diff --git a/mempack.go b/mempack.go new file mode 100644 index 0000000..0b82cd4 --- /dev/null +++ b/mempack.go @@ -0,0 +1,97 @@ +package git + +/* +#include +#include + +extern int git_mempack_new(git_odb_backend **out); +extern int git_mempack_dump(git_buf *pack, git_repository *repo, git_odb_backend *backend); +extern void git_mempack_reset(git_odb_backend *backend); +extern void _go_git_odb_backend_free(git_odb_backend *backend); +*/ +import "C" + +import ( + "runtime" + "unsafe" +) + +// Mempack is a custom ODB backend that permits packing object in-memory. +type Mempack struct { + ptr *C.git_odb_backend +} + +// NewMempack creates a new mempack instance and registers it to the ODB. +func NewMempack(odb *Odb) (mempack *Mempack, err error) { + mempack = new(Mempack) + + runtime.LockOSThread() + defer runtime.UnlockOSThread() + + ret := C.git_mempack_new(&mempack.ptr) + if ret < 0 { + return nil, MakeGitError(ret) + } + runtime.SetFinalizer(mempack, (*Mempack).Free) + + ret = C.git_odb_add_backend(odb.ptr, mempack.ptr, C.int(999)) + if ret < 0 { + // Since git_odb_add_alternate() takes ownership of the ODB backend, the + // only case in which we free the mempack's memory is if it fails to be + // added to the ODB. Mempack.Free() is actually just a no-op. + C._go_git_odb_backend_free(mempack.ptr) + mempack.Free() + return nil, MakeGitError(ret) + } + + return mempack, nil +} + +// Dump dumps all the queued in-memory writes to a packfile. +// +// It is the caller's responsibility to ensure that the generated packfile is +// available to the repository (e.g. by writing it to disk, or doing something +// crazy like distributing it across several copies of the repository over a +// network). +// +// Once the generated packfile is available to the repository, call +// Mempack.Reset to cleanup the memory store. +// +// Calling Mempack.Reset before the packfile has been written to disk will +// result in an inconsistent repository (the objects in the memory store won't +// be accessible). +func (mempack *Mempack) Dump(repository *Repository) ([]byte, error) { + buf := C.git_buf{} + + runtime.LockOSThread() + defer runtime.UnlockOSThread() + + var repoPtr *C.git_repository + if repository != nil { + repoPtr = repository.ptr + } + + ret := C.git_mempack_dump(&buf, repoPtr, mempack.ptr) + if ret < 0 { + return nil, MakeGitError(ret) + } + defer C.git_buf_free(&buf) + + return C.GoBytes(unsafe.Pointer(buf.ptr), C.int(buf.size)), nil +} + +// Reset resets the memory packer by clearing all the queued objects. +// +// This assumes that Mempack.Dump has been called before to store all the +// queued objects into a single packfile. +func (mempack *Mempack) Reset() { + runtime.LockOSThread() + defer runtime.UnlockOSThread() + + C.git_mempack_reset(mempack.ptr) +} + +// Free frees the mempack and its resources. +func (mempack *Mempack) Free() { + runtime.SetFinalizer(mempack, nil) +}