height, byte[] stateData, byte[] stateHash, Long fees, boolean isInitial) {
+	public ATStateData(String ATAddress, Integer height, byte[] stateData, byte[] stateHash, Long fees,
+			boolean isInitial, Long sleepUntilMessageTimestamp) {
 		this.ATAddress = ATAddress;
 		this.height = height;
 		this.stateData = stateData;
 		this.stateHash = stateHash;
 		this.fees = fees;
 		this.isInitial = isInitial;
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
 	}
 
 	/** For recreating per-block ATStateData from repository where not all info is needed */
 	public ATStateData(String ATAddress, int height, byte[] stateHash, Long fees, boolean isInitial) {
-		this(ATAddress, height, null, stateHash, fees, isInitial);
+		this(ATAddress, height, null, stateHash, fees, isInitial, null);
-	}
-
-	/** For creating ATStateData from serialized bytes when we don't have all the info */
-	public ATStateData(String ATAddress, byte[] stateHash) {
-		// This won't ever be initial AT state from deployment as that's never serialized over the network,
-		// but generated when the DeployAtTransaction is processed locally.
-		this(ATAddress, null, null, stateHash, null, false);
 	}
 
 	/** For creating ATStateData from serialized bytes when we don't have all the info */
 	public ATStateData(String ATAddress, byte[] stateHash, Long fees) {
-		// This won't ever be initial AT state from deployment as that's never serialized over the network,
+		// This won't ever be initial AT state from deployment, as that's never serialized over the network.
-		// but generated when the DeployAtTransaction is processed locally.
+		this(ATAddress, null, null, stateHash, fees, false, null);
-		this(ATAddress, null, null, stateHash, fees, false);
 	}
 
 	// Getters / setters
@@ -72,4 +69,12 @@ public class ATStateData {
 		return this.isInitial;
 	}
 
+	public Long getSleepUntilMessageTimestamp() {
+		return this.sleepUntilMessageTimestamp;
+	}
+
+	public void setSleepUntilMessageTimestamp(Long sleepUntilMessageTimestamp) {
+		this.sleepUntilMessageTimestamp = sleepUntilMessageTimestamp;
+	}
+
 }

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

@@ -103,7 +103,7 @@ public interface ATRepository {
 	/**
 	 * Returns all ATStateData for a given block height.
 	 * <p>
-	 * Unlike <tt>getATState</tt>, only returns ATStateData saved at the given height.
+	 * Unlike <tt>getATState</tt>, only returns <i>partial</i> ATStateData saved at the given height.
 	 *
 	 * @param height
 	 *            - block height

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

@@ -32,7 +32,7 @@ public class HSQLDBATRepository implements ATRepository {
 	public ATData fromATAddress(String atAddress) throws DataException {
 		String sql = "SELECT creator, created_when, version, asset_id, code_bytes, code_hash, "
 				+ "is_sleeping, sleep_until_height, is_finished, had_fatal_error, "
-				+ "is_frozen, frozen_balance "
+				+ "is_frozen, frozen_balance, sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "WHERE AT_address = ? LIMIT 1";
 
@@ -60,8 +60,13 @@ public class HSQLDBATRepository implements ATRepository {
 			if (frozenBalance == 0 && resultSet.wasNull())
 				frozenBalance = null;
 
+			Long sleepUntilMessageTimestamp = resultSet.getLong(13);
+			if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+				sleepUntilMessageTimestamp = null;
+
 			return new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-					isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+					isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance,
+					sleepUntilMessageTimestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch AT from repository", e);
 		}
@@ -94,7 +99,7 @@ public class HSQLDBATRepository implements ATRepository {
 	public List<ATData> getAllExecutableATs() throws DataException {
 		String sql = "SELECT AT_address, creator, created_when, version, asset_id, code_bytes, code_hash, "
 				+ "is_sleeping, sleep_until_height, had_fatal_error, "
-				+ "is_frozen, frozen_balance "
+				+ "is_frozen, frozen_balance, sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "WHERE is_finished = false "
 				+ "ORDER BY created_when ASC";
@@ -128,8 +133,13 @@ public class HSQLDBATRepository implements ATRepository {
 				if (frozenBalance == 0 && resultSet.wasNull())
 					frozenBalance = null;
 
+				Long sleepUntilMessageTimestamp = resultSet.getLong(13);
+				if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+					sleepUntilMessageTimestamp = null;
+
 				ATData atData = new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance,
+						sleepUntilMessageTimestamp);
 
 				executableATs.add(atData);
 			} while (resultSet.next());
@@ -147,7 +157,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 		sql.append("SELECT AT_address, creator, created_when, version, asset_id, code_bytes, ")
 				.append("is_sleeping, sleep_until_height, is_finished, had_fatal_error, ")
-				.append("is_frozen, frozen_balance ")
+				.append("is_frozen, frozen_balance, sleep_until_message_timestamp ")
 				.append("FROM ATs ")
 				.append("WHERE code_hash = ? ");
 		bindParams.add(codeHash);
@@ -191,8 +201,13 @@ public class HSQLDBATRepository implements ATRepository {
 				if (frozenBalance == 0 && resultSet.wasNull())
 					frozenBalance = null;
 
