Add DB method for getting amount of data to sync.

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

@@ -292,6 +292,16 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	Message getMessage(Transaction txn, MessageId m) throws DbException;
 
+	/**
+	 * Returns the total length, including headers, of any messages that are
+	 * eligible to be sent to the given contact via a transport with the given
+	 * max latency.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getMessageBytesToSend(Transaction txn, ContactId c, int maxLatency)
+			throws DbException;
+
 	/**
 	 * Returns the IDs of all delivered messages in the given group.
 	 * <p/>

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

@@ -347,6 +347,16 @@ interface Database<T> {
 	 */
 	Message getMessage(T txn, MessageId m) throws DbException;
 
+	/**
+	 * Returns the total length, including headers, of any messages that are
+	 * eligible to be sent to the given contact via a transport with the given
+	 * max latency.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getMessageBytesToSend(T txn, ContactId c, int maxLatency)
+			throws DbException;
+
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
 	 * For missing dependencies and dependencies in other groups, the state

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

@@ -575,6 +575,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessage(txn, m);
 	}
 
+	@Override
+	public long getMessageBytesToSend(Transaction transaction, ContactId c,
+			int maxLatency) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		return db.getMessageBytesToSend(txn, c, maxLatency);
+	}
+
 	@Override
 	public Collection<MessageId> getMessageIds(Transaction transaction,
 			GroupId g) throws DbException {

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

@@ -1758,6 +1758,37 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long getMessageBytesToSend(Connection txn, ContactId c,
+			int maxLatency) throws DbException {
+		long now = clock.currentTimeMillis();
+		long eta = now + maxLatency;
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT SUM(length) FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE AND seen = FALSE"
+					+ " AND (expiry <= ? OR eta > ?)";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			ps.setLong(3, now);
+			ps.setLong(4, eta);
+			rs = ps.executeQuery();
+			rs.next();
+			long total = rs.getInt(1);
+			rs.close();
+			ps.close();
+			return total;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Collection<MessageId> getMessageIds(Connection txn, GroupId g)
 			throws DbException {

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

@@ -298,11 +298,11 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			throws Exception {
 		context.checking(new Expectations() {{
 			// Check whether the contact is in the DB (which it's not)
-			exactly(18).of(database).startTransaction();
+			exactly(19).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(18).of(database).containsContact(txn, contactId);
+			exactly(19).of(database).containsContact(txn, contactId);
 			will(returnValue(false));
-			exactly(18).of(database).abortTransaction(txn);
+			exactly(19).of(database).abortTransaction(txn);
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				eventExecutor, shutdownManager);
@@ -349,7 +349,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getContact(transaction, contactId));
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -357,7 +357,15 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
+					db.getMessageBytesToSend(transaction, contactId, 123));
+			fail();
+		} catch (NoSuchContactException expected) {
+			// Expected
+		}
+
+		try {
+			db.transaction(true, transaction ->
 					db.getMessageStatus(transaction, contactId, groupId));
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -365,7 +373,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageStatus(transaction, contactId, messageId));
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -373,7 +381,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getGroupVisibility(transaction, contactId, groupId));
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -381,7 +389,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getSyncVersions(transaction, contactId));
 			fail();
 		} catch (NoSuchContactException expected) {

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

@@ -227,6 +227,8 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(singletonList(messageId), ids);
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertEquals(singletonList(messageId), ids);
+		assertEquals(message.getRawLength(),
+				db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Changing the status to seen = true should make the message unsendable
 		db.raiseSeenFlag(txn, contactId, messageId);
@@ -234,6 +236,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		db.commitTransaction(txn);
 		db.close();
@@ -258,6 +261,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Marking the message delivered should make it sendable
 		db.setMessageState(txn, messageId, DELIVERED);
@@ -265,6 +269,8 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(singletonList(messageId), ids);
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertEquals(singletonList(messageId), ids);
+		assertEquals(message.getRawLength(),
+				db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Marking the message invalid should make it unsendable
 		db.setMessageState(txn, messageId, INVALID);
@@ -272,6 +278,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Marking the message pending should make it unsendable
 		db.setMessageState(txn, messageId, PENDING);
@@ -279,6 +286,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		db.commitTransaction(txn);
 		db.close();
@@ -302,6 +310,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Making the group visible should not make the message sendable
 		db.addGroupVisibility(txn, contactId, groupId, false);
@@ -309,6 +318,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Sharing the group should make the message sendable
 		db.setGroupVisibility(txn, contactId, groupId, true);
@@ -316,6 +326,8 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(singletonList(messageId), ids);
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertEquals(singletonList(messageId), ids);
+		assertEquals(message.getRawLength(),
+				db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Unsharing the group should make the message unsendable
 		db.setGroupVisibility(txn, contactId, groupId, false);
@@ -323,6 +335,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Making the group invisible should make the message unsendable
 		db.removeGroupVisibility(txn, contactId, groupId);
@@ -330,6 +343,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		db.commitTransaction(txn);
 		db.close();
@@ -354,6 +368,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(0, db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		// Sharing the message should make it sendable
 		db.setMessageShared(txn, messageId, true);
@@ -361,6 +376,8 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(singletonList(messageId), ids);
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
 		assertEquals(singletonList(messageId), ids);
+		assertEquals(message.getRawLength(),
+				db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		db.commitTransaction(txn);
 		db.close();
@@ -384,10 +401,15 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.getMessagesToSend(txn, contactId, message.getRawLength() - 1,
 						MAX_LATENCY);
 		assertTrue(ids.isEmpty());
+		assertEquals(message.getRawLength(),
+				db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
+
 		// The message is just the right size to send
 		ids = db.getMessagesToSend(txn, contactId, message.getRawLength(),
 				MAX_LATENCY);
 		assertEquals(singletonList(messageId), ids);
+		assertEquals(message.getRawLength(),
+				db.getMessageBytesToSend(txn, contactId, MAX_LATENCY));
 
 		db.commitTransaction(txn);
 		db.close();