Use reconstruct insetad of decode/encode

With bumping PyECLib up to 1.0.7 on global requirements,
we can use the "reconstruct" function directly instead
of the current hack doing decode/encode on reconstructor.
That is because the hack was for treating PyECLib < 1.0.7
(strictly jearsure scheme) reconstruction bug so we don't
have to do decode/encode anymore.

Closes-Bug: 1446801
Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>
Change-Id: I69aae495670e3d0bdebe665f73915547a4d56f99

swift/obj/reconstructor.py

@@ -276,14 +276,8 @@ class ObjectReconstructor(Daemon):
                                           rebuilt_fragment_iter)
 
     def _reconstruct(self, policy, fragment_payload, frag_index):
-        # XXX with jerasure this doesn't work if we need to rebuild a
-        # parity fragment, and not all data fragments are available
-        # segment = policy.pyeclib_driver.reconstruct(
-        #     fragment_payload, [frag_index])[0]
-
-        # for safety until pyeclib 1.0.7 we'll just use decode and encode
-        segment = policy.pyeclib_driver.decode(fragment_payload)
-        return policy.pyeclib_driver.encode(segment)[frag_index]
+        return policy.pyeclib_driver.reconstruct(fragment_payload,
+                                                 [frag_index])[0]
 
     def make_rebuilt_fragment_iter(self, responses, path, policy, frag_index):
         """

test/unit/obj/test_reconstructor.py

@@ -2347,6 +2347,45 @@ class TestObjectReconstructor(unittest.TestCase):
                 self.assertEqual(md5(fixed_body).hexdigest(),
                                  md5(broken_body).hexdigest())
 
+    def test_reconstruct_parity_fa_with_data_node_failure(self):
+        job = {
+            'partition': 0,
+            'policy': self.policy,
+        }
+        part_nodes = self.policy.object_ring.get_part_nodes(0)
+        node = part_nodes[-4]
+        metadata = {
+            'name': '/a/c/o',
+            'Content-Length': 0,
+            'ETag': 'etag',
+        }
+
+        # make up some data (trim some amount to make it unaligned with
+        # segment size)
+        test_data = ('rebuild' * self.policy.ec_segment_size)[:-454]
+        etag = md5(test_data).hexdigest()
+        ec_archive_bodies = make_ec_archive_bodies(self.policy, test_data)
+
+        # the scheme is 10+4, so this gets a parity node
+        broken_body = ec_archive_bodies.pop(-4)
+
+        base_responses = list((200, body) for body in ec_archive_bodies)
+        for error in (Timeout(), 404, Exception('kaboom!')):
+            responses = list(base_responses)
+            # grab a data node index
+            error_index = random.randint(0, self.policy.ec_ndata - 1)
+            responses[error_index] = (error, '')
+            headers = {'X-Object-Sysmeta-Ec-Etag': etag}
+            codes, body_iter = zip(*responses)
+            with mocked_http_conn(*codes, body_iter=body_iter,
+                                  headers=headers):
+                df = self.reconstructor.reconstruct_fa(
+                    job, node, dict(metadata))
+                fixed_body = ''.join(df.reader())
+                self.assertEqual(len(fixed_body), len(broken_body))
+                self.assertEqual(md5(fixed_body).hexdigest(),
+                                 md5(broken_body).hexdigest())
+
     def test_reconstruct_fa_errors_fails(self):
         job = {
             'partition': 0,