Merge pull request #698 from jfontan/improvement/use-decoder-cache

plumbing: cache, enforce the use of cache in packfile decoder

5 files changed, 106 insertions, 58 deletions

diff --git a/plumbing/cache/common.go b/plumbing/cache/common.go
index 9efc26c..e77baf0 100644
--- a/plumbing/cache/common.go
+++ b/plumbing/cache/common.go
@@ -11,6 +11,8 @@ const (
 
 type FileSize int64
 
+const DefaultMaxSize FileSize = 96 * MiByte
+
 // Object is an interface to a object cache.
 type Object interface {
 	// Put puts the given object into the cache. Whether this object will
diff --git a/plumbing/cache/object_lru.go b/plumbing/cache/object_lru.go
index e8414ab..d99a5c9 100644
--- a/plumbing/cache/object_lru.go
+++ b/plumbing/cache/object_lru.go
@@ -24,6 +24,11 @@ func NewObjectLRU(maxSize FileSize) *ObjectLRU {
 	return &ObjectLRU{MaxSize: maxSize}
 }
 
+// NewObjectLRUDefault creates a new ObjectLRU with the default cache size.
+func NewObjectLRUDefault() *ObjectLRU {
+	return &ObjectLRU{MaxSize: DefaultMaxSize}
+}
+
 // Put puts an object into the cache. If the object is already in the cache, it
 // will be marked as used. Otherwise, it will be inserted. A single object might
 // be evicted to make room for the new object.
diff --git a/plumbing/cache/object_test.go b/plumbing/cache/object_test.go
index b38272f..ec01d60 100644
--- a/plumbing/cache/object_test.go
+++ b/plumbing/cache/object_test.go
@@ -14,7 +14,7 @@ import (
 func Test(t *testing.T) { TestingT(t) }
 
 type ObjectSuite struct {
-	c       Object
+	c       map[string]Object
 	aObject plumbing.EncodedObject
 	bObject plumbing.EncodedObject
 	cObject plumbing.EncodedObject
@@ -29,70 +29,89 @@ func (s *ObjectSuite) SetUpTest(c *C) {
 	s.cObject = newObject("cccccccccccccccccccccccccccccccccccccccc", 1*Byte)
 	s.dObject = newObject("dddddddddddddddddddddddddddddddddddddddd", 1*Byte)
 
-	s.c = NewObjectLRU(2 * Byte)
+	s.c = make(map[string]Object)
+	s.c["two_bytes"] = NewObjectLRU(2 * Byte)
+	s.c["default_lru"] = NewObjectLRUDefault()
 }
 
 func (s *ObjectSuite) TestPutSameObject(c *C) {
-	s.c.Put(s.aObject)
-	s.c.Put(s.aObject)
-	_, ok := s.c.Get(s.aObject.Hash())
-	c.Assert(ok, Equals, true)
+	for _, o := range s.c {
+		o.Put(s.aObject)
+		o.Put(s.aObject)
+		_, ok := o.Get(s.aObject.Hash())
+		c.Assert(ok, Equals, true)
+	}
 }
 
 func (s *ObjectSuite) TestPutBigObject(c *C) {
-	s.c.Put(s.bObject)
-	_, ok := s.c.Get(s.aObject.Hash())
-	c.Assert(ok, Equals, false)
+	for _, o := range s.c {
+		o.Put(s.bObject)
+		_, ok := o.Get(s.aObject.Hash())
+		c.Assert(ok, Equals, false)
+	}
 }
 
 func (s *ObjectSuite) TestPutCacheOverflow(c *C) {
-	s.c.Put(s.aObject)
-	s.c.Put(s.cObject)
-	s.c.Put(s.dObject)
+	// this test only works with an specific size
+	o := s.c["two_bytes"]
+
+	o.Put(s.aObject)
+	o.Put(s.cObject)
+	o.Put(s.dObject)
 
-	obj, ok := s.c.Get(s.aObject.Hash())
+	obj, ok := o.Get(s.aObject.Hash())
 	c.Assert(ok, Equals, false)
 	c.Assert(obj, IsNil)
-	obj, ok = s.c.Get(s.cObject.Hash())
+	obj, ok = o.Get(s.cObject.Hash())
 	c.Assert(ok, Equals, true)
 	c.Assert(obj, NotNil)
-	obj, ok = s.c.Get(s.dObject.Hash())
+	obj, ok = o.Get(s.dObject.Hash())
 	c.Assert(ok, Equals, true)
 	c.Assert(obj, NotNil)
 }
 
 func (s *ObjectSuite) TestClear(c *C) {
-	s.c.Put(s.aObject)
-	s.c.Clear()
-	obj, ok := s.c.Get(s.aObject.Hash())
-	c.Assert(ok, Equals, false)
-	c.Assert(obj, IsNil)
+	for _, o := range s.c {
+		o.Put(s.aObject)
+		o.Clear()
+		obj, ok := o.Get(s.aObject.Hash())
+		c.Assert(ok, Equals, false)
+		c.Assert(obj, IsNil)
+	}
 }
 
