Move lookup of latest conversation timestamp to core.

2026-02-12 10:49:06 +01:00 · 2020-12-01 15:55:37 +00:00
parent 47db28a738
commit e72169ecee
12 changed files with 204 additions and 197 deletions
--- a/briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java
@@ -736,18 +736,10 @@ public class ConversationActivity extends BriarActivity
 			List<AttachmentHeader> attachmentHeaders) {
 		if (isNullOrEmpty(text) && attachmentHeaders.isEmpty())
 			throw new AssertionError();
-		long timestamp = System.currentTimeMillis();
-		timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
-		viewModel.sendMessage(text, attachmentHeaders, timestamp);
+		viewModel.sendMessage(text, attachmentHeaders);
 		textInputView.clearText();
 	}

-	private long getMinTimestampForNewMessage() {
-		// Don't use an earlier timestamp than the newest message
-		ConversationItem item = adapter.getLastItem();
-		return item == null ? 0 : item.getTime() + 1;
-	}
-
 	private void onAddedPrivateMessage(@Nullable PrivateMessageHeader h) {
 		if (h == null) return;
 		addConversationItem(h.accept(visitor));
@@ -955,13 +947,11 @@ public class ConversationActivity extends BriarActivity
 			adapter.notifyItemChanged(position, item);
 		}
 		runOnDbThread(() -> {
-			long timestamp = System.currentTimeMillis();
-			timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
 			try {
 				switch (item.getRequestType()) {
 					case INTRODUCTION:
 						respondToIntroductionRequest(item.getSessionId(),
-								accept, timestamp);
+								accept);
 						break;
 					case FORUM:
 						respondToForumRequest(item.getSessionId(), accept);
@@ -1037,9 +1027,8 @@ public class ConversationActivity extends BriarActivity

 	@DatabaseExecutor
 	private void respondToIntroductionRequest(SessionId sessionId,
-			boolean accept, long time) throws DbException {
-		introductionManager.respondToIntroduction(contactId, sessionId, time,
-				accept);
+			boolean accept) throws DbException {
+		introductionManager.respondToIntroduction(contactId, sessionId, accept);
 	}

 	@DatabaseExecutor
--- a/briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java
@@ -35,6 +35,7 @@ import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
 import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 import org.briarproject.briar.api.avatar.event.AvatarUpdatedEvent;
+import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -90,6 +91,7 @@ public class ConversationViewModel extends DbViewModel
 	private final AttachmentRetriever attachmentRetriever;
 	private final AttachmentCreator attachmentCreator;
 	private final AutoDeleteManager autoDeleteManager;
+	private final ConversationManager conversationManager;

 	@Nullable
 	private ContactId contactId = null;
@@ -125,7 +127,8 @@ public class ConversationViewModel extends DbViewModel
 			PrivateMessageFactory privateMessageFactory,
 			AttachmentRetriever attachmentRetriever,
 			AttachmentCreator attachmentCreator,
-			AutoDeleteManager autoDeleteManager) {
+			AutoDeleteManager autoDeleteManager,
+			ConversationManager conversationManager) {
 		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.db = db;
 		this.eventBus = eventBus;
@@ -137,6 +140,7 @@ public class ConversationViewModel extends DbViewModel
 		this.attachmentRetriever = attachmentRetriever;
 		this.attachmentCreator = attachmentCreator;
 		this.autoDeleteManager = autoDeleteManager;
+		this.conversationManager = conversationManager;
 		messagingGroupId = map(contactItem, c ->
 				messagingManager.getContactGroup(c.getContact()).getId());
 		contactDeleted.setValue(false);
@@ -244,14 +248,13 @@ public class ConversationViewModel extends DbViewModel
 	}

 	@UiThread
-	void sendMessage(@Nullable String text,
-			List<AttachmentHeader> headers, long timestamp) {
+	void sendMessage(@Nullable String text, List<AttachmentHeader> headers) {
 		// messagingGroupId is loaded with the contact
 		observeForeverOnce(messagingGroupId, groupId -> {
 			requireNonNull(groupId);
 			observeForeverOnce(privateMessageFormat, format ->
 					storeMessage(requireNonNull(contactId), groupId, text,
-							headers, timestamp, format));
+							headers, format));
 		});
 	}

