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-rw-r--r--plumbing/format/packfile/delta_selector.go47
-rw-r--r--plumbing/format/packfile/delta_selector_test.go31
-rw-r--r--plumbing/format/packfile/encoder.go23
-rw-r--r--plumbing/format/packfile/encoder_advanced_test.go17
-rw-r--r--plumbing/format/packfile/encoder_test.go8
5 files changed, 89 insertions, 37 deletions
diff --git a/plumbing/format/packfile/delta_selector.go b/plumbing/format/packfile/delta_selector.go
index 0b3539d..77573ac 100644
--- a/plumbing/format/packfile/delta_selector.go
+++ b/plumbing/format/packfile/delta_selector.go
@@ -9,9 +9,6 @@ import (
)
const (
- // How far back in the sorted list to search for deltas. 10 is
- // the default in command line git.
- deltaWindowSize = 10
// deltas based on deltas, how many steps we can do.
// 50 is the default value used in JGit
maxDepth = int64(50)
@@ -31,14 +28,24 @@ func newDeltaSelector(s storer.EncodedObjectStorer) *deltaSelector {
return &deltaSelector{s}
}
-// ObjectsToPack creates a list of ObjectToPack from the hashes provided,
-// creating deltas if it's suitable, using an specific internal logic
-func (dw *deltaSelector) ObjectsToPack(hashes []plumbing.Hash) ([]*ObjectToPack, error) {
- otp, err := dw.objectsToPack(hashes)
+// ObjectsToPack creates a list of ObjectToPack from the hashes
+// provided, creating deltas if it's suitable, using an specific
+// internal logic. `packWindow` specifies the size of the sliding
+// window used to compare objects for delta compression; 0 turns off
+// delta compression entirely.
+func (dw *deltaSelector) ObjectsToPack(
+ hashes []plumbing.Hash,
+ packWindow uint,
+) ([]*ObjectToPack, error) {
+ otp, err := dw.objectsToPack(hashes, packWindow)
if err != nil {
return nil, err
}
+ if packWindow == 0 {
+ return otp, nil
+ }
+
dw.sort(otp)
var objectGroups [][]*ObjectToPack
@@ -60,7 +67,7 @@ func (dw *deltaSelector) ObjectsToPack(hashes []plumbing.Hash) ([]*ObjectToPack,
objs := objs
wg.Add(1)
go func() {
- if walkErr := dw.walk(objs); walkErr != nil {
+ if walkErr := dw.walk(objs, packWindow); walkErr != nil {
once.Do(func() {
err = walkErr
})
@@ -77,10 +84,19 @@ func (dw *deltaSelector) ObjectsToPack(hashes []plumbing.Hash) ([]*ObjectToPack,
return otp, nil
}
-func (dw *deltaSelector) objectsToPack(hashes []plumbing.Hash) ([]*ObjectToPack, error) {
+func (dw *deltaSelector) objectsToPack(
+ hashes []plumbing.Hash,
+ packWindow uint,
+) ([]*ObjectToPack, error) {
var objectsToPack []*ObjectToPack
for _, h := range hashes {
- o, err := dw.encodedDeltaObject(h)
+ var o plumbing.EncodedObject
+ var err error
+ if packWindow == 0 {
+ o, err = dw.encodedObject(h)
+ } else {
+ o, err = dw.encodedDeltaObject(h)
+ }
if err != nil {
return nil, err
}
@@ -93,6 +109,10 @@ func (dw *deltaSelector) objectsToPack(hashes []plumbing.Hash) ([]*ObjectToPack,
objectsToPack = append(objectsToPack, otp)
}
+ if packWindow == 0 {
+ return objectsToPack, nil
+ }
+
if err := dw.fixAndBreakChains(objectsToPack); err != nil {
return nil, err
}
@@ -201,7 +221,10 @@ func (dw *deltaSelector) sort(objectsToPack []*ObjectToPack) {
sort.Sort(byTypeAndSize(objectsToPack))
}
-func (dw *deltaSelector) walk(objectsToPack []*ObjectToPack) error {
+func (dw *deltaSelector) walk(
+ objectsToPack []*ObjectToPack,
+ packWindow uint,
+) error {
indexMap := make(map[plumbing.Hash]*deltaIndex)
for i := 0; i < len(objectsToPack); i++ {
target := objectsToPack[i]
@@ -218,7 +241,7 @@ func (dw *deltaSelector) walk(objectsToPack []*ObjectToPack) error {
continue
}
- for j := i - 1; j >= 0 && i-j < deltaWindowSize; j-- {
+ for j := i - 1; j >= 0 && i-j < int(packWindow); j-- {
base := objectsToPack[j]
// Objects must use only the same type as their delta base.