 func (s *ObjectSuite) TestConcurrentAccess(c *C) {
-	var wg sync.WaitGroup
-
-	for i := 0; i < 1000; i++ {
-		wg.Add(3)
-		go func(i int) {
-			s.c.Put(newObject(fmt.Sprint(i), FileSize(i)))
-			wg.Done()
-		}(i)
-
-		go func(i int) {
-			if i%30 == 0 {
-				s.c.Clear()
-			}
-			wg.Done()
-		}(i)
-
-		go func(i int) {
-			s.c.Get(plumbing.NewHash(fmt.Sprint(i)))
-			wg.Done()
-		}(i)
+	for _, o := range s.c {
+		var wg sync.WaitGroup
+
+		for i := 0; i < 1000; i++ {
+			wg.Add(3)
+			go func(i int) {
+				o.Put(newObject(fmt.Sprint(i), FileSize(i)))
+				wg.Done()
+			}(i)
+
+			go func(i int) {
+				if i%30 == 0 {
+					o.Clear()
+				}
+				wg.Done()
+			}(i)
+
+			go func(i int) {
+				o.Get(plumbing.NewHash(fmt.Sprint(i)))
+				wg.Done()
+			}(i)
+		}
+
+		wg.Wait()
 	}
+}
+
+func (s *ObjectSuite) TestDefaultLRU(c *C) {
+	defaultLRU := s.c["default_lru"].(*ObjectLRU)
 
-	wg.Wait()
+	c.Assert(defaultLRU.MaxSize, Equals, DefaultMaxSize)
 }
 
 type dummyObject struct {
diff --git a/plumbing/format/packfile/decoder.go b/plumbing/format/packfile/decoder.go
index ad72ea0..cb78701 100644
--- a/plumbing/format/packfile/decoder.go
+++ b/plumbing/format/packfile/decoder.go
@@ -52,7 +52,7 @@ var (
 // is destroyed. The Offsets and CRCs are calculated whether an
 // ObjectStorer was provided or not.
 type Decoder struct {
-	DeltaBaseCache cache.Object
+	deltaBaseCache cache.Object
 
 	s  *Scanner
 	o  storer.EncodedObjectStorer
@@ -80,15 +80,27 @@ type Decoder struct {
 // If the ObjectStorer implements storer.Transactioner, a transaction is created
 // during the Decode execution. If anything fails, Rollback is called
 func NewDecoder(s *Scanner, o storer.EncodedObjectStorer) (*Decoder, error) {
-	return NewDecoderForType(s, o, plumbing.AnyObject)
+	return NewDecoderForType(s, o, plumbing.AnyObject,
+		cache.NewObjectLRUDefault())
+}
+
+// NewDecoderWithCache is a version of NewDecoder where cache can be specified.
+func NewDecoderWithCache(s *Scanner, o storer.EncodedObjectStorer,
+	cacheObject cache.Object) (*Decoder, error) {
+
+	return NewDecoderForType(s, o, plumbing.AnyObject, cacheObject)
 }
 
 // NewDecoderForType returns a new Decoder but in this case for a specific object type.
 // When an object is read using this Decoder instance and it is not of the same type of
 // the specified one, nil will be returned. This is intended to avoid the content
-// deserialization of all the objects
+// deserialization of all the objects.
+//
+// cacheObject is a cache.Object implementation that is used to speed up the
+// process. If cache is not needed you can pass nil. To create an LRU cache
+// object with the default size you can use the helper cache.ObjectLRUDefault().
 func NewDecoderForType(s *Scanner, o storer.EncodedObjectStorer,
-	t plumbing.ObjectType) (*Decoder, error) {
+	t plumbing.ObjectType, cacheObject cache.Object) (*Decoder, error) {
 
 	if t == plumbing.OFSDeltaObject ||
 		t == plumbing.REFDeltaObject ||
@@ -101,8 +113,9 @@ func NewDecoderForType(s *Scanner, o storer.EncodedObjectStorer,
 	}
 
 	return &Decoder{
-		s: s,
-		o: o,
+		s:              s,
+		o:              o,
+		deltaBaseCache: cacheObject,
 
 		idx:          NewIndex(0),
 		offsetToType: make(map[int64]plumbing.ObjectType),
@@ -404,19 +417,19 @@ func (d *Decoder) fillOFSDeltaObjectContent(obj plumbing.EncodedObject, offset i
 }
 
 func (d *Decoder) cacheGet(h plumbing.Hash) (plumbing.EncodedObject, bool) {
-	if d.DeltaBaseCache == nil {
+	if d.deltaBaseCache == nil {
 		return nil, false
 	}
 