@@ -313,8 +316,10 @@ public class ConversationViewModel extends DbViewModel

 	private PrivateMessage createMessage(Transaction txn, ContactId c,
 			GroupId groupId, @Nullable String text,
-			List<AttachmentHeader> headers, long timestamp,
-			PrivateMessageFormat format) throws DbException {
+			List<AttachmentHeader> headers, PrivateMessageFormat format)
+			throws DbException {
+		long timestamp =
+				conversationManager.getTimestampForOutgoingMessage(txn, c);
 		try {
 			if (format == TEXT_ONLY) {
 				return privateMessageFactory.createLegacyPrivateMessage(
@@ -335,13 +340,13 @@ public class ConversationViewModel extends DbViewModel
 	@UiThread
 	private void storeMessage(ContactId c, GroupId groupId,
 			@Nullable String text, List<AttachmentHeader> headers,
-			long timestamp, PrivateMessageFormat format) {
+			PrivateMessageFormat format) {
 		runOnDbThread(() -> {
 			try {
 				db.transaction(false, txn -> {
 					long start = now();
 					PrivateMessage m = createMessage(txn, c, groupId, text,
-							headers, timestamp, format);
+							headers, format);
 					messagingManager.addLocalMessage(txn, m);
 					logDuration(LOG, "Storing message", start);
 					Message message = m.getMessage();
--- a/briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionMessageFragment.java
+++ b/briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionMessageFragment.java
@@ -219,8 +219,7 @@ public class IntroductionMessageFragment extends BaseFragment
 		introductionActivity.runOnDbThread(() -> {
 			// actually make the introduction
 			try {
-				long timestamp = System.currentTimeMillis();
-				introductionManager.makeIntroduction(c1, c2, text, timestamp);
+				introductionManager.makeIntroduction(c1, c2, text);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				introductionError();
--- a/briar-api/src/main/java/org/briarproject/briar/api/conversation/ConversationManager.java
+++ b/briar-api/src/main/java/org/briarproject/briar/api/conversation/ConversationManager.java
@@ -48,6 +48,13 @@ public interface ConversationManager {
 	 */
 	GroupCount getGroupCount(Transaction txn, ContactId c) throws DbException;

+	/**
+	 * Returns a timestamp for an outgoing message, which is later than the
+	 * timestamp of any visible message sent or received so far.
+	 */
+	long getTimestampForOutgoingMessage(Transaction txn, ContactId c)
+			throws DbException;
+
 	/**
 	 * Deletes all messages exchanged with the given contact.
 	 */
--- a/briar-api/src/main/java/org/briarproject/briar/api/introduction/IntroductionManager.java
+++ b/briar-api/src/main/java/org/briarproject/briar/api/introduction/IntroductionManager.java
@@ -36,13 +36,13 @@ public interface IntroductionManager extends ConversationClient {
 	/**
 	 * Sends two initial introduction messages.
 	 */
-	void makeIntroduction(Contact c1, Contact c2, @Nullable String text,
-			long timestamp) throws DbException;
+	void makeIntroduction(Contact c1, Contact c2, @Nullable String text)
+			throws DbException;

 	/**
 	 * Responds to an introduction.
 	 */
 	void respondToIntroduction(ContactId contactId, SessionId sessionId,
-			long timestamp, boolean accept) throws DbException;
+			boolean accept) throws DbException;

 }
--- a/briar-core/src/main/java/org/briarproject/briar/introduction/AbstractProtocolEngine.java
+++ b/briar-core/src/main/java/org/briarproject/briar/introduction/AbstractProtocolEngine.java
@@ -20,11 +20,11 @@ import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
+import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
@@ -61,7 +61,7 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 	protected final MessageEncoder messageEncoder;
 	protected final ClientVersioningManager clientVersioningManager;
 	protected final AutoDeleteManager autoDeleteManager;
-	protected final Clock clock;
+	protected final ConversationManager conversationManager;

 	AbstractProtocolEngine(
 			DatabaseComponent db,
@@ -75,7 +75,7 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 			MessageEncoder messageEncoder,
 			ClientVersioningManager clientVersioningManager,
 			AutoDeleteManager autoDeleteManager,
-			Clock clock) {
+			ConversationManager conversationManager) {
 		this.db = db;
 		this.clientHelper = clientHelper;
 		this.contactManager = contactManager;
@@ -87,7 +87,7 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		this.messageEncoder = messageEncoder;
 		this.clientVersioningManager = clientVersioningManager;
 		this.autoDeleteManager = autoDeleteManager;
-		this.clock = clock;
+		this.conversationManager = conversationManager;
 	}

 	Message sendRequestMessage(Transaction txn, PeerSession s,
@@ -231,14 +231,10 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		return !dependency.equals(lastRemoteMessageId);
 	}

-	long getLocalTimestamp(long localTimestamp, long requestTimestamp) {
-		return Math.max(
-				clock.currentTimeMillis(),
-				Math.max(
-						localTimestamp,
-						requestTimestamp
-				) + 1
-		);
+	long getTimestampForOutgoingMessage(Transaction txn, GroupId contactGroupId)
+			throws DbException {
+		ContactId c = getContactId(txn, contactGroupId);
+		return conversationManager.getTimestampForOutgoingMessage(txn, c);
 	}

 	private ContactId getContactId(Transaction txn, GroupId contactGroupId)
--- a/briar-core/src/main/java/org/briarproject/briar/introduction/IntroduceeProtocolEngine.java
+++ b/briar-core/src/main/java/org/briarproject/briar/introduction/IntroduceeProtocolEngine.java
@@ -22,7 +22,6 @@ import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.KeyManager;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
@@ -30,6 +29,7 @@ import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
+import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
@@ -44,6 +44,7 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;