// Since objectsToPack is sorted by type and size, once we find
diff --git a/plumbing/format/packfile/delta_selector_test.go b/plumbing/format/packfile/delta_selector_test.go
index ca4a96b..7d7fd0c 100644
--- a/plumbing/format/packfile/delta_selector_test.go
+++ b/plumbing/format/packfile/delta_selector_test.go
@@ -146,7 +146,8 @@ func (s *DeltaSelectorSuite) createTestObjects() {
func (s *DeltaSelectorSuite) TestObjectsToPack(c *C) {
// Different type
hashes := []plumbing.Hash{s.hashes["base"], s.hashes["treeType"]}
- otp, err := s.ds.ObjectsToPack(hashes)
+ deltaWindowSize := uint(10)
+ otp, err := s.ds.ObjectsToPack(hashes, deltaWindowSize)
c.Assert(err, IsNil)
c.Assert(len(otp), Equals, 2)
c.Assert(otp[0].Object, Equals, s.store.Objects[s.hashes["base"]])
@@ -154,7 +155,7 @@ func (s *DeltaSelectorSuite) TestObjectsToPack(c *C) {
// Size radically different
hashes = []plumbing.Hash{s.hashes["bigBase"], s.hashes["target"]}
- otp, err = s.ds.ObjectsToPack(hashes)
+ otp, err = s.ds.ObjectsToPack(hashes, deltaWindowSize)
c.Assert(err, IsNil)
c.Assert(len(otp), Equals, 2)
c.Assert(otp[0].Object, Equals, s.store.Objects[s.hashes["bigBase"]])
@@ -162,7 +163,7 @@ func (s *DeltaSelectorSuite) TestObjectsToPack(c *C) {
// Delta Size Limit with no best delta yet
hashes = []plumbing.Hash{s.hashes["smallBase"], s.hashes["smallTarget"]}
- otp, err = s.ds.ObjectsToPack(hashes)
+ otp, err = s.ds.ObjectsToPack(hashes, deltaWindowSize)
c.Assert(err, IsNil)
c.Assert(len(otp), Equals, 2)
c.Assert(otp[0].Object, Equals, s.store.Objects[s.hashes["smallBase"]])
@@ -170,7 +171,7 @@ func (s *DeltaSelectorSuite) TestObjectsToPack(c *C) {
// It will create the delta
hashes = []plumbing.Hash{s.hashes["base"], s.hashes["target"]}
- otp, err = s.ds.ObjectsToPack(hashes)
+ otp, err = s.ds.ObjectsToPack(hashes, deltaWindowSize)
c.Assert(err, IsNil)
c.Assert(len(otp), Equals, 2)
c.Assert(otp[0].Object, Equals, s.store.Objects[s.hashes["target"]])
@@ -185,7 +186,7 @@ func (s *DeltaSelectorSuite) TestObjectsToPack(c *C) {
s.hashes["o2"],
s.hashes["o3"],
}
- otp, err = s.ds.ObjectsToPack(hashes)
+ otp, err = s.ds.ObjectsToPack(hashes, deltaWindowSize)
c.Assert(err, IsNil)
c.Assert(len(otp), Equals, 3)
c.Assert(otp[0].Object, Equals, s.store.Objects[s.hashes["o1"]])
@@ -201,20 +202,32 @@ func (s *DeltaSelectorSuite) TestObjectsToPack(c *C) {
// a delta.
hashes = make([]plumbing.Hash, 0, deltaWindowSize+2)
hashes = append(hashes, s.hashes["base"])
- for i := 0; i < deltaWindowSize; i++ {
+ for i := uint(0); i < deltaWindowSize; i++ {
hashes = append(hashes, s.hashes["smallTarget"])
}
hashes = append(hashes, s.hashes["target"])
// Don't sort so we can easily check the sliding window without
// creating a bunch of new objects.
- otp, err = s.ds.objectsToPack(hashes)
+ otp, err = s.ds.objectsToPack(hashes, deltaWindowSize)
c.Assert(err, IsNil)
- err = s.ds.walk(otp)
+ err = s.ds.walk(otp, deltaWindowSize)
c.Assert(err, IsNil)
- c.Assert(len(otp), Equals, deltaWindowSize+2)
+ c.Assert(len(otp), Equals, int(deltaWindowSize)+2)
targetIdx := len(otp) - 1
c.Assert(otp[targetIdx].IsDelta(), Equals, false)
+
+ // Check that no deltas are created, and the objects are unsorted,
+ // if compression is off.
+ hashes = []plumbing.Hash{s.hashes["base"], s.hashes["target"]}
+ otp, err = s.ds.ObjectsToPack(hashes, 0)
+ c.Assert(err, IsNil)
+ c.Assert(len(otp), Equals, 2)
+ c.Assert(otp[0].Object, Equals, s.store.Objects[s.hashes["base"]])
+ c.Assert(otp[0].IsDelta(), Equals, false)
+ c.Assert(otp[1].Original, Equals, s.store.Objects[s.hashes["target"]])
+ c.Assert(otp[1].IsDelta(), Equals, false)
+ c.Assert(otp[1].Depth, Equals, 0)
}
func (s *DeltaSelectorSuite) TestMaxDepth(c *C) {
diff --git a/plumbing/format/packfile/encoder.go b/plumbing/format/packfile/encoder.go
index 1426559..7ee6546 100644
--- a/plumbing/format/packfile/encoder.go
+++ b/plumbing/format/packfile/encoder.go
@@ -14,10 +14,10 @@ import (
// Encoder gets the data from the storage and write it into the writer in PACK
// format
type Encoder struct {
- selector *deltaSelector
- w *offsetWriter
- zw *zlib.Writer
- hasher plumbing.Hasher
+ selector *deltaSelector
+ w *offsetWriter
+ zw *zlib.Writer
+ hasher plumbing.Hasher
// offsets is a map of object hashes to corresponding offsets in the packfile.
// It is used to determine offset of the base of a delta when a OFS_DELTA is
// used.
@@ -45,10 +45,15 @@ func NewEncoder(w io.Writer, s storer.EncodedObjectStorer, useRefDeltas bool) *E
}
}
-// Encode creates a packfile containing all the objects referenced in hashes
-// and writes it to the writer in the Encoder.
-func (e *Encoder) Encode(hashes []plumbing.Hash) (plumbing.Hash, error) {
- objects, err := e.selector.ObjectsToPack(hashes)
+// Encode creates a packfile containing all the objects referenced in
+// hashes and writes it to the writer in the Encoder. `packWindow`
+// specifies the size of the sliding window used to compare objects
+// for delta compression; 0 turns off delta compression entirely.
+func (e *Encoder) Encode(
+ hashes []plumbing.Hash,
+ packWindow uint,
+) (plumbing.Hash, error) {
+ objects, err := e.selector.ObjectsToPack(hashes, packWindow)
if err != nil {
return plumbing.ZeroHash, err
}
@@ -137,7 +142,7 @@ func (e *Encoder) writeOfsDeltaHeader(deltaOffset int64, base plumbing.Hash) err
// for OFS_DELTA, offset of the base is interpreted as negative offset
// relative to the type-byte of the header of the ofs-delta entry.
