Free Git objects via finalizers or manually

Provide a manual way of freeing objects, but set finalizers for them
in case the user does not want to worry about memory management, which
would be useful for commits or trees, which sare typically small.

When the objects are freed manually, the finalizer is unset to avoid
double-freeing, mimicking what the go runtime does.

blob.go

@@ -7,6 +7,7 @@ package git
 */
 import "C"
 import (
+	"runtime"
 	"unsafe"
 )
 
@@ -14,8 +15,9 @@ type Blob struct {
 	ptr *C.git_object
 }
 
-func freeBlob(blob *Blob) {
+func (v *Blob) Free() {
-	C.git_object_free(blob.ptr)
+	runtime.SetFinalizer(v, nil)
+	C.git_object_free(v.ptr)
 }
 
 func (v *Blob) Contents() []byte {

commit.go

@@ -9,6 +9,7 @@ extern int _go_git_treewalk(git_tree *tree, git_treewalk_mode mode, void *ptr);
 import "C"
 
 import (
+	"runtime"
 	"time"
 )
 
@@ -32,6 +33,8 @@ func (c *Commit) Tree() (*Tree, error) {
 	if err < 0 {
 		return nil, LastError()
 	}
+
+	runtime.SetFinalizer(tree, (*Tree).Free)
 	return tree, nil
 }
 

odb.go

@@ -49,7 +49,7 @@ func (v *Odb) Read(oid *Oid) (obj *OdbObject, err error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(obj, freeOdbObject)
+	runtime.SetFinalizer(obj, (*OdbObject).Free)
 	return
 }
 
@@ -57,8 +57,9 @@ type OdbObject struct {
 	ptr *C.git_odb_object
 }
 
-func freeOdbObject(obj *OdbObject) {
+func (v *OdbObject) Free() {
-	C.git_odb_object_free(obj.ptr)
+	runtime.SetFinalizer(v, nil)
+	C.git_odb_object_free(v.ptr)
 }
 
 func (v *OdbObject) Type() int {

repository.go

@@ -27,7 +27,7 @@ func Open(path string) (*Repository, error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(repo, freeRepository)
+	runtime.SetFinalizer(repo, (*Repository).Free)
 	return repo, nil
 }
 
@@ -42,12 +42,13 @@ func Init(path string, isbare bool) (*Repository, error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(repo, freeRepository)
+	runtime.SetFinalizer(repo, (*Repository).Free)
 	return repo, nil
 }
 
-func freeRepository(repo *Repository) {
+func (v *Repository) Free() {
-	C.git_repository_free(repo.ptr)
+	runtime.SetFinalizer(v, nil)
+	C.git_repository_free(v.ptr)
 }
 
 func (v *Repository) Config() (*Config, error) {
@@ -127,8 +128,9 @@ func (v *Repository) Commit(
 }
 */
 
-func freeOdb(odb *Odb) {
+func (v *Odb) Free() {
-	C.git_odb_free(odb.ptr)
+	runtime.SetFinalizer(v, nil)
+	C.git_odb_free(v.ptr)
 }
 
 func (v *Repository) Odb() (odb *Odb, err error) {
@@ -137,7 +139,7 @@ func (v *Repository) Odb() (odb *Odb, err error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(odb, freeOdb)
+	runtime.SetFinalizer(odb, (*Odb).Free)
 	return
 }
 

tree.go

@@ -9,6 +9,7 @@ extern int _go_git_treewalk(git_tree *tree, git_treewalk_mode mode, void *ptr);
 import "C"
 
 import (
+	"runtime"
 	"unsafe"
 )
 
@@ -31,6 +32,7 @@ func newTreeEntry(entry *C.git_tree_entry) *TreeEntry {
 }
 
 func (t *Tree) Free() {
+	runtime.SetFinalizer(t, nil)
 	C.git_tree_free(t.ptr)
 }
 
@@ -40,6 +42,8 @@ func TreeLookup(repo *Repository, oid *Oid) (*Tree, error) {
 	if err < 0 {
 		return nil, LastError()
 	}
+
+	runtime.SetFinalizer(tree, (*Tree).Free)
 	return tree, nil
 }
 
@@ -99,7 +103,8 @@ type TreeBuilder struct {
 	repo *Repository
 }
 
-func freeTreeBuilder(v *TreeBuilder) {
+func (v *TreeBuilder) Free() {
+	runtime.SetFinalizer(v, nil)
 	C.git_treebuilder_free(v.ptr)
 }