+				Long sleepUntilMessageTimestamp = resultSet.getLong(13);
+				if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+					sleepUntilMessageTimestamp = null;
+
 				ATData atData = new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance,
+						sleepUntilMessageTimestamp);
 
 				matchingATs.add(atData);
 			} while (resultSet.next());
@@ -210,7 +225,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 		sql.append("SELECT AT_address, creator, created_when, version, asset_id, code_bytes, ")
 				.append("is_sleeping, sleep_until_height, is_finished, had_fatal_error, ")
-				.append("is_frozen, frozen_balance, code_hash ")
+				.append("is_frozen, frozen_balance, code_hash, sleep_until_message_timestamp ")
 				.append("FROM ");
 
 		// (VALUES (?), (?), ...) AS ATCodeHashes (code_hash)
@@ -264,9 +279,10 @@ public class HSQLDBATRepository implements ATRepository {
 					frozenBalance = null;
 
 				byte[] codeHash = resultSet.getBytes(13);
+				Long sleepUntilMessageTimestamp = resultSet.getLong(14);
 
 				ATData atData = new ATData(atAddress, creatorPublicKey, created, version, assetId, codeBytes, codeHash,
-						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance);
+						isSleeping, sleepUntilHeight, isFinished, hadFatalError, isFrozen, frozenBalance, sleepUntilMessageTimestamp);
 
 				matchingATs.add(atData);
 			} while (resultSet.next());
@@ -305,7 +321,7 @@ public class HSQLDBATRepository implements ATRepository {
 				.bind("code_bytes", atData.getCodeBytes()).bind("code_hash", atData.getCodeHash())
 				.bind("is_sleeping", atData.getIsSleeping()).bind("sleep_until_height", atData.getSleepUntilHeight())
 				.bind("is_finished", atData.getIsFinished()).bind("had_fatal_error", atData.getHadFatalError()).bind("is_frozen", atData.getIsFrozen())
-				.bind("frozen_balance", atData.getFrozenBalance());
+				.bind("frozen_balance", atData.getFrozenBalance()).bind("sleep_until_message_timestamp", atData.getSleepUntilMessageTimestamp());
 
 		try {
 			saveHelper.execute(this.repository);
@@ -328,7 +344,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public ATStateData getATStateAtHeight(String atAddress, int height) throws DataException {
-		String sql = "SELECT state_data, state_hash, fees, is_initial "
+		String sql = "SELECT state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 				+ "FROM ATStates "
 				+ "LEFT OUTER JOIN ATStatesData USING (AT_address, height) "
 				+ "WHERE ATStates.AT_address = ? AND ATStates.height = ? "
@@ -343,7 +359,11 @@ public class HSQLDBATRepository implements ATRepository {
 			long fees = resultSet.getLong(3);
 			boolean isInitial = resultSet.getBoolean(4);
 
-			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+			Long sleepUntilMessageTimestamp = resultSet.getLong(5);
+			if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+				sleepUntilMessageTimestamp = null;
+
+			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial, sleepUntilMessageTimestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch AT state from repository", e);
 		}
@@ -351,7 +371,7 @@ public class HSQLDBATRepository implements ATRepository {
 
 	@Override
 	public ATStateData getLatestATState(String atAddress) throws DataException {
-		String sql = "SELECT height, state_data, state_hash, fees, is_initial "
+		String sql = "SELECT height, state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 				+ "FROM ATStates "
 				+ "JOIN ATStatesData USING (AT_address, height) "
 				+ "WHERE ATStates.AT_address = ? "
@@ -370,7 +390,11 @@ public class HSQLDBATRepository implements ATRepository {
 			long fees = resultSet.getLong(4);
 			boolean isInitial = resultSet.getBoolean(5);
 
-			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+			Long sleepUntilMessageTimestamp = resultSet.getLong(6);
+			if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+				sleepUntilMessageTimestamp = null;
+
+			return new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial, sleepUntilMessageTimestamp);
 		} catch (SQLException e) {
 			throw new DataException("Unable to fetch latest AT state from repository", e);
 		}
@@ -383,10 +407,10 @@ public class HSQLDBATRepository implements ATRepository {
 		StringBuilder sql = new StringBuilder(1024);
 		List<Object> bindParams = new ArrayList<>();
 
