Don't fail response if caching failed

Fixes bug 929762

Change-Id: I90761b69cc556b14fd4bdb931541804244b653e8

Authors

@@ -28,6 +28,7 @@ Kevin L. Mitchell <kevin.mitchell@rackspace.com>
 Lorin Hochstein <lorin@isi.edu>
 Major Hayden <major@mhtx.net>
 Mark McLoughlin <markmc@redhat.com>
+Mark Washenberger <mark.washenberger@rackspace.com>
 Matt Dietz <matt.dietz@rackspace.com>
 Mike Lundy <mike@pistoncloud.com>
 Monty Taylor <mordred@inaugust.com>

glance/image_cache/__init__.py

@@ -220,11 +220,22 @@ def get_caching_iter(self, image_id, image_iter):
         logger.debug(_("Tee'ing image '%s' into cache"), image_id)
 
         def tee_iter(image_id):
-            with self.driver.open_for_write(image_id) as cache_file:
-                for chunk in image_iter:
-                    cache_file.write(chunk)
-                    yield chunk
-                cache_file.flush()
+            try:
+                with self.driver.open_for_write(image_id) as cache_file:
+                    for chunk in image_iter:
+                        try:
+                            cache_file.write(chunk)
+                        finally:
+                            yield chunk
+                    cache_file.flush()
+            except Exception:
+                logger.exception(_("Exception encountered while tee'ing "
+                                   "image '%s' into cache. Continuing "
+                                   "with response.") % image_id)
+
+            # NOTE(markwash): continue responding even if caching failed
+            for chunk in image_iter:
+                yield chunk
 
         return tee_iter(image_id)
 

glance/tests/unit/test_image_cache.py

@@ -15,6 +15,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from contextlib import contextmanager
 import os
 import random
 import shutil
@@ -24,6 +25,7 @@
 import stubout
 
 from glance import image_cache
+from glance.common import cfg
 from glance.common import exception
 from glance.common import utils
 from glance.tests import utils as test_utils
@@ -308,3 +310,62 @@ def setUp(self):
     def tearDown(self):
         if os.path.exists(self.cache_dir):
             shutil.rmtree(self.cache_dir)
+
+
+class TestImageCacheNoDep(unittest.TestCase):
+
+    def setUp(self):
+        self.driver = None
+
+        def init_driver(self2):
+            self2.driver = self.driver
+
+        self.stubs = stubout.StubOutForTesting()
+        self.stubs.Set(image_cache.ImageCache, 'init_driver', init_driver)
+
+    def tearDown(self):
+        self.stubs.UnsetAll()
+
+    def test_get_caching_iter_when_write_fails(self):
+
+        class FailingFile(object):
+
+            def write(self, data):
+                if data == "Fail":
+                    raise IOError
+
+        class FailingFileDriver(object):
+
+            def is_cacheable(self, *args, **kwargs):
+                return True
+
+            @contextmanager
+            def open_for_write(self, *args, **kwargs):
+                yield FailingFile()
+
+        self.driver = FailingFileDriver()
+        conf = cfg.ConfigOpts()
+        cache = image_cache.ImageCache(conf)
+        data = ['a', 'b', 'c', 'Fail', 'd', 'e', 'f']
+
+        caching_iter = cache.get_caching_iter('dummy_id', iter(data))
+        self.assertEqual(list(caching_iter), data)
+
+    def test_get_caching_iter_when_open_fails(self):
+
+        class OpenFailingDriver(object):
+
+            def is_cacheable(self, *args, **kwargs):
+                return True
+
+            @contextmanager
+            def open_for_write(self, *args, **kwargs):
+                raise IOError
+
+        self.driver = OpenFailingDriver()
+        conf = cfg.ConfigOpts()
+        cache = image_cache.ImageCache(conf)
+        data = ['a', 'b', 'c', 'd', 'e', 'f']
+
+        caching_iter = cache.get_caching_iter('dummy_id', iter(data))
+        self.assertEqual(list(caching_iter), data)