Code cleanup and comments.

components/net/sf/briar/transport/stream/StreamConnection.java

@@ -52,9 +52,9 @@ abstract class StreamConnection implements DatabaseListener {
 	protected final ContactId contactId;
 	protected final StreamTransportConnection connection;
 
-	// The following fields must only be accessed with this's lock held
+	// These fields must only be accessed with this's lock held
 	private int writerFlags = 0;
-	private Collection<MessageId> outgoingOffer = null;
+	private Collection<MessageId> offered = null;
 	private Collection<MessageId> requested = null;
 	private Offer incomingOffer = null;
 
@@ -107,6 +107,7 @@ abstract class StreamConnection implements DatabaseListener {
 					db.receiveBatch(contactId, b);
 				} else if(proto.hasOffer()) {
 					Offer o = proto.readOffer();
+					// Store the incoming offer and notify the writer
 					synchronized(this) {
 						writerFlags |= Flags.OFFER_RECEIVED;
 						incomingOffer = o;
@@ -114,31 +115,33 @@ abstract class StreamConnection implements DatabaseListener {
 					}
 				} else if(proto.hasRequest()) {
 					Request r = proto.readRequest();
-					Collection<MessageId> offered, seen, unseen;
+					// Retrieve the offered message IDs
+					Collection<MessageId> off;
 					synchronized(this) {
-						if(outgoingOffer == null)
+						if(offered == null)
 							throw new IOException("Unexpected request packet");
-						offered = outgoingOffer;
+						off = offered;
+						offered = null;
 					}
 					// Work out which messages were requested
 					BitSet b = r.getBitmap();
-					seen = new ArrayList<MessageId>();
+					Collection<MessageId> req = new LinkedList<MessageId>();
-					unseen = new LinkedList<MessageId>();
+					Collection<MessageId> seen = new ArrayList<MessageId>();
 					int i = 0;
-					for(MessageId m : offered) {
+					for(MessageId m : off) {
-						if(b.get(i++)) unseen.add(m);
+						if(b.get(i++)) req.add(m);
 						else seen.add(m);
 					}
+					// Mark the unrequested messages as seen
+					db.setSeen(contactId, seen);
+					// Store the requested message IDs and notify the writer
 					synchronized(this) {
-						assert outgoingOffer != null;
+						if(requested != null)
-						if(requested != null && !requested.isEmpty())
 							throw new IOException("Unexpected request packet");
-						outgoingOffer = null;
+						requested = req;
-						requested = unseen;
 						writerFlags |= Flags.REQUEST_RECEIVED;
 						notifyAll();
 					}
-					db.setSeen(contactId, seen);
 				} else if(proto.hasSubscriptionUpdate()) {
 					SubscriptionUpdate s = proto.readSubscriptionUpdate();
 					db.receiveSubscriptionUpdate(contactId, s);
@@ -179,12 +182,12 @@ abstract class StreamConnection implements DatabaseListener {
 			sendAcks(ackWriter);
 			State state = State.SEND_OFFER;
 			// Main loop
-			boolean close = false;
+			while(true) {
-			while(!close) {
 				int flags = 0;
 				switch(state) {
 
 				case SEND_OFFER:
+					// Try to send an offer
 					if(sendOffer(offerWriter)) state = State.AWAIT_REQUEST;
 					else state = State.IDLE;
 					break;
@@ -203,8 +206,8 @@ abstract class StreamConnection implements DatabaseListener {
 					// Handle the flags in approximate order of urgency
 					if((flags & Flags.CONTACTS_UPDATED) != 0) {
 						if(!db.getContacts().contains(contactId)) {
-							close = true;
+							connection.dispose(true);
-							break;
+							return;
 						}
 					}
 					if((flags & Flags.TRANSPORTS_UPDATED) != 0) {
@@ -220,6 +223,7 @@ abstract class StreamConnection implements DatabaseListener {
 						sendRequest(requestWriter);
 					}
 					if((flags & Flags.REQUEST_RECEIVED) != 0) {
+						// Should only be received in state AWAIT_REQUEST
 						throw new IOException("Unexpected request packet");
 					}
 					if((flags & Flags.MESSAGES_ADDED) != 0) {
@@ -241,8 +245,8 @@ abstract class StreamConnection implements DatabaseListener {
 					// Handle the flags in approximate order of urgency
 					if((flags & Flags.CONTACTS_UPDATED) != 0) {
 						if(!db.getContacts().contains(contactId)) {
-							close = true;
+							connection.dispose(true);
-							break;
+							return;
 						}
 					}
 					if((flags & Flags.TRANSPORTS_UPDATED) != 0) {
@@ -274,8 +278,8 @@ abstract class StreamConnection implements DatabaseListener {
 					// Handle the flags in approximate order of urgency
 					if((flags & Flags.CONTACTS_UPDATED) != 0) {
 						if(!db.getContacts().contains(contactId)) {
-							close = true;
+							connection.dispose(true);
-							break;
+							return;
 						}
 					}
 					if((flags & Flags.TRANSPORTS_UPDATED) != 0) {
@@ -291,12 +295,13 @@ abstract class StreamConnection implements DatabaseListener {
 						sendRequest(requestWriter);
 					}
 					if((flags & Flags.REQUEST_RECEIVED) != 0) {
+						// Should only be received in state AWAIT_REQUEST
 						throw new IOException("Unexpected request packet");
 					}
 					if((flags & Flags.MESSAGES_ADDED) != 0) {
 						// Ignored in this state
 					}
-					// Send a batch if possible, otherwise an offer
+					// Try to send a batch
 					if(!sendBatch(batchWriter)) state = State.SEND_OFFER;
 					break;
 				}
@@ -317,35 +322,47 @@ abstract class StreamConnection implements DatabaseListener {
 	}
 
 	private boolean sendBatch(BatchWriter b) throws DbException, IOException {
-		Collection<MessageId> ids;
+		Collection<MessageId> req;
+		// Retrieve the requested message IDs
 		synchronized(this) {
-			assert outgoingOffer == null;
+			assert offered == null;
 			assert requested != null;
-			ids = requested;
+			req = requested;
+		}
+		// Try to generate a batch, updating the collection of message IDs
+		boolean anyAdded = db.generateBatch(contactId, b, req);
+		// If no more batches can be generated, discard the remaining IDs
+		if(!anyAdded) {
+			synchronized(this) {
+				assert offered == null;
+				assert requested == req;
+				requested = null;
+			}
 		}
-		boolean anyAdded = db.generateBatch(contactId, b, ids);
-		if(!anyAdded) ids.clear();
 		return anyAdded;
 	}
 
 	private boolean sendOffer(OfferWriter o) throws DbException, IOException {
-		Collection<MessageId> ids = db.generateOffer(contactId, o);
+		// Generate an offer
+		Collection<MessageId> off = db.generateOffer(contactId, o);
+		// Store the offered message IDs
 		synchronized(this) {
-			assert outgoingOffer == null;
+			assert offered == null;
-			assert requested == null || requested.isEmpty();
+			assert requested == null;
-			outgoingOffer = ids;
+			offered = off;
 		}
-		boolean anyOffered = !ids.isEmpty();
+		return !off.isEmpty();
-		return anyOffered;
 	}
 
 	private void sendRequest(RequestWriter r) throws DbException, IOException {
 		Offer o;
+		// Retrieve the incoming offer
 		synchronized(this) {
 			assert incomingOffer != null;
 			o = incomingOffer;
 			incomingOffer = null;
 		}
+		// Process the offer and generate a request
 		db.receiveOffer(contactId, o, r);
 	}