+import static java.lang.Math.max;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.introduction.IntroduceeState.AWAIT_AUTH;
@@ -77,16 +78,16 @@ class IntroduceeProtocolEngine
 			AuthorManager authorManager,
 			MessageParser messageParser,
 			MessageEncoder messageEncoder,
-			Clock clock,
 			IntroductionCrypto crypto,
 			KeyManager keyManager,
 			TransportPropertyManager transportPropertyManager,
 			ClientVersioningManager clientVersioningManager,
-			AutoDeleteManager autoDeleteManager) {
+			AutoDeleteManager autoDeleteManager,
+			ConversationManager conversationManager) {
 		super(db, clientHelper, contactManager, contactGroupFactory,
 				messageTracker, identityManager, authorManager, messageParser,
 				messageEncoder, clientVersioningManager, autoDeleteManager,
-				clock);
+				conversationManager);
 		this.crypto = crypto;
 		this.keyManager = keyManager;
 		this.transportPropertyManager = transportPropertyManager;
@@ -94,18 +95,18 @@ class IntroduceeProtocolEngine

 	@Override
 	public IntroduceeSession onRequestAction(Transaction txn,
-			IntroduceeSession session, @Nullable String text, long timestamp) {
+			IntroduceeSession session, @Nullable String text) {
 		throw new UnsupportedOperationException(); // Invalid in this role
 	}

 	@Override
 	public IntroduceeSession onAcceptAction(Transaction txn,
-			IntroduceeSession session, long timestamp) throws DbException {
+			IntroduceeSession session) throws DbException {
 		switch (session.getState()) {
 			case AWAIT_RESPONSES:
 			case REMOTE_DECLINED:
 			case REMOTE_ACCEPTED:
-				return onLocalAccept(txn, session, timestamp);
+				return onLocalAccept(txn, session);
 			case START:
 			case LOCAL_DECLINED:
 			case LOCAL_ACCEPTED:
@@ -119,12 +120,12 @@ class IntroduceeProtocolEngine

 	@Override
 	public IntroduceeSession onDeclineAction(Transaction txn,
-			IntroduceeSession session, long timestamp) throws DbException {
+			IntroduceeSession session) throws DbException {
 		switch (session.getState()) {
 			case AWAIT_RESPONSES:
 			case REMOTE_DECLINED:
 			case REMOTE_ACCEPTED:
-				return onLocalDecline(txn, session, timestamp);
+				return onLocalDecline(txn, session);
 			case START:
 			case LOCAL_DECLINED:
 			case LOCAL_ACCEPTED:
@@ -275,7 +276,7 @@ class IntroduceeProtocolEngine
 	}

 	private IntroduceeSession onLocalAccept(Transaction txn,
-			IntroduceeSession s, long timestamp) throws DbException {
+			IntroduceeSession s) throws DbException {
 		// Mark the request message unavailable to answer
 		markRequestsUnavailableToAnswer(txn, s);

@@ -287,7 +288,7 @@ class IntroduceeProtocolEngine
 				transportPropertyManager.getLocalProperties(txn);

 		// Send a ACCEPT message
-		long localTimestamp = Math.max(timestamp + 1, getLocalTimestamp(s));
+		long localTimestamp = getLocalTimestamp(txn, s);
 		Message sent = sendAcceptMessage(txn, s, localTimestamp, publicKey,
 				localTimestamp, transportProperties, true);
 		// Track the message
@@ -312,12 +313,12 @@ class IntroduceeProtocolEngine
 	}

 	private IntroduceeSession onLocalDecline(Transaction txn,
-			IntroduceeSession s, long timestamp) throws DbException {
+			IntroduceeSession s) throws DbException {
 		// Mark the request message unavailable to answer
 		markRequestsUnavailableToAnswer(txn, s);

 		// Send a DECLINE message
-		long localTimestamp = Math.max(timestamp + 1, getLocalTimestamp(s));
+		long localTimestamp = getLocalTimestamp(txn, s);
 		Message sent = sendDeclineMessage(txn, s, localTimestamp, true);

 		// Track the message
@@ -415,8 +416,8 @@ class IntroduceeProtocolEngine
 			return abort(txn, s);
 		}
 		if (s.getState() != AWAIT_AUTH) throw new AssertionError();
-		Message sent = sendAuthMessage(txn, s, getLocalTimestamp(s), mac,
-				signature);
+		long localTimestamp = getLocalTimestamp(txn, s);
+		Message sent = sendAuthMessage(txn, s, localTimestamp, mac, signature);
 		return IntroduceeSession.addLocalAuth(s, AWAIT_AUTH, sent, masterKey,
 				aliceMacKey, bobMacKey);
 	}
@@ -465,7 +466,8 @@ class IntroduceeProtocolEngine

 		// send ACTIVATE message with a MAC
 		byte[] mac = crypto.activateMac(s);
-		Message sent = sendActivateMessage(txn, s, getLocalTimestamp(s), mac);
+		long localTimestamp = getLocalTimestamp(txn, s);
+		Message sent = sendActivateMessage(txn, s, localTimestamp, mac);

