Function newGraph

internal/graph/graph.go:341–392

newGraph computes a graph from a profile. It returns the graph, and a map from the profile location indices to the corresponding graph nodes.

(prof *profile.Profile, o *Options)

// a map from the profile location indices to the corresponding graph
// nodes.
func newGraph(prof *profile.Profile, o *Options) (*Graph, map[uint64]Nodes) {
	nodes, locationMap := CreateNodes(prof, o)
	seenNode := make(map[*Node]bool)
	seenEdge := make(map[nodePair]bool)
	for _, sample := range prof.Sample {
		var w, dw int64
		w = o.SampleValue(sample.Value)
		if o.SampleMeanDivisor != nil {
			dw = o.SampleMeanDivisor(sample.Value)
		}
		if dw == 0 && w == 0 {
			continue
		}
		clear(seenNode)
		clear(seenEdge)
		var parent *Node
		// A residual edge goes over one or more nodes that were not kept.
		residual := false

		labels := joinLabels(sample)
		// Group the sample frames, based on a global map.
		for i := len(sample.Location) - 1; i >= 0; i-- {
			l := sample.Location[i]
			locNodes := locationMap[l.ID]
			for ni := len(locNodes) - 1; ni >= 0; ni-- {
				n := locNodes[ni]
				if n == nil {
					residual = true
					continue
				}
				// Add cum weight to all nodes in stack, avoiding double counting.
				if _, ok := seenNode[n]; !ok {
					seenNode[n] = true
					n.addSample(dw, w, labels, sample.NumLabel, sample.NumUnit, o.FormatTag, false)
				}
				// Update edge weights for all edges in stack, avoiding double counting.
				if _, ok := seenEdge[nodePair{n, parent}]; !ok && parent != nil && n != parent {
					seenEdge[nodePair{n, parent}] = true
					parent.AddToEdgeDiv(n, dw, w, residual, ni != len(locNodes)-1)
				}
				parent = n
				residual = false
			}
		}
		if parent != nil && !residual {
			// Add flat weight to leaf node.
			parent.addSample(dw, w, labels, sample.NumLabel, sample.NumUnit, o.FormatTag, true)
		}
	}

	return selectNodesForGraph(nodes, o.DropNegative), locationMap
}

func selectNodesForGraph(nodes Nodes, dropNegative bool) *Graph {
	// Collect nodes into a graph.