implement Attributes.refresh

Author: alimanfoo

docs/api/attrs.rst

@@ -13,3 +13,4 @@ The Attributes class (``zarr.attrs``)
     .. automethod:: asdict
     .. automethod:: put
     .. automethod:: update
+    .. automethod:: refresh

zarr/attrs.py

@@ -55,6 +55,11 @@ def asdict(self):
             self._cached_asdict = d
         return d
 
+    def refresh(self):
+        """Refresh cached attributes from the store."""
+        if self.cache:
+            self._cached_asdict = self._get_nosync()
+
     def __contains__(self, x):
         return x in self.asdict()
 

zarr/tests/test_attrs.py

@@ -168,6 +168,16 @@ def test_caching_on(self):
         eq(4, store.counter['__getitem__', 'attrs'])
         eq(4, store.counter['__setitem__', 'attrs'])
 
+        # test refresh()
+        store['attrs'] = json.dumps(dict(foo='xxx', bar=42)).encode('ascii')
+        eq(4, store.counter['__getitem__', 'attrs'])
+        a.refresh()
+        eq(5, store.counter['__getitem__', 'attrs'])
+        eq(a['foo'], 'xxx')
+        eq(5, store.counter['__getitem__', 'attrs'])
+        eq(a['bar'], 42)
+        eq(5, store.counter['__getitem__', 'attrs'])
+
     def test_caching_off(self):
 
         # setup store