-	return d.DeltaBaseCache.Get(h)
+	return d.deltaBaseCache.Get(h)
 }
 
 func (d *Decoder) cachePut(obj plumbing.EncodedObject) {
-	if d.DeltaBaseCache == nil {
+	if d.deltaBaseCache == nil {
 		return
 	}
 
-	d.DeltaBaseCache.Put(obj)
+	d.deltaBaseCache.Put(obj)
 }
 
 func (d *Decoder) recallByOffset(o int64) (plumbing.EncodedObject, error) {
diff --git a/plumbing/format/packfile/decoder_test.go b/plumbing/format/packfile/decoder_test.go
index 1a1a74a..b5bc7b7 100644
--- a/plumbing/format/packfile/decoder_test.go
+++ b/plumbing/format/packfile/decoder_test.go
@@ -4,6 +4,7 @@ import (
 	"io"
 
 	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/cache"
 	"gopkg.in/src-d/go-git.v4/plumbing/format/idxfile"
 	"gopkg.in/src-d/go-git.v4/plumbing/format/packfile"
 	"gopkg.in/src-d/go-git.v4/plumbing/storer"
@@ -51,7 +52,8 @@ func (s *ReaderSuite) TestDecodeByTypeRefDelta(c *C) {
 
 	storage := memory.NewStorage()
 	scanner := packfile.NewScanner(f.Packfile())
-	d, err := packfile.NewDecoderForType(scanner, storage, plumbing.CommitObject)
+	d, err := packfile.NewDecoderForType(scanner, storage, plumbing.CommitObject,
+		cache.NewObjectLRUDefault())
 	c.Assert(err, IsNil)
 
 	// Index required to decode by ref-delta.
@@ -77,7 +79,8 @@ func (s *ReaderSuite) TestDecodeByTypeRefDeltaError(c *C) {
 	fixtures.Basic().ByTag("ref-delta").Test(c, func(f *fixtures.Fixture) {
 		storage := memory.NewStorage()
 		scanner := packfile.NewScanner(f.Packfile())
-		d, err := packfile.NewDecoderForType(scanner, storage, plumbing.CommitObject)
+		d, err := packfile.NewDecoderForType(scanner, storage,
+			plumbing.CommitObject, cache.NewObjectLRUDefault())
 		c.Assert(err, IsNil)
 
 		defer d.Close()
@@ -111,7 +114,8 @@ func (s *ReaderSuite) TestDecodeByType(c *C) {
 		for _, t := range ts {
 			storage := memory.NewStorage()
 			scanner := packfile.NewScanner(f.Packfile())
-			d, err := packfile.NewDecoderForType(scanner, storage, t)
+			d, err := packfile.NewDecoderForType(scanner, storage, t,
+				cache.NewObjectLRUDefault())
 			c.Assert(err, IsNil)
 
 			// when the packfile is ref-delta based, the offsets are required
@@ -141,13 +145,17 @@ func (s *ReaderSuite) TestDecodeByTypeConstructor(c *C) {
 	storage := memory.NewStorage()
 	scanner := packfile.NewScanner(f.Packfile())
 
-	_, err := packfile.NewDecoderForType(scanner, storage, plumbing.OFSDeltaObject)
+	_, err := packfile.NewDecoderForType(scanner, storage,
+		plumbing.OFSDeltaObject, cache.NewObjectLRUDefault())
 	c.Assert(err, Equals, plumbing.ErrInvalidType)
 
-	_, err = packfile.NewDecoderForType(scanner, storage, plumbing.REFDeltaObject)
+	_, err = packfile.NewDecoderForType(scanner, storage,
+		plumbing.REFDeltaObject, cache.NewObjectLRUDefault())
+
 	c.Assert(err, Equals, plumbing.ErrInvalidType)
 
-	_, err = packfile.NewDecoderForType(scanner, storage, plumbing.InvalidObject)
+	_, err = packfile.NewDecoderForType(scanner, storage, plumbing.InvalidObject,
+		cache.NewObjectLRUDefault())
 	c.Assert(err, Equals, plumbing.ErrInvalidType)
 }
 
@@ -313,7 +321,8 @@ func (s *ReaderSuite) TestDecodeObjectAt(c *C) {
 func (s *ReaderSuite) TestDecodeObjectAtForType(c *C) {
 	f := fixtures.Basic().One()
 	scanner := packfile.NewScanner(f.Packfile())
-	d, err := packfile.NewDecoderForType(scanner, nil, plumbing.TreeObject)
+	d, err := packfile.NewDecoderForType(scanner, nil, plumbing.TreeObject,
+		cache.NewObjectLRUDefault())
 	c.Assert(err, IsNil)
 
 	// when the packfile is ref-delta based, the offsets are required