 		// Move to AWAIT_ACTIVATE state and clear key material from session
 		return IntroduceeSession.awaitActivate(s, m, sent, keys);
@@ -516,7 +518,8 @@ class IntroduceeProtocolEngine
 		markRequestsUnavailableToAnswer(txn, s);

 		// Send an ABORT message
-		Message sent = sendAbortMessage(txn, s, getLocalTimestamp(s));
+		long localTimestamp = getLocalTimestamp(txn, s);
+		Message sent = sendAbortMessage(txn, s, localTimestamp);

 		// Broadcast abort event for testing
 		txn.attach(new IntroductionAbortedEvent(s.getSessionId()));
@@ -531,9 +534,18 @@ class IntroduceeProtocolEngine
 		return isInvalidDependency(s.getLastRemoteMessageId(), dependency);
 	}

-	private long getLocalTimestamp(IntroduceeSession s) {
-		return getLocalTimestamp(s.getLocalTimestamp(),
-				s.getRequestTimestamp());
+	/**
+	 * Returns a timestamp for an outgoing message, which is later than the
+	 * timestamp of any message sent or received so far in the conversation
+	 * or the session.
+	 */
+	private long getLocalTimestamp(Transaction txn, IntroduceeSession s)
+			throws DbException {
+		long conversationTimestamp =
+				getTimestampForOutgoingMessage(txn, s.getContactGroupId());
+		long sessionTimestamp =
+				max(s.getLocalTimestamp(), s.getRequestTimestamp()) + 1;
+		return max(conversationTimestamp, sessionTimestamp);
 	}

 	private void addSessionId(Transaction txn, MessageId m, SessionId sessionId)
--- a/briar-core/src/main/java/org/briarproject/briar/introduction/IntroducerProtocolEngine.java
+++ b/briar-core/src/main/java/org/briarproject/briar/introduction/IntroducerProtocolEngine.java
@@ -12,11 +12,11 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.ProtocolStateException;
+import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.identity.AuthorManager;
 import org.briarproject.briar.api.introduction.event.IntroductionAbortedEvent;
 import org.briarproject.briar.introduction.IntroducerSession.Introducee;
@@ -25,6 +25,7 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;

+import static java.lang.Math.max;
 import static org.briarproject.briar.introduction.IntroducerState.AWAIT_ACTIVATES;
 import static org.briarproject.briar.introduction.IntroducerState.AWAIT_ACTIVATE_A;
 import static org.briarproject.briar.introduction.IntroducerState.AWAIT_ACTIVATE_B;
@@ -56,20 +57,20 @@ class IntroducerProtocolEngine
 			MessageEncoder messageEncoder,
 			ClientVersioningManager clientVersioningManager,
 			AutoDeleteManager autoDeleteManager,
-			Clock clock) {
+			ConversationManager conversationManager) {
 		super(db, clientHelper, contactManager, contactGroupFactory,
 				messageTracker, identityManager, authorManager, messageParser,
 				messageEncoder, clientVersioningManager, autoDeleteManager,
-				clock);
+				conversationManager);
 	}

 	@Override
 	public IntroducerSession onRequestAction(Transaction txn,
-			IntroducerSession s, @Nullable String text, long timestamp)
+			IntroducerSession s, @Nullable String text)
 			throws DbException {
 		switch (s.getState()) {
 			case START:
-				return onLocalRequest(txn, s, text, timestamp);
+				return onLocalRequest(txn, s, text);
 			case AWAIT_RESPONSES:
 			case AWAIT_RESPONSE_A:
 			case AWAIT_RESPONSE_B:
@@ -89,37 +90,24 @@ class IntroducerProtocolEngine

 	@Override
 	public IntroducerSession onAcceptAction(Transaction txn,
-			IntroducerSession s, long timestamp) {
+			IntroducerSession s) {
 		throw new UnsupportedOperationException(); // Invalid in this role
 	}

 	@Override
 	public IntroducerSession onDeclineAction(Transaction txn,
-			IntroducerSession s, long timestamp) {
+			IntroducerSession s) {
 		throw new UnsupportedOperationException(); // Invalid in this role
 	}

 	IntroducerSession onIntroduceeRemoved(Transaction txn,
 			Introducee remainingIntroducee, IntroducerSession session)
 			throws DbException {
-		// abort session
-		IntroducerSession s = abort(txn, session);
-		// reset information for introducee that was removed
-		Introducee introduceeA, introduceeB;
-		if (remainingIntroducee.author.equals(s.getIntroduceeA().author)) {
-			introduceeA = s.getIntroduceeA();
-			introduceeB =
-					new Introducee(s.getSessionId(), s.getIntroduceeB().groupId,
-							s.getIntroduceeB().author);
-		} else if (remainingIntroducee.author
-				.equals(s.getIntroduceeB().author)) {
-			introduceeA =
-					new Introducee(s.getSessionId(), s.getIntroduceeA().groupId,
-							s.getIntroduceeA().author);
-			introduceeB = s.getIntroduceeB();
-		} else throw new DbException();
+		// abort session with remaining introducee
+		IntroducerSession s = abort(txn, session, remainingIntroducee);
 		return new IntroducerSession(s.getSessionId(), s.getState(),
-				s.getRequestTimestamp(), introduceeA, introduceeB);
+				s.getRequestTimestamp(), s.getIntroduceeA(),
+				s.getIntroduceeB());
 	}

