Method Aggregate

stack/bucket.go:42–98

Aggregate merges similar goroutines into buckets. The buckets are ordered in library provided order of relevancy. You can reorder at your choosing.

(similar Similarity)

// The buckets are ordered in library provided order of relevancy. You can
// reorder at your choosing.
func (s *Snapshot) Aggregate(similar Similarity) *Aggregated {
	type count struct {
		ids   []int
		first bool
	}
	b := map[*Signature]*count{}
	// O(n²). Fix eventually.
	for _, routine := range s.Goroutines {
		found := false
		for key, c := range b {
			// When a match is found, this effectively drops the other goroutine ID.
			if key.similar(&routine.Signature, similar) {
				found = true
				c.ids = append(c.ids, routine.ID)
				c.first = c.first || routine.First
				if !key.equal(&routine.Signature) {
					// Almost but not quite equal. There's different pointers passed
					// around but the same values. Zap out the different values.
					newKey := key.merge(&routine.Signature)
					b[newKey] = c
					delete(b, key)
				}
				break
			}
		}
		if !found {
			// Create a copy of the Signature, since it will be mutated.
			key := &Signature{}
			*key = routine.Signature
			b[key] = &count{ids: []int{routine.ID}, first: routine.First}
		}
	}
	bs := make([]*Bucket, 0, len(b))
	for signature, c := range b {
		sort.Ints(c.ids)
		bs = append(bs, &Bucket{Signature: *signature, IDs: c.ids, First: c.first})
	}
	// Do reverse sort.
	sort.SliceStable(bs, func(i, j int) bool {
		l := bs[i]
		r := bs[j]
		if l.First || r.First {
			return l.First
		}
		if l.Signature.less(&r.Signature) {
			return true
		}
		if r.Signature.less(&l.Signature) {
			return false
		}
		return len(r.IDs) > len(l.IDs)
	})
	return &Aggregated{
		Snapshot: s,
		Buckets:  bs,
	}
}