-		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial "
+		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial, FinalATStates.sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "CROSS JOIN LATERAL("
-					+ "SELECT height, state_data, state_hash, fees, is_initial "
+					+ "SELECT height, state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 					+ "FROM ATStates "
 					+ "JOIN ATStatesData USING (AT_address, height) "
 					+ "WHERE ATStates.AT_address = ATs.AT_address ");
@@ -440,7 +464,11 @@ public class HSQLDBATRepository implements ATRepository {
 				long fees = resultSet.getLong(5);
 				boolean isInitial = resultSet.getBoolean(6);
 
-				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+				Long sleepUntilMessageTimestamp = resultSet.getLong(7);
+				if (sleepUntilMessageTimestamp == 0 && resultSet.wasNull())
+					sleepUntilMessageTimestamp = null;
+
+				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial, sleepUntilMessageTimestamp);
 
 				atStates.add(atStateData);
 			} while (resultSet.next());
@@ -471,7 +499,7 @@ public class HSQLDBATRepository implements ATRepository {
 		StringBuilder sql = new StringBuilder(1024);
 		List<Object> bindParams = new ArrayList<>();
 
-		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial "
+		sql.append("SELECT AT_address, height, state_data, state_hash, fees, is_initial, sleep_until_message_timestamp "
 				+ "FROM ATs "
 				+ "CROSS JOIN LATERAL("
 					+ "SELECT height, state_data, state_hash, fees, is_initial "
@@ -526,8 +554,10 @@ public class HSQLDBATRepository implements ATRepository {
 				byte[] stateHash = resultSet.getBytes(4);
 				long fees = resultSet.getLong(5);
 				boolean isInitial = resultSet.getBoolean(6);
+				Long sleepUntilMessageTimestamp = resultSet.getLong(7);
 
-				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial);
+				ATStateData atStateData = new ATStateData(atAddress, height, stateData, stateHash, fees, isInitial,
+						sleepUntilMessageTimestamp);
 
 				atStates.add(atStateData);
 			} while (resultSet.next());
@@ -662,7 +692,8 @@ public class HSQLDBATRepository implements ATRepository {
 
 		atStatesSaver.bind("AT_address", atStateData.getATAddress()).bind("height", atStateData.getHeight())
 				.bind("state_hash", atStateData.getStateHash())
-				.bind("fees", atStateData.getFees()).bind("is_initial", atStateData.isInitial());
+				.bind("fees", atStateData.getFees()).bind("is_initial", atStateData.isInitial())
+				.bind("sleep_until_message_timestamp", atStateData.getSleepUntilMessageTimestamp());
 
 		try {
 			atStatesSaver.execute(this.repository);

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

@@ -699,7 +699,7 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("CHECKPOINT");
 					break;
 
-				case 30:
+				case 30: {
 					// Split AT state data off to new table for better performance/management.
 
 					if (!wasPristine && !"mem".equals(HSQLDBRepository.getDbPathname(connection.getMetaData().getURL()))) {
@@ -774,6 +774,7 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("ALTER TABLE ATStatesNew RENAME TO ATStates");
 					stmt.execute("CHECKPOINT");
 					break;
+				}
 
 				case 31:
 					// Fix latest AT state cache which was previous created as TEMPORARY
@@ -822,6 +823,41 @@ public class HSQLDBDatabaseUpdates {
 							+ "timestamp_signature Signature NOT NULL, " + TRANSACTION_KEYS + ")");
 					break;
 
+				case 34: {
+					// AT sleep-until-message support
+					LOGGER.info("Altering AT table in repository - this might take a while... (approx. 20 seconds on high-spec)");
+					stmt.execute("ALTER TABLE ATs ADD sleep_until_message_timestamp BIGINT");
+
+					// Create new AT-states table with new column
+					stmt.execute("CREATE TABLE ATStatesNew ("
+							+ "AT_address QortalAddress, height INTEGER NOT NULL, state_hash ATStateHash NOT NULL, "
+							+ "fees QortalAmount NOT NULL, is_initial BOOLEAN NOT NULL, sleep_until_message_timestamp BIGINT, "
+							+ "PRIMARY KEY (AT_address, height), "
+							+ "FOREIGN KEY (AT_address) REFERENCES ATs (AT_address) ON DELETE CASCADE)");
+					stmt.execute("SET TABLE ATStatesNew NEW SPACE");
+					stmt.execute("CHECKPOINT");
+
+					ResultSet resultSet = stmt.executeQuery("SELECT height FROM Blocks ORDER BY height DESC LIMIT 1");
+					final int blockchainHeight = resultSet.next() ? resultSet.getInt(1) : 0;
+					final int heightStep = 100;
+
+					LOGGER.info("Altering AT states table in repository - this might take a while... (approx. 3 mins on high-spec)");
+					for (int minHeight = 1; minHeight < blockchainHeight; minHeight += heightStep) {
+						stmt.execute("INSERT INTO ATStatesNew ("
+								+ "SELECT AT_address, height, state_hash, fees, is_initial, NULL "
+								+ "FROM ATStates "
+								+ "WHERE height BETWEEN " + minHeight + " AND " + (minHeight + heightStep - 1)
+								+ ")");
+						stmt.execute("COMMIT");
+					}
+					stmt.execute("CHECKPOINT");
+
+					stmt.execute("DROP TABLE ATStates");
+					stmt.execute("ALTER TABLE ATStatesNew RENAME TO ATStates");
+					stmt.execute("CHECKPOINT");
+					break;
+				}
+
 				default:
 					// nothing to do
 					return false;

