Asynchronous offers and requests for BMP.

Offered and requested message IDs are stored in the database rather than
being owned by DuplexConnections. This paves the way for moving to a
simplex transport layer.

briar-api/src/net/sf/briar/api/db/AckAndRequest.java

@@ -1,27 +0,0 @@
-package net.sf.briar.api.db;
-
-import net.sf.briar.api.messaging.Ack;
-import net.sf.briar.api.messaging.Request;
-
-/**
- * A tuple of an {@link net.sf.briar.api.messaging.Ack} and a
- * {@link net.sf.briar.api.messaging.Request}.
- */
-public class AckAndRequest {
-
-	private final Ack ack;
-	private final Request request;
-
-	public AckAndRequest(Ack ack, Request request) {
-		this.ack = ack;
-		this.request = request;
-	}
-
-	public Ack getAck() {
-		return ack;
-	}
-
-	public Request getRequest() {
-		return request;
-	}
-}

briar-api/src/net/sf/briar/api/db/DatabaseComponent.java

@@ -20,6 +20,7 @@ import net.sf.briar.api.messaging.GroupStatus;
 import net.sf.briar.api.messaging.Message;
 import net.sf.briar.api.messaging.MessageId;
 import net.sf.briar.api.messaging.Offer;
+import net.sf.briar.api.messaging.Request;
 import net.sf.briar.api.messaging.RetentionAck;
 import net.sf.briar.api.messaging.RetentionUpdate;
 import net.sf.briar.api.messaging.SubscriptionAck;
@@ -80,9 +81,6 @@ public interface DatabaseComponent {
 	 */
 	boolean addTransport(TransportId t, long maxLatency) throws DbException;
 
-	/** Returns true if any messages are sendable to the given contact. */
-	boolean containsSendableMessages(ContactId c) throws DbException;
-
 	/**
 	 * Returns an acknowledgement for the given contact, or null if there are
 	 * no messages to acknowledge.
@@ -99,23 +97,28 @@ public interface DatabaseComponent {
 			long maxLatency) throws DbException;
 
 	/**
-	 * Returns a batch of raw messages for the given contact from the given
-	 * collection of requested messages, with a total length less than or equal
-	 * to the given length, for transmission over a transport with the given
-	 * maximum latency. Any messages that were either added to the batch, or
-	 * were considered but are not sendable to the contact, are removed from
-	 * the collection of requested messages before returning. Returns null if
-	 * there are no sendable messages that fit in the given length.
+	 * Returns an offer for the given contact for transmission over a
+	 * transport with the given maximum latency, or null if there are no
+	 * messages to offer.
 	 */
-	Collection<byte[]> generateBatch(ContactId c, int maxLength,
-			long maxLatency, Collection<MessageId> requested)
-					throws DbException;
+	Offer generateOffer(ContactId c, int maxMessages, long maxLatency)
+			throws DbException;
 
 	/**
-	 * Returns an offer for the given contact, or null if there are no messages
-	 * to offer.
+	 * Returns a request for the given contact, or null if there are no
+	 * messages to request.
 	 */
-	Offer generateOffer(ContactId c, int maxMessages) throws DbException;
+	Request generateRequest(ContactId c, int maxMessages) throws DbException;
+
+	/**
+	 * Returns a batch of raw messages for the given contact, with a total
+	 * length less than or equal to the given length, for transmission over a
+	 * transport with the given maximum latency. Only messages that have been
+	 * requested by the contact are returned. Returns null if there are no
+	 * sendable messages that fit in the given length.
+	 */
+	Collection<byte[]> generateRequestedBatch(ContactId c, int maxLength,
+			long maxLatency) throws DbException;
 
 	/**
 	 * Returns a retention ack for the given contact, or null if no retention
@@ -220,7 +223,7 @@ public interface DatabaseComponent {
 	Collection<MessageHeader> getMessageHeaders(GroupId g)
 			throws DbException;
 
-	/** Returns true if the given message has been read. */
+	/** Returns true if the given message is marked as read. */
 	boolean getReadFlag(MessageId m) throws DbException;
 
 	/** Returns all remote transport properties for the given transport. */
@@ -266,18 +269,11 @@ public interface DatabaseComponent {
 	/** Processes a message from the given contact. */
 	void receiveMessage(ContactId c, Message m) throws DbException;
 
