Merge "Cache fragment size for EC policy"

swift/common/storage_policy.py

@@ -475,6 +475,7 @@ class ECStoragePolicy(BaseStoragePolicy):
         # quorum size in the EC case depends on the choice of EC scheme.
         self._ec_quorum_size = \
             self._ec_ndata + self.pyeclib_driver.min_parity_fragments_needed()
+        self._fragment_size = None
 
     @property
     def ec_type(self):
@@ -511,8 +512,11 @@ class ECStoragePolicy(BaseStoragePolicy):
         # segment_size we'll still only read *the whole one and only last
         # fragment* and pass than into pyeclib who will know what to do with
         # it just as it always does when the last fragment is < fragment_size.
-        return self.pyeclib_driver.get_segment_info(
-            self.ec_segment_size, self.ec_segment_size)['fragment_size']
+        if self._fragment_size is None:
+            self._fragment_size = self.pyeclib_driver.get_segment_info(
+                self.ec_segment_size, self.ec_segment_size)['fragment_size']
+
+        return self._fragment_size
 
     @property
     def ec_scheme_description(self):

test/unit/common/test_storage_policy.py

@@ -27,6 +27,7 @@ from swift.common.storage_policy import (
     VALID_EC_TYPES, DEFAULT_EC_OBJECT_SEGMENT_SIZE, BindPortsCache)
 from swift.common.ring import RingData
 from swift.common.exceptions import RingValidationError
+from pyeclib.ec_iface import ECDriver
 
 
 @BaseStoragePolicy.register('fake')
@@ -1244,6 +1245,29 @@ class TestStoragePolicies(unittest.TestCase):
             expected_info = expected[(int(policy), False)]
             self.assertEqual(policy.get_info(config=False), expected_info)
 
+    def test_ec_fragment_size_cached(self):
+        policy = ECStoragePolicy(
+            0, 'ec2-1', ec_type=DEFAULT_TEST_EC_TYPE,
+            ec_ndata=2, ec_nparity=1, object_ring=FakeRing(replicas=3),
+            ec_segment_size=DEFAULT_EC_OBJECT_SEGMENT_SIZE, is_default=True)
+
+        ec_driver = ECDriver(ec_type=DEFAULT_TEST_EC_TYPE,
+                             k=2, m=1)
+        expected_fragment_size = ec_driver.get_segment_info(
+            DEFAULT_EC_OBJECT_SEGMENT_SIZE,
+            DEFAULT_EC_OBJECT_SEGMENT_SIZE)['fragment_size']
+
+        with mock.patch.object(
+                policy.pyeclib_driver, 'get_segment_info') as fake:
+            fake.return_value = {
+                'fragment_size': expected_fragment_size}
+
+            for x in range(10):
+                self.assertEqual(expected_fragment_size,
+                                 policy.fragment_size)
+                # pyeclib_driver.get_segment_info is called only once
+                self.assertEqual(1, fake.call_count)
+
 
 if __name__ == '__main__':
     unittest.main()