 	@Override
@@ -229,13 +217,11 @@ class IntroducerProtocolEngine
 	}

 	private IntroducerSession onLocalRequest(Transaction txn,
-			IntroducerSession s, @Nullable String text, long timestamp)
-			throws DbException {
+			IntroducerSession s, @Nullable String text) throws DbException {
 		// Send REQUEST messages
-		long maxIntroduceeTimestamp =
-				Math.max(getLocalTimestamp(s, s.getIntroduceeA()),
-						getLocalTimestamp(s, s.getIntroduceeB()));
-		long localTimestamp = Math.max(timestamp, maxIntroduceeTimestamp);
+		long timestampA = getLocalTimestamp(txn, s, s.getIntroduceeA());
+		long timestampB = getLocalTimestamp(txn, s, s.getIntroduceeB());
+		long localTimestamp = max(timestampA, timestampB);
 		Message sentA = sendRequestMessage(txn, s.getIntroduceeA(),
 				localTimestamp, s.getIntroduceeB().author, text);
 		Message sentB = sendRequestMessage(txn, s.getIntroduceeB(),
@@ -275,11 +261,10 @@ class IntroducerProtocolEngine

 		// Forward ACCEPT message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		long timestamp = getLocalTimestamp(s, i);
-		Message sent =
-				sendAcceptMessage(txn, i, timestamp, m.getEphemeralPublicKey(),
-						m.getAcceptTimestamp(), m.getTransportProperties(),
-						false);
+		long localTimestamp = getLocalTimestamp(txn, s, i);
+		Message sent = sendAcceptMessage(txn, i, localTimestamp,
+				m.getEphemeralPublicKey(), m.getAcceptTimestamp(),
+				m.getTransportProperties(), false);

 		// Create the next state
 		IntroducerState state = AWAIT_AUTHS;
@@ -336,7 +321,8 @@ class IntroducerProtocolEngine

 		// Forward ACCEPT message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		Message sent = sendAcceptMessage(txn, i, getLocalTimestamp(s, i),
+		long localTimestamp = getLocalTimestamp(txn, s, i);
+		Message sent = sendAcceptMessage(txn, i, localTimestamp,
 				m.getEphemeralPublicKey(), m.getAcceptTimestamp(),
 				m.getTransportProperties(), false);

@@ -387,8 +373,8 @@ class IntroducerProtocolEngine

 		// Forward DECLINE message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		long timestamp = getLocalTimestamp(s, i);
-		Message sent = sendDeclineMessage(txn, i, timestamp, false);
+		long localTimestamp = getLocalTimestamp(txn, s, i);
+		Message sent = sendDeclineMessage(txn, i, localTimestamp, false);

 		// Create the next state
 		IntroducerState state = START;
@@ -439,8 +425,8 @@ class IntroducerProtocolEngine

 		// Forward DECLINE message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		long timestamp = getLocalTimestamp(s, i);
-		Message sent = sendDeclineMessage(txn, i, timestamp, false);
+		long localTimestamp = getLocalTimestamp(txn, s, i);
+		Message sent = sendDeclineMessage(txn, i, localTimestamp, false);

 		Introducee introduceeA, introduceeB;
 		Author sender, other;
@@ -480,8 +466,8 @@ class IntroducerProtocolEngine

 		// Forward AUTH message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		long timestamp = getLocalTimestamp(s, i);
-		Message sent = sendAuthMessage(txn, i, timestamp, m.getMac(),
+		long localTimestamp = getLocalTimestamp(txn, s, i);
+		Message sent = sendAuthMessage(txn, i, localTimestamp, m.getMac(),
 				m.getSignature());

 		// Move to the next state
@@ -516,8 +502,8 @@ class IntroducerProtocolEngine

 		// Forward ACTIVATE message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		long timestamp = getLocalTimestamp(s, i);
-		Message sent = sendActivateMessage(txn, i, timestamp, m.getMac());
+		long localTimestamp = getLocalTimestamp(txn, s, i);
+		Message sent = sendActivateMessage(txn, i, localTimestamp, m.getMac());

 		// Move to the next state
 		IntroducerState state = START;
@@ -539,8 +525,9 @@ class IntroducerProtocolEngine
 			IntroducerSession s, AbortMessage m) throws DbException {
 		// Forward ABORT message
 		Introducee i = getOtherIntroducee(s, m.getGroupId());
-		long timestamp = getLocalTimestamp(s, i);
-		Message sent = sendAbortMessage(txn, i, timestamp);
+		long localTimestamp = max(i.getLocalTimestamp(),
+				s.getRequestTimestamp()) + 1;
+		Message sent = sendAbortMessage(txn, i, localTimestamp);

