storage: reuse deltas from packfiles

* plumbing: add DeltaObject interface for EncodedObjects that
  are deltas and hold additional information about them, such
  as the hash of the base object.

* plumbing/storer: add DeltaObjectStorer interface for object
  storers that can return DeltaObject. Note that calls to
  EncodedObject will never return instances of DeltaObject.
  That requires explicit calls to DeltaObject.

* storage/filesystem: implement DeltaObjectStorer interface.

* plumbing/packfile: packfile encoder now supports reusing
  deltas that are already computed (e.g. from an existing
  packfile) if the storage implements DeltaObjectStorer.
  Reusing deltas boosts performance of packfile generation
  (e.g. on push).

1 files changed, 0 insertions, 76 deletions

diff --git a/plumbing/format/packfile/encoder_test.go b/plumbing/format/packfile/encoder_test.go
index 551d7ec..b5b0c42 100644
--- a/plumbing/format/packfile/encoder_test.go
+++ b/plumbing/format/packfile/encoder_test.go
@@ -2,11 +2,9 @@ package packfile
 
 import (
 	"bytes"
-	"io"
 
 	"github.com/src-d/go-git-fixtures"
 	"gopkg.in/src-d/go-git.v4/plumbing"
-	"gopkg.in/src-d/go-git.v4/plumbing/storer"
 	"gopkg.in/src-d/go-git.v4/storage/memory"
 
 	. "gopkg.in/check.v1"
@@ -88,80 +86,6 @@ func (s *EncoderSuite) TestHashNotFound(c *C) {
 	c.Assert(err, Equals, plumbing.ErrObjectNotFound)
 }
 
-func (s *EncoderSuite) TestDecodeEncodeDecode(c *C) {
-	fixtures.Basic().ByTag("packfile").Test(c, func(f *fixtures.Fixture) {
-		pf := f.Packfile()
-		ph := f.PackfileHash
-		storage := memory.NewStorage()
-		s.testDecodeEncodeDecode(c, pf, ph, storage)
-	})
-}
-
-func (s *EncoderSuite) testDecodeEncodeDecode(c *C,
-	pf io.ReadCloser,
-	ph plumbing.Hash,
-	storage storer.Storer) {
-
-	defer func() {
-		c.Assert(pf.Close(), IsNil)
-	}()
-
-	scanner := NewScanner(pf)
-
-	d, err := NewDecoder(scanner, storage)
-	c.Assert(err, IsNil)
-
-	ch, err := d.Decode()
-	c.Assert(err, IsNil)
-	c.Assert(ch, Equals, ph)
-
-	objIter, err := storage.IterEncodedObjects(plumbing.AnyObject)
-	c.Assert(err, IsNil)
-
-	expectedObjects := map[plumbing.Hash]bool{}
-	var hashes []plumbing.Hash
-	err = objIter.ForEach(func(o plumbing.EncodedObject) error {
-		expectedObjects[o.Hash()] = true
-		hashes = append(hashes, o.Hash())
-		return err
-
-	})
-	c.Assert(err, IsNil)
-
-	enc := NewEncoder(s.buf, storage, false)
-	_, err = enc.Encode(hashes)
-	c.Assert(err, IsNil)
-
-	scanner = NewScanner(s.buf)
-	storage = memory.NewStorage()
-	d, err = NewDecoder(scanner, storage)
-	c.Assert(err, IsNil)
-	_, err = d.Decode()
-	c.Assert(err, IsNil)
-
-	objIter, err = storage.IterEncodedObjects(plumbing.AnyObject)
-	c.Assert(err, IsNil)
-	obtainedObjects := map[plumbing.Hash]bool{}
-	err = objIter.ForEach(func(o plumbing.EncodedObject) error {
-		obtainedObjects[o.Hash()] = true
-		return nil
-	})
-	c.Assert(err, IsNil)
-	c.Assert(obtainedObjects, DeepEquals, expectedObjects)
-
-	for h := range obtainedObjects {
-		if !expectedObjects[h] {
-			c.Errorf("obtained unexpected object: %s", h)
-		}
-	}
-
-	for h := range expectedObjects {
-		if !obtainedObjects[h] {
-			c.Errorf("missing object: %s", h)
-		}
-	}
-}
-
 func (s *EncoderSuite) TestDecodeEncodeWithDeltaDecodeREF(c *C) {
 	s.enc = NewEncoder(s.buf, s.store, true)
 	s.simpleDeltaTest(c)