src/test/java/org/qortal/test/at/AtRepositoryTests.java

@@ -354,7 +354,8 @@ public class AtRepositoryTests extends Common {
 					/*StateData*/ null,
 					atStateData.getStateHash(),
 					atStateData.getFees(),
-					atStateData.isInitial());
+					atStateData.isInitial(),
+					atStateData.getSleepUntilMessageTimestamp());
 			repository.getATRepository().save(newAtStateData);
 
 			atStateData = repository.getATRepository().getATStateAtHeight(atAddress, testHeight);

src/test/java/org/qortal/test/at/SleepUntilMessageOrHeightTests.java

@@ -0,0 +1,365 @@
+package org.qortal.test.at;
+
+import static org.junit.Assert.*;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import org.ciyam.at.CompilationException;
+import org.ciyam.at.FunctionCode;
+import org.ciyam.at.MachineState;
+import org.ciyam.at.OpCode;
+import org.ciyam.at.Timestamp;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.account.Account;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.block.Block;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.block.BlockData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.test.common.BlockUtils;
+import org.qortal.test.common.Common;
+import org.qortal.test.common.TransactionUtils;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.utils.BitTwiddling;
+
+public class SleepUntilMessageOrHeightTests extends Common {
+
+	private static final byte[] messageData = new byte[] { 0x44 };
+	private static final byte[] creationBytes = buildSleepUntilMessageOrHeightAT();
+	private static final long fundingAmount = 1_00000000L;
+	private static final long WAKE_HEIGHT = 10L;
+
+	private Repository repository = null;
+	private PrivateKeyAccount deployer;
+	private DeployAtTransaction deployAtTransaction;
+	private Account atAccount;
+	private String atAddress;
+	private byte[] rawNextTimestamp = new byte[32];
+	private Transaction transaction;
+
+	@Before
+	public void before() throws DataException {
+		Common.useDefaultSettings();
+
+		this.repository = RepositoryManager.getRepository();
+		this.deployer = Common.getTestAccount(repository, "alice");
+
+		this.deployAtTransaction = doDeploy(repository, deployer, creationBytes, fundingAmount);
+		this.atAccount = deployAtTransaction.getATAccount();
+		this.atAddress = deployAtTransaction.getATAccount().getAddress();
+	}
+
+	@After
+	public void after() throws DataException {
+		if (this.repository != null)
+			this.repository.close();
+
+		this.repository = null;
+	}
+
+	@Test
+	public void testDeploy() throws DataException {
+			// Confirm initial value is zero
+			extractNextTxTimestamp(repository, atAddress, rawNextTimestamp);
+			assertArrayEquals(new byte[32], rawNextTimestamp);
+	}
+
+	@Test
+	public void testFeelessSleep() throws DataException {
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE
+		BlockUtils.mintBlock(repository);
+
+		// Fetch AT's balance for this height
+		long preMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		// Mint block
+		BlockUtils.mintBlock(repository);
+
+		// Fetch new AT balance
+		long postMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		assertEquals(preMintBalance, postMintBalance);
+	}
+
+	@Test
+	public void testFeelessSleep2() throws DataException {
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE
+		BlockUtils.mintBlock(repository);
+
+		// Fetch AT's balance for this height
+		long preMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		// Mint several blocks
+		for (int i = 0; i < 5; ++i)
+			BlockUtils.mintBlock(repository);
+
+		// Fetch new AT balance
+		long postMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		assertEquals(preMintBalance, postMintBalance);
+	}
+
+	@Test
+	public void testSleepUntilMessage() throws DataException {
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE_OR_HEIGHT
+		BlockUtils.mintBlock(repository);
+
+		// Send message to AT
+		transaction = sendMessage(repository, deployer, messageData, atAddress);
+		BlockUtils.mintBlock(repository);
+
+		// Mint block so AT executes and finds message
+		BlockUtils.mintBlock(repository);
+
+		// Confirm AT finds message
+		assertTimestamp(repository, atAddress, transaction);
+	}
+
+	@Test
+	public void testSleepUntilHeight() throws DataException {
+		// AT deployment in block 2
+
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE_OR_HEIGHT
+		BlockUtils.mintBlock(repository); // height now 3
+
+		// Fetch AT's balance for this height
+		long preMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		// Mint several blocks
+		for (int i = 3; i < WAKE_HEIGHT; ++i)
+			BlockUtils.mintBlock(repository);
+
+		// We should now be at WAKE_HEIGHT
+		long height = repository.getBlockRepository().getBlockchainHeight();
+		assertEquals(WAKE_HEIGHT, height);
+
+		// AT should have woken and run at this height so balance should have changed
+
+		// Fetch new AT balance
+		long postMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		assertNotSame(preMintBalance, postMintBalance);
+
+		// Confirm AT has no message
+		extractNextTxTimestamp(repository, atAddress, rawNextTimestamp);
+		assertArrayEquals(new byte[32], rawNextTimestamp);
+
+		// Mint yet another block
+		BlockUtils.mintBlock(repository);
+
+		// AT should also have woken and run at this height so balance should have changed
+
+		// Fetch new AT balance
+		long postMint2Balance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		assertNotSame(postMintBalance, postMint2Balance);
+
+		// Confirm AT still has no message
+		extractNextTxTimestamp(repository, atAddress, rawNextTimestamp);
+		assertArrayEquals(new byte[32], rawNextTimestamp);
+
+	}
+
+	private static byte[] buildSleepUntilMessageOrHeightAT() {
+		// Labels for data segment addresses
+		int addrCounter = 0;
+
+		// Beginning of data segment for easy extraction
+		final int addrNextTx = addrCounter;
+		addrCounter += 4;
+
+		final int addrNextTxIndex = addrCounter++;
+
+		final int addrLastTxTimestamp = addrCounter++;
+
+		final int addrWakeHeight = addrCounter++;
