Fix ZeroDivisionError in reconstructor.stats_line

Despite a check to prevent zero values in the denominator python
integer division could result in ZeroDivisionError in the compute_eta
helper function.  Make sure we always have a non-zero value even if it
is small.

NotImplemented:

 * stats calculation is still not great, see lp bug #1488608

Closes-Bug: #1549110
Change-Id: I54f2081c92c2a0b8f02c31e82f44f4250043d837

swift/obj/reconstructor.py

@@ -354,7 +354,7 @@ class ObjectReconstructor(Daemon):
                 self.reconstruction_device_count):
             elapsed = (time.time() - self.start) or 0.000001
             rate = self.reconstruction_part_count / elapsed
-            total_part_count = (self.part_count *
+            total_part_count = (1.0 * self.part_count *
                                 self.device_count /
                                 self.reconstruction_device_count)
             self.logger.info(

test/unit/__init__.py

@@ -200,6 +200,7 @@ class PatchPolicies(object):
     def __enter__(self):
         self._orig_POLICIES = storage_policy._POLICIES
         storage_policy._POLICIES = self.policies
+        self._setup_rings()
 
     def __exit__(self, *args):
         storage_policy._POLICIES = self._orig_POLICIES

test/unit/obj/test_reconstructor.py

@@ -1145,6 +1145,9 @@ class TestObjectReconstructor(unittest.TestCase):
         # directly, so you end up with a /0 when you try to show the
         # percentage of complete jobs as ratio of the total job count
         self.reconstructor.job_count = 1
+        # if we ever let a test through without properly patching the
+        # REPLICATE and SSYNC calls - let's fail sort fast-ish
+        self.reconstructor.lockup_timeout = 3
 
     def tearDown(self):
         self.reconstructor._reset_stats()
@@ -1154,6 +1157,29 @@ class TestObjectReconstructor(unittest.TestCase):
     def ts(self):
         return next(self.ts_iter)
 
+    def test_two_ec_policies(self):
+        with patch_policies([
+                StoragePolicy(0, name='zero', is_deprecated=True),
+                ECStoragePolicy(1, name='one', is_default=True,
+                                ec_type=DEFAULT_TEST_EC_TYPE,
+                                ec_ndata=4, ec_nparity=3),
+                ECStoragePolicy(2, name='two',
+                                ec_type=DEFAULT_TEST_EC_TYPE,
+                                ec_ndata=8, ec_nparity=2)],
+                            fake_ring_args=[
+                                {}, {'replicas': 7}, {'replicas': 10}]):
+            self._configure_reconstructor()
+            jobs = []
+
+            def process_job(job):
+                jobs.append(job)
+
+            self.reconstructor.process_job = process_job
+
+            os.makedirs(os.path.join(self.devices, 'sda', 'objects-1', '0'))
+            self.reconstructor.run_once()
+            self.assertEqual(1, len(jobs))
+
     def test_collect_parts_skips_non_ec_policy_and_device(self):
         stub_parts = (371, 78, 419, 834)
         for policy in POLICIES: