+
+ log.Infof("%04d: renumber/dedup variants for tags %d-%d", infileIdx, tagstart, tagend)
+ variantRemap := make([][]tileVariantID, tagend-tagstart)
+ throttleCPU := throttle{Max: runtime.GOMAXPROCS(0)}
+ for tag, variants := range seq {
+ tag, variants := tag, variants
+ throttleCPU.Acquire()
+ go func() {
+ defer throttleCPU.Release()
+ count := make(map[[blake2b.Size256]byte]int, len(variants))
+ for _, cg := range cgs {
+ idx := (tag - tagstart) * 2
+ if int(idx) < len(cg.Variants) {
+ count[variants[cg.Variants[idx]].Blake2b]++
+ count[variants[cg.Variants[idx+1]].Blake2b]++
+ }
+ }
+ // hash[i] will be the hash of
+ // the variant(s) that should
+ // be at rank i (0-based).
+ hash := make([][blake2b.Size256]byte, 0, len(count))
+ for b := range count {
+ hash = append(hash, b)
+ }
+ sort.Slice(hash, func(i, j int) bool {
+ bi, bj := &hash[i], &hash[j]
+ if ci, cj := count[*bi], count[*bj]; ci != cj {
+ return ci > cj
+ } else {
+ return bytes.Compare((*bi)[:], (*bj)[:]) < 0
+ }
+ })
+ // rank[b] will be the 1-based
+ // new variant number for
+ // variants whose hash is b.
+ rank := make(map[[blake2b.Size256]byte]tileVariantID, len(hash))
+ for i, h := range hash {
+ rank[h] = tileVariantID(i + 1)
+ }
+ // remap[v] will be the new
+ // variant number for original
+ // variant number v.
+ remap := make([]tileVariantID, len(variants))
+ for i, tv := range variants {
+ remap[i] = rank[tv.Blake2b]
+ }
+ variantRemap[tag-tagstart] = remap
+ }()
+ }
+ throttleCPU.Wait()