+
+		// Data segment
+		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
+
+		// skip addrNextTx
+		dataByteBuffer.position(dataByteBuffer.position() + 4 * MachineState.VALUE_SIZE);
+
+		// Store pointer to addrNextTx at addrNextTxIndex
+		dataByteBuffer.putLong(addrNextTx);
+
+		// skip addrLastTxTimestamp
+		dataByteBuffer.position(dataByteBuffer.position() + MachineState.VALUE_SIZE);
+
+		// Store fixed wake height (block 10)
+		dataByteBuffer.putLong(WAKE_HEIGHT);
+
+		ByteBuffer codeByteBuffer = ByteBuffer.allocate(512);
+
+		// Two-pass version
+		for (int pass = 0; pass < 2; ++pass) {
+			codeByteBuffer.clear();
+
+			try {
+				/* Initialization */
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxTimestamp));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message to AT */
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT_2.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE_OR_HEIGHT.value, addrLastTxTimestamp, addrWakeHeight));
+
+				// Find next transaction to this AT since the last one (if any)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxTimestamp));
+
+				// Copy A to data segment, starting at addrNextTx (as pointed to by addrNextTxIndex)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_A_IND, addrNextTxIndex));
+
+				// Stop if timestamp part of A is zero
+				codeByteBuffer.put(OpCode.STZ_DAT.compile(addrNextTx));
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxTimestamp));
+
+				// We're done
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+			} catch (CompilationException e) {
+				throw new IllegalStateException("Unable to compile AT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		final short ciyamAtVersion = 2;
+		final short numCallStackPages = 0;
+		final short numUserStackPages = 0;
+		final long minActivationAmount = 0L;
+
+		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
+	}
+
+	private DeployAtTransaction doDeploy(Repository repository, PrivateKeyAccount deployer, byte[] creationBytes, long fundingAmount) throws DataException {
+		long txTimestamp = System.currentTimeMillis();
+		byte[] lastReference = deployer.getLastReference();
+
+		if (lastReference == null) {
+			System.err.println(String.format("Qortal account %s has no last reference", deployer.getAddress()));
+			System.exit(2);
+		}
+
+		Long fee = null;
+		String name = "Test AT";
+		String description = "Test AT";
+		String atType = "Test";
+		String tags = "TEST";
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, deployer.getPublicKey(), fee, null);
+		TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, fundingAmount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		TransactionUtils.signAndMint(repository, deployAtTransactionData, deployer);
+
+		return deployAtTransaction;
+	}
+
+	private void extractNextTxTimestamp(Repository repository, String atAddress, byte[] rawNextTimestamp) throws DataException {
+		// Check AT result
+		ATStateData atStateData = repository.getATRepository().getLatestATState(atAddress);
+		byte[] stateData = atStateData.getStateData();
+
+		byte[] dataBytes = MachineState.extractDataBytes(stateData);
+
+		System.arraycopy(dataBytes, 0, rawNextTimestamp, 0, rawNextTimestamp.length);
+	}
+
+	private MessageTransaction sendMessage(Repository repository, PrivateKeyAccount sender, byte[] data, String recipient) throws DataException {
+		long txTimestamp = System.currentTimeMillis();
+		byte[] lastReference = sender.getLastReference();
+
+		if (lastReference == null) {
+			System.err.println(String.format("Qortal account %s has no last reference", sender.getAddress()));
+			System.exit(2);
+		}
+
+		Long fee = null;
+		int version = 4;
+		int nonce = 0;
+		long amount = 0;
+		Long assetId = null; // because amount is zero
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, sender.getPublicKey(), fee, null);
+		TransactionData messageTransactionData = new MessageTransactionData(baseTransactionData, version, nonce, recipient, amount, assetId, data, false, false);
+
+		MessageTransaction messageTransaction = new MessageTransaction(repository, messageTransactionData);
+
+		fee = messageTransaction.calcRecommendedFee();
+		messageTransactionData.setFee(fee);
+
+		TransactionUtils.signAndImportValid(repository, messageTransactionData, sender);
+
+		return messageTransaction;
+	}
+
+	private void assertTimestamp(Repository repository, String atAddress, Transaction transaction) throws DataException {
+		int height = transaction.getHeight();
+		byte[] transactionSignature = transaction.getTransactionData().getSignature();
+
+		BlockData blockData = repository.getBlockRepository().fromHeight(height);
+		assertNotNull(blockData);
+
+		Block block = new Block(repository, blockData);
+
+		List<Transaction> blockTransactions = block.getTransactions();
+		int sequence;
+		for (sequence = blockTransactions.size() - 1; sequence >= 0; --sequence)
+			if (Arrays.equals(blockTransactions.get(sequence).getTransactionData().getSignature(), transactionSignature))
+				break;
+
+		assertNotSame(-1, sequence);
+
+		byte[] rawNextTimestamp = new byte[32];
+		extractNextTxTimestamp(repository, atAddress, rawNextTimestamp);
+
+		Timestamp expectedTimestamp = new Timestamp(height, sequence);
+		Timestamp actualTimestamp = new Timestamp(BitTwiddling.longFromBEBytes(rawNextTimestamp, 0));
+
+		assertEquals(String.format("Expected height %d, seq %d but was height %d, seq %d",
+					height, sequence,
+					actualTimestamp.blockHeight, actualTimestamp.transactionSequence
+				),
+				expectedTimestamp.longValue(),
+				actualTimestamp.longValue());
+
+		byte[] expectedPartialSignature = new byte[24];
+		System.arraycopy(transactionSignature, 8, expectedPartialSignature, 0, expectedPartialSignature.length);
+
+		byte[] actualPartialSignature = new byte[24];
+		System.arraycopy(rawNextTimestamp, 8, actualPartialSignature, 0, actualPartialSignature.length);
+
+		assertArrayEquals(expectedPartialSignature, actualPartialSignature);
+	}
+
+}

