diff options
| -rw-r--r-- | plumbing/format/packfile/delta_index.go | 23 | ||||
| -rw-r--r-- | plumbing/format/packfile/diff_delta.go | 31 |
2 files changed, 38 insertions, 16 deletions
diff --git a/plumbing/format/packfile/delta_index.go b/plumbing/format/packfile/delta_index.go index fad9dc8..349bedf 100644 --- a/plumbing/format/packfile/delta_index.go +++ b/plumbing/format/packfile/delta_index.go @@ -19,7 +19,19 @@ func (idx *deltaIndex) init(buf []byte) { idx.copyEntries(scanner) } +// findMatch returns the offset of src where the block starting at tgtOffset +// is and the length of the match. A length of 0 means there was no match. A +// length of -1 means the src length is lower than the blksz and whatever +// other positive length is the length of the match in bytes. func (idx *deltaIndex) findMatch(src, tgt []byte, tgtOffset int) (srcOffset, l int) { + if len(tgt) < tgtOffset+s { + return 0, len(tgt) - tgtOffset + } + + if len(src) < blksz { + return 0, -1 + } + if len(tgt) >= tgtOffset+s && len(src) >= blksz { h := hashBlock(tgt, tgtOffset) tIdx := h & idx.mask @@ -36,6 +48,17 @@ func (idx *deltaIndex) findMatch(src, tgt []byte, tgtOffset int) (srcOffset, l i return } +func matchLength(src, tgt []byte, otgt, osrc int) (l int) { + lensrc := len(src) + lentgt := len(tgt) + for (osrc < lensrc && otgt < lentgt) && src[osrc] == tgt[otgt] { + l++ + osrc++ + otgt++ + } + return +} + func countEntries(scan *deltaIndexScanner) (cnt int) { // Figure out exactly how many entries we need. As we do the // enumeration truncate any delta chains longer than what we diff --git a/plumbing/format/packfile/diff_delta.go b/plumbing/format/packfile/diff_delta.go index 2e58ec6..d4b207a 100644 --- a/plumbing/format/packfile/diff_delta.go +++ b/plumbing/format/packfile/diff_delta.go @@ -81,8 +81,22 @@ func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte { for i := 0; i < len(tgt); i++ { offset, l := index.findMatch(src, tgt, i) - if l < s { + if l == 0 { + // couldn't find a match, just write the current byte and continue ibuf.WriteByte(tgt[i]) + } else if l < 0 { + // src is less than blksz, copy the rest of the target to avoid + // calls to findMatch + for ; i < len(tgt); i++ { + ibuf.WriteByte(tgt[i]) + } + } else if l < s { + // remaining target is less than blksz, copy what's left of it + // and avoid calls to findMatch + for j := i; j < i+l; j++ { + ibuf.WriteByte(tgt[j]) + } + i += l - 1 } else { encodeInsertOperation(ibuf, buf) @@ -135,21 +149,6 @@ func encodeInsertOperation(ibuf, buf *bytes.Buffer) { ibuf.Reset() } -func matchLength(src, tgt []byte, otgt, osrc int) int { - l := 0 - for { - if (osrc >= len(src) || otgt >= len(tgt)) || src[osrc] != tgt[otgt] { - break - } - - l++ - osrc++ - otgt++ - } - - return l -} - func deltaEncodeSize(size int) []byte { var ret []byte c := size & 0x7f |