 		// Broadcast abort event for testing
 		txn.attach(new IntroductionAbortedEvent(s.getSessionId()));
@@ -558,15 +545,42 @@ class IntroducerProtocolEngine
 				s.getRequestTimestamp(), introduceeA, introduceeB);
 	}

-	private IntroducerSession abort(Transaction txn,
-			IntroducerSession s) throws DbException {
+	private IntroducerSession abort(Transaction txn, IntroducerSession s,
+			Introducee remainingIntroducee) throws DbException {
+		// Broadcast abort event for testing
+		txn.attach(new IntroductionAbortedEvent(s.getSessionId()));
+
+		// Send an ABORT message to the remaining introducee
+		long localTimestamp = getLocalTimestamp(txn, s, remainingIntroducee);
+		Message sent =
+				sendAbortMessage(txn, remainingIntroducee, localTimestamp);
+		// Reset the session back to initial state
+		Introducee introduceeA = s.getIntroduceeA();
+		Introducee introduceeB = s.getIntroduceeB();
+		if (remainingIntroducee.author.equals(introduceeA.author)) {
+			introduceeA = new Introducee(introduceeA, sent);
+			introduceeB = new Introducee(s.getSessionId(), introduceeB.groupId,
+					introduceeB.author);
+		} else if (remainingIntroducee.author.equals(introduceeB.author)) {
+			introduceeA = new Introducee(s.getSessionId(), introduceeA.groupId,
+					introduceeA.author);
+			introduceeB = new Introducee(introduceeB, sent);
+		} else {
+			throw new DbException();
+		}
+		return new IntroducerSession(s.getSessionId(), START,
+				s.getRequestTimestamp(), introduceeA, introduceeB);
+	}
+
+	private IntroducerSession abort(Transaction txn, IntroducerSession s)
+			throws DbException {
 		// Broadcast abort event for testing
 		txn.attach(new IntroductionAbortedEvent(s.getSessionId()));

 		// Send an ABORT message to both introducees
-		long timestampA = getLocalTimestamp(s, s.getIntroduceeA());
+		long timestampA = getLocalTimestamp(txn, s, s.getIntroduceeA());
 		Message sentA = sendAbortMessage(txn, s.getIntroduceeA(), timestampA);
-		long timestampB = getLocalTimestamp(s, s.getIntroduceeB());
+		long timestampB = getLocalTimestamp(txn, s, s.getIntroduceeB());
 		Message sentB = sendAbortMessage(txn, s.getIntroduceeB(), timestampB);
 		// Reset the session back to initial state
 		Introducee introduceeA = new Introducee(s.getIntroduceeA(), sentA);
@@ -596,9 +610,17 @@ class IntroducerProtocolEngine
 		return isInvalidDependency(expected, dependency);
 	}

-	private long getLocalTimestamp(IntroducerSession s, PeerSession p) {
-		return getLocalTimestamp(p.getLocalTimestamp(),
-				s.getRequestTimestamp());
+	/**
+	 * Returns a timestamp for an outgoing message, which is later than the
+	 * timestamp of any message sent or received so far in the conversation
+	 * or the session.
+	 */
+	private long getLocalTimestamp(Transaction txn, IntroducerSession s,
+			PeerSession p) throws DbException {
+		long conversationTimestamp =
+				getTimestampForOutgoingMessage(txn, p.getContactGroupId());
+		long sessionTimestamp =
+				max(p.getLocalTimestamp(), s.getRequestTimestamp()) + 1;
+		return max(conversationTimestamp, sessionTimestamp);
 	}
-
 }
--- a/briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionManagerImpl.java
+++ b/briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionManagerImpl.java
@@ -315,8 +315,8 @@ class IntroductionManagerImpl extends ConversationClientImpl
 	}

 	@Override
-	public void makeIntroduction(Contact c1, Contact c2, @Nullable String text,
-			long timestamp) throws DbException {
+	public void makeIntroduction(Contact c1, Contact c2, @Nullable String text)
+			throws DbException {
 		Transaction txn = db.startTransaction(false);
 		try {
 			// Look up the session, if there is one
@@ -348,8 +348,7 @@ class IntroductionManagerImpl extends ConversationClientImpl
 				storageId = ss.storageId;
 			}
 			// Handle the request action
-			session = introducerEngine
-					.onRequestAction(txn, session, text, timestamp);
+			session = introducerEngine.onRequestAction(txn, session, text);
 			// Store the updated session
 			storeSession(txn, storageId, session);
 			db.commitTransaction(txn);
@@ -362,7 +361,7 @@ class IntroductionManagerImpl extends ConversationClientImpl

