bool ReceivedPacketProcessor::process() {
if (_packets.size() == 0) {
_waitingOnPacketsMutex.lock();
_hasPackets.wait(&_waitingOnPacketsMutex);
_waitingOnPacketsMutex.unlock();
}
while (_packets.size() > 0) {
lock(); // lock to make sure nothing changes on us
NetworkPacket& packet = _packets.front(); // get the oldest packet
NetworkPacket temporary = packet; // make a copy of the packet in case the vector is resized on us
_packets.erase(_packets.begin()); // remove the oldest packet
_nodePacketCounts[temporary.getNode()->getUUID()]--;
unlock(); // let others add to the packets
processPacket(temporary.getNode(), temporary.getByteArray()); // process our temporary copy
}
return isStillRunning(); // keep running till they terminate us
}
// We may be called more frequently than we get packets or need to send packets, we may also get called less frequently.
//
// If we're called more often then out target PPS then we will space out our actual sends to be a single packet for multiple
// calls to process. Those calls to proces in which we do not need to send a packet to keep up with our target PPS we will
// just track our call rate (in order to predict our sends per call) but we won't actually send any packets.
//
// When we are called less frequently than we have packets to send, we will send enough packets per call to keep up with our
// target PPS.
//
// We also keep a running total of packets sent over multiple calls to process() so that we can adjust up or down for
// possible rounding error that would occur if we only considered whole integer packet counts per call to process
bool PacketSender::nonThreadedProcess() {
quint64 now = usecTimestampNow();
if (_lastProcessCallTime == 0) {
_lastProcessCallTime = now - _usecsPerProcessCallHint;
}
const quint64 MINIMUM_POSSIBLE_CALL_TIME = 10; // in usecs
const quint64 USECS_PER_SECOND = 1000 * 1000;
const float ZERO_RESET_CALLS_PER_SECOND = 1; // used in guard against divide by zero
// keep track of our process call times, so we have a reliable account of how often our caller calls us
quint64 elapsedSinceLastCall = now - _lastProcessCallTime;
_lastProcessCallTime = now;
_averageProcessCallTime.updateAverage(elapsedSinceLastCall);
float averageCallTime = 0;
const int TRUST_AVERAGE_AFTER = AVERAGE_CALL_TIME_SAMPLES * 2;
if (_usecsPerProcessCallHint == 0 || _averageProcessCallTime.getSampleCount() > TRUST_AVERAGE_AFTER) {
averageCallTime = _averageProcessCallTime.getAverage();
} else {
averageCallTime = _usecsPerProcessCallHint;
}
if (_packets.size() == 0) {
// in non-threaded mode, if there's nothing to do, just return, keep running till they terminate us
return isStillRunning();
}
// This only happens once, the first time we get this far... so we can use it as an accurate initialization
// point for these important timing variables
if (_lastPPSCheck == 0) {
_lastPPSCheck = now;
// pretend like our lifetime began once call cycle for now, this makes our lifetime PPS start out most accurately
_started = now - (quint64)averageCallTime;
}
float averagePacketsPerCall = 0; // might be less than 1, if our caller calls us more frequently than the target PPS
int packetsSentThisCall = 0;
int packetsToSendThisCall = 0;
// Since we're in non-threaded mode, we need to determine how many packets to send per call to process
// based on how often we get called... We do this by keeping a running average of our call times, and we determine
// how many packets to send per call
// We assume you can't possibly call us less than MINIMUM_POSSIBLE_CALL_TIME apart
if (averageCallTime <= 0) {
averageCallTime = MINIMUM_POSSIBLE_CALL_TIME;
}
// we can determine how many packets we need to send per call to achieve our desired
// packets per second send rate.
float callsPerSecond = USECS_PER_SECOND / averageCallTime;
// theoretically we could get called less than 1 time per second... but since we're using floats, it really shouldn't be
// possible to get 0 calls per second, but we will guard agains that here, just in case.
if (callsPerSecond == 0) {
callsPerSecond = ZERO_RESET_CALLS_PER_SECOND;
}
// This is the average number of packets per call...
averagePacketsPerCall = _packetsPerSecond / callsPerSecond;
packetsToSendThisCall = averagePacketsPerCall;
// if we get called more than 1 per second, we want to mostly divide the packets evenly across the calls...
