package object
import (
"errors"
"io"
"sort"
"strings"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/filemode"
"github.com/go-git/go-git/v5/utils/ioutil"
"github.com/go-git/go-git/v5/utils/merkletrie"
)
// DetectRenames detects the renames in the given changes on two trees with
// the given options. It will return the given changes grouping additions and
// deletions into modifications when possible.
// If options is nil, the default diff tree options will be used.
func DetectRenames(
changes Changes,
opts *DiffTreeOptions,
) (Changes, error) {
if opts == nil {
opts = DefaultDiffTreeOptions
}
detector := &renameDetector{
renameScore: int(opts.RenameScore),
renameLimit: int(opts.RenameLimit),
onlyExact: opts.OnlyExactRenames,
}
for _, c := range changes {
action, err := c.Action()
if err != nil {
return nil, err
}
switch action {
case merkletrie.Insert:
detector.added = append(detector.added, c)
case merkletrie.Delete:
detector.deleted = append(detector.deleted, c)
default:
detector.modified = append(detector.modified, c)
}
}
return detector.detect()
}
// renameDetector will detect and resolve renames in a set of changes.
// see: https://github.com/eclipse/jgit/blob/master/org.eclipse.jgit/src/org/eclipse/jgit/diff/RenameDetector.java
type renameDetector struct {
added []*Change
deleted []*Change
modified []*Change
renameScore int
renameLimit int
onlyExact bool
}
// detectExactRenames detects matches files that were deleted with files that
// were added where the hash is the same on both. If there are multiple targets
// the one with the most similar path will be chosen as the rename and the
// rest as either deletions or additions.
func (d *renameDetector) detectExactRenames() {
added := groupChangesByHash(d.added)
deletes := groupChangesByHash(d.deleted)
var uniqueAdds []*Change
var nonUniqueAdds [][]*Change
var addedLeft []*Change
for _, cs := range added {
if len(cs) == 1 {
uniqueAdds = append(uniqueAdds, cs[0])
} else {
nonUniqueAdds = append(nonUniqueAdds, cs)
}
}
for _, c := range uniqueAdds {
hash := changeHash(c)
deleted := deletes[hash]
if len(deleted) == 1 {
if sameMode(c, deleted[0]) {
d.modified = append(d.modified, &Change{From: deleted[0].From, To: c.To})
delete(deletes, hash)
} else {
addedLeft = append(addedLeft, c)
}
} else if len(deleted) > 1 {
bestMatch := bestNameMatch(c, deleted)
if bestMatch != nil && sameMode(c, bestMatch) {
d.modified = append(d.modified, &Change{From: bestMatch.From, To: c.To})
delete(deletes, hash)
var newDeletes = make([]*Change, 0, len(deleted)-1)
for _, d := range deleted {
if d != bestMatch {
newDeletes = append(newDeletes, d)
}
}
deletes[hash] = newDeletes
}
} else {
addedLeft = append(addedLeft, c)
}
}
for _, added := range nonUniqueAdds {
hash := changeHash(added[0])
deleted := deletes[hash]
if len(deleted) == 1 {
deleted := deleted[0]
bestMatch := bestNameMatch(deleted, added)
if bestMatch != nil && sameMode(deleted, bestMatch) {
d.modified = append(d.modified, &Change{From: deleted.From, To: bestMatch.To})
delete(deletes, hash)
for _, c := range added {
if c != bestMatch {
addedLeft = append(addedLeft, c)
}
}
} else {
addedLeft = append(addedLeft, added...)