- relativeOffset := deltaOffset-baseOffset
+ relativeOffset := deltaOffset - baseOffset
if relativeOffset <= 0 {
return fmt.Errorf("bad offset for OFS_DELTA entry: %d", relativeOffset)
}
diff --git a/plumbing/format/packfile/encoder_advanced_test.go b/plumbing/format/packfile/encoder_advanced_test.go
index d92e2c4..39c0700 100644
--- a/plumbing/format/packfile/encoder_advanced_test.go
+++ b/plumbing/format/packfile/encoder_advanced_test.go
@@ -27,12 +27,23 @@ func (s *EncoderAdvancedSuite) TestEncodeDecode(c *C) {
fixs.Test(c, func(f *fixtures.Fixture) {
storage, err := filesystem.NewStorage(f.DotGit())
c.Assert(err, IsNil)
- s.testEncodeDecode(c, storage)
+ s.testEncodeDecode(c, storage, 10)
})
}
-func (s *EncoderAdvancedSuite) testEncodeDecode(c *C, storage storer.Storer) {
+func (s *EncoderAdvancedSuite) TestEncodeDecodeNoDeltaCompression(c *C) {
+ fixs := fixtures.Basic().ByTag("packfile").ByTag(".git")
+ fixs = append(fixs, fixtures.ByURL("https://github.com/src-d/go-git.git").
+ ByTag("packfile").ByTag(".git").One())
+ fixs.Test(c, func(f *fixtures.Fixture) {
+ storage, err := filesystem.NewStorage(f.DotGit())
+ c.Assert(err, IsNil)
+ s.testEncodeDecode(c, storage, 0)
+ })
+}
+
+func (s *EncoderAdvancedSuite) testEncodeDecode(c *C, storage storer.Storer, packWindow uint) {
objIter, err := storage.IterEncodedObjects(plumbing.AnyObject)
c.Assert(err, IsNil)
@@ -57,7 +68,7 @@ func (s *EncoderAdvancedSuite) testEncodeDecode(c *C, storage storer.Storer) {
buf := bytes.NewBuffer(nil)
enc := NewEncoder(buf, storage, false)
- _, err = enc.Encode(hashes)
+ _, err = enc.Encode(hashes, packWindow)
c.Assert(err, IsNil)
scanner := NewScanner(buf)
diff --git a/plumbing/format/packfile/encoder_test.go b/plumbing/format/packfile/encoder_test.go
index b5b0c42..2cb9094 100644
--- a/plumbing/format/packfile/encoder_test.go
+++ b/plumbing/format/packfile/encoder_test.go
@@ -26,7 +26,7 @@ func (s *EncoderSuite) SetUpTest(c *C) {
}
func (s *EncoderSuite) TestCorrectPackHeader(c *C) {
- hash, err := s.enc.Encode([]plumbing.Hash{})
+ hash, err := s.enc.Encode([]plumbing.Hash{}, 10)
c.Assert(err, IsNil)
hb := [20]byte(hash)
@@ -47,7 +47,7 @@ func (s *EncoderSuite) TestCorrectPackWithOneEmptyObject(c *C) {
_, err := s.store.SetEncodedObject(o)
c.Assert(err, IsNil)
- hash, err := s.enc.Encode([]plumbing.Hash{o.Hash()})
+ hash, err := s.enc.Encode([]plumbing.Hash{o.Hash()}, 10)
c.Assert(err, IsNil)
// PACK + VERSION(2) + OBJECT NUMBER(1)
@@ -74,13 +74,13 @@ func (s *EncoderSuite) TestMaxObjectSize(c *C) {
o.SetType(plumbing.CommitObject)
_, err := s.store.SetEncodedObject(o)
c.Assert(err, IsNil)
- hash, err := s.enc.Encode([]plumbing.Hash{o.Hash()})
+ hash, err := s.enc.Encode([]plumbing.Hash{o.Hash()}, 10)
c.Assert(err, IsNil)
c.Assert(hash.IsZero(), Not(Equals), true)
}
func (s *EncoderSuite) TestHashNotFound(c *C) {
- h, err := s.enc.Encode([]plumbing.Hash{plumbing.NewHash("BAD")})
+ h, err := s.enc.Encode([]plumbing.Hash{plumbing.NewHash("BAD")}, 10)
c.Assert(h, Equals, plumbing.ZeroHash)
c.Assert(err, NotNil)
c.Assert(err, Equals, plumbing.ErrObjectNotFound)
generated by cgit (git 2.34.1) at 2024-09-21 14:16:29 +0000