// but we want to track the remainder and make sure over the course of a second, we are sending the target PPS
// e.g.
// 200pps called 60 times per second...
// 200/60 = 3.333... so really...
// each call we should send 3
// every 3rd call we should send 4...
// 3,3,4,3,3,4...3,3,4 = 200...
// if we get called less than 1 per second, then we want to send more than our PPS each time...
// e.g.
// 200pps called ever 1332.5ms
// 200 / (1000/1332.5) = 200/(0.7505) = 266.5 packets per call
// so...
// every other call we should send 266 packets
// then on the next call we should send 267 packets
// So no mater whether or not we're getting called more or less than once per second, we still need to do some bookkeeping
// to make sure we send a few extra packets to even out our flow rate.
quint64 elapsedSinceLastCheck = now - _lastPPSCheck;
// we might want to tun this in the future and only check after a certain number of call intervals. for now we check
// each time and adjust accordingly
const float CALL_INTERVALS_TO_CHECK = 1;
const float MIN_CALL_INTERVALS_PER_RESET = 5;
// we will reset our check PPS and time each second (callsPerSecond) or at least 5 calls (if we get called less frequently
// than 5 times per second) This gives us sufficient smoothing in our packet adjustments
float callIntervalsPerReset = std::max(callsPerSecond, MIN_CALL_INTERVALS_PER_RESET);
if (elapsedSinceLastCheck > (averageCallTime * CALL_INTERVALS_TO_CHECK)) {
float ppsOverCheckInterval = (float)_packetsOverCheckInterval;
float ppsExpectedForCheckInterval = (float)_packetsPerSecond * ((float)elapsedSinceLastCheck / (float)USECS_PER_SECOND);
if (ppsOverCheckInterval < ppsExpectedForCheckInterval) {
int adjust = ppsExpectedForCheckInterval - ppsOverCheckInterval;
packetsToSendThisCall += adjust;
} else if (ppsOverCheckInterval > ppsExpectedForCheckInterval) {
int adjust = ppsOverCheckInterval - ppsExpectedForCheckInterval;
packetsToSendThisCall -= adjust;
}
// now, do we want to reset the check interval? don't want to completely reset, because we would still have
// a rounding error. instead, we check to see that we've passed the reset interval (which is much larger than
// the check interval), and on those reset intervals we take the second half average and keep that for the next
// interval window...
if (elapsedSinceLastCheck > (averageCallTime * callIntervalsPerReset)) {
// Keep average packets and time for "second half" of check interval
_lastPPSCheck += (elapsedSinceLastCheck / 2);
_packetsOverCheckInterval = (_packetsOverCheckInterval / 2);
elapsedSinceLastCheck = now - _lastPPSCheck;
}
}
int packetsLeft = _packets.size();
// Now that we know how many packets to send this call to process, just send them.
while ((packetsSentThisCall < packetsToSendThisCall) && (packetsLeft > 0)) {
lock();
NetworkPacket& packet = _packets.front();
NetworkPacket temporary = packet; // make a copy
_packets.erase(_packets.begin());
packetsLeft = _packets.size();
unlock();
// send the packet through the NodeList...
NodeList::getInstance()->writeDatagram(temporary.getByteArray(), temporary.getDestinationNode());
packetsSentThisCall++;
_packetsOverCheckInterval++;
_totalPacketsSent++;
_totalBytesSent += temporary.getByteArray().size();
emit packetSent(temporary.getByteArray().size());
_lastSendTime = now;
}
return isStillRunning();
}
NetworkPacket::NetworkPacket(const NetworkPacket& packet) {
copyContents(packet.getNode(), packet.getByteArray());
}