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Add protection to the multiplayer (AI) interpolation to protect against segfaults when the previous and next packets contain different properties.

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This commit is contained in:
Richard Harrison 2017-01-30 23:24:39 +01:00
parent e39eac8a6d
commit 0bf80f9b2a
1 changed files with 47 additions and 29 deletions
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26
src/AIModel/AIMultiplayer.cxx
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@ -319,18 +319,31 @@ void FGAIMultiplayer::update(double dt)
int ival;
float val;
/*
* RJH - 2017-01-25
* During multiplayer operations a series of crashes were encountered that affected all players
* within range of each other and resulting in an exception being thrown at exactly the same moment in time
* (within case props::STRING: ref http://i.imgur.com/y6MBoXq.png)
* Investigation showed that the nextPropIt and prevPropIt were pointing to different properties
* which may be caused due to certain models that have overloaded mp property transmission and
* these craft have their properties truncated due to packet size. However the result of this
* will be different contents in the previous and current packets, so here we protect against
* this by only considering properties where the previous and next id are the same.
* It might be a better solution to search the previous and next lists to locate the matching id's
*/
if (*nextPropIt && (*nextPropIt)->id == (*prevPropIt)->id ) {
switch ((*prevPropIt)->type) {
case props::INT:
case props::BOOL:
case props::LONG:
ival = (int) (0.5+(1-tau)*((double) (*prevPropIt)->int_value) +
tau*((double) (*nextPropIt)->int_value));
ival = (int)(0.5 + (1 - tau)*((double)(*prevPropIt)->int_value) +
tau*((double)(*nextPropIt)->int_value));
pIt->second->setIntValue(ival);
//cout << "Int: " << ival << "\n";
break;
case props::FLOAT:
case props::DOUBLE:
val = (1-tau)*(*prevPropIt)->float_value +
val = (1 - tau)*(*prevPropIt)->float_value +
tau*(*nextPropIt)->float_value;
//cout << "Flo: " << val << "\n";
pIt->second->setFloatValue(val);
@ -342,7 +355,7 @@ void FGAIMultiplayer::update(double dt)
break;
default:
// FIXME - currently defaults to float values
val = (1-tau)*(*prevPropIt)->float_value +
val = (1 - tau)*(*prevPropIt)->float_value +
tau*(*nextPropIt)->float_value;
//cout << "Unk: " << val << "\n";
pIt->second->setFloatValue(val);
@ -350,6 +363,11 @@ void FGAIMultiplayer::update(double dt)
}
}
else
{
SG_LOG(SG_AI, SG_WARN, "MP packet mismatch during lag interpolation: " << (*prevPropIt)->id << " != " << (*nextPropIt)->id << "\n");
}
}
else
{
SG_LOG(SG_AI, SG_DEBUG, "Unable to find property: " << (*prevPropIt)->id << "\n");
}