Implement FTP backend and other code cleanups.

[cumulus.git] / python / cumulus / store / __init__.py

diff --git a/python/cumulus/store/__init__.py b/python/cumulus/store/__init__.py
index 5ebf0d7..f32ff9f 100644 (file)
--- a/python/cumulus/store/__init__.py
+++ b/python/cumulus/store/__init__.py
@@ -1,4 +1,4 @@
-import re
+import exceptions, re, urlparse
 
 type_patterns = {
     'checksums': re.compile(r"^snapshot-(.*)\.(\w+)sums$"),
@@ -6,17 +6,59 @@ type_patterns = {
     'snapshots': re.compile(r"^snapshot-(.*)\.lbs$")
 }
 
-class Store:
+class NotFoundError(exceptions.KeyError):
+    """Exception thrown when a file is not found in a repository."""
+
+    pass
+
+class Store (object):
     """Base class for all cumulus storage backends."""
 
+    def __new__ (cls, url, **kw):
+        """ Return the correct sub-class depending on url,
+        pass parsed url parameters to object
+        """
+        if cls != Store:
+            return super(Store, cls).__new__(cls, url, **kw)
+        (scheme, netloc, path, params, query, fragment) \
+            = urlparse.urlparse(url)
+
+        try:
+            cumulus = __import__('cumulus.store.%s' % scheme, globals())
+            subcls = getattr (cumulus.store, scheme).Store
+            obj = super(Store, cls).__new__(subcls, url, **kw)
+            obj.scheme = scheme
+            obj.netloc = netloc
+            obj.path = path
+            obj.params = params
+            obj.query = query
+            obj.fragment = fragment
+            return obj
+        except ImportError:
+            raise NotImplementedError, "Scheme %s not implemented" % scheme
+
     def list(self, type):
-        raise NotImplementedException
+        raise NotImplementedError
 
     def get(self, type, name):
-        raise NotImplementedException
+        raise NotImplementedError
 
     def put(self, type, name, fp):
-        raise NotImplementedException
+        raise NotImplementedError
 
     def delete(self, type, name):
-        raise NotImplementedException
+        raise NotImplementedError
+
+    def stat(self, type, name):
+        raise NotImplementedError
+
+    def scan(self):
+        """Cache file information stored in this backend.
+
+        This might make subsequent list or stat calls more efficient, but this
+        function is intended purely as a performance optimization."""
+
+        pass
+
+def open(url):
+    return Store(url)