src/test/java/org/qortal/test/at/SleepUntilMessageTests.java

@@ -0,0 +1,311 @@
+package org.qortal.test.at;
+
+import static org.junit.Assert.*;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+
+import org.ciyam.at.CompilationException;
+import org.ciyam.at.FunctionCode;
+import org.ciyam.at.MachineState;
+import org.ciyam.at.OpCode;
+import org.ciyam.at.Timestamp;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.qortal.account.Account;
+import org.qortal.account.PrivateKeyAccount;
+import org.qortal.asset.Asset;
+import org.qortal.at.QortalFunctionCode;
+import org.qortal.block.Block;
+import org.qortal.data.at.ATStateData;
+import org.qortal.data.block.BlockData;
+import org.qortal.data.transaction.BaseTransactionData;
+import org.qortal.data.transaction.DeployAtTransactionData;
+import org.qortal.data.transaction.MessageTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.group.Group;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.test.common.BlockUtils;
+import org.qortal.test.common.Common;
+import org.qortal.test.common.TransactionUtils;
+import org.qortal.transaction.DeployAtTransaction;
+import org.qortal.transaction.MessageTransaction;
+import org.qortal.transaction.Transaction;
+import org.qortal.utils.BitTwiddling;
+
+public class SleepUntilMessageTests extends Common {
+
+	private static final byte[] messageData = new byte[] { 0x44 };
+	private static final byte[] creationBytes = buildSleepUntilMessageAT();
+	private static final long fundingAmount = 1_00000000L;
+
+	private Repository repository = null;
+	private PrivateKeyAccount deployer;
+	private DeployAtTransaction deployAtTransaction;
+	private Account atAccount;
+	private String atAddress;
+	private byte[] rawNextTimestamp = new byte[32];
+	private Transaction transaction;
+
+	@Before
+	public void before() throws DataException {
+		Common.useDefaultSettings();
+
+		this.repository = RepositoryManager.getRepository();
+		this.deployer = Common.getTestAccount(repository, "alice");
+
+		this.deployAtTransaction = doDeploy(repository, deployer, creationBytes, fundingAmount);
+		this.atAccount = deployAtTransaction.getATAccount();
+		this.atAddress = deployAtTransaction.getATAccount().getAddress();
+	}
+
+	@After
+	public void after() throws DataException {
+		if (this.repository != null)
+			this.repository.close();
+
+		this.repository = null;
+	}
+
+	@Test
+	public void testDeploy() throws DataException {
+			// Confirm initial value is zero
+			extractNextTxTimestamp(repository, atAddress, rawNextTimestamp);
+			assertArrayEquals(new byte[32], rawNextTimestamp);
+	}
+
+	@Test
+	public void testFeelessSleep() throws DataException {
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE
+		BlockUtils.mintBlock(repository);
+
+		// Fetch AT's balance for this height
+		long preMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		// Mint block
+		BlockUtils.mintBlock(repository);
+
+		// Fetch new AT balance
+		long postMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		assertEquals(preMintBalance, postMintBalance);
+	}
+
+	@Test
+	public void testFeelessSleep2() throws DataException {
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE
+		BlockUtils.mintBlock(repository);
+
+		// Fetch AT's balance for this height
+		long preMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		// Mint several blocks
+		for (int i = 0; i < 10; ++i)
+			BlockUtils.mintBlock(repository);
+
+		// Fetch new AT balance
+		long postMintBalance = atAccount.getConfirmedBalance(Asset.QORT);
+
+		assertEquals(preMintBalance, postMintBalance);
+	}
+
+	@Test
+	public void testSleepUntilMessage() throws DataException {
+		// Mint block to allow AT to initialize and call SLEEP_UNTIL_MESSAGE