}
} else if len(deleted) > 1 {
maxSize := len(deleted) * len(added)
if d.renameLimit > 0 && d.renameLimit < maxSize {
maxSize = d.renameLimit
}
matrix := make(similarityMatrix, 0, maxSize)
for delIdx, del := range deleted {
deletedName := changeName(del)
for addIdx, add := range added {
addedName := changeName(add)
score := nameSimilarityScore(addedName, deletedName)
matrix = append(matrix, similarityPair{added: addIdx, deleted: delIdx, score: score})
if len(matrix) >= maxSize {
break
}
}
if len(matrix) >= maxSize {
break
}
}
sort.Stable(matrix)
usedAdds := make(map[*Change]struct{})
usedDeletes := make(map[*Change]struct{})
for i := len(matrix) - 1; i >= 0; i-- {
del := deleted[matrix[i].deleted]
add := added[matrix[i].added]
if add == nil || del == nil {
// it was already matched
continue
}
usedAdds[add] = struct{}{}
usedDeletes[del] = struct{}{}
d.modified = append(d.modified, &Change{From: del.From, To: add.To})
added[matrix[i].added] = nil
deleted[matrix[i].deleted] = nil
}
for _, c := range added {
if _, ok := usedAdds[c]; !ok && c != nil {
addedLeft = append(addedLeft, c)
}
}
var newDeletes = make([]*Change, 0, len(deleted)-len(usedDeletes))
for _, c := range deleted {
if _, ok := usedDeletes[c]; !ok && c != nil {
newDeletes = append(newDeletes, c)
}
}
deletes[hash] = newDeletes
} else {
addedLeft = append(addedLeft, added...)
}
}
d.added = addedLeft
d.deleted = nil
for _, dels := range deletes {
d.deleted = append(d.deleted, dels...)
}
}
// detectContentRenames detects renames based on the similarity of the content
// in the files by building a matrix of pairs between sources and destinations
// and matching by the highest score.
// see: https://github.com/eclipse/jgit/blob/master/org.eclipse.jgit/src/org/eclipse/jgit/diff/SimilarityRenameDetector.java
func (d *renameDetector) detectContentRenames() error {
cnt := max(len(d.added), len(d.deleted))
if d.renameLimit > 0 && cnt > d.renameLimit {
return nil
}
srcs, dsts := d.deleted, d.added
matrix, err := buildSimilarityMatrix(srcs, dsts, d.renameScore)
if err != nil {
return err
}
renames := make([]*Change, 0, min(len(matrix), len(dsts)))
// Match rename pairs on a first come, first serve basis until
// we have looked at everything that is above the minimum score.
for i := len(matrix) - 1; i >= 0; i-- {
pair := matrix[i]
src := srcs[pair.deleted]
dst := dsts[pair.added]
if dst == nil || src == nil {
// It was already matched before
continue
}
renames = append(renames, &Change{From: src.From, To: dst.To})
// Claim destination and source as matched
dsts[pair.added] = nil
srcs[pair.deleted] = nil
}
d.modified = append(d.modified, renames...)
d.added = compactChanges(dsts)
d.deleted = compactChanges(srcs)
return nil
}
func (d *renameDetector) detect() (Changes, error) {
if len(d.added) > 0 && len(d.deleted) > 0 {
d.detectExactRenames()
if !d.onlyExact {
if err := d.detectContentRenames(); err != nil {
return nil, err
}
}
}
result := make(Changes, 0, len(d.added)+len(d.deleted)+len(d.modified))
result = append(result, d.added...)
result = append(result, d.deleted...)
result = append(result, d.modified...)
