Author: mrogers
Date: 2006-07-27 09:21:15 +0000 (Thu, 27 Jul 2006)
New Revision: 9791
Modified:
trunk/apps/load-balancing-sims/phase5/Peer.java
Log:
Don't send empty packets
Modified: trunk/apps/load-balancing-sims/phase5/Peer.java
===================================================================
--- trunk/apps/load-balancing-sims/phase5/Peer.java 2006-07-27 08:59:44 UTC
(rev 9790)
+++ trunk/apps/load-balancing-sims/phase5/Peer.java 2006-07-27 09:21:15 UTC
(rev 9791)
@@ -35,7 +35,6 @@
private LinkedList<DataPacket> txBuffer; // Retransmission buffer
private LinkedList<Message> txQueue; // Messages waiting to be sent
private int txQueueSize = 0; // Size of transmission queue in bytes
- private int txHeadSize = 0; // Size of first message in transmission q
// Receiver state
private int rxSeq = 0; // Sequence number of next in-order packet
@@ -59,7 +58,6 @@
log (m + " added to transmission queue");
// Warning: until token-passing is implemented the length of
// the transmission queue is unlimited
- if (txQueue.isEmpty()) txHeadSize = m.size;
txQueue.add (m);
txQueueSize += m.size;
log (txQueue.size() + " messages in transmission queue");
@@ -75,50 +73,50 @@
return false;
}
+ // Return to slow start when the link is idle
+ double now = Event.time();
+ if (now - lastTransmission > RTO * rtt) {
+ log ("returning to slow start");
+ cwind = MIN_CWIND;
+ slowStart = true;
+ }
+ lastTransmission = now;
+
+ if (cwind - inflight <= Packet.HEADER_SIZE) {
+ log ("no room in congestion window");
+ return false;
+ }
+
// Work out how large a packet we can send
int payload = Packet.MAX_PAYLOAD;
if (payload > txQueueSize) payload = txQueueSize;
if (payload > cwind - inflight - Packet.HEADER_SIZE)
payload = (int) cwind - inflight - Packet.HEADER_SIZE;
- if (payload < txHeadSize) {
- log ("no room in congestion window");
- return false;
- }
-
// Nagle's algorithm - try to coalesce small packets
if (payload < Packet.SENSIBLE_PAYLOAD && inflight > 0) {
log ("delaying transmission of " + payload + " bytes");
return false;
}
- // Return to slow start when the link is idle
- double now = Event.time();
- if (now - lastTransmission > RTO * rtt) {
- log ("returning to slow start");
- cwind = MIN_CWIND;
- slowStart = true;
- }
- lastTransmission = now;
-
// Put as many messages as possible in the packet
DataPacket p = new DataPacket (payload);
- while (payload >= txHeadSize) {
- try {
- Message m = txQueue.removeFirst();
- p.addMessage (m);
- payload -= txHeadSize;
- txQueueSize -= txHeadSize;
- // Move on to the next message
- txHeadSize = txQueue.getFirst().size;
- }
- catch (NoSuchElementException nse) {
- // No more messages in the txQueue
- txHeadSize = 0;
- break;
- }
+ Iterator<Message> i = txQueue.iterator();
+ while (i.hasNext()) {
+ Message m = i.next();
+ if (m.size > payload) break;
+ i.remove();
+ txQueueSize -= m.size;
+ p.addMessage (m);
+ payload -= m.size;
}
+ // Don't send empty packets
+ if (p.messages == null) {
+ log ("message too large for congestion window");
+ return false;
+ }
+
// Send the packet
p.seq = txSeq++;
log ("sending packet " + p.seq + ", " + p.size + " bytes");
