/**
* Sorts the linear segments of the given layered graph by finding a topological ordering in the
* corresponding segment ordering graph.
*
* @param layeredGraph layered graph to process
* @return a sorted array of linear segments
*/
private LinearSegment[] sortLinearSegments(final LGraph layeredGraph) {
// set the identifier and input / output priority for all nodes
List<LinearSegment> segmentList = Lists.newArrayList();
for (Layer layer : layeredGraph) {
for (LNode node : layer) {
node.id = -1;
int inprio = Integer.MIN_VALUE, outprio = Integer.MIN_VALUE;
for (LPort port : node.getPorts()) {
for (LEdge edge : port.getIncomingEdges()) {
int prio = edge.getProperty(InternalProperties.PRIORITY);
inprio = Math.max(inprio, prio);
}
for (LEdge edge : port.getOutgoingEdges()) {
int prio = edge.getProperty(InternalProperties.PRIORITY);
outprio = Math.max(outprio, prio);
}
}
node.setProperty(INPUT_PRIO, inprio);
node.setProperty(OUTPUT_PRIO, outprio);
}
}
// create linear segments for the layered graph, ignoring odd port side dummies
int nextLinearSegmentID = 0;
for (Layer layer : layeredGraph) {
for (LNode node : layer) {
// Test for the node ID; calls to fillSegment(...) may have caused the node ID
// to be != -1.
if (node.id < 0) {
LinearSegment segment = new LinearSegment();
segment.id = nextLinearSegmentID++;
fillSegment(node, segment);
segmentList.add(segment);
}
}
}
// create and initialize segment ordering graph
List<List<LinearSegment>> outgoingList = Lists.newArrayListWithCapacity(segmentList.size());
List<Integer> incomingCountList = Lists.newArrayListWithCapacity(segmentList.size());
for (int i = 0; i < segmentList.size(); i++) {
outgoingList.add(new ArrayList<LinearSegment>());
incomingCountList.add(0);
}
// create edges for the segment ordering graph
createDependencyGraphEdges(layeredGraph, segmentList, outgoingList, incomingCountList);
// turn lists into arrays
LinearSegment[] segments = segmentList.toArray(new LinearSegment[segmentList.size()]);
@SuppressWarnings("unchecked")
List<LinearSegment>[] outgoing = outgoingList.toArray(new List[outgoingList.size()]);
int[] incomingCount = new int[incomingCountList.size()];
for (int i = 0; i < incomingCount.length; i++) {
incomingCount[i] = incomingCountList.get(i);
}
// gather the sources of the segment ordering graph
int nextRank = 0;
List<LinearSegment> noIncoming = Lists.newArrayList();
for (int i = 0; i < segments.length; i++) {
if (incomingCount[i] == 0) {
noIncoming.add(segments[i]);
}
}
// find a topological ordering of the segment ordering graph
int[] newRanks = new int[segments.length];
while (!noIncoming.isEmpty()) {
LinearSegment segment = noIncoming.remove(0);
newRanks[segment.id] = nextRank++;
while (!outgoing[segment.id].isEmpty()) {
LinearSegment target = outgoing[segment.id].remove(0);
incomingCount[target.id]--;
if (incomingCount[target.id] == 0) {
noIncoming.add(target);
}
}
}
// apply the new ordering to the array of linear segments
linearSegments = new LinearSegment[segments.length];
for (int i = 0; i < segments.length; i++) {
assert outgoing[i].isEmpty();
LinearSegment ls = segments[i];
int rank = newRanks[i];
linearSegments[rank] = ls;
ls.id = rank;
for (LNode node : ls.nodes) {
node.id = rank;
}
}
return linearSegments;
}
