Merge branch '542-retransmission' into 'master'

Don't poll for retransmission

Closes #542

See merge request akwizgran/briar!695

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -378,6 +378,16 @@ public interface DatabaseComponent {
 	MessageStatus getMessageStatus(Transaction txn, ContactId c, MessageId m)
 			throws DbException;
 
+	/*
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be sent to the given contact. The returned value may
+	 * be zero if a message is due to be sent immediately, or Long.MAX_VALUE if
+	 * no messages are scheduled to be sent.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextSendTime(Transaction txn, ContactId c) throws DbException;
+
 	/**
 	 * Returns all settings in the given namespace.
 	 * <p/>

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -449,6 +449,16 @@ interface Database<T> {
 	Collection<MessageId> getMessagesToShare(T txn, ClientId c)
 			throws DbException;
 
+	/**
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be sent to the given contact. The returned value may
+	 * be zero if a message is due to be sent immediately, or Long.MAX_VALUE
+	 * if no messages are scheduled to be sent.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextSendTime(T txn, ContactId c) throws DbException;
+
 	/**
 	 * Returns the message with the given ID, in serialised form, or null if
 	 * the message has been deleted.

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -569,6 +569,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageDependents(txn, m);
 	}
 
+	@Override
+	public long getNextSendTime(Transaction transaction, ContactId c)
+		throws DbException {
+		T txn = unbox(transaction);
+		return db.getNextSendTime(txn, c);
+	}
+
 	@Override
 	public Settings getSettings(Transaction transaction, String namespace)
 			throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -1929,6 +1929,37 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long getNextSendTime(Connection txn, ContactId c)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT expiry FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE"
+					+ " AND seen = FALSE AND requested = FALSE"
+					+ " ORDER BY expiry LIMIT 1";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			rs = ps.executeQuery();
+			long nextSendTime = Long.MAX_VALUE;
+			if (rs.next()) {
+				nextSendTime = rs.getLong(1);
+				if (rs.next()) throw new AssertionError();
+			}
+			rs.close();
+			ps.close();
+			return nextSendTime;
+		} catch (SQLException e) {
+			tryToClose(rs);
+			tryToClose(ps);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	@Nullable
 	public byte[] getRawMessage(Connection txn, MessageId m)

bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java

@@ -30,6 +30,7 @@ import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.ThreadSafe;
@@ -50,13 +51,14 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD
 @NotNullByDefault
 class DuplexOutgoingSession implements SyncSession, EventListener {
 
-	// Check for retransmittable records once every 60 seconds
-	private static final int RETX_QUERY_INTERVAL = 60 * 1000;
 	private static final Logger LOG =
 			Logger.getLogger(DuplexOutgoingSession.class.getName());
 
 	private static final ThrowingRunnable<IOException> CLOSE = () -> {
 	};
+	private static final ThrowingRunnable<IOException>
+			NEXT_SEND_TIME_DECREASED = () -> {
+	};
 
 	private final DatabaseComponent db;
 	private final Executor dbExecutor;
@@ -72,6 +74,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	private final AtomicBoolean generateOfferQueued = new AtomicBoolean(false);
 	private final AtomicBoolean generateRequestQueued =
 			new AtomicBoolean(false);
+	private final AtomicLong nextSendTime = new AtomicLong(Long.MAX_VALUE);
 
 	private volatile boolean interrupted = false;
 
@@ -101,15 +104,15 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			generateRequest();
 			long now = clock.currentTimeMillis();
 			long nextKeepalive = now + maxIdleTime;
-			long nextRetxQuery = now + RETX_QUERY_INTERVAL;
 			boolean dataToFlush = true;
 			// Write records until interrupted
 			try {
 				while (!interrupted) {
 					// Work out how long we should wait for a record
 					now = clock.currentTimeMillis();
-					long wait = Math.min(nextKeepalive, nextRetxQuery) - now;
+					long keepaliveWait = Math.max(0, nextKeepalive - now);
-					if (wait < 0) wait = 0;
+					long sendWait = Math.max(0, nextSendTime.get() - now);
+					long wait = Math.min(keepaliveWait, sendWait);
 					// Flush any unflushed data if we're going to wait
 					if (wait > 0 && dataToFlush && writerTasks.isEmpty()) {
 						recordWriter.flush();
@@ -121,20 +124,25 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 							MILLISECONDS);
 					if (task == null) {
 						now = clock.currentTimeMillis();
-						if (now >= nextRetxQuery) {
+						if (now >= nextSendTime.get()) {
-							// Check for retransmittable records
+							// Check for retransmittable messages
+							LOG.info("Checking for retransmittable messages");
+							setNextSendTime(Long.MAX_VALUE);
 							generateBatch();
 							generateOffer();
-							nextRetxQuery = now + RETX_QUERY_INTERVAL;
 						}
 						if (now >= nextKeepalive) {
 							// Flush the stream to keep it alive
+							LOG.info("Sending keepalive");
 							recordWriter.flush();
 							dataToFlush = false;
 							nextKeepalive = now + maxIdleTime;
 						}
 					} else if (task == CLOSE) {
+						LOG.info("Closed");
 						break;
+					} else if (task == NEXT_SEND_TIME_DECREASED) {
+						LOG.info("Next send time decreased");
 					} else {
 						task.run();
 						dataToFlush = true;
@@ -170,6 +178,11 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			dbExecutor.execute(new GenerateRequest());
 	}
 