 	@Override
 	public void respondToIntroduction(ContactId contactId, SessionId sessionId,
-			long timestamp, boolean accept) throws DbException {
+			boolean accept) throws DbException {
 		Transaction txn = db.startTransaction(false);
 		try {
 			// Look up the session
@@ -380,11 +379,9 @@ class IntroductionManagerImpl extends ConversationClientImpl
 					.parseIntroduceeSession(contactGroupId, ss.bdfSession);
 			// Handle the join or leave action
 			if (accept) {
-				session = introduceeEngine
-						.onAcceptAction(txn, session, timestamp);
+				session = introduceeEngine.onAcceptAction(txn, session);
 			} else {
-				session = introduceeEngine
-						.onDeclineAction(txn, session, timestamp);
+				session = introduceeEngine.onDeclineAction(txn, session);
 			}
 			// Store the updated session
 			storeSession(txn, ss.storageId, session);
--- a/briar-core/src/main/java/org/briarproject/briar/introduction/ProtocolEngine.java
+++ b/briar-core/src/main/java/org/briarproject/briar/introduction/ProtocolEngine.java
@@ -8,16 +8,14 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.Nullable;

@NotNullByDefault
-interface ProtocolEngine<S extends Session> {
+interface ProtocolEngine<S extends Session<?>> {

-	S onRequestAction(Transaction txn, S session, @Nullable String text,
-			long timestamp) throws DbException;
-
-	S onAcceptAction(Transaction txn, S session, long timestamp)
+	S onRequestAction(Transaction txn, S session, @Nullable String text)
 			throws DbException;

-	S onDeclineAction(Transaction txn, S session, long timestamp)
-			throws DbException;
+	S onAcceptAction(Transaction txn, S session) throws DbException;
+
+	S onDeclineAction(Transaction txn, S session) throws DbException;

 	S onRequestMessage(Transaction txn, S session, RequestMessage m)
 			throws DbException, FormatException;
--- a/briar-core/src/main/java/org/briarproject/briar/messaging/ConversationManagerImpl.java
+++ b/briar-core/src/main/java/org/briarproject/briar/messaging/ConversationManagerImpl.java
@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
@@ -20,16 +21,20 @@ import java.util.concurrent.CopyOnWriteArraySet;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;

+import static java.lang.Math.max;
+
@ThreadSafe
@NotNullByDefault
 class ConversationManagerImpl implements ConversationManager {

 	private final DatabaseComponent db;
+	private final Clock clock;
 	private final Set<ConversationClient> clients;

 	@Inject
-	ConversationManagerImpl(DatabaseComponent db) {
+	ConversationManagerImpl(DatabaseComponent db, Clock clock) {
 		this.db = db;
+		this.clock = clock;
 		clients = new CopyOnWriteArraySet<>();
 	}

@@ -76,6 +81,14 @@ class ConversationManagerImpl implements ConversationManager {
 		return new GroupCount(msgCount, unreadCount, latestTime);
 	}

+	@Override
+	public long getTimestampForOutgoingMessage(Transaction txn, ContactId c)
+			throws DbException {
+		long now = clock.currentTimeMillis();
+		GroupCount gc = getGroupCount(txn, c);
+		return max(now, gc.getLatestMsgTime() + 1);
+	}
+
 	@Override
 	public DeletionResult deleteAllMessages(ContactId c) throws DbException {
 		return db.transactionWithResult(false, txn -> {
--- a/briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java
+++ b/briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java
@@ -140,11 +140,9 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		Contact introducee1 = contact1From0;
 		Contact introducee2 = contact2From0;
-		introductionManager0
-				.makeIntroduction(introducee1, introducee2, "Hi!", time);
+		introductionManager0.makeIntroduction(introducee1, introducee2, "Hi!");

 		// check that messages are tracked properly
 		Group g1 = introductionManager0.getContactGroup(introducee1);
@@ -264,11 +262,9 @@ public class IntroductionIntegrationTest
 		addListeners(false, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		Contact introducee1 = contact1From0;
 		Contact introducee2 = contact2From0;
-		introductionManager0
-				.makeIntroduction(introducee1, introducee2, null, time);
+		introductionManager0.makeIntroduction(introducee1, introducee2, null);

 		// sync request messages
 		sync0To1(1, true);
@@ -356,9 +352,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, false);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync request messages
 		sync0To1(1, true);
@@ -412,9 +407,8 @@ public class IntroductionIntegrationTest
 		addListeners(false, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync request messages
 		sync0To1(1, true);
@@ -438,9 +432,8 @@ public class IntroductionIntegrationTest
 		assertFalse(listener1.aborted);
 		assertFalse(listener2.aborted);

-		time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync request messages
 		sync0To1(1, true);
@@ -457,9 +450,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync first request message
 		sync0To1(1, true);
@@ -482,7 +474,7 @@ public class IntroductionIntegrationTest

 		// answer request manually
 		introductionManager2.respondToIntroduction(contactId0From2,
-				listener2.sessionId, time, true);
+				listener2.sessionId, true);

 		// sync second response and AUTH
 		sync2To0(2, true);
@@ -518,11 +510,10 @@ public class IntroductionIntegrationTest
 		listener2.answerRequests = false;

 		// make introduction
-		long time = clock.currentTimeMillis();
 		Contact introducee1 = contact1From0;
 		Contact introducee2 = contact2From0;
 		introductionManager0
-				.makeIntroduction(introducee1, introducee2, null, time);
+				.makeIntroduction(introducee1, introducee2, null);

