repository: add listall_reference_objects() method

This allows for efficient reading of many references and their targets,
without incurring the overhead of lookup_reference() (which stats for
a loose ref and then reads packed-refs) which can be expensive on NFS
with thousands of refs.

docs/references.rst

@@ -4,6 +4,7 @@ References
 
 .. contents::
 
+.. automethod:: pygit2.Repository.listall_reference_objects
 .. automethod:: pygit2.Repository.listall_references
 .. automethod:: pygit2.Repository.lookup_reference
 

src/repository.c

@@ -1123,6 +1123,56 @@ out:
 }
 
 
+PyDoc_STRVAR(Repository_listall_reference_objects__doc__,
+  "listall_reference_objects() -> [Reference, ...]\n"
+  "\n"
+  "Return a list with all the reference objects in the repository.");
+
+PyObject *
+Repository_listall_reference_objects(Repository *self, PyObject *args)
+{
+    git_reference_iterator *iter;
+    git_reference *ref = NULL;
+    int err;
+    PyObject *list;
+
+    list = PyList_New(0);
+    if (list == NULL)
+        return NULL;
+
+    if ((err = git_reference_iterator_new(&iter, self->repo)) < 0)
+        return Error_set(err);
+
+    while ((err = git_reference_next(&ref, iter)) == 0) {
+        PyObject *py_ref = wrap_reference(ref, self);
+        if (py_ref == NULL)
+            goto error;
+
+        err = PyList_Append(list, py_ref);
+        Py_DECREF(py_ref);
+
+        if (err < 0)
+            goto error;
+    }
+
+    git_reference_iterator_free(iter);
+    if (err == GIT_ITEROVER)
+        err = 0;
+
+    if (err < 0) {
+        Py_CLEAR(list);
+        return Error_set(err);
+    }
+
+    return list;
+
+error:
+    git_reference_iterator_free(iter);
+    Py_CLEAR(list);
+    return NULL;
+}
+
+
 PyDoc_STRVAR(Repository_listall_branches__doc__,
   "listall_branches([flag]) -> [str, ...]\n"
   "\n"
@@ -1643,6 +1693,7 @@ PyMethodDef Repository_methods[] = {
     METHOD(Repository, create_reference_direct, METH_VARARGS),
     METHOD(Repository, create_reference_symbolic, METH_VARARGS),
     METHOD(Repository, listall_references, METH_NOARGS),
+    METHOD(Repository, listall_reference_objects, METH_NOARGS),
     METHOD(Repository, listall_submodules, METH_NOARGS),
     METHOD(Repository, lookup_reference, METH_O),
     METHOD(Repository, revparse_single, METH_O),

src/repository.h

@@ -58,6 +58,8 @@ PyObject* Repository_create_commit(Repository *self, PyObject *args);
 PyObject* Repository_create_tag(Repository *self, PyObject *args);
 PyObject* Repository_create_branch(Repository *self, PyObject *args);
 PyObject* Repository_listall_references(Repository *self, PyObject *args);
+PyObject* Repository_listall_reference_objects(Repository *self,
+                                               PyObject *args);
 PyObject* Repository_listall_branches(Repository *self, PyObject *args);
 PyObject* Repository_lookup_reference(Repository *self, PyObject *py_name);
 

test/test_refs.py

@@ -42,6 +42,17 @@ LAST_COMMIT = '2be5719152d4f82c7302b1c0932d8e5f0a4a0e98'
 
 class ReferencesTest(utils.RepoTestCase):
 
+    def test_list_all_reference_objects(self):
+        repo = self.repo
+
+        refs = [(ref.name, ref.target.hex)
+                for ref in repo.listall_reference_objects()]
+        self.assertEqual(sorted(refs),
+                         [('refs/heads/i18n',
+                           '5470a671a80ac3789f1a6a8cefbcf43ce7af0563'),
+                          ('refs/heads/master',
+                           '2be5719152d4f82c7302b1c0932d8e5f0a4a0e98')])
+
     def test_list_all_references(self):
         repo = self.repo