+		BlockUtils.mintBlock(repository);
+
+		// Send message to AT
+		transaction = sendMessage(repository, deployer, messageData, atAddress);
+		BlockUtils.mintBlock(repository);
+
+		// Mint block so AT executes and finds message
+		BlockUtils.mintBlock(repository);
+
+		// Confirm AT finds message
+		assertTimestamp(repository, atAddress, transaction);
+	}
+
+	private static byte[] buildSleepUntilMessageAT() {
+		// Labels for data segment addresses
+		int addrCounter = 0;
+
+		// Beginning of data segment for easy extraction
+		final int addrNextTx = addrCounter;
+		addrCounter += 4;
+
+		final int addrNextTxIndex = addrCounter++;
+
+		final int addrLastTxTimestamp = addrCounter++;
+
+		// Data segment
+		ByteBuffer dataByteBuffer = ByteBuffer.allocate(addrCounter * MachineState.VALUE_SIZE);
+
+		// skip addrNextTx
+		dataByteBuffer.position(dataByteBuffer.position() + 4 * MachineState.VALUE_SIZE);
+
+		// Store pointer to addrNextTx at addrNextTxIndex
+		dataByteBuffer.putLong(addrNextTx);
+
+		ByteBuffer codeByteBuffer = ByteBuffer.allocate(512);
+
+		// Two-pass version
+		for (int pass = 0; pass < 2; ++pass) {
+			codeByteBuffer.clear();
+
+			try {
+				/* Initialization */
+
+				// Use AT creation 'timestamp' as starting point for finding transactions sent to AT
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_CREATION_TIMESTAMP, addrLastTxTimestamp));
+
+				// Set restart position to after this opcode
+				codeByteBuffer.put(OpCode.SET_PCS.compile());
+
+				/* Loop, waiting for message to AT */
+
+				/* Sleep until message arrives */
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(QortalFunctionCode.SLEEP_UNTIL_MESSAGE.value, addrLastTxTimestamp));
+
+				// Find next transaction to this AT since the last one (if any)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.PUT_TX_AFTER_TIMESTAMP_INTO_A, addrLastTxTimestamp));
+
+				// Copy A to data segment, starting at addrNextTx (as pointed to by addrNextTxIndex)
+				codeByteBuffer.put(OpCode.EXT_FUN_DAT.compile(FunctionCode.GET_A_IND, addrNextTxIndex));
+
+				// Stop if timestamp part of A is zero
+				codeByteBuffer.put(OpCode.STZ_DAT.compile(addrNextTx));
+
+				// Update our 'last found transaction's timestamp' using 'timestamp' from transaction
+				codeByteBuffer.put(OpCode.EXT_FUN_RET.compile(FunctionCode.GET_TIMESTAMP_FROM_TX_IN_A, addrLastTxTimestamp));
+
+				// We're done
+				codeByteBuffer.put(OpCode.FIN_IMD.compile());
+
+			} catch (CompilationException e) {
+				throw new IllegalStateException("Unable to compile AT?", e);
+			}
+		}
+
+		codeByteBuffer.flip();
+
+		byte[] codeBytes = new byte[codeByteBuffer.limit()];
+		codeByteBuffer.get(codeBytes);
+
+		final short ciyamAtVersion = 2;
+		final short numCallStackPages = 0;
+		final short numUserStackPages = 0;
+		final long minActivationAmount = 0L;
+
+		return MachineState.toCreationBytes(ciyamAtVersion, codeBytes, dataByteBuffer.array(), numCallStackPages, numUserStackPages, minActivationAmount);
+	}
+
+	private DeployAtTransaction doDeploy(Repository repository, PrivateKeyAccount deployer, byte[] creationBytes, long fundingAmount) throws DataException {
+		long txTimestamp = System.currentTimeMillis();
+		byte[] lastReference = deployer.getLastReference();
+
+		if (lastReference == null) {
+			System.err.println(String.format("Qortal account %s has no last reference", deployer.getAddress()));
+			System.exit(2);
+		}
+
+		Long fee = null;
+		String name = "Test AT";
+		String description = "Test AT";
+		String atType = "Test";
+		String tags = "TEST";
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, deployer.getPublicKey(), fee, null);
