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authorNao YONASHIRO <owan.orisano@gmail.com>2019-06-29 02:04:34 +0900
committerNao YONASHIRO <owan.orisano@gmail.com>2019-07-31 00:23:33 +0900
commitd456ce9c8190f0e9d785a1e5729c75bec5890e6f (patch)
treea211c9d6cf7fc5b1bde129c07acf3056c5f14f2f /plumbing
parentc1086eafdf45fe85ce0050890da6b42a146c7ddc (diff)
downloadgo-git-d456ce9c8190f0e9d785a1e5729c75bec5890e6f.tar.gz
feat: avoid memory allocation on ApplyDelta, PatchDelta
Signed-off-by: Nao YONASHIRO <owan.orisano@gmail.com>
Diffstat (limited to 'plumbing')
-rw-r--r--plumbing/format/packfile/patch_delta.go45
1 files changed, 30 insertions, 15 deletions
diff --git a/plumbing/format/packfile/patch_delta.go b/plumbing/format/packfile/patch_delta.go
index 7840f17..e1a5141 100644
--- a/plumbing/format/packfile/patch_delta.go
+++ b/plumbing/format/packfile/patch_delta.go
@@ -3,6 +3,7 @@ package packfile
import (
"bytes"
"errors"
+ "io"
"gopkg.in/src-d/go-git.v4/plumbing"
)
@@ -35,14 +36,20 @@ func ApplyDelta(target, base plumbing.EncodedObject, delta []byte) error {
}
src := buf.Bytes()
- dst, err := PatchDelta(src, delta)
+ dst := bufPool.Get().(*bytes.Buffer)
+ defer bufPool.Put(dst)
+ dst.Reset()
+ err = patchDelta(dst, src, delta)
if err != nil {
return err
}
- target.SetSize(int64(len(dst)))
- _, err = w.Write(dst)
+ target.SetSize(int64(dst.Len()))
+
+ b := byteSlicePool.Get().([]byte)
+ _, err = io.CopyBuffer(w, dst, b)
+ byteSlicePool.Put(b)
return err
}
@@ -55,23 +62,31 @@ var (
// An error will be returned if delta is corrupted (ErrDeltaLen) or an action command
// is not copy from source or copy from delta (ErrDeltaCmd).
func PatchDelta(src, delta []byte) ([]byte, error) {
+ b := &bytes.Buffer{}
+ if err := patchDelta(b, src, delta); err != nil {
+ return nil, err
+ }
+ return b.Bytes(), nil
+}
+
+func patchDelta(dst *bytes.Buffer, src, delta []byte) error {
if len(delta) < deltaSizeMin {
- return nil, ErrInvalidDelta
+ return ErrInvalidDelta
}
srcSz, delta := decodeLEB128(delta)
if srcSz != uint(len(src)) {
- return nil, ErrInvalidDelta
+ return ErrInvalidDelta
}
targetSz, delta := decodeLEB128(delta)
remainingTargetSz := targetSz
var cmd byte
- dest := make([]byte, 0, targetSz)
+ dst.Grow(int(targetSz))
for {
if len(delta) == 0 {
- return nil, ErrInvalidDelta
+ return ErrInvalidDelta
}
cmd = delta[0]
@@ -81,35 +96,35 @@ func PatchDelta(src, delta []byte) ([]byte, error) {
var err error
offset, delta, err = decodeOffset(cmd, delta)
if err != nil {
- return nil, err
+ return err
}
sz, delta, err = decodeSize(cmd, delta)
if err != nil {
- return nil, err
+ return err
}
if invalidSize(sz, targetSz) ||
invalidOffsetSize(offset, sz, srcSz) {
break
}
- dest = append(dest, src[offset:offset+sz]...)
+ dst.Write(src[offset:offset+sz])
remainingTargetSz -= sz
} else if isCopyFromDelta(cmd) {
sz := uint(cmd) // cmd is the size itself
if invalidSize(sz, targetSz) {
- return nil, ErrInvalidDelta
+ return ErrInvalidDelta
}
if uint(len(delta)) < sz {
- return nil, ErrInvalidDelta
+ return ErrInvalidDelta
}
- dest = append(dest, delta[0:sz]...)
+ dst.Write(delta[0:sz])
remainingTargetSz -= sz
delta = delta[sz:]
} else {
- return nil, ErrDeltaCmd
+ return ErrDeltaCmd
}
if remainingTargetSz <= 0 {
@@ -117,7 +132,7 @@ func PatchDelta(src, delta []byte) ([]byte, error) {
}
}
- return dest, nil
+ return nil
}
// Decodes a number encoded as an unsigned LEB128 at the start of some