-	/**
-	 * Processes an offer from the given contact and generates an ack for any
-	 * messages in the offer that are present in the database, and a request
-	 * for any messages that are not. The ack or the request may be null if no
-	 * messages meet the respective criteria.
-	 * <p>
-	 * To prevent contacts from using offers to test for subscriptions that are
-	 * not visible to them, any messages belonging to groups that are not
-	 * visible to the contact are requested just as though they were not
-	 * present in the database.
-	 */
-	AckAndRequest receiveOffer(ContactId c, Offer o) throws DbException;
+	/** Processes an offer from the given contact. */
+	void receiveOffer(ContactId c, Offer o) throws DbException;
+
+	/** Processes a request from the given contact. */
+	void receiveRequest(ContactId c, Request r) throws DbException;
 
 	/** Processes a retention ack from the given contact. */
 	void receiveRetentionAck(ContactId c, RetentionAck a) throws DbException;
@@ -335,10 +331,9 @@ public interface DatabaseComponent {
 	public void setInboxGroup(ContactId c, Group g) throws DbException;
 
 	/**
-	 * Marks a message read or unread and returns true if it was previously
-	 * read.
+	 * Marks a message as read or unread.
 	 */
-	boolean setReadFlag(MessageId m, boolean read) throws DbException;
+	void setReadFlag(MessageId m, boolean read) throws DbException;
 
 	/**
 	 * Sets the remote transport properties for the given contact, replacing
@@ -347,9 +342,6 @@ public interface DatabaseComponent {
 	void setRemoteProperties(ContactId c,
 			Map<TransportId, TransportProperties> p) throws DbException;
 
-	/** Records the given messages as having been seen by the given contact. */
-	void setSeen(ContactId c, Collection<MessageId> seen) throws DbException;
-
 	/**
 	 * Makes a group visible to the given set of contacts and invisible to any
 	 * other current or future contacts.

briar-api/src/net/sf/briar/api/db/event/MessageRequestedEvent.java

@@ -2,12 +2,12 @@ package net.sf.briar.api.db.event;
 
 import net.sf.briar.api.ContactId;
 
-/** An event that is broadcast when a message is received. */
-public class MessageReceivedEvent extends DatabaseEvent {
+/** An event that is broadcast when a message is requested by a contact. */
+public class MessageRequestedEvent extends DatabaseEvent {
 
 	private final ContactId contactId;
 
-	public MessageReceivedEvent(ContactId contactId) {
+	public MessageRequestedEvent(ContactId contactId) {
 		this.contactId = contactId;
 	}
 

briar-api/src/net/sf/briar/api/db/event/MessageToAckEvent.java

@@ -0,0 +1,20 @@
+package net.sf.briar.api.db.event;
+
+import net.sf.briar.api.ContactId;
+
+/**
+ * An event that is broadcast when a message is received or offered from a
+ * contact and needs to be acknowledged.
+ */
+public class MessageToAckEvent extends DatabaseEvent {
+
+	private final ContactId contactId;
+
+	public MessageToAckEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

briar-api/src/net/sf/briar/api/db/event/MessageToRequestEvent.java

@@ -0,0 +1,20 @@
+package net.sf.briar.api.db.event;
+
+import net.sf.briar.api.ContactId;
+
+/**
+ * An event that is broadcast when a message is offered by a contact and needs
+ * to be requested.
+ */
+public class MessageToRequestEvent extends DatabaseEvent {
+
+	private final ContactId contactId;
+
+	public MessageToRequestEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

briar-api/src/net/sf/briar/api/messaging/MessagingConstants.java

@@ -37,8 +37,9 @@ public interface MessagingConstants {
 	int MESSAGE_SALT_LENGTH = 32;
 
 	/**
-	 * The timestamp of the oldest message in the database is rounded using
-	 * this modulus to avoid revealing the presence of any particular message.
+	 * When calculating the retention time of the database, the timestamp of
+	 * the oldest message in the database is rounded down to a multiple of
+	 * this value to avoid revealing the presence of any particular message.
 	 */
-	int RETENTION_MODULUS = 60 * 60 * 1000; // 1 hour
+	int RETENTION_GRANULARITY = 60 * 1000; // 1 minute
 }

briar-api/src/net/sf/briar/api/messaging/PacketWriter.java

@@ -4,7 +4,7 @@ import java.io.IOException;
 
 public interface PacketWriter {
 
-	int getMaxMessagesForAck(long capacity);
+	int getMaxMessagesForRequest(long capacity);
 
 	int getMaxMessagesForOffer(long capacity);