 		// sync request messages
 		sync0To1(1, true);
@@ -564,7 +555,7 @@ public class IntroductionIntegrationTest

 		// answer request manually
 		introductionManager2.respondToIntroduction(contactId0From2,
-				listener2.sessionId, time, false);
+				listener2.sessionId, false);

 		// now introducee2 should have returned to the START state
 		introduceeSession = getIntroduceeSession(c2);
@@ -611,9 +602,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, false);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact1From0, null, time);
+				.makeIntroduction(contact1From0, contact1From0, null);

 		// sync request messages
 		sync0To1(1, false);
@@ -637,9 +627,8 @@ public class IntroductionIntegrationTest
 				.canIntroduce(contact1From0, contact2From0));

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// no more introduction allowed while the existing one is in progress
 		assertFalse(introductionManager0
@@ -647,7 +636,7 @@ public class IntroductionIntegrationTest

 		// try it anyway and fail
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);
 	}

 	@Test
@@ -661,9 +650,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -719,9 +707,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -766,9 +753,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync REQUEST to introducee1
 		sync0To1(1, true);
@@ -803,9 +789,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync REQUEST to introducee1
 		sync0To1(1, true);
@@ -838,9 +823,8 @@ public class IntroductionIntegrationTest
 		addListeners(false, true);

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync REQUEST to introducee1
 		sync0To1(1, true);
@@ -873,9 +857,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make the introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -914,9 +897,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync first request message
 		sync0To1(1, true);
@@ -943,9 +925,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync first request message
 		sync0To1(1, true);
@@ -987,9 +968,8 @@ public class IntroductionIntegrationTest
 	@Test
 	public void testIntroductionAfterReAddingContacts() throws Exception {
 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// 0 and 1 remove and re-add each other
 		contactManager0.removeContact(contactId1From0);
@@ -1016,9 +996,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make new introduction
-		time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, null, time);
+				.makeIntroduction(contact1From0, contact2From0, null);

 		// introduction should sync and not be INVALID or PENDING
 		sync0To1(1, true);
@@ -1032,9 +1011,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync request messages
 		sync0To1(1, true);
@@ -1147,9 +1125,8 @@ public class IntroductionIntegrationTest
 		addListeners(true, true);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync first REQUEST message
 		sync0To1(1, true);
@@ -1292,7 +1269,7 @@ public class IntroductionIntegrationTest
 		assertTrue(introductionManager0
 				.canIntroduce(contact1From0, contact2From0));
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Ho!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Ho!");
 		sync0To1(1, true);
 		sync0To2(1, true);

@@ -1332,9 +1309,8 @@ public class IntroductionIntegrationTest
 		addListeners(false, false);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -1399,9 +1375,8 @@ public class IntroductionIntegrationTest
 		// a new introduction is still possible
 		assertTrue(introductionManager0
 				.canIntroduce(contact1From0, contact2From0));
-		time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Ho!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Ho!");
 		sync0To1(1, true);
 		sync0To2(1, true);

@@ -1428,9 +1403,8 @@ public class IntroductionIntegrationTest
 		addListeners(false, false);

 		// make introduction
-		long time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Hi!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -1458,9 +1432,8 @@ public class IntroductionIntegrationTest
 		// a new introduction is still possible
 		assertTrue(introductionManager0
 				.canIntroduce(contact1From0, contact2From0));
-		time = clock.currentTimeMillis();
 		introductionManager0
-				.makeIntroduction(contact1From0, contact2From0, "Ho!", time);
+				.makeIntroduction(contact1From0, contact2From0, "Ho!");
 		sync0To1(1, true);
 		sync0To2(1, true);

@@ -1496,9 +1469,8 @@ public class IntroductionIntegrationTest
 		addListeners(false, false);

 		// make introduction
-		long time = clock.currentTimeMillis();
-		introductionManager0.makeIntroduction(contact1From0, contact2From0,
-				"Hi!", time);
+		introductionManager0
+				.makeIntroduction(contact1From0, contact2From0, "Hi!");

 		// deleting the introduction for introducee1 will fail
 		Collection<ConversationMessageHeader> m1From0 = getMessages1From0();
@@ -1795,16 +1767,13 @@ public class IntroductionIntegrationTest
 				IntroductionRequest ir = introEvent.getMessageHeader();
 				ContactId contactId = introEvent.getContactId();
 				sessionId = ir.getSessionId();
-				long time = clock.currentTimeMillis();
 				try {
 					if (introducee == 1 && answerRequests) {
-						introductionManager1
-								.respondToIntroduction(contactId, sessionId,
-										time, accept);
+						introductionManager1.respondToIntroduction(contactId,
+								sessionId, accept);
 					} else if (introducee == 2 && answerRequests) {
-						introductionManager2
-								.respondToIntroduction(contactId, sessionId,
-										time, accept);
+						introductionManager2.respondToIntroduction(contactId,
+								sessionId, accept);
 					}
 				} catch (DbException exception) {
 					eventWaiter.rethrow(exception);