+	private void setNextSendTime(long time) {
+		long old = nextSendTime.getAndSet(time);
+		if (time < old) writerTasks.add(NEXT_SEND_TIME_DECREASED);
+	}
+
 	@Override
 	public void interrupt() {
 		interrupted = true;
@@ -259,6 +272,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 				try {
 					b = db.generateRequestedBatch(txn, contactId,
 							MAX_RECORD_PAYLOAD_LENGTH, maxLatency);
+					setNextSendTime(db.getNextSendTime(txn, contactId));
 					db.commitTransaction(txn);
 				} finally {
 					db.endTransaction(txn);
@@ -305,6 +319,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 				try {
 					o = db.generateOffer(txn, contactId, MAX_MESSAGE_IDS,
 							maxLatency);
+					setNextSendTime(db.getNextSendTime(txn, contactId));
 					db.commitTransaction(txn);
 				} finally {
 					db.endTransaction(txn);

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -1605,7 +1605,6 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 	@Test
 	public void testSetMessageState() throws Exception {
-
 		Database<Connection> db = open(false);
 		Connection txn = db.startTransaction();
 
@@ -1626,6 +1625,52 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.close();
 	}
 
+	@Test
+	public void testGetNextSendTime() throws Exception {
+		long now = System.currentTimeMillis();
+		Database<Connection> db = open(false, new StoppedClock(now));
+		Connection txn = db.startTransaction();
+
+		// Add a contact, a group and a message
+		db.addLocalAuthor(txn, localAuthor);
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
+				true, true));
+		db.addGroup(txn, group);
+		db.addMessage(txn, message, UNKNOWN, false, null);
+
+		// There should be no messages to send
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		// Share the group with the contact - still no messages to send
+		db.addGroupVisibility(txn, contactId, groupId, true);
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		// Set the message's state to DELIVERED - still no messages to send
+		db.setMessageState(txn, messageId, DELIVERED);
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		// Share the message - now it should be sendable immediately
+		db.setMessageShared(txn, messageId);
+		assertEquals(0, db.getNextSendTime(txn, contactId));
+
+		// Update the message's expiry time as though we sent it - now the
+		// message should be sendable after one round-trip
+		db.updateExpiryTime(txn, contactId, messageId, 1000);
+		assertEquals(now + 2000, db.getNextSendTime(txn, contactId));
+
+		// Update the message's expiry time again - now it should be sendable
+		// after two round-trips
+		db.updateExpiryTime(txn, contactId, messageId, 1000);
+		assertEquals(now + 4000, db.getNextSendTime(txn, contactId));
+
+		// Delete the message - there should be no messages to send
+		db.deleteMessage(txn, messageId);
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		db.commitTransaction(txn);
+		db.close();
+	}
+
 	@Test
 	public void testExceptionHandling() throws Exception {
 		Database<Connection> db = open(false);
@@ -1643,8 +1688,13 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 	}
 
 	private Database<Connection> open(boolean resume) throws Exception {
+		return open(resume, new SystemClock());
+	}
+
+	private Database<Connection> open(boolean resume, Clock clock)
+			throws Exception {
 		Database<Connection> db = createDatabase(
-				new TestDatabaseConfig(testDir, MAX_SIZE), new SystemClock());
+				new TestDatabaseConfig(testDir, MAX_SIZE), clock);
 		if (!resume) TestUtils.deleteTestDirectory(testDir);
 		db.open();
 		return db;
@@ -1674,4 +1724,23 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 	public void tearDown() {
 		TestUtils.deleteTestDirectory(testDir);
 	}
+
+	private static class StoppedClock implements Clock {
+
+		private final long time;
+
+		private StoppedClock(long time) {
+			this.time = time;
+		}
+
+		@Override
+		public long currentTimeMillis() {
+			return time;
+		}
+
+		@Override
+		public void sleep(long milliseconds) throws InterruptedException {
+			Thread.sleep(milliseconds);
+		}
+	}
 }