Adds code version to cache. (Fixes #129)

Current code version is added to the cache on writting. If the cache
version does not match the code version on read, the cache is ignored
which means it resets.

pubs/databroker.py

@@ -1,6 +1,7 @@
 from . import filebroker
 from . import endecoder
 from .p3 import pickle
+from . import __version__
 
 
 class DataBroker(object):
@@ -22,12 +23,16 @@ class DataBroker(object):
         pass
 
     def pull_cache(self, name):
-        """Load cache data from distk. Exceptions are handled by the caller."""
+        """Load cache data from disk. Exceptions are handled by the caller."""
         data_raw = self.filebroker.pull_cachefile(name)
-        return pickle.loads(data_raw)
+        cache = pickle.loads(data_raw)
+        if cache['version'] != __version__:
+            raise ValueError('Cache not matching code version.')
+        return cache['data']
 
     def push_cache(self, name, data):
-        data_raw = pickle.dumps(data)
+        cache_content = {'version': __version__, 'data': data}
+        data_raw = pickle.dumps(cache_content)
         self.filebroker.push_cachefile(name, data_raw)
 
     # filebroker+endecoder

pubs/datacache.py

@@ -91,8 +91,6 @@ class DataCache(object):
         2. Keeps an up-to-date, pickled version of the repository, to speed up things
            when they are a lot of files. Update are also done only when required.
            Changes are detected using data modification timestamps.
-
-        For the moment, only (1) is implemented.
     """
     def __init__(self, pubsdir, docsdir, create=False):
         self.pubsdir = pubsdir

pubs/version.py

@@ -1 +1 @@
-__version__ = '0.7.0'
+__version__ = '0.8.dev1'

tests/test_databroker.py

@@ -16,7 +16,6 @@ class TestDataBroker(fake_env.TestFakeFs):
 
     def test_databroker(self):
 
-
         ende = endecoder.EnDecoder()
         page99_metadata = ende.decode_metadata(str_fixtures.metadata_raw0)
         page99_bibentry = ende.decode_bibdata(str_fixtures.bibtex_raw0)
@@ -71,6 +70,25 @@ class TestDataBroker(fake_env.TestFakeFs):
 
             db.remove_doc('docsdir://Page99.pdf')
 
+    def test_push_pull_cache(self):
+        db = databroker.DataBroker('tmp', 'tmp/doc', create=True)
+        data_in = {'a': 1}
+        db.push_cache('meta', data_in)
+        data_out = db.pull_cache('meta')
+        self.assertEqual(data_in, data_out)
+
+    def test_pull_cache_fails_on_version_mismatch(self):
+        db = databroker.DataBroker('tmp', 'tmp/doc', create=True)
+        data_in = {'a': 1}
+        db.push_cache('meta', data_in)
+        ver = databroker.__version__
+        databroker.__version__ = '0.0.0'
+        try:
+            with self.assertRaises(ValueError):
+                db.pull_cache('meta')
+        finally:
+            databroker.__version__ = ver
+
 
 if __name__ == '__main__':
     unittest.main()

tests/test_datacache.py

@@ -126,7 +126,6 @@ class TestCacheEntrySet(unittest.TestCase):
         value = self.bibcache.pull('a')
         self.assertEqual(value, 'b')
 
-
     def test_is_outdated_when_unknown_citekey(self):
         self.assertTrue(self.metacache._is_outdated('a'))