Add support for indexers and alternate odb packfiles

This allows for implementations of git servers written in Go.

indexer.go

@@ -0,0 +1,94 @@
+package git
+
+/*
+#include <git2.h>
+
+extern const git_oid * git_indexer_hash(const git_indexer *idx);
+extern int git_indexer_append(git_indexer *idx, const void *data, size_t size, git_transfer_progress *stats);
+extern int git_indexer_commit(git_indexer *idx, git_transfer_progress *stats);
+extern int _go_git_indexer_new(git_indexer **out, const char *path, unsigned int mode, git_odb *odb, void *progress_cb_payload);
+extern void git_indexer_free(git_indexer *idx);
+*/
+import "C"
+import (
+	"reflect"
+	"runtime"
+	"unsafe"
+)
+
+//export indexerTransferProgress
+func indexerTransferProgress(_stats *C.git_transfer_progress, ptr unsafe.Pointer) C.int {
+	callback, ok := pointerHandles.Get(ptr).(TransferProgressCallback)
+	if !ok {
+		return 0
+	}
+	return C.int(callback(newTransferProgressFromC(_stats)))
+}
+
+type Indexer struct {
+	ptr      *C.git_indexer
+	stats    C.git_transfer_progress
+	callback unsafe.Pointer
+}
+
+func NewIndexer(packfilePath string, odb *Odb, callback TransferProgressCallback) (indexer *Indexer, err error) {
+	indexer = new(Indexer)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	var odbPtr *C.git_odb = nil
+	if odb != nil {
+		odbPtr = odb.ptr
+	}
+
+	if callback != nil {
+		indexer.callback = pointerHandles.Track(callback)
+	}
+
+	ret := C._go_git_indexer_new(&indexer.ptr, C.CString(packfilePath), 0, odbPtr, indexer.callback)
+	if ret < 0 {
+		if indexer.callback != nil {
+			pointerHandles.Untrack(indexer.callback)
+		}
+		return nil, MakeGitError(ret)
+	}
+
+	runtime.SetFinalizer(indexer, (*Indexer).Free)
+	return indexer, nil
+}
+
+func (indexer *Indexer) Write(data []byte) (int, error) {
+	header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
+	ptr := unsafe.Pointer(header.Data)
+	size := C.size_t(header.Len)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_indexer_append(indexer.ptr, ptr, size, &indexer.stats)
+	if ret < 0 {
+		return 0, MakeGitError(ret)
+	}
+
+	return len(data), nil
+}
+
+func (indexer *Indexer) Commit() (*Oid, error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_indexer_commit(indexer.ptr, &indexer.stats)
+	if ret < 0 {
+		return nil, MakeGitError(ret)
+	}
+
+	return newOidFromC(C.git_indexer_hash(indexer.ptr)), nil
+}
+
+func (indexer *Indexer) Free() {
+	if indexer.callback != nil {
+		pointerHandles.Untrack(indexer.callback)
+	}
+	C.git_indexer_free(indexer.ptr)
+}

odb.go

@@ -3,6 +3,7 @@ package git
 /*
 #include <git2.h>
 
+extern int git_odb_backend_one_pack(git_odb_backend **out, const char *index_file);
 extern int _go_git_odb_foreach(git_odb *db, void *payload);
 extern void _go_git_odb_backend_free(git_odb_backend *backend);
 */
@@ -41,8 +42,19 @@ func NewOdbBackendFromC(ptr *C.git_odb_backend) (backend *OdbBackend) {
 	return backend
 }
 
-func (v *Odb) AddBackend(backend *OdbBackend, priority int) (err error) {
+func (v *Odb) AddAlternate(backend *OdbBackend, priority int) (err error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
 
+	ret := C.git_odb_add_alternate(v.ptr, backend.ptr, C.int(priority))
+	if ret < 0 {
+		backend.Free()
+		return MakeGitError(ret)
+	}
+	return nil
+}
+
+func (v *Odb) AddBackend(backend *OdbBackend, priority int) (err error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
 
@@ -54,12 +66,24 @@ func (v *Odb) AddBackend(backend *OdbBackend, priority int) (err error) {
 	return nil
 }
 
+func NewOdbBackendOnePack(packfileIndexPath string) (backend *OdbBackend, err error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	var odbOnePack *C.git_odb_backend = nil
+	ret := C.git_odb_backend_one_pack(&odbOnePack, C.CString(packfileIndexPath))
+	if ret < 0 {
+		return nil, MakeGitError(ret)
+	}
+	return NewOdbBackendFromC(odbOnePack), nil
+}
+
 func (v *Odb) ReadHeader(oid *Oid) (uint64, ObjectType, error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
-	
+
 	var sz C.size_t
-	var cotype C.git_otype 
+	var cotype C.git_otype
 
 	ret := C.git_odb_read_header(&sz, &cotype, v.ptr, oid.toC())
 	if ret < 0 {
@@ -68,7 +92,7 @@ func (v *Odb) ReadHeader(oid *Oid) (uint64, ObjectType, error) {
 
 	return uint64(sz), ObjectType(cotype), nil
 }
-	
+
 func (v *Odb) Exists(oid *Oid) bool {
 	ret := C.git_odb_exists(v.ptr, oid.toC())
 	return ret != 0

wrapper.c

@@ -174,4 +174,9 @@ void _go_git_writestream_free(git_writestream *stream)
 	stream->free(stream);
 }
 
+int _go_git_indexer_new(git_indexer **out, const char *path, unsigned int mode, git_odb *odb, void *progress_cb_payload)
+{
+	return git_indexer_new(out, path, mode, odb, (git_transfer_progress_cb)&indexerTransferProgress, progress_cb_payload);
+}
+
 /* EOF */