+		TransactionData deployAtTransactionData = new DeployAtTransactionData(baseTransactionData, name, description, atType, tags, creationBytes, fundingAmount, Asset.QORT);
+
+		DeployAtTransaction deployAtTransaction = new DeployAtTransaction(repository, deployAtTransactionData);
+
+		fee = deployAtTransaction.calcRecommendedFee();
+		deployAtTransactionData.setFee(fee);
+
+		TransactionUtils.signAndMint(repository, deployAtTransactionData, deployer);
+
+		return deployAtTransaction;
+	}
+
+	private void extractNextTxTimestamp(Repository repository, String atAddress, byte[] rawNextTimestamp) throws DataException {
+		// Check AT result
+		ATStateData atStateData = repository.getATRepository().getLatestATState(atAddress);
+		byte[] stateData = atStateData.getStateData();
+
+		byte[] dataBytes = MachineState.extractDataBytes(stateData);
+
+		System.arraycopy(dataBytes, 0, rawNextTimestamp, 0, rawNextTimestamp.length);
+	}
+
+	private MessageTransaction sendMessage(Repository repository, PrivateKeyAccount sender, byte[] data, String recipient) throws DataException {
+		long txTimestamp = System.currentTimeMillis();
+		byte[] lastReference = sender.getLastReference();
+
+		if (lastReference == null) {
+			System.err.println(String.format("Qortal account %s has no last reference", sender.getAddress()));
+			System.exit(2);
+		}
+
+		Long fee = null;
+		int version = 4;
+		int nonce = 0;
+		long amount = 0;
+		Long assetId = null; // because amount is zero
+
+		BaseTransactionData baseTransactionData = new BaseTransactionData(txTimestamp, Group.NO_GROUP, lastReference, sender.getPublicKey(), fee, null);
+		TransactionData messageTransactionData = new MessageTransactionData(baseTransactionData, version, nonce, recipient, amount, assetId, data, false, false);
+
+		MessageTransaction messageTransaction = new MessageTransaction(repository, messageTransactionData);
+
+		fee = messageTransaction.calcRecommendedFee();
+		messageTransactionData.setFee(fee);
+
+		TransactionUtils.signAndImportValid(repository, messageTransactionData, sender);
+
+		return messageTransaction;
+	}
+
+	private void assertTimestamp(Repository repository, String atAddress, Transaction transaction) throws DataException {
+		int height = transaction.getHeight();
+		byte[] transactionSignature = transaction.getTransactionData().getSignature();
+
+		BlockData blockData = repository.getBlockRepository().fromHeight(height);
+		assertNotNull(blockData);
+
+		Block block = new Block(repository, blockData);
+
+		List<Transaction> blockTransactions = block.getTransactions();
+		int sequence;
+		for (sequence = blockTransactions.size() - 1; sequence >= 0; --sequence)
+			if (Arrays.equals(blockTransactions.get(sequence).getTransactionData().getSignature(), transactionSignature))
+				break;
+
+		assertNotSame(-1, sequence);
+
+		byte[] rawNextTimestamp = new byte[32];
+		extractNextTxTimestamp(repository, atAddress, rawNextTimestamp);
+
+		Timestamp expectedTimestamp = new Timestamp(height, sequence);
+		Timestamp actualTimestamp = new Timestamp(BitTwiddling.longFromBEBytes(rawNextTimestamp, 0));
+
+		assertEquals(String.format("Expected height %d, seq %d but was height %d, seq %d",
+					height, sequence,
+					actualTimestamp.blockHeight, actualTimestamp.transactionSequence
+				),
+				expectedTimestamp.longValue(),
+				actualTimestamp.longValue());
+
+		byte[] expectedPartialSignature = new byte[24];
+		System.arraycopy(transactionSignature, 8, expectedPartialSignature, 0, expectedPartialSignature.length);
+
+		byte[] actualPartialSignature = new byte[24];
+		System.arraycopy(rawNextTimestamp, 8, actualPartialSignature, 0, actualPartialSignature.length);
+
+		assertArrayEquals(expectedPartialSignature, actualPartialSignature);
+	}
+
+}