private void negotiate(final ProgressMonitor monitor) throws IOException, CancelledException {
final MutableObjectId ackId = new MutableObjectId();
int resultsPending = 0;
int havesSent = 0;
int havesSinceLastContinue = 0;
boolean receivedContinue = false;
boolean receivedAck = false;
boolean sendHaves = true;
negotiateBegin();
while (sendHaves) {
final RevCommit c = walk.next();
if (c == null) break;
pckOut.writeString("have " + c.getId().name() + "\n");
havesSent++;
havesSinceLastContinue++;
if ((31 & havesSent) != 0) {
// We group the have lines into blocks of 32, each marked
// with a flush (aka end). This one is within a block so
// continue with another have line.
//
continue;
}
if (monitor.isCancelled()) throw new CancelledException();
pckOut.end();
resultsPending++; // Each end will cause a result to come back.
if (havesSent == 32) {
// On the first block we race ahead and try to send
// more of the second block while waiting for the
// remote to respond to our first block request.
// This keeps us one block ahead of the peer.
//
continue;
}
while (resultsPending > 0) {
final PacketLineIn.AckNackResult anr;
anr = pckIn.readACK(ackId);
resultsPending--;
if (anr == PacketLineIn.AckNackResult.NAK) {
// More have lines are necessary to compute the
// pack on the remote side. Keep doing that.
//
break;
}
if (anr == PacketLineIn.AckNackResult.ACK) {
// The remote side is happy and knows exactly what
// to send us. There is no further negotiation and
// we can break out immediately.
//
multiAck = false;
resultsPending = 0;
receivedAck = true;
sendHaves = false;
break;
}
if (anr == PacketLineIn.AckNackResult.ACK_CONTINUE) {
// The server knows this commit (ackId). We don't
// need to send any further along its ancestry, but
// we need to continue to talk about other parts of
// our local history.
//
markCommon(walk.parseAny(ackId));
receivedAck = true;
receivedContinue = true;
havesSinceLastContinue = 0;
}
if (monitor.isCancelled()) throw new CancelledException();
}
if (receivedContinue && havesSinceLastContinue > MAX_HAVES) {
// Our history must be really different from the remote's.
// We just sent a whole slew of have lines, and it did not
// recognize any of them. Avoid sending our entire history
// to them by giving up early.
//
break;
}
}
// Tell the remote side we have run out of things to talk about.
//
if (monitor.isCancelled()) throw new CancelledException();
pckOut.writeString("done\n");
pckOut.flush();
if (!receivedAck) {
// Apparently if we have never received an ACK earlier
// there is one more result expected from the done we
// just sent to the remote.
//
multiAck = false;
resultsPending++;
}
while (resultsPending > 0 || multiAck) {
final PacketLineIn.AckNackResult anr;
anr = pckIn.readACK(ackId);
resultsPending--;
if (anr == PacketLineIn.AckNackResult.ACK) break; // commit negotiation is finished.
if (anr == PacketLineIn.AckNackResult.ACK_CONTINUE) {
// There must be a normal ACK following this.
//
multiAck = true;
}
if (monitor.isCancelled()) throw new CancelledException();
}
}