sort.Stable(result)
return result, nil
}
func bestNameMatch(change *Change, changes []*Change) *Change {
var best *Change
var bestScore int
cname := changeName(change)
for _, c := range changes {
score := nameSimilarityScore(cname, changeName(c))
if score > bestScore {
bestScore = score
best = c
}
}
return best
}
func nameSimilarityScore(a, b string) int {
aDirLen := strings.LastIndexByte(a, '/') + 1
bDirLen := strings.LastIndexByte(b, '/') + 1
dirMin := min(aDirLen, bDirLen)
dirMax := max(aDirLen, bDirLen)
var dirScoreLtr, dirScoreRtl int
if dirMax == 0 {
dirScoreLtr = 100
dirScoreRtl = 100
} else {
var dirSim int
for ; dirSim < dirMin; dirSim++ {
if a[dirSim] != b[dirSim] {
break
}
}
dirScoreLtr = dirSim * 100 / dirMax
if dirScoreLtr == 100 {
dirScoreRtl = 100
} else {
for dirSim = 0; dirSim < dirMin; dirSim++ {
if a[aDirLen-1-dirSim] != b[bDirLen-1-dirSim] {
break
}
}
dirScoreRtl = dirSim * 100 / dirMax
}
}
fileMin := min(len(a)-aDirLen, len(b)-bDirLen)
fileMax := max(len(a)-aDirLen, len(b)-bDirLen)
fileSim := 0
for ; fileSim < fileMin; fileSim++ {
if a[len(a)-1-fileSim] != b[len(b)-1-fileSim] {
break
}
}
fileScore := fileSim * 100 / fileMax
return (((dirScoreLtr + dirScoreRtl) * 25) + (fileScore * 50)) / 100
}
func changeName(c *Change) string {
if c.To != empty {
return c.To.Name
}
return c.From.Name
}
func changeHash(c *Change) plumbing.Hash {
if c.To != empty {
return c.To.TreeEntry.Hash
}
return c.From.TreeEntry.Hash
}
func changeMode(c *Change) filemode.FileMode {
if c.To != empty {
return c.To.TreeEntry.Mode
}
return c.From.TreeEntry.Mode
}
func sameMode(a, b *Change) bool {
return changeMode(a) == changeMode(b)
}
func groupChangesByHash(changes []*Change) map[plumbing.Hash][]*Change {
var result = make(map[plumbing.Hash][]*Change)
for _, c := range changes {
hash := changeHash(c)
result[hash] = append(result[hash], c)
}
return result
}
type similarityMatrix []similarityPair
func (m similarityMatrix) Len() int { return len(m) }
func (m similarityMatrix) Swap(i, j int) { m[i], m[j] = m[j], m[i] }
func (m similarityMatrix) Less(i, j int) bool {
if m[i].score == m[j].score {
if m[i].added == m[j].added {
return m[i].deleted < m[j].deleted
}
return m[i].added < m[j].added
}
return m[i].score < m[j].score
}
type similarityPair struct {
// index of the added file
added int
// index of the deleted file
deleted int
// similarity score
score int
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
func min(a, b int) int {
if a < b {
return a
}
return b
}
func buildSimilarityMatrix(srcs, dsts []*Change, renameScore int) (similarityMatrix, error) {
// Allocate for the worst-case scenario where every pair has a score
// that we need to consider. We might not need that many.
matrix := make(similarityMatrix, 0, len(srcs)*len(dsts))
srcSizes := make([]int64, len(srcs))
dstSizes := make([]int64, len(dsts))
dstTooLarge := make(map[int]bool)
// Consider each pair of files, if the score is above the minimum
// threshold we need to record that scoring in the matrix so we can
// later find the best matches.
outerLoop:
for srcIdx, src := range srcs {
if changeMode(src) != filemode.Regular {
continue
}
// Declare the from file and the similarity index here to be able to
// reuse it inside the inner loop. The reason to not initialize them
// here is so we can skip the initialization in case they happen to
// not be needed later. They will be initialized inside the inner
// loop if and only if they're needed and reused in subsequent passes.
var from *File
var s *similarityIndex
var err error
for dstIdx, dst := range dsts {
if changeMode(dst) != filemode.Regular {
continue
}
if dstTooLarge[dstIdx] {
continue
}
var to *File
srcSize := srcSizes[srcIdx]
if srcSize == 0 {
from, _, err = src.Files()
if err != nil {
return nil, err
}
srcSize = from.Size + 1
srcSizes[srcIdx] = srcSize
}
dstSize := dstSizes[dstIdx]
if dstSize == 0 {
_, to, err = dst.Files()
if err != nil {
return nil, err
}
dstSize = to.Size + 1
dstSizes[dstIdx] = dstSize
}
min, max := srcSize, dstSize
if dstSize < srcSize {
min = dstSize
max = srcSize
}
if int(min*100/max) < renameScore {
// File sizes are too different to be a match
continue
}
if s == nil {
s, err = fileSimilarityIndex(from)
if err != nil {
if err == errIndexFull {
continue outerLoop
}
return nil, err
}
}
if to == nil {
_, to, err = dst.Files()
if err != nil {
return nil, err
}
}
di, err := fileSimilarityIndex(to)
if err != nil {
if err == errIndexFull {
dstTooLarge[dstIdx] = true
}
return nil, err
}
contentScore := s.score(di, 10000)
// The name score returns a value between 0 and 100, so we need to
// convert it to the same range as the content score.
