private Hop FindSpliceHop(SortedSet <SegLink> segset, SegLink max, long joinTime, long delayDec)
{
long spliceTime = joinTime - delayDec - 1;
var query = new SegLink()
{
pos = null, time = spliceTime + 1
};
var spliceSet = segset.GetViewBetween(query, max);
Debug.Assert(spliceSet.Any());
var spliceLink = spliceSet.First();
Pipe spliceSeg = spliceLink.pos.Value;
long segEndTime = spliceLink.time;
long segDelay = spliceSeg.GetDelay(_a);
long segStartTime = spliceLink.time - segDelay;
Debug.Assert(segStartTime <= spliceTime);
Debug.Assert(segEndTime > spliceTime);
Hop spliceHop;
if (segStartTime == spliceTime)
{
spliceHop = spliceSeg.GetSource(_a);
}
else
{
spliceHop = new InsertionHop(_a, spliceSeg, spliceTime - segStartTime, segEndTime - spliceTime);
}
return(spliceHop);
}
private long ShortcutPath(Path path, long delayDec, out Path xpath)
{
var segset = new SortedSet <SegLink>();
var seglist = new LinkedList <Pipe>();
long time = 0;
for (int i = 0; i < path.Segments.Length; i++)
{
Pipe seg = path.Segments[i];
time += seg.GetDelay(_a);
var pos = seglist.AddLast(seg);
segset.Add(new SegLink()
{
pos = pos, time = time
});
}
SegLink max = new SegLink()
{
pos = null, time = time + 1
};
SegLink minJoin = new SegLink()
{
pos = null, time = delayDec + 1
};
var joinset = segset.GetViewBetween(minJoin, max);
Debug.Assert(joinset.Any());
Hop bestSpliceHop = null;
Hop bestJoinHop = null;
long bestCost = long.MaxValue;
long bestJoinTime = -1;
foreach (var seglink in joinset)
{
long joinTime = seglink.time;
Pipe seg = seglink.pos.Value;
Hop joinHop = seg.GetSink(_a);
long joinCost = _a.Preds[joinHop.Node].Count();
if (joinCost < bestCost)
{
bestCost = joinCost;
bestJoinHop = joinHop;
bestJoinTime = joinTime;
bestSpliceHop = FindSpliceHop(segset, max, joinTime, delayDec);
}
long segDelay = seg.GetDelay(_a);
--joinTime;
if (segDelay > 1 && joinTime > delayDec && bestCost > 1)
{
bestCost = 1;
var insHop = new InsertionHop(_a, seg, segDelay - 1, 1);
bestJoinHop = insHop;
bestJoinTime = joinTime;
var left = seglist.AddBefore(seglink.pos, insHop.LeftPipe);
var right = seglist.AddAfter(seglink.pos, insHop.RightPipe);
seglist.Remove(seglink.pos);
segset.Remove(seglink);
var leftLink = new SegLink()
{
pos = left, time = seglink.time - 1
};
segset.Add(leftLink);
var rightLink = new SegLink()
{
pos = right, time = seglink.time
};
segset.Add(rightLink);
bestSpliceHop = FindSpliceHop(segset, max, joinTime, delayDec);
break;
}
}
long bestSpliceTime = bestJoinTime - delayDec - 1;
var newSegments = new List <Pipe>();
var wormhole = new InsertionPipe(bestSpliceHop, bestJoinHop, 1);
time = 0;
var curpos = seglist.First;
while (curpos != null)
{
Pipe seg = curpos.Value;
long nextTime = time + seg.GetDelay(_a);
if (nextTime <= bestSpliceTime || time >= bestJoinTime)
{
newSegments.Add(seg);
}
else if (time == bestSpliceTime)
{
newSegments.Add(wormhole);
}
else if (time < bestSpliceTime && nextTime > bestSpliceTime)
{
var joinHop = (InsertionHop)bestSpliceHop;
newSegments.Add(joinHop.LeftPipe);
newSegments.Add(wormhole);
}
time = nextTime;
curpos = curpos.Next;
}
xpath = new Path(_a, newSegments.ToArray());
return(bestCost + 1);
}