nameScore := nameSimilarityScore(src.From.Name, dst.To.Name) * 100
score := (contentScore*99 + nameScore*1) / 10000
if score < renameScore {
continue
}
matrix = append(matrix, similarityPair{added: dstIdx, deleted: srcIdx, score: score})
}
}
sort.Stable(matrix)
return matrix, nil
}
func compactChanges(changes []*Change) []*Change {
var result []*Change
for _, c := range changes {
if c != nil {
result = append(result, c)
}
}
return result
}
const (
keyShift = 32
maxCountValue = (1 << keyShift) - 1
)
var errIndexFull = errors.New("index is full")
// similarityIndex is an index structure of lines/blocks in one file.
// This structure can be used to compute an approximation of the similarity
// between two files.
// To save space in memory, this index uses a space efficient encoding which
// will not exceed 1MiB per instance. The index starts out at a smaller size
// (closer to 2KiB), but may grow as more distinct blocks withing the scanned
// file are discovered.
// see: https://github.com/eclipse/jgit/blob/master/org.eclipse.jgit/src/org/eclipse/jgit/diff/SimilarityIndex.java
type similarityIndex struct {
hashed uint64
// number of non-zero entries in hashes
numHashes int
growAt int
hashes []keyCountPair
hashBits int
}
func fileSimilarityIndex(f *File) (*similarityIndex, error) {
idx := newSimilarityIndex()
if err := idx.hash(f); err != nil {
return nil, err
}
sort.Stable(keyCountPairs(idx.hashes))
return idx, nil
}
func newSimilarityIndex() *similarityIndex {
return &similarityIndex{
hashBits: 8,
hashes: make([]keyCountPair, 1<<8),
growAt: shouldGrowAt(8),
}
}
func (i *similarityIndex) hash(f *File) error {
isBin, err := f.IsBinary()
if err != nil {
return err
}
r, err := f.Reader()
if err != nil {
return err
}
defer ioutil.CheckClose(r, &err)
return i.hashContent(r, f.Size, isBin)
}
func (i *similarityIndex) hashContent(r io.Reader, size int64, isBin bool) error {
var buf = make([]byte, 4096)
var ptr, cnt int
remaining := size
for 0 < remaining {
hash := 5381
var blockHashedCnt uint64
// Hash one line or block, whatever happens first
n := int64(0)
for {
if ptr == cnt {
ptr = 0
var err error
cnt, err = io.ReadFull(r, buf)
if err != nil && err != io.ErrUnexpectedEOF {
return err
}
if cnt == 0 {
return io.EOF
}
}
n++
c := buf[ptr] & 0xff
ptr++
// Ignore CR in CRLF sequence if it's text
if !isBin && c == '\r' && ptr < cnt && buf[ptr] == '\n' {
continue
}
blockHashedCnt++
if c == '\n' {
break
}
hash = (hash << 5) + hash + int(c)
if n >= 64 || n >= remaining {
break
}
}
i.hashed += blockHashedCnt
if err := i.add(hash, blockHashedCnt); err != nil {
return err
}
remaining -= n
}
return nil
}
// score computes the similarity score between this index and another one.
// A region of a file is defined as a line in a text file or a fixed-size
// block in a binary file. To prepare an index, each region in the file is
// hashed; the values and counts of hashes are retained in a sorted table.
// Define the similarity fraction F as the count of matching regions between
// the two files divided between the maximum count of regions in either file.
// The similarity score is F multiplied by the maxScore constant, yielding a
// range [0, maxScore]. It is defined as maxScore for the degenerate case of
// two empty files.
// The similarity score is symmetrical; i.e. a.score(b) == b.score(a).
func (i *similarityIndex) score(other *similarityIndex, maxScore int) int {
var maxHashed = i.hashed
if maxHashed < other.hashed {
maxHashed = other.hashed
}
if maxHashed == 0 {
return maxScore
}
return int(i.common(other) * uint64(maxScore) / maxHashed)
}
func (i *similarityIndex) common(dst *similarityIndex) uint64 {
srcIdx, dstIdx := 0, 0
if i.numHashes == 0 || dst.numHashes == 0 {
return 0
}
var common uint64
srcKey, dstKey := i.hashes[srcIdx].key(), dst.hashes[dstIdx].key()
for {
if srcKey == dstKey {
srcCnt, dstCnt := i.hashes[srcIdx].count(), dst.hashes[dstIdx].count()
if srcCnt < dstCnt {
common += srcCnt
} else {
common += dstCnt
}
srcIdx++
if srcIdx == len(i.hashes) {
break
}
srcKey = i.hashes[srcIdx].key()
dstIdx++
if dstIdx == len(dst.hashes) {
break
}
dstKey = dst.hashes[dstIdx].key()
} else if srcKey < dstKey {
// Region of src that is not in dst
srcIdx++
if srcIdx == len(i.hashes) {
break
}
srcKey = i.hashes[srcIdx].key()
} else {
// Region of dst that is not in src
dstIdx++
if dstIdx == len(dst.hashes) {
break
}
dstKey = dst.hashes[dstIdx].key()
}
}
return common
}
func (i *similarityIndex) add(key int, cnt uint64) error {
key = int(uint32(key) * 0x9e370001 >> 1)
j := i.slot(key)
for {
v := i.hashes[j]
if v == 0 {
// It's an empty slot, so we can store it here.
if i.growAt <= i.numHashes {
if err := i.grow(); err != nil {
return err
}
j = i.slot(key)
continue
}
var err error
i.hashes[j], err = newKeyCountPair(key, cnt)
if err != nil {
return err
}
i.numHashes++
return nil
} else if v.key() == key {
// It's the same key, so increment the counter.
var err error
i.hashes[j], err = newKeyCountPair(key, v.count()+cnt)
if err != nil {
return err
}
return nil
} else if j+1 >= len(i.hashes) {
j = 0
} else {
j++
}
}
}
type keyCountPair uint64
func newKeyCountPair(key int, cnt uint64) (keyCountPair, error) {
if cnt > maxCountValue {
return 0, errIndexFull
}
return keyCountPair((uint64(key) << keyShift) | cnt), nil
}
func (p keyCountPair) key() int {
return int(p >> keyShift)
}
func (p keyCountPair) count() uint64 {
return uint64(p) & maxCountValue
}
func (i *similarityIndex) slot(key int) int {
// We use 31 - hashBits because the upper bit was already forced
// to be 0 and we want the remaining high bits to be used as the
// table slot.
return int(uint32(key) >> (31 - i.hashBits))
}
func shouldGrowAt(hashBits int) int {
return (1 << hashBits) * (hashBits - 3) / hashBits
}
func (i *similarityIndex) grow() error {
if i.hashBits == 30 {
return errIndexFull
}
old := i.hashes
i.hashBits++
i.growAt = shouldGrowAt(i.hashBits)
// TODO(erizocosmico): find a way to check if it will OOM and return
// errIndexFull instead.
i.hashes = make([]keyCountPair, 1<<i.hashBits)
for _, v := range old {
if v != 0 {
j := i.slot(v.key())
for i.hashes[j] != 0 {
j++
if j >= len(i.hashes) {
j = 0
}
}
i.hashes[j] = v
}
}
return nil
}
type keyCountPairs []keyCountPair
func (p keyCountPairs) Len() int { return len(p) }
func (p keyCountPairs) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
func (p keyCountPairs) Less(i, j int